aboutsummaryrefslogblamecommitdiffstats
path: root/lib/compiler/src/v3_codegen.erl
blob: 36d35a81226de8ad89b16efdfa8145542800edb5 (plain) (tree)
1
2
3
4
5
6
7
8
9
10
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008

                   
  
                                                        
  




                                                                      
  



                                                                         
  






































                                                                             
























                                                                                  
                                                                 
       

                                                              










                                                              
                                                       






























                                                                   


                                                                    
                                                                       















                                                                 




























































                                                                         

























                                                                     
                                                         
























































                                                                       
















































































































































































































































































































































































































































































































































































































































































































































                                                                                        
                                                     








                                                                


                                                                      
                                                      




























                                                                              
                                                     

























                                                                        
                                               







                                                                 
                               
                                          






                                                                 

                                       














                                                                 
















                                                         




































                                                                        





                                                             





























                                                                          
                                                            

                                               
                               







                                                                      







                                                                    



























                                                                       




                                                                   
















                                                                           
                                                                     














































































































































                                                                                


                                    
                                          

















                                                                        

                                                        


                                                                        

                                                                





















































                                                                                                   


                                             



















































































































































































































































































































































































































































































































                                                                                 



                            





















                                                                         





















                                                                
                                  








                                                    




                                              
%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 1999-2011. All Rights Reserved.
%%
%% The contents of this file are subject to the Erlang Public License,
%% Version 1.1, (the "License"); you may not use this file except in
%% compliance with the License. You should have received a copy of the
%% Erlang Public License along with this software. If not, it can be
%% retrieved online at http://www.erlang.org/.
%%
%% Software distributed under the License is distributed on an "AS IS"
%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
%% the License for the specific language governing rights and limitations
%% under the License.
%%
%% %CopyrightEnd%
%%
%% Purpose : Code generator for Beam.

%% The following assumptions have been made:
%%
%% 1. Matches, i.e. things with {match,M,Ret} wrappers, only return
%% values; no variables are exported. If the match would have returned
%% extra variables then these have been transformed to multiple return
%% values.
%% 
%% 2. All BIF's called in guards are gc-safe so there is no need to
%% put thing on the stack in the guard.  While this would in principle
%% work it would be difficult to keep track of the stack depth when
%% trimming.
%%
%% The code generation uses variable lifetime information added by
%% the v3_life module to save variables, allocate registers and 
%% move registers to the stack when necessary.
%%
%% We try to use a consistent variable name scheme throughout.  The
%% StackReg record is always called Bef,Int<n>,Aft.

-module(v3_codegen).

%% The main interface.
-export([module/2]).

-import(lists, [member/2,keymember/3,keysort/2,keydelete/3,
		append/1,map/2,flatmap/2,filter/2,foldl/3,foldr/3,mapfoldl/3,
		sort/1,reverse/1,reverse/2]).
-import(v3_life, [vdb_find/2]).

%%-compile([export_all]).

-include("v3_life.hrl").

%% Main codegen structure.
-record(cg, {lcount=1,				%Label counter
	     bfail,				%Fail label for BIFs
	     break,				%Break label
	     recv,				%Receive label
	     is_top_block,			%Boolean: top block or not
	     functable=gb_trees:empty(),	%Gb tree of local functions:
						% {{Name,Arity},Label}
	     in_catch=false,			%Inside a catch or not.
	     need_frame,			%Need a stack frame.
	     ultimate_failure			%Label for ultimate match failure.
	    }).			

%% Stack/register state record.
-record(sr, {reg=[],				%Register table
	     stk=[],				%Stack table
	     res=[]}).				%Reserved regs: [{reserved,I,V}]

module({Mod,Exp,Attr,Forms}, Options) ->
    put(?MODULE, Options),
    {Fs,St} = functions(Forms, {atom,Mod}),
    erase(?MODULE),
    {ok,{Mod,Exp,Attr,Fs,St#cg.lcount}}.

functions(Forms, AtomMod) ->
    mapfoldl(fun (F, St) -> function(F, AtomMod, St) end, #cg{lcount=1}, Forms).

function({function,Name,Arity,Asm0,Vb,Vdb,Anno}, AtomMod, St0) ->
    try
	{Asm,EntryLabel,St} = cg_fun(Vb, Asm0, Vdb, AtomMod,
				     {Name,Arity}, Anno, St0),
	Func = {function,Name,Arity,EntryLabel,Asm},
	{Func,St}
    catch
	Class:Error ->
	    Stack = erlang:get_stacktrace(),
	    io:fwrite("Function: ~w/~w\n", [Name,Arity]),
	    erlang:raise(Class, Error, Stack)
    end.

%% cg_fun([Lkexpr], [HeadVar], Vdb, State) -> {[Ainstr],State}

cg_fun(Les, Hvs, Vdb, AtomMod, NameArity, Anno, St0) ->
    {Fi,St1} = new_label(St0),			%FuncInfo label
    {Fl,St2} = local_func_label(NameArity, St1),

    %%
    %% The pattern matching compiler (in v3_kernel) no longer
    %% provides its own catch-all clause, because the 
    %% call to erlang:exit/1 caused problem when cases were
    %% used in guards. Therefore, there may be tests that
    %% cannot fail (providing that there is not a bug in a
    %% previous optimzation pass), but still need to provide
    %% a label (there are instructions, such as is_tuple/2,
    %% that do not allow {f,0}).
    %%
    %% We will generate an ultimate failure label and put it
    %% at the end of function, followed by an 'if_end' instruction.
    %% Note that and 'if_end' instruction does not need any
    %% live x registers, so it will always be safe to jump to
    %% it. (We never ever expect the jump to be taken, and in
    %% must functions there will never be any references to
    %% the label in the first place.)
    %%

    {UltimateMatchFail,St3} = new_label(St2),

    %% Create initial stack/register state, clear unused arguments.
    Bef = clear_dead(#sr{reg=foldl(fun ({var,V}, Reg) ->
					   put_reg(V, Reg)
				   end, [], Hvs),
			 stk=[]}, 0, Vdb),
    {B,_Aft,St} = cg_list(Les, 0, Vdb, Bef,
			  St3#cg{bfail=0,
				 ultimate_failure=UltimateMatchFail,
				 is_top_block=true}),
    {Name,Arity} = NameArity,
    Asm = [{label,Fi},line(Anno),{func_info,AtomMod,{atom,Name},Arity},
	   {label,Fl}|B++[{label,UltimateMatchFail},if_end]],
    {Asm,Fl,St}.

%% cg(Lkexpr, Vdb, StackReg, State) -> {[Ainstr],StackReg,State}.
%%  Generate code for a kexpr.
%%  Split function into two steps for clarity, not efficiency.

cg(Le, Vdb, Bef, St) ->
    cg(Le#l.ke, Le, Vdb, Bef, St).

cg({block,Es}, Le, Vdb, Bef, St) ->
    block_cg(Es, Le, Vdb, Bef, St);
cg({match,M,Rs}, Le, Vdb, Bef, St) ->
    match_cg(M, Rs, Le, Vdb, Bef, St);
cg({guard_match,M,Rs}, Le, Vdb, Bef, St) ->
    guard_match_cg(M, Rs, Le, Vdb, Bef, St);
cg({call,Func,As,Rs}, Le, Vdb, Bef, St) ->
    call_cg(Func, As, Rs, Le, Vdb, Bef, St);
cg({enter,Func,As}, Le, Vdb, Bef, St) ->
    enter_cg(Func, As, Le, Vdb, Bef, St);
cg({bif,Bif,As,Rs}, Le, Vdb, Bef, St) ->
    bif_cg(Bif, As, Rs, Le, Vdb, Bef, St);
cg({gc_bif,Bif,As,Rs}, Le, Vdb, Bef, St) ->
    gc_bif_cg(Bif, As, Rs, Le, Vdb, Bef, St);
cg({receive_loop,Te,Rvar,Rm,Tes,Rs}, Le, Vdb, Bef, St) ->
    recv_loop_cg(Te, Rvar, Rm, Tes, Rs, Le, Vdb, Bef, St);
cg(receive_next, Le, Vdb, Bef, St) ->
    recv_next_cg(Le, Vdb, Bef, St);
cg(receive_accept, _Le, _Vdb, Bef, St) -> {[remove_message],Bef,St};
cg({'try',Ta,Vs,Tb,Evs,Th,Rs}, Le, Vdb, Bef, St) ->
    try_cg(Ta, Vs, Tb, Evs, Th, Rs, Le, Vdb, Bef, St);
cg({try_enter,Ta,Vs,Tb,Evs,Th}, Le, Vdb, Bef, St) ->
    try_enter_cg(Ta, Vs, Tb, Evs, Th, Le, Vdb, Bef, St);
cg({'catch',Cb,R}, Le, Vdb, Bef, St) ->
    catch_cg(Cb, R, Le, Vdb, Bef, St);
cg({set,Var,Con}, Le, Vdb, Bef, St) ->
    set_cg(Var, Con, Le, Vdb, Bef, St);
cg({return,Rs}, Le, Vdb, Bef, St) -> return_cg(Rs, Le, Vdb, Bef, St);
cg({break,Bs}, Le, Vdb, Bef, St) -> break_cg(Bs, Le, Vdb, Bef, St);
cg({guard_break,Bs,N}, Le, Vdb, Bef, St) ->
    guard_break_cg(Bs, N, Le, Vdb, Bef, St);
cg({need_heap,H}, _Le, _Vdb, Bef, St) ->
    {[{test_heap,H,max_reg(Bef#sr.reg)}],Bef,St}.

%% cg_list([Kexpr], FirstI, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.

cg_list(Kes, I, Vdb, Bef, St0) ->
    {Keis,{Aft,St1}} =
	flatmapfoldl(fun (Ke, {Inta,Sta}) ->
			     {Keis,Intb,Stb} = cg(Ke, Vdb, Inta, Sta),
			     {Keis,{Intb,Stb}}
		     end, {Bef,St0}, need_heap(Kes, I)),
    {Keis,Aft,St1}.

%% need_heap([Lkexpr], I, St) -> [Lkexpr].
%%  Insert need_heap instructions in Kexpr list.  Try to be smart and
%%  collect them together as much as possible.

need_heap(Kes0, I) ->
    {Kes,H} = need_heap_0(reverse(Kes0), 0, []),

    %% Prepend need_heap if necessary.
    need_heap_need(I, H) ++ Kes.

need_heap_0([Ke|Kes], H0, Acc) ->
    {Ns,H} = need_heap_1(Ke, H0),
    need_heap_0(Kes, H, [Ke|Ns]++Acc);
need_heap_0([], H, Acc) ->
    {Acc,H}.

need_heap_1(#l{ke={set,_,{binary,_}},i=I}, H) ->
    {need_heap_need(I, H),0};
need_heap_1(#l{ke={set,_,Val}}, H) ->
    %% Just pass through adding to needed heap.
    {[],H + case Val of
		{cons,_} -> 2;
		{tuple,Es} -> 1 + length(Es);
		_Other -> 0
	    end};
need_heap_1(#l{ke={bif,dsetelement,_As,_Rs},i=I}, H) ->
    {need_heap_need(I, H),0};
need_heap_1(#l{ke={bif,{make_fun,_,_,_,_},_As,_Rs},i=I}, H) ->
    {need_heap_need(I, H),0};
need_heap_1(#l{ke={bif,bs_init_writable,_As,_Rs},i=I}, H) ->
    {need_heap_need(I, H),0};
need_heap_1(#l{ke={bif,_Bif,_As,_Rs}}, H) ->
    {[],H};
need_heap_1(#l{i=I}, H) ->
    {need_heap_need(I, H),0}.

need_heap_need(_I, 0) -> [];
need_heap_need(I, H) -> [#l{ke={need_heap,H},i=I}].

%% match_cg(Match, [Ret], Le, Vdb, StackReg, State) ->
%%	{[Ainstr],StackReg,State}.
%%  Generate code for a match.  First save all variables on the stack
%%  that are to survive after the match.  We leave saved variables in
%%  their registers as they might actually be in the right place.

match_cg(M, Rs, Le, Vdb, Bef, St0) ->
    I = Le#l.i,
    {Sis,Int0} = adjust_stack(Bef, I, I+1, Vdb),
    {B,St1} = new_label(St0),
    {Mis,Int1,St2} = match_cg(M, St1#cg.ultimate_failure,
			      Int0, St1#cg{break=B}),
    %% Put return values in registers.
    Reg = load_vars(Rs, Int1#sr.reg),
    {Sis ++ Mis ++ [{label,B}],
     clear_dead(Int1#sr{reg=Reg}, I, Vdb),
     St2#cg{break=St1#cg.break}}.

guard_match_cg(M, Rs, Le, Vdb, Bef, St0) ->
    I = Le#l.i,
    {B,St1} = new_label(St0),
    #cg{bfail=Fail} = St1,
    {Mis,Aft,St2} = match_cg(M, Fail, Bef, St1#cg{break=B}),
    %% Update the register descriptors for the return registers.
    Reg = guard_match_regs(Aft#sr.reg, Rs),
    {Mis ++ [{label,B}],
     clear_dead(Aft#sr{reg=Reg}, I, Vdb),
     St2#cg{break=St1#cg.break}}.

guard_match_regs([{I,gbreakvar}|Rs], [{var,V}|Vs]) ->
    [{I,V}|guard_match_regs(Rs, Vs)];
guard_match_regs([R|Rs], Vs) ->
    [R|guard_match_regs(Rs, Vs)];
guard_match_regs([], []) -> [].
    

%% match_cg(Match, Fail, StackReg, State) -> {[Ainstr],StackReg,State}.
%%  Generate code for a match tree.  N.B. there is no need pass Vdb
%%  down as each level which uses this takes its own internal Vdb not
%%  the outer one.

match_cg(Le, Fail, Bef, St) ->
    match_cg(Le#l.ke, Le, Fail, Bef, St).

match_cg({alt,F,S}, _Le, Fail, Bef, St0) ->
    {Tf,St1} = new_label(St0),
    {Fis,Faft,St2} = match_cg(F, Tf, Bef, St1),
    {Sis,Saft,St3} = match_cg(S, Fail, Bef, St2),
    Aft = sr_merge(Faft, Saft),
    {Fis ++ [{label,Tf}] ++ Sis,Aft,St3};
match_cg({select,{var,Vname}=V,Scs0}, #l{a=Anno}, Fail, Bef, St) ->
    ReuseForContext = member(reuse_for_context, Anno) andalso
	find_reg(Vname, Bef#sr.reg) =/= error,
    Scs = case ReuseForContext of
	      false -> Scs0;
	      true -> bsm_rename_ctx(Scs0, Vname)
	  end,
    match_fmf(fun (S, F, Sta) ->
		      select_cg(S, V, F, Fail, Bef, Sta) end,
	      Fail, St, Scs);
match_cg({guard,Gcs}, _Le, Fail, Bef, St) ->
    match_fmf(fun (G, F, Sta) -> guard_clause_cg(G, F, Bef, Sta) end,
	      Fail, St, Gcs);
match_cg({block,Es}, Le, _Fail, Bef, St) ->
    %% Must clear registers and stack of dead variables.
    Int = clear_dead(Bef, Le#l.i, Le#l.vdb),
    block_cg(Es, Le, Int, St).

%% bsm_rename_ctx([Clause], Var) -> [Clause]
%%  We know from an annotation that the register for a binary can
%%  be reused for the match context because the two are not truly
%%  alive at the same time (even though the conservative life time
%%  information calculated by v3_life says so).
%%
%%  The easiest way to have those variables share the same register is
%%  to rename the variable with the shortest life-span (the match
%%  context) to the variable for the binary (which can have a very
%%  long life-time because it is locked during matching). We KNOW that
%%  the match state variable will only be alive during the matching.
%%
%%  We must also remove all information about the match context
%%  variable from all life-time information databases (Vdb).

bsm_rename_ctx([#l{ke={type_clause,binary,
		       [#l{ke={val_clause,{binary,{var,Old}},Ke0}}=L2]}}=L1|Cs], New) ->
    Ke = bsm_rename_ctx(Ke0, Old, New, false),
    [L1#l{ke={type_clause,binary,
	      [L2#l{ke={val_clause,{binary,{var,New}},Ke}}]}}|bsm_rename_ctx(Cs, New)];
bsm_rename_ctx([C|Cs], New) -> 
    [C|bsm_rename_ctx(Cs, New)];
bsm_rename_ctx([], _) -> [].

%% bsm_rename_ctx(Ke, OldName, NewName, InProt) -> Ke'
%%  Rename and clear OldName from life-time information. We must
%%  recurse into any block contained in a protected, but it would
%%  only complicatate things to recurse into blocks not in a protected
%%  (the match context variable is not live inside them).

bsm_rename_ctx(#l{ke={select,{var,V},Cs0}}=L, Old, New, InProt) ->
    Cs = bsm_rename_ctx_list(Cs0, Old, New, InProt),
    L#l{ke={select,{var,bsm_rename_var(V, Old, New)},Cs}};
bsm_rename_ctx(#l{ke={type_clause,Type,Cs0}}=L, Old, New, InProt) ->
    Cs = bsm_rename_ctx_list(Cs0, Old, New, InProt),
    L#l{ke={type_clause,Type,Cs}};
bsm_rename_ctx(#l{ke={val_clause,{bin_end,V},Ke0}}=L, Old, New, InProt) ->
    Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
    L#l{ke={val_clause,{bin_end,bsm_rename_var(V, Old, New)},Ke}};
bsm_rename_ctx(#l{ke={val_clause,{bin_seg,V,Sz,U,Type,Fl,Vs},Ke0}}=L,
	       Old, New, InProt) ->
    Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
    L#l{ke={val_clause,{bin_seg,bsm_rename_var(V, Old, New),Sz,U,Type,Fl,Vs},Ke}};
bsm_rename_ctx(#l{ke={val_clause,{bin_int,V,Sz,U,Fl,Val,Vs},Ke0}}=L,
	       Old, New, InProt) ->
    Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
    L#l{ke={val_clause,{bin_int,bsm_rename_var(V, Old, New),Sz,U,Fl,Val,Vs},Ke}};
bsm_rename_ctx(#l{ke={val_clause,Val,Ke0}}=L, Old, New, InProt) ->
    Ke = bsm_rename_ctx(Ke0, Old, New, InProt),
    L#l{ke={val_clause,Val,Ke}};
bsm_rename_ctx(#l{ke={alt,F0,S0}}=L, Old, New, InProt) ->
    F = bsm_rename_ctx(F0, Old, New, InProt),
    S = bsm_rename_ctx(S0, Old, New, InProt),
    L#l{ke={alt,F,S}};
bsm_rename_ctx(#l{ke={guard,Gcs0}}=L, Old, New, InProt) ->
    Gcs = bsm_rename_ctx_list(Gcs0, Old, New, InProt),
    L#l{ke={guard,Gcs}};
bsm_rename_ctx(#l{ke={guard_clause,G0,B0}}=L, Old, New, InProt) ->
    G = bsm_rename_ctx(G0, Old, New, InProt),
    B = bsm_rename_ctx(B0, Old, New, InProt),
    %% A guard clause may cause unsaved variables to be saved on the stack.
    %% Since the match state variable Old is an alias for New (uses the
    %% same register), it is neither in the stack nor register descriptor
    %% lists and we would crash when we didn't find it unless we remove
    %% it from the database.
    bsm_forget_var(L#l{ke={guard_clause,G,B}}, Old);
bsm_rename_ctx(#l{ke={protected,Ts0,Rs}}=L, Old, New, _InProt) ->
    InProt = true,
    Ts = bsm_rename_ctx_list(Ts0, Old, New, InProt),
    bsm_forget_var(L#l{ke={protected,Ts,Rs}}, Old);
bsm_rename_ctx(#l{ke={match,Ms0,Rs}}=L, Old, New, InProt) ->
    Ms = bsm_rename_ctx(Ms0, Old, New, InProt),
    L#l{ke={match,Ms,Rs}};
bsm_rename_ctx(#l{ke={guard_match,Ms0,Rs}}=L, Old, New, InProt) ->
    Ms = bsm_rename_ctx(Ms0, Old, New, InProt),
    L#l{ke={guard_match,Ms,Rs}};
bsm_rename_ctx(#l{ke={test,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={bif,_,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={gc_bif,_,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={set,_,_}}=L, _, _, _) -> L;
bsm_rename_ctx(#l{ke={block,_}}=L, Old, _, false) ->
    %% This block is not inside a protected. The match context variable cannot
    %% possibly be live inside the block.
    bsm_forget_var(L, Old);
bsm_rename_ctx(#l{ke={block,Bl0}}=L, Old, New, true) ->
    %% A block in a protected. We must recursively rename the variable
    %% inside the block.
    Bl = bsm_rename_ctx_list(Bl0, Old, New, true),
    bsm_forget_var(L#l{ke={block,Bl}}, Old);
bsm_rename_ctx(#l{ke={guard_break,Bs,Locked0}}=L0, Old, _New, _InProt) ->
    Locked = Locked0 -- [Old],
    L = L0#l{ke={guard_break,Bs,Locked}},
    bsm_forget_var(L, Old).

bsm_rename_ctx_list([C|Cs], Old, New, InProt) ->
    [bsm_rename_ctx(C, Old, New, InProt)|
     bsm_rename_ctx_list(Cs, Old, New, InProt)];
bsm_rename_ctx_list([], _, _, _) -> [].
    
bsm_rename_var(Old, Old, New) -> New;
bsm_rename_var(V, _, _) -> V.

%% bsm_forget_var(#l{}, Variable) -> #l{}
%%  Remove a variable from the variable life-time database.

bsm_forget_var(#l{vdb=Vdb}=L, V) ->
    L#l{vdb=keydelete(V, 1, Vdb)}.

%% block_cg([Kexpr], Le, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.
%% block_cg([Kexpr], Le, StackReg, St) -> {[Ainstr],StackReg,St}.

block_cg(Es, Le, _Vdb, Bef, St) ->
    block_cg(Es, Le, Bef, St).

block_cg(Es, Le, Bef, #cg{is_top_block=false}=St) ->
    cg_block(Es, Le#l.i, Le#l.vdb, Bef, St);
block_cg(Es, Le, Bef, St0) ->
    {Is0,Aft,St} = cg_block(Es, Le#l.i, Le#l.vdb, Bef,
			    St0#cg{is_top_block=false,need_frame=false}),
    Is = top_level_block(Is0, Aft, max_reg(Bef#sr.reg), St),
    {Is,Aft,St#cg{is_top_block=true}}.

cg_block([], _I, _Vdb, Bef, St0) ->
    {[],Bef,St0};
cg_block(Kes0, I, Vdb, Bef, St0) ->
    {Kes2,Int1,St1} =
	case basic_block(Kes0) of
	    {Kes1,LastI,Args,Rest} ->
		Ke = hd(Kes1),
		Fb = Ke#l.i,
		cg_basic_block(Kes1, Fb, LastI, Args, Vdb, Bef, St0);
	    {Kes1,Rest} ->
		cg_list(Kes1, I, Vdb, Bef, St0)
	end,
    {Kes3,Int2,St2} = cg_block(Rest, I, Vdb, Int1, St1),
    {Kes2 ++ Kes3,Int2,St2}.

basic_block(Kes) -> basic_block(Kes, []).

basic_block([Le|Les], Acc) ->
    case collect_block(Le#l.ke) of
	include -> basic_block(Les, [Le|Acc]);
	{block_end,As} ->
	    case Acc of
		[] ->
		    %% If the basic block does not contain any set instructions,
		    %% it serves no useful purpose to do basic block optimizations.
		    {[Le],Les};
		_ ->
		    {reverse(Acc, [Le]),Le#l.i,As,Les}
	    end;
	no_block -> {reverse(Acc, [Le]),Les}
    end.
	
collect_block({set,_,{binary,_}})    -> no_block;
collect_block({set,_,_})             -> include;
collect_block({call,{var,_}=Var,As,_Rs}) -> {block_end,As++[Var]};
collect_block({call,Func,As,_Rs})   -> {block_end,As++func_vars(Func)};
collect_block({enter,{var,_}=Var,As})-> {block_end,As++[Var]};
collect_block({enter,Func,As})       -> {block_end,As++func_vars(Func)};
collect_block({return,Rs})           -> {block_end,Rs};
collect_block({break,Bs})            -> {block_end,Bs};
collect_block(_)                     -> no_block.

func_vars({remote,M,F}) when element(1, M) =:= var;
			     element(1, F) =:= var ->
    [M,F];
func_vars(_) -> [].

%% cg_basic_block([Kexpr], FirstI, LastI, As, Vdb, StackReg, State) ->
%%      {[Ainstr],StackReg,State}.

cg_basic_block(Kes, Fb, Lf, As, Vdb, Bef, St0) ->
    Res = make_reservation(As, 0),
    Regs0 = reserve(Res, Bef#sr.reg, Bef#sr.stk),
    Stk = extend_stack(Bef, Lf, Lf+1, Vdb),
    Int0 = Bef#sr{reg=Regs0,stk=Stk,res=Res},
    X0_v0 = x0_vars(As, Fb, Lf, Vdb),
    {Keis,{Aft,_,St1}} =
	flatmapfoldl(fun(Ke, St) -> cg_basic_block(Ke, St, Lf, Vdb) end,
		     {Int0,X0_v0,St0}, need_heap(Kes, Fb)),
    {Keis,Aft,St1}.

cg_basic_block(#l{ke={need_heap,_}}=Ke, {Inta,X0v,Sta}, _Lf, Vdb) ->
    {Keis,Intb,Stb} = cg(Ke, Vdb, Inta, Sta),
    {Keis, {Intb,X0v,Stb}};
cg_basic_block(Ke, {Inta,X0_v1,Sta}, Lf, Vdb) ->
    {Sis,Intb} = save_carefully(Inta, Ke#l.i, Lf+1, Vdb),
    {X0_v2,Intc} = allocate_x0(X0_v1, Ke#l.i, Intb),
    Intd = reserve(Intc),
    {Keis,Inte,Stb} = cg(Ke, Vdb, Intd, Sta),
    {Sis ++ Keis, {Inte,X0_v2,Stb}}.

make_reservation([], _) -> [];
make_reservation([{var,V}|As], I) -> [{I,V}|make_reservation(As, I+1)];
make_reservation([A|As], I) -> [{I,A}|make_reservation(As, I+1)].

reserve(Sr) -> Sr#sr{reg=reserve(Sr#sr.res, Sr#sr.reg, Sr#sr.stk)}.

reserve([{I,V}|Rs], [free|Regs], Stk) -> [{reserved,I,V}|reserve(Rs, Regs, Stk)];
reserve([{I,V}|Rs], [{I,V}|Regs], Stk) -> [{I,V}|reserve(Rs, Regs, Stk)];
reserve([{I,V}|Rs], [{I,Var}|Regs], Stk) ->
    case on_stack(Var, Stk) of
	true -> [{reserved,I,V}|reserve(Rs, Regs, Stk)];
	false -> [{I,Var}|reserve(Rs, Regs, Stk)]
    end;
reserve([{I,V}|Rs], [{reserved,I,_}|Regs], Stk) ->
    [{reserved,I,V}|reserve(Rs, Regs, Stk)];
%reserve([{I,V}|Rs], [Other|Regs], Stk) -> [Other|reserve(Rs, Regs, Stk)];
reserve([{I,V}|Rs], [], Stk) -> [{reserved,I,V}|reserve(Rs, [], Stk)];
reserve([], Regs, _) -> Regs.

extend_stack(Bef, Fb, Lf, Vdb) ->
    Stk0 = clear_dead_stk(Bef#sr.stk, Fb, Vdb),
    Saves = [V || {V,F,L} <- Vdb,
		  F < Fb,
		  L >= Lf,
		  not on_stack(V, Stk0)],
    Stk1 = foldl(fun (V, Stk) -> put_stack(V, Stk) end, Stk0, Saves),
    Bef#sr.stk ++ lists:duplicate(length(Stk1) - length(Bef#sr.stk), free).

save_carefully(Bef, Fb, Lf, Vdb) ->
    Stk = Bef#sr.stk,
    %% New variables that are in use but not on stack.
    New = [VFL || {V,F,L} = VFL <- Vdb,
		  F < Fb,
		  L >= Lf,
		  not on_stack(V, Stk)],
    Saves = [V || {V,_,_} <- keysort(2, New)],
    save_carefully(Saves, Bef, []).

save_carefully([], Bef, Acc) -> {reverse(Acc),Bef};
save_carefully([V|Vs], Bef, Acc) ->
    case put_stack_carefully(V, Bef#sr.stk) of
	error -> {reverse(Acc),Bef};
	Stk1 ->
	    SrcReg = fetch_reg(V, Bef#sr.reg),
	    Move = {move,SrcReg,fetch_stack(V, Stk1)},
	    {x,_} = SrcReg,			%Assertion - must be X register.
	    save_carefully(Vs, Bef#sr{stk=Stk1}, [Move|Acc])
    end.

x0_vars([], _Fb, _Lf, _Vdb) -> [];
x0_vars([{var,V}|_], Fb, _Lf, Vdb) ->
    {V,F,_L} = VFL = vdb_find(V, Vdb),
    x0_vars1([VFL], Fb, F, Vdb);
x0_vars([X0|_], Fb, Lf, Vdb) ->
    x0_vars1([{X0,Lf,Lf}], Fb, Lf, Vdb).

x0_vars1(X0, Fb, Xf, Vdb) ->
    Vs0 = [VFL || {_V,F,L}=VFL <- Vdb,
		  F >= Fb,
		  L < Xf],
    Vs1 = keysort(3, Vs0),
    keysort(2, X0++Vs1).

allocate_x0([], _, Bef) -> {[],Bef#sr{res=[]}};
allocate_x0([{_,_,L}|Vs], I, Bef) when L =< I ->
    allocate_x0(Vs, I, Bef);
allocate_x0([{V,_F,_L}=VFL|Vs], _, Bef) ->
    {[VFL|Vs],Bef#sr{res=reserve_x0(V, Bef#sr.res)}}.

reserve_x0(V, [_|Res]) -> [{0,V}|Res];
reserve_x0(V, []) -> [{0,V}].

top_level_block(Keis, #sr{stk=[]}, _MaxRegs, #cg{need_frame=false}) ->
    Keis;
top_level_block(Keis, Bef, MaxRegs, _St) ->
    %% This top block needs an allocate instruction before it, and a
    %% deallocate instruction before each return.
    FrameSz = length(Bef#sr.stk),
    MaxY = FrameSz-1,
    Keis1 = flatmap(fun ({call_only,Arity,Func}) ->
			    [{call_last,Arity,Func,FrameSz}];
			({call_ext_only,Arity,Func}) ->
			    [{call_ext_last,Arity,Func,FrameSz}];
			({apply_only,Arity}) ->
			    [{apply_last,Arity,FrameSz}];
			(return) ->
			    [{deallocate,FrameSz},return];
			(Tuple) when is_tuple(Tuple) ->
			    [turn_yregs(tuple_size(Tuple), Tuple, MaxY)];
			(Other) ->
			    [Other]
		    end, Keis),
    [{allocate_zero,FrameSz,MaxRegs}|Keis1].

%% turn_yregs(Size, Tuple, MaxY) -> Tuple'
%%   Renumber y register so that {y,0} becomes {y,FrameSize-1},
%%   {y,FrameSize-1} becomes {y,0} and so on.  This is to make nested
%%   catches work.  The code generation algorithm gives a lower register
%%   number to the outer catch, which is wrong.

turn_yregs(0, Tp, _) -> Tp;
turn_yregs(El, Tp, MaxY) when element(1, element(El, Tp)) =:= yy ->
    turn_yregs(El-1, setelement(El, Tp, {y,MaxY-element(2, element(El, Tp))}), MaxY);
turn_yregs(El, Tp, MaxY) when is_list(element(El, Tp)) ->
    New = map(fun ({yy,YY}) -> {y,MaxY-YY};
		  (Other) -> Other end, element(El, Tp)),
    turn_yregs(El-1, setelement(El, Tp, New), MaxY);
turn_yregs(El, Tp, MaxY) ->
    turn_yregs(El-1, Tp, MaxY).

%% select_cg(Sclause, V, TypeFail, ValueFail, StackReg, State) ->
%%      {Is,StackReg,State}.
%%  Selecting type and value needs two failure labels, TypeFail is the
%%  label to jump to of the next type test when this type fails, and
%%  ValueFail is the label when this type is correct but the value is
%%  wrong.  These are different as in the second case there is no need
%%  to try the next type, it will always fail.

select_cg(#l{ke={type_clause,cons,[S]}}, {var,V}, Tf, Vf, Bef, St) ->
    select_cons(S, V, Tf, Vf, Bef, St);
select_cg(#l{ke={type_clause,nil,[S]}}, {var,V}, Tf, Vf, Bef, St) ->
    select_nil(S, V, Tf, Vf, Bef, St);
select_cg(#l{ke={type_clause,binary,[S]}}, {var,V}, Tf, Vf, Bef, St) ->
    select_binary(S, V, Tf, Vf, Bef, St);
select_cg(#l{ke={type_clause,bin_seg,S}}, {var,V}, Tf, _Vf, Bef, St) ->
    select_bin_segs(S, V, Tf, Bef, St);
select_cg(#l{ke={type_clause,bin_int,S}}, {var,V}, Tf, _Vf, Bef, St) ->
    select_bin_segs(S, V, Tf, Bef, St);
select_cg(#l{ke={type_clause,bin_end,[S]}}, {var,V}, Tf, _Vf, Bef, St) ->
    select_bin_end(S, V, Tf, Bef, St);
select_cg(#l{ke={type_clause,Type,Scs}}, {var,V}, Tf, Vf, Bef, St0) ->
    {Vis,{Aft,St1}} =
	mapfoldl(fun (S, {Int,Sta}) ->
			 {Val,Is,Inta,Stb} = select_val(S, V, Vf, Bef, Sta),
			 {{Is,[Val]},{sr_merge(Int, Inta),Stb}}
		 end, {void,St0}, Scs),
    OptVls = combine(lists:sort(combine(Vis))),
    {Vls,Sis,St2} = select_labels(OptVls, St1, [], []),
    {select_val_cg(Type, fetch_var(V, Bef), Vls, Tf, Vf, Sis), Aft, St2}.

select_val_cg(tuple, R, [Arity,{f,Lbl}], Tf, Vf, [{label,Lbl}|Sis]) ->
    [{test,is_tuple,{f,Tf},[R]},{test,test_arity,{f,Vf},[R,Arity]}|Sis];
select_val_cg(tuple, R, Vls, Tf, Vf, Sis) ->
    [{test,is_tuple,{f,Tf},[R]},{select_tuple_arity,R,{f,Vf},{list,Vls}}|Sis];
select_val_cg(Type, R, [Val, {f,Lbl}], Fail, Fail, [{label,Lbl}|Sis]) ->
    [{test,is_eq_exact,{f,Fail},[R,{Type,Val}]}|Sis];
select_val_cg(Type, R, [Val, {f,Lbl}], Tf, Vf, [{label,Lbl}|Sis]) ->
    [{test,select_type_test(Type),{f,Tf},[R]},
     {test,is_eq_exact,{f,Vf},[R,{Type,Val}]}|Sis];
select_val_cg(Type, R, Vls0, Tf, Vf, Sis) ->
    Vls1 = map(fun ({f,_Lbl} = F) -> F;
		   (Value) -> {Type,Value}
	       end, Vls0),
    [{test,select_type_test(Type),{f,Tf},[R]}, {select_val,R,{f,Vf},{list,Vls1}}|Sis].
    
select_type_test(integer) -> is_integer;
select_type_test(atom) -> is_atom;
select_type_test(float) -> is_float.

combine([{Is,Vs1}, {Is,Vs2}|Vis]) -> combine([{Is,Vs1 ++ Vs2}|Vis]);
combine([V|Vis]) -> [V|combine(Vis)];
combine([]) -> [].

select_labels([{Is,Vs}|Vis], St0, Vls, Sis) ->
    {Lbl,St1} = new_label(St0),
    select_labels(Vis, St1, add_vls(Vs, Lbl, Vls), [[{label,Lbl}|Is]|Sis]);
select_labels([], St, Vls, Sis) ->
    {Vls,append(Sis),St}.

add_vls([V|Vs], Lbl, Acc) ->
    add_vls(Vs, Lbl, [V, {f,Lbl}|Acc]);
add_vls([], _, Acc) -> Acc.

select_cons(#l{ke={val_clause,{cons,Es},B},i=I,vdb=Vdb}, V, Tf, Vf, Bef, St0) ->
    {Eis,Int,St1} = select_extract_cons(V, Es, I, Vdb, Bef, St0),
    {Bis,Aft,St2} = match_cg(B, Vf, Int, St1),
    {[{test,is_nonempty_list,{f,Tf},[fetch_var(V, Bef)]}] ++ Eis ++ Bis,Aft,St2}.

select_nil(#l{ke={val_clause,nil,B}}, V, Tf, Vf, Bef, St0) ->
    {Bis,Aft,St1} = match_cg(B, Vf, Bef, St0),
    {[{test,is_nil,{f,Tf},[fetch_var(V, Bef)]}] ++ Bis,Aft,St1}.

select_binary(#l{ke={val_clause,{binary,{var,V}},B},i=I,vdb=Vdb},
	      V, Tf, Vf, Bef, St0) ->
    Int0 = clear_dead(Bef#sr{reg=Bef#sr.reg}, I, Vdb),
    {Bis,Aft,St1} = match_cg(B, Vf, Int0, St0),
    CtxReg = fetch_var(V, Int0),
    Live = max_reg(Bef#sr.reg),
    {[{test,bs_start_match2,{f,Tf},Live,[CtxReg,V],CtxReg},
      {bs_save2,CtxReg,{V,V}}|Bis],
     Aft,St1};
select_binary(#l{ke={val_clause,{binary,{var,Ivar}},B},i=I,vdb=Vdb},
	      V, Tf, Vf, Bef, St0) ->
    Regs = put_reg(Ivar, Bef#sr.reg),
    Int0 = clear_dead(Bef#sr{reg=Regs}, I, Vdb),
    {Bis,Aft,St1} = match_cg(B, Vf, Int0, St0),
    CtxReg = fetch_var(Ivar, Int0),
    Live = max_reg(Bef#sr.reg),
    {[{test,bs_start_match2,{f,Tf},Live,[fetch_var(V, Bef),Ivar],CtxReg},
      {bs_save2,CtxReg,{Ivar,Ivar}}|Bis],
     Aft,St1}.

%% New instructions for selection of binary segments.

select_bin_segs(Scs, Ivar, Tf, Bef, St) ->
    match_fmf(fun(S, Fail, Sta) ->
		      select_bin_seg(S, Ivar, Fail, Bef, Sta) end,
	      Tf, St, Scs).

select_bin_seg(#l{ke={val_clause,{bin_seg,Ctx,Size,U,T,Fs0,Es},B},i=I,vdb=Vdb,a=A},
	       Ivar, Fail, Bef, St0) ->
    Fs = [{anno,A}|Fs0],
    {Mis,Int,St1} = select_extract_bin(Es, Size, U, T, Fs, Fail,
				       I, Vdb, Bef, Ctx, B, St0),
    {Bis,Aft,St2} = match_cg(B, Fail, Int, St1),
    CtxReg = fetch_var(Ctx, Bef),
    Is = if
	     Mis =:= [] ->
		 %% No bs_restore2 instruction needed if no match instructions.
		 Bis;
	     true ->
		 [{bs_restore2,CtxReg,{Ctx,Ivar}}|Mis++Bis]
	 end,
    {Is,Aft,St2};
select_bin_seg(#l{ke={val_clause,{bin_int,Ctx,Sz,U,Fs,Val,Es},B},i=I,vdb=Vdb},
	       Ivar, Fail, Bef, St0) ->
    {Mis,Int,St1} = select_extract_int(Es, Val, Sz, U, Fs, Fail,
				       I, Vdb, Bef, Ctx, St0),
    {Bis,Aft,St2} = match_cg(B, Fail, Int, St1),
    CtxReg = fetch_var(Ctx, Bef),
    {[{bs_restore2,CtxReg,{Ctx,Ivar}}|Mis] ++ Bis,Aft,St2}.

select_extract_int([{var,Tl}], Val, {integer,Sz}, U, Fs, Vf,
		   I, Vdb, Bef, Ctx, St) ->
    Bits = U*Sz,
    Bin = case member(big, Fs) of
	      true ->
		  <<Val:Bits>>;
	      false ->
		  true = member(little, Fs),	%Assertion.
		  <<Val:Bits/little>>
	  end,
    Bits = bit_size(Bin),			%Assertion.
    CtxReg = fetch_var(Ctx, Bef),
    Is = if
	     Bits =:= 0 ->
		 [{bs_save2,CtxReg,{Ctx,Tl}}];
	     true ->
		 [{test,bs_match_string,{f,Vf},[CtxReg,Bin]},
		  {bs_save2,CtxReg,{Ctx,Tl}}]
	 end,
    {Is,clear_dead(Bef, I, Vdb),St}.

select_extract_bin([{var,Hd},{var,Tl}], Size0, Unit, Type, Flags, Vf,
		   I, Vdb, Bef, Ctx, _Body, St) ->
    SizeReg = get_bin_size_reg(Size0, Bef),
    {Es,Aft} =
	case vdb_find(Hd, Vdb) of
	    {_,_,Lhd} when Lhd =< I ->
		%% The extracted value will not be used.
		CtxReg = fetch_var(Ctx, Bef),
		Live = max_reg(Bef#sr.reg),
		Skip = build_skip_instr(Type, Vf, CtxReg, Live,
					SizeReg, Unit, Flags),
		{[Skip,{bs_save2,CtxReg,{Ctx,Tl}}],Bef};
	    {_,_,_} ->
		Reg = put_reg(Hd, Bef#sr.reg),
		Int1 = Bef#sr{reg=Reg},
		Rhd = fetch_reg(Hd, Reg),
		CtxReg = fetch_reg(Ctx, Reg),
		Live = max_reg(Bef#sr.reg),
		{[build_bs_instr(Type, Vf, CtxReg, Live, SizeReg,
				 Unit, Flags, Rhd),
		  {bs_save2,CtxReg,{Ctx,Tl}}],Int1}
	end,
    {Es,clear_dead(Aft, I, Vdb),St};
select_extract_bin([{var,Hd}], Size0, Unit, binary, Flags, Vf,
		   I, Vdb, Bef, Ctx, Body, St) ->
    SizeReg = get_bin_size_reg(Size0, Bef),
    {Es,Aft} =
	case vdb_find(Hd, Vdb) of
	    {_,_,Lhd} when Lhd =< I ->
		CtxReg = fetch_var(Ctx, Bef),
		{case SizeReg =:= {atom,all} andalso is_context_unused(Body) of
		     true when Unit =:= 1 ->
			 [];
		     true ->
			 [{test,bs_test_unit,{f,Vf},[CtxReg,Unit]}];
		     false ->
			 [{test,bs_skip_bits2,{f,Vf},
			   [CtxReg,SizeReg,Unit,{field_flags,Flags}]}]
		 end,Bef};
	    {_,_,_} ->
		case is_context_unused(Body) of
		    false ->
			Reg = put_reg(Hd, Bef#sr.reg),
			Int1 = Bef#sr{reg=Reg},
			Rhd = fetch_reg(Hd, Reg),
			CtxReg = fetch_reg(Ctx, Reg),
			Name = bs_get_binary2,
			Live = max_reg(Bef#sr.reg),
			{[{test,Name,{f,Vf},Live,
			   [CtxReg,SizeReg,Unit,{field_flags,Flags}],Rhd}],
			 Int1};
		    true ->
			%% Since the matching context will not be used again,
			%% we can reuse its register. Reusing the register
			%% opens some interesting optimizations in the
			%% run-time system.

			Reg0 = Bef#sr.reg,
			CtxReg = fetch_reg(Ctx, Reg0),
			Reg = replace_reg_contents(Ctx, Hd, Reg0),
			Int1 = Bef#sr{reg=Reg},
			Name = bs_get_binary2,
			Live = max_reg(Int1#sr.reg),
			{[{test,Name,{f,Vf},Live,
			   [CtxReg,SizeReg,Unit,{field_flags,Flags}],CtxReg}],
			 Int1}
		end
	end,
    {Es,clear_dead(Aft, I, Vdb),St}.

%% is_context_unused(Ke) -> true | false
%%   Simple heurististic to determine whether the code that follows will
%%   use the current matching context again. (The information of liveness
%%   calculcated by v3_life is too conservative to be useful for this purpose.)
%%   'true' means that the code that follows will definitely not use the context
%%   again (because it is a block, not guard or matching code); 'false' that we
%%   are not sure (there is either a guard, or more matching, either which may
%%   reference the context again).

is_context_unused(#l{ke=Ke}) -> is_context_unused(Ke);
is_context_unused({block,_}) -> true;
is_context_unused(_) -> false.

select_bin_end(#l{ke={val_clause,{bin_end,Ctx},B}},
	       Ivar, Tf, Bef, St0) ->
    {Bis,Aft,St2} = match_cg(B, Tf, Bef, St0),
    CtxReg = fetch_var(Ctx, Bef),
    {[{bs_restore2,CtxReg,{Ctx,Ivar}},
      {test,bs_test_tail2,{f,Tf},[CtxReg,0]}|Bis],Aft,St2}.

get_bin_size_reg({var,V}, Bef) ->
    fetch_var(V, Bef);
get_bin_size_reg(Literal, _Bef) ->
    Literal.

build_bs_instr(Type, Vf, CtxReg, Live, SizeReg, Unit, Flags, Rhd) ->
    {Format,Name} = case Type of
			integer -> {plain,bs_get_integer2};
			float ->   {plain,bs_get_float2};
			binary ->  {plain,bs_get_binary2};
			utf8 ->    {utf,bs_get_utf8};
			utf16 ->   {utf,bs_get_utf16};
			utf32 ->   {utf,bs_get_utf32}
		   end,
    case Format of
	plain ->
	    {test,Name,{f,Vf},Live,
	     [CtxReg,SizeReg,Unit,{field_flags,Flags}],Rhd};
	utf ->
	    {test,Name,{f,Vf},Live,
	     [CtxReg,{field_flags,Flags}],Rhd}
    end.

build_skip_instr(Type, Vf, CtxReg, Live, SizeReg, Unit, Flags) ->
    {Format,Name} = case Type of
			utf8 -> {utf,bs_skip_utf8};
			utf16 -> {utf,bs_skip_utf16};
			utf32 -> {utf,bs_skip_utf32};
			_ -> {plain,bs_skip_bits2}
		    end,
    case Format of
	plain ->
	    {test,Name,{f,Vf},[CtxReg,SizeReg,Unit,{field_flags,Flags}]};
	utf ->
	    {test,Name,{f,Vf},[CtxReg,Live,{field_flags,Flags}]}
    end.

select_val(#l{ke={val_clause,{tuple,Es},B},i=I,vdb=Vdb}, V, Vf, Bef, St0) ->
    {Eis,Int,St1} = select_extract_tuple(V, Es, I, Vdb, Bef, St0),
    {Bis,Aft,St2} = match_cg(B, Vf, Int, St1),
    {length(Es),Eis ++ Bis,Aft,St2};
select_val(#l{ke={val_clause,{_,Val},B}}, _V, Vf, Bef, St0) ->
    {Bis,Aft,St1} = match_cg(B, Vf, Bef, St0),
    {Val,Bis,Aft,St1}.

%% select_extract_tuple(Src, [V], I, Vdb, StackReg, State) ->
%%      {[E],StackReg,State}.
%%  Extract tuple elements, but only if they do not immediately die.

select_extract_tuple(Src, Vs, I, Vdb, Bef, St) ->
    F = fun ({var,V}, {Int0,Elem}) ->
		case vdb_find(V, Vdb) of
		    {V,_,L} when L =< I -> {[], {Int0,Elem+1}};
		    _Other ->
			Reg1 = put_reg(V, Int0#sr.reg),
			Int1 = Int0#sr{reg=Reg1},
			Rsrc = fetch_var(Src, Int1),
			{[{get_tuple_element,Rsrc,Elem,fetch_reg(V, Reg1)}],
			 {Int1,Elem+1}}
		end
	end,
    {Es,{Aft,_}} = flatmapfoldl(F, {Bef,0}, Vs),
    {Es,Aft,St}.

select_extract_cons(Src, [{var,Hd}, {var,Tl}], I, Vdb, Bef, St) ->
    {Es,Aft} = case {vdb_find(Hd, Vdb), vdb_find(Tl, Vdb)} of
		   {{_,_,Lhd}, {_,_,Ltl}} when Lhd =< I, Ltl =< I ->
		       %% Both head and tail are dead.  No need to generate
		       %% any instruction.
		       {[], Bef};
		   _ ->
		       %% At least one of head and tail will be used,
		       %% but we must always fetch both.  We will call
		       %% clear_dead/2 to allow reuse of the register
		       %% in case only of them is used.

		       Reg0 = put_reg(Tl, put_reg(Hd, Bef#sr.reg)),
		       Int0 = Bef#sr{reg=Reg0},
		       Rsrc = fetch_var(Src, Int0),
		       Rhd = fetch_reg(Hd, Reg0),
		       Rtl = fetch_reg(Tl, Reg0),
		       Int1 = clear_dead(Int0, I, Vdb),
		       {[{get_list,Rsrc,Rhd,Rtl}], Int1}
	       end,
    {Es,Aft,St}.
    

guard_clause_cg(#l{ke={guard_clause,G,B},vdb=Vdb}, Fail, Bef, St0) ->
    {Gis,Int,St1} = guard_cg(G, Fail, Vdb, Bef, St0),
    {Bis,Aft,St} = match_cg(B, Fail, Int, St1),
    {Gis ++ Bis,Aft,St}.

%% guard_cg(Guard, Fail, Vdb, StackReg, State) ->
%%      {[Ainstr],StackReg,State}.
%%  A guard is a boolean expression of tests.  Tests return true or
%%  false.  A fault in a test causes the test to return false.  Tests
%%  never return the boolean, instead we generate jump code to go to
%%  the correct exit point.  Primops and tests all go to the next
%%  instruction on success or jump to a failure label.

guard_cg(#l{ke={protected,Ts,Rs},i=I,vdb=Pdb}, Fail, _Vdb, Bef, St) ->
    protected_cg(Ts, Rs, Fail, I, Pdb, Bef, St);
guard_cg(#l{ke={block,Ts},i=I,vdb=Bdb}, Fail, _Vdb, Bef, St) ->
    guard_cg_list(Ts, Fail, I, Bdb, Bef, St);
guard_cg(#l{ke={test,Test,As},i=I,vdb=_Tdb}, Fail, Vdb, Bef, St) ->
    test_cg(Test, As, Fail, I, Vdb, Bef, St);
guard_cg(G, _Fail, Vdb, Bef, St) ->
    %%ok = io:fwrite("cg ~w: ~p~n", [?LINE,{G,Fail,Vdb,Bef}]),
    {Gis,Aft,St1} = cg(G, Vdb, Bef, St),
    %%ok = io:fwrite("cg ~w: ~p~n", [?LINE,{Aft}]),
    {Gis,Aft,St1}.

%% protected_cg([Kexpr], [Ret], Fail, I, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%%  Do a protected.  Protecteds without return values are just done
%%  for effect, the return value is not checked, success passes on to
%%  the next instruction and failure jumps to Fail.  If there are
%%  return values then these must be set to 'false' on failure,
%%  control always passes to the next instruction.

protected_cg(Ts, [], Fail, I, Vdb, Bef, St0) ->
    %% Protect these calls, revert when done.
    {Tis,Aft,St1} = guard_cg_list(Ts, Fail, I, Vdb, Bef,
				  St0#cg{bfail=Fail}),
    {Tis,Aft,St1#cg{bfail=St0#cg.bfail}};
protected_cg(Ts, Rs, _Fail, I, Vdb, Bef, St0) ->
    {Pfail,St1} = new_label(St0),
    {Psucc,St2} = new_label(St1),
    {Tis,Aft,St3} = guard_cg_list(Ts, Pfail, I, Vdb, Bef,
				  St2#cg{bfail=Pfail}),
    %%ok = io:fwrite("cg ~w: ~p~n", [?LINE,{Rs,I,Vdb,Aft}]),
    %% Set return values to false.
    Mis = map(fun ({var,V}) -> {move,{atom,false},fetch_var(V, Aft)} end, Rs),
    {Tis ++ [{jump,{f,Psucc}},
	     {label,Pfail}] ++ Mis ++ [{label,Psucc}],
     Aft,St3#cg{bfail=St0#cg.bfail}}.    

%% test_cg(TestName, Args, Fail, I, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%%  Generate test instruction.  Use explicit fail label here.

test_cg(Test, As, Fail, I, Vdb, Bef, St) ->
    Args = cg_reg_args(As, Bef),
    Aft = clear_dead(Bef, I, Vdb),
    {[beam_utils:bif_to_test(Test, Args, {f,Fail})],Aft,St}.

%% guard_cg_list([Kexpr], Fail, I, Vdb, StackReg, St) ->
%%      {[Ainstr],StackReg,St}.

guard_cg_list(Kes, Fail, I, Vdb, Bef, St0) ->
    {Keis,{Aft,St1}} =
	flatmapfoldl(fun (Ke, {Inta,Sta}) ->
			     {Keis,Intb,Stb} =
				 guard_cg(Ke, Fail, Vdb, Inta, Sta),
			     {Keis,{Intb,Stb}}
		     end, {Bef,St0}, need_heap(Kes, I)),
    {Keis,Aft,St1}.

%% match_fmf(Fun, LastFail, State, [Clause]) -> {Is,Aft,State}.
%%  This is a special flatmapfoldl for match code gen where we
%%  generate a "failure" label for each clause. The last clause uses
%%  an externally generated failure label, LastFail.  N.B. We do not
%%  know or care how the failure labels are used.

match_fmf(F, LastFail, St, [H]) ->
    F(H, LastFail, St);
match_fmf(F, LastFail, St0, [H|T]) ->
    {Fail,St1} = new_label(St0),
    {R,Aft1,St2} = F(H, Fail, St1),
    {Rs,Aft2,St3} = match_fmf(F, LastFail, St2, T),
    {R ++ [{label,Fail}] ++ Rs,sr_merge(Aft1, Aft2),St3}.

%% call_cg(Func, [Arg], [Ret], Le, Vdb, StackReg, State) ->
%%      {[Ainstr],StackReg,State}.
%% enter_cg(Func, [Arg], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%%  Call and enter first put the arguments into registers and save any
%%  other registers, then clean up and compress the stack and set the
%%  frame size. Finally the actual call is made.  Call then needs the
%%  return values filled in.

call_cg({var,_V} = Var, As, Rs, Le, Vdb, Bef, St0) ->
    {Sis,Int} = cg_setup_call(As++[Var], Bef, Le#l.i, Vdb),
    %% Put return values in registers.
    Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
    %% Build complete code and final stack/register state.
    Arity = length(As),
    {Frees,Aft} = free_dead(clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb)),
    {Sis ++ Frees ++ [line(Le),{call_fun,Arity}],Aft,
     need_stack_frame(St0)};
call_cg({remote,Mod,Name}, As, Rs, Le, Vdb, Bef, St0)
  when element(1, Mod) =:= var;
       element(1, Name) =:= var ->
    {Sis,Int} = cg_setup_call(As++[Mod,Name], Bef, Le#l.i, Vdb),
    %% Put return values in registers.
    Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
    %% Build complete code and final stack/register state.
    Arity = length(As),
    St = need_stack_frame(St0),
    %%{Call,St1} = build_call(Func, Arity, St0),
    {Frees,Aft} = free_dead(clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb)),
    {Sis ++ Frees ++ [line(Le),{apply,Arity}],Aft,St};
call_cg(Func, As, Rs, Le, Vdb, Bef, St0) ->
    case St0 of
	#cg{bfail=Fail} when Fail =/= 0 ->
	    %% Inside a guard. The only allowed function call is to
	    %% erlang:error/1,2. We will generate the following code:
	    %%
	    %%     jump FailureLabel
	    %%     move {atom,ok} DestReg
	    %%
	    %% The 'move' instruction will never be executed, but we
	    %% generate it anyway in case the beam_validator is run
	    %% on unoptimized code.
	    {remote,{atom,erlang},{atom,error}} = Func,	%Assertion.
	    [{var,DestVar}] = Rs,
	    Int0 = clear_dead(Bef, Le#l.i, Vdb),
	    Reg = put_reg(DestVar, Int0#sr.reg),
	    Int = Int0#sr{reg=Reg},
	    Dst = fetch_reg(DestVar, Reg),
	    {[{jump,{f,Fail}},{move,{atom,ok},Dst}],
	     clear_dead(Int, Le#l.i, Vdb),St0};
	#cg{} ->
	    %% Ordinary function call in a function body.
	    {Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
	    %% Put return values in registers.
	    Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
	    %% Build complete code and final stack/register state.
	    Arity = length(As),
	    {Call,St1} = build_call(Func, Arity, St0),
	    {Frees,Aft} = free_dead(clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb)),
	    {Sis ++ Frees ++ [line(Le)|Call],Aft,St1}
    end.

build_call({remote,{atom,erlang},{atom,'!'}}, 2, St0) ->
    {[send],need_stack_frame(St0)};
build_call({remote,{atom,Mod},{atom,Name}}, Arity, St0) ->
    {[{call_ext,Arity,{extfunc,Mod,Name,Arity}}],need_stack_frame(St0)};
build_call(Name, Arity, St0) when is_atom(Name) ->
    {Lbl,St1} = local_func_label(Name, Arity, need_stack_frame(St0)),
    {[{call,Arity,{f,Lbl}}],St1}.

free_dead(#sr{stk=Stk0}=Aft) ->
    {Instr,Stk} = free_dead(Stk0, 0, [], []),
    {Instr,Aft#sr{stk=Stk}}.

free_dead([dead|Stk], Y, Instr, StkAcc) ->
    %% Note: kill/1 is equivalent to init/1 (translated by beam_asm).
    %% We use kill/1 to help further optimisation passes.
    free_dead(Stk, Y+1, [{kill,{yy,Y}}|Instr], [free|StkAcc]);
free_dead([Any|Stk], Y, Instr, StkAcc) ->
    free_dead(Stk, Y+1, Instr, [Any|StkAcc]);
free_dead([], _, Instr, StkAcc) -> {Instr,reverse(StkAcc)}.

enter_cg({var,_V} = Var, As, Le, Vdb, Bef, St0) ->
    {Sis,Int} = cg_setup_call(As++[Var], Bef, Le#l.i, Vdb),
    %% Build complete code and final stack/register state.
    Arity = length(As),
    {Sis ++ [line(Le),{call_fun,Arity},return],
     clear_dead(Int#sr{reg=clear_regs(Int#sr.reg)}, Le#l.i, Vdb),
     need_stack_frame(St0)};
enter_cg({remote,Mod,Name}, As, Le, Vdb, Bef, St0)
  when element(1, Mod) =:= var;
       element(1, Name) =:= var ->
    {Sis,Int} = cg_setup_call(As++[Mod,Name], Bef, Le#l.i, Vdb),
    %% Build complete code and final stack/register state.
    Arity = length(As),
    St = need_stack_frame(St0),
    {Sis ++ [line(Le),{apply_only,Arity}],
     clear_dead(Int#sr{reg=clear_regs(Int#sr.reg)}, Le#l.i, Vdb),
     St};
enter_cg(Func, As, Le, Vdb, Bef, St0) ->
    {Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
    %% Build complete code and final stack/register state.
    Arity = length(As),
    {Call,St1} = build_enter(Func, Arity, St0),
    Line = enter_line(Func, Arity, Le),
    {Sis ++ Line ++ Call,
     clear_dead(Int#sr{reg=clear_regs(Int#sr.reg)}, Le#l.i, Vdb),
     St1}.

build_enter({remote,{atom,erlang},{atom,'!'}}, 2, St0) ->
    {[send,return],need_stack_frame(St0)};
build_enter({remote,{atom,Mod},{atom,Name}}, Arity, St0) ->
    St1 = case trap_bif(Mod, Name, Arity) of
	      true -> need_stack_frame(St0);
	      false -> St0
	  end,
    {[{call_ext_only,Arity,{extfunc,Mod,Name,Arity}}],St1};
build_enter(Name, Arity, St0) when is_atom(Name) ->
    {Lbl,St1} = local_func_label(Name, Arity, St0),
    {[{call_only,Arity,{f,Lbl}}],St1}.

enter_line({remote,{atom,Mod},{atom,Name}}, Arity, Le) ->
    case erl_bifs:is_safe(Mod, Name, Arity) of
	false ->
	    %% Tail-recursive call, possibly to a BIF.
	    %% We'll need a line instruction in case the
	    %% BIF call fails.
	    [line(Le)];
	true ->
	    %% Call to a safe BIF. Since it cannot fail,
	    %% we don't need any line instruction here.
	    []
    end;
enter_line(_, _, _) ->
    %% Tail-recursive call to a local function. A line
    %% instruction will not be useful.
    [].

%% local_func_label(Name, Arity, State) -> {Label,State'}
%% local_func_label({Name,Arity}, State) -> {Label,State'}
%%  Get the function entry label for a local function.

local_func_label(Name, Arity, St) ->
    local_func_label({Name,Arity}, St).

local_func_label(Key, #cg{functable=Tab}=St0) ->
    case gb_trees:lookup(Key, Tab) of
	{value,Label} ->
	    {Label,St0};
	none ->
  	    {Label,St} = new_label(St0),
	    {Label,St#cg{functable=gb_trees:insert(Key, Label, Tab)}}
    end.

%% need_stack_frame(State) -> State'
%%  Make a note in the state that this function will need a stack frame.

need_stack_frame(#cg{need_frame=true}=St) -> St;
need_stack_frame(St) -> St#cg{need_frame=true}.

%% trap_bif(Mod, Name, Arity) -> true|false
%%   Trap bifs that need a stack frame.

trap_bif(erlang, link, 1) -> true;
trap_bif(erlang, unlink, 1) -> true;
trap_bif(erlang, monitor_node, 2) -> true;
trap_bif(erlang, group_leader, 2) -> true;
trap_bif(erlang, exit, 2) -> true;
trap_bif(_, _, _) -> false.

%% bif_cg(Bif, [Arg], [Ret], Le, Vdb, StackReg, State) ->
%%      {[Ainstr],StackReg,State}.

bif_cg(bs_context_to_binary=Instr, [Src0], [], Le, Vdb, Bef, St0) ->
    [Src] = cg_reg_args([Src0], Bef),
    case is_register(Src) of
	false ->
	    {[],clear_dead(Bef, Le#l.i, Vdb), St0};
	true ->
	    {[{Instr,Src}],clear_dead(Bef, Le#l.i, Vdb), St0}
    end;
bif_cg(dsetelement, [Index0,Tuple0,New0], _Rs, Le, Vdb, Bef, St0) ->
    [New,Tuple,{integer,Index1}] = cg_reg_args([New0,Tuple0,Index0], Bef),
    Index = Index1-1,
    {[{set_tuple_element,New,Tuple,Index}],
     clear_dead(Bef, Le#l.i, Vdb), St0};
bif_cg({make_fun,Func,Arity,Index,Uniq}, As, Rs, Le, Vdb, Bef, St0) ->
    %% This behaves more like a function call.
    {Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
    Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
    {FuncLbl,St1} = local_func_label(Func, Arity, St0),
    MakeFun = {make_fun2,{f,FuncLbl},Index,Uniq,length(As)},
    {Sis ++ [MakeFun],
     clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb),
     St1};
bif_cg(bs_init_writable=I, As, Rs, Le, Vdb, Bef, St) ->
    %% This behaves like a function call.
    {Sis,Int} = cg_setup_call(As, Bef, Le#l.i, Vdb),
    Reg = load_vars(Rs, clear_regs(Int#sr.reg)),
    {Sis++[I],clear_dead(Int#sr{reg=Reg}, Le#l.i, Vdb),St};
bif_cg(Bif, As, [{var,V}], Le, Vdb, Bef, St0) ->
    Ars = cg_reg_args(As, Bef),

    %% If we are inside a catch and in a body (not in guard) and the
    %% BIF may fail, we must save everything that will be alive after
    %% the catch (because the code after the code assumes that all
    %% variables that are live are stored on the stack).
    %%
    %%   Currently, we are somewhat pessimistic in
    %% that we save any variable that will be live after this BIF call.

    MayFail = not erl_bifs:is_safe(erlang, Bif, length(As)),
    {Sis,Int0} = case St0#cg.in_catch andalso
		     St0#cg.bfail =:= 0 andalso
		     MayFail of
		     true -> adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb);
		     false -> {[],Bef}
		 end,
    Int1 = clear_dead(Int0, Le#l.i, Vdb),
    Reg = put_reg(V, Int1#sr.reg),
    Int = Int1#sr{reg=Reg},
    Dst = fetch_reg(V, Reg),
    BifFail = {f,St0#cg.bfail},
    %% We need a line instructions for BIFs that may fail in a body.
    Line = case BifFail of
	       {f,0} when MayFail ->
		   [line(Le)];
	       _ ->
		   []
	   end,
    {Sis++Line++[{bif,Bif,BifFail,Ars,Dst}],
     clear_dead(Int, Le#l.i, Vdb), St0}.


%% gc_bif_cg(Bif, [Arg], [Ret], Le, Vdb, StackReg, State) ->
%%      {[Ainstr],StackReg,State}.

gc_bif_cg(Bif, As, [{var,V}], Le, Vdb, Bef, St0) ->
    Ars = cg_reg_args(As, Bef),

    %% If we are inside a catch and in a body (not in guard) and the
    %% BIF may fail, we must save everything that will be alive after
    %% the catch (because the code after the code assumes that all
    %% variables that are live are stored on the stack).
    %%
    %%   Currently, we are somewhat pessimistic in
    %% that we save any variable that will be live after this BIF call.

    {Sis,Int0} =
	case St0#cg.in_catch andalso St0#cg.bfail =:= 0 of
	    true -> adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb);
	    false -> {[],Bef}
	end,

    Int1 = clear_dead(Int0, Le#l.i, Vdb),
    Reg = put_reg(V, Int1#sr.reg),
    Int = Int1#sr{reg=Reg},
    Dst = fetch_reg(V, Reg),
    BifFail = {f,St0#cg.bfail},
    Line = case BifFail of
	       {f,0} -> [line(Le)];
	       {f,_} -> []
	   end,
    {Sis++Line++[{gc_bif,Bif,BifFail,max_reg(Bef#sr.reg),Ars,Dst}],
     clear_dead(Int, Le#l.i, Vdb), St0}.

%% recv_loop_cg(TimeOut, ReceiveVar, ReceiveMatch, TimeOutExprs,
%%              [Ret], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.

recv_loop_cg(Te, Rvar, Rm, Tes, Rs, Le, Vdb, Bef, St0) ->
    {Sis,Int0} = adjust_stack(Bef, Le#l.i, Le#l.i, Vdb),
    Int1 = Int0#sr{reg=clear_regs(Int0#sr.reg)},
    %% Get labels.
    {Rl,St1} = new_label(St0),
    {Tl,St2} = new_label(St1),
    {Bl,St3} = new_label(St2),
    St4 = St3#cg{break=Bl,recv=Rl},		%Set correct receive labels
    {Ris,Raft,St5} = cg_recv_mesg(Rvar, Rm, Tl, Int1, St4),
    {Wis,Taft,St6} = cg_recv_wait(Te, Tes, Le#l.i, Int1, St5),
    Int2 = sr_merge(Raft, Taft),		%Merge stack/registers
    Reg = load_vars(Rs, Int2#sr.reg),
    {Sis ++ [line(Le)] ++ Ris ++ [{label,Tl}] ++ Wis ++ [{label,Bl}],
     clear_dead(Int2#sr{reg=Reg}, Le#l.i, Vdb),
     St6#cg{break=St0#cg.break,recv=St0#cg.recv}}.

%% cg_recv_mesg( ) -> {[Ainstr],Aft,St}.

cg_recv_mesg({var,R}, Rm, Tl, Bef, St0) ->
    Int0 = Bef#sr{reg=put_reg(R, Bef#sr.reg)},
    Ret = fetch_reg(R, Int0#sr.reg),
    %% Int1 = clear_dead(Int0, I, Rm#l.vdb),
    Int1 = Int0,
    {Mis,Int2,St1} = match_cg(Rm, none, Int1, St0),
    {[{label,St1#cg.recv},{loop_rec,{f,Tl},Ret}|Mis],Int2,St1}.

%% cg_recv_wait(Te, Tes, I, Vdb, Int2, St3) -> {[Ainstr],Aft,St}.

cg_recv_wait({atom,infinity}, Tes, I, Bef, St0) ->
    %% We know that the 'after' body will never be executed.
    %% But to keep the stack and register information up to date,
    %% we will generate the code for the 'after' body, and then discard it.
    Int1 = clear_dead(Bef, I, Tes#l.vdb),
    {_,Int2,St1} = cg_block(Tes#l.ke, Tes#l.i, Tes#l.vdb,
			      Int1#sr{reg=clear_regs(Int1#sr.reg)}, St0),
    {[{wait,{f,St1#cg.recv}}],Int2,St1};
cg_recv_wait({integer,0}, Tes, _I, Bef, St0) ->
    {Tis,Int,St1} = cg_block(Tes#l.ke, Tes#l.i, Tes#l.vdb, Bef, St0),
    {[timeout|Tis],Int,St1};
cg_recv_wait(Te, Tes, I, Bef, St0) ->
    Reg = cg_reg_arg(Te, Bef),
    %% Must have empty registers here!  Bug if anything in registers.
    Int0 = clear_dead(Bef, I, Tes#l.vdb),
    {Tis,Int,St1} = cg_block(Tes#l.ke, Tes#l.i, Tes#l.vdb,
			     Int0#sr{reg=clear_regs(Int0#sr.reg)}, St0),
    {[{wait_timeout,{f,St1#cg.recv},Reg},timeout] ++ Tis,Int,St1}.

%% recv_next_cg(Le, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.
%%  Use adjust stack to clear stack, but only need it for Aft.

recv_next_cg(Le, Vdb, Bef, St) ->
    {Sis,Aft} = adjust_stack(Bef, Le#l.i, Le#l.i+1, Vdb),
    {[{loop_rec_end,{f,St#cg.recv}}] ++ Sis,Aft,St}.	%Joke

%% try_cg(TryBlock, [BodyVar], TryBody, [ExcpVar], TryHandler, [Ret],
%%        Le, Vdb, StackReg, St) -> {[Ainstr],StackReg,St}.

try_cg(Ta, Vs, Tb, Evs, Th, Rs, Le, Vdb, Bef, St0) ->
    {B,St1} = new_label(St0),			%Body label
    {H,St2} = new_label(St1),			%Handler label
    {E,St3} = new_label(St2),			%End label
    TryTag = Ta#l.i,
    Int1 = Bef#sr{stk=put_catch(TryTag, Bef#sr.stk)},
    TryReg = fetch_stack({catch_tag,TryTag}, Int1#sr.stk),
    {Ais,Int2,St4} = cg(Ta, Vdb, Int1, St3#cg{break=B,in_catch=true}),
    Int3 = Int2#sr{stk=drop_catch(TryTag, Int2#sr.stk)},
    St5 = St4#cg{break=E,in_catch=St3#cg.in_catch},
    {Bis,Baft,St6} = cg(Tb, Vdb, Int3#sr{reg=load_vars(Vs, Int3#sr.reg)}, St5),
    {His,Haft,St7} = cg(Th, Vdb, Int3#sr{reg=load_vars(Evs, Int3#sr.reg)}, St6),
    Int4 = sr_merge(Baft, Haft),		%Merge stack/registers
    Aft = Int4#sr{reg=load_vars(Rs, Int4#sr.reg)},
    {[{'try',TryReg,{f,H}}] ++ Ais ++ 
     [{label,B},{try_end,TryReg}] ++ Bis ++
     [{label,H},{try_case,TryReg}] ++ His ++
     [{label,E}],
     clear_dead(Aft, Le#l.i, Vdb),
     St7#cg{break=St0#cg.break}}.     

try_enter_cg(Ta, Vs, Tb, Evs, Th, Le, Vdb, Bef, St0) ->
    {B,St1} = new_label(St0),			%Body label
    {H,St2} = new_label(St1),			%Handler label
    TryTag = Ta#l.i,
    Int1 = Bef#sr{stk=put_catch(TryTag, Bef#sr.stk)},
    TryReg = fetch_stack({catch_tag,TryTag}, Int1#sr.stk),
    {Ais,Int2,St3} = cg(Ta, Vdb, Int1, St2#cg{break=B,in_catch=true}),
    Int3 = Int2#sr{stk=drop_catch(TryTag, Int2#sr.stk)},
    St4 = St3#cg{in_catch=St2#cg.in_catch},
    {Bis,Baft,St5} = cg(Tb, Vdb, Int3#sr{reg=load_vars(Vs, Int3#sr.reg)}, St4),
    {His,Haft,St6} = cg(Th, Vdb, Int3#sr{reg=load_vars(Evs, Int3#sr.reg)}, St5),
    Int4 = sr_merge(Baft, Haft),		%Merge stack/registers
    Aft = Int4,
    {[{'try',TryReg,{f,H}}] ++ Ais ++ 
     [{label,B},{try_end,TryReg}] ++ Bis ++
     [{label,H},{try_case,TryReg}] ++ His,
     clear_dead(Aft, Le#l.i, Vdb),
     St6#cg{break=St0#cg.break}}.     

%% catch_cg(CatchBlock, Ret, Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.

catch_cg(C, {var,R}, Le, Vdb, Bef, St0) ->
    {B,St1} = new_label(St0),
    CatchTag = Le#l.i,
    Int1 = Bef#sr{stk=put_catch(CatchTag, Bef#sr.stk)},
    CatchReg = fetch_stack({catch_tag,CatchTag}, Int1#sr.stk),
    {Cis,Int2,St2} = cg_block(C, Le#l.i, Le#l.vdb, Int1,
			      St1#cg{break=B,in_catch=true}),
    [] = Int2#sr.reg,				%Assertion.
    Aft = Int2#sr{reg=[{0,R}],stk=drop_catch(CatchTag, Int2#sr.stk)},
    {[{'catch',CatchReg,{f,B}}] ++ Cis ++
     [{label,B},{catch_end,CatchReg}],
     clear_dead(Aft, Le#l.i, Vdb),
     St2#cg{break=St1#cg.break,in_catch=St1#cg.in_catch}}.

%% set_cg([Var], Constr, Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%%  We have to be careful how a 'set' works. First the structure is
%%  built, then it is filled and finally things can be cleared. The
%%  annotation must reflect this and make sure that the return
%%  variable is allocated first.
%%
%%  put_list for constructing a cons is an atomic instruction
%%  which can safely resuse one of the source registers as target.
%%  Also binaries can reuse a source register as target.

set_cg([{var,R}], {cons,Es}, Le, Vdb, Bef, St) ->
    [S1,S2] = map(fun ({var,V}) -> fetch_var(V, Bef);
		      (Other) -> Other
		  end, Es),
    Int0 = clear_dead(Bef, Le#l.i, Vdb),
    Int1 = Int0#sr{reg=put_reg(R, Int0#sr.reg)},
    Ret = fetch_reg(R, Int1#sr.reg),
    {[{put_list,S1,S2,Ret}], Int1, St};
set_cg([{var,R}], {binary,Segs}, Le, Vdb, Bef,
       #cg{in_catch=InCatch, bfail=Bfail}=St) ->
    Int0 = Bef#sr{reg=put_reg(R, Bef#sr.reg)},
    Target = fetch_reg(R, Int0#sr.reg),
    Fail = {f,Bfail},
    Temp = find_scratch_reg(Int0#sr.reg),
    PutCode = cg_bin_put(Segs, Fail, Bef),
    {Sis,Int1} =
	case InCatch of
	    true -> adjust_stack(Int0, Le#l.i, Le#l.i+1, Vdb);
	    false -> {[],Int0}
	end,
    MaxRegs = max_reg(Bef#sr.reg),
    Aft = clear_dead(Int1, Le#l.i, Vdb),
    Code = cg_binary(PutCode, Target, Temp, Fail, MaxRegs, Le#l.a),
    {Sis++Code,Aft,St};
set_cg([{var,R}], Con, Le, Vdb, Bef, St) ->
    %% Find a place for the return register first.
    Int = Bef#sr{reg=put_reg(R, Bef#sr.reg)},
    Ret = fetch_reg(R, Int#sr.reg),
    Ais = case Con of
	      {tuple,Es} ->
		  [{put_tuple,length(Es),Ret}] ++ cg_build_args(Es, Bef);
	      {var,V} ->	  % Normally removed by kernel optimizer.
		  [{move,fetch_var(V, Int),Ret}];
	      Other ->
		  [{move,Other,Ret}]
	  end,
    {Ais,clear_dead(Int, Le#l.i, Vdb),St}.

%%%
%%% Code generation for constructing binaries.
%%%

cg_binary([{bs_put_binary,Fail,{atom,all},U,_Flags,Src}|PutCode],
	  Target, Temp, Fail, MaxRegs, Anno) ->
    Live = cg_live(Target, MaxRegs),
    SzCode = cg_bitstr_size(PutCode, Target, Temp, Fail, Live),
    BinFlags = {field_flags,[]},
    Code = SzCode ++
	[case member(single_use, Anno) of
	     true ->
		 {bs_private_append,Fail,Target,U,Src,BinFlags,Target};
	     false ->
		 {bs_append,Fail,Target,0,MaxRegs,U,Src,BinFlags,Target}
	 end] ++ PutCode,
    cg_bin_opt(Code);
cg_binary(PutCode, Target, Temp, Fail, MaxRegs, Anno) ->
    Line = line(Anno),
    Live = cg_live(Target, MaxRegs),
    {InitOp,SzCode} = cg_binary_size(PutCode, Target, Temp, Fail, Live),

    Code = [Line|SzCode] ++ [{InitOp,Fail,Target,0,MaxRegs,
			      {field_flags,[]},Target}|PutCode],
    cg_bin_opt(Code).

cg_live({x,X}, MaxRegs) when X =:= MaxRegs -> MaxRegs+1;
cg_live({x,X}, MaxRegs) when X < MaxRegs -> MaxRegs.

%% Generate code that calculate the size of the bitstr to be
%% built in BITS.

cg_bitstr_size(PutCode, Target, Temp, Fail, Live) ->
    {Bits,Es} = cg_bitstr_size_1(PutCode, 0, []),
    reverse(cg_gen_binsize(Es, Target, Temp, Fail, Live,
			   [{move,{integer,Bits},Target}])).

cg_bitstr_size_1([{bs_put_utf8,_,_,Src}|Next], Bits, Acc) ->
    cg_bitstr_size_1(Next, Bits, [{'*',{bs_utf8_size,Src},8}|Acc]);
cg_bitstr_size_1([{bs_put_utf16,_,_,Src}|Next], Bits, Acc) ->
    cg_bitstr_size_1(Next, Bits, [{'*',{bs_utf16_size,Src},8}|Acc]);
cg_bitstr_size_1([{bs_put_utf32,_,_,_}|Next], Bits, Acc) ->
    cg_bitstr_size_1(Next, Bits+32, Acc);
cg_bitstr_size_1([{_,_,S,U,_,Src}|Next], Bits, Acc) ->
    case S of
	{integer,N} -> cg_bitstr_size_1(Next, Bits+N*U, Acc);
	{atom,all} -> cg_bitstr_size_1(Next, Bits, [{bit_size,Src}|Acc]);
	_ when U =:= 1 -> cg_bitstr_size_1(Next, Bits, [S|Acc]);
	_ -> cg_bitstr_size_1(Next, Bits, [{'*',S,U}|Acc])
    end;
cg_bitstr_size_1([], Bits, Acc) -> {Bits,Acc}.

%% Generate code that calculate the size of the bitstr to be
%% built in BYTES or BITS (depending on what is easiest).

cg_binary_size(PutCode, Target, Temp, Fail, Live) ->
    {InitInstruction,Szs} = cg_binary_size_1(PutCode, 0, []),
    SizeExpr = reverse(cg_gen_binsize(Szs, Target, Temp, Fail, Live, [{move,{integer,0},Target}])),
    {InitInstruction,SizeExpr}.

cg_binary_size_1([{bs_put_utf8,_Fail,_Flags,Src}|T], Bits, Acc) ->
    cg_binary_size_1(T, Bits, [{8,{bs_utf8_size,Src}}|Acc]);
cg_binary_size_1([{bs_put_utf16,_Fail,_Flags,Src}|T], Bits, Acc) ->
    cg_binary_size_1(T, Bits, [{8,{bs_utf16_size,Src}}|Acc]);
cg_binary_size_1([{bs_put_utf32,_Fail,_Flags,_Src}|T], Bits, Acc) ->
    cg_binary_size_1(T, Bits+32, Acc);
cg_binary_size_1([{_Put,_Fail,S,U,_Flags,Src}|T], Bits, Acc) ->
    cg_binary_size_2(S, U, Src, T, Bits, Acc);
cg_binary_size_1([], Bits, Acc) ->
    Bytes = Bits div 8,
    RemBits = Bits rem 8,
    Sizes0 = sort([{1,{integer,RemBits}},{8,{integer,Bytes}}|Acc]),
    Sizes = filter(fun({_,{integer,0}}) -> false;
		      (_) -> true end, Sizes0),
    case Sizes of
	[{1,_}|_] ->
	    {bs_init_bits,cg_binary_bytes_to_bits(Sizes, [])};
	[{8,_}|_] ->
	    {bs_init2,[E || {8,E} <- Sizes]};
	[] ->
	    {bs_init_bits,[]}
    end.

cg_binary_size_2({integer,N}, U, _, Next, Bits, Acc) ->
    cg_binary_size_1(Next, Bits+N*U, Acc);
cg_binary_size_2({atom,all}, U, E, Next, Bits, Acc) ->
    if 
	U rem 8 =:= 0 ->
	    cg_binary_size_1(Next, Bits, [{8,{byte_size,E}}|Acc]);
	true ->
	    cg_binary_size_1(Next, Bits, [{1,{bit_size,E}}|Acc])
    end;
cg_binary_size_2(Reg, 1, _, Next, Bits, Acc) ->
    cg_binary_size_1(Next, Bits, [{1,Reg}|Acc]);
cg_binary_size_2(Reg, 8, _, Next, Bits, Acc) ->
    cg_binary_size_1(Next, Bits, [{8,Reg}|Acc]);
cg_binary_size_2(Reg, U, _, Next, Bits, Acc) ->
    cg_binary_size_1(Next, Bits, [{1,{'*',Reg,U}}|Acc]).

cg_binary_bytes_to_bits([{8,{integer,N}}|T], Acc) ->
    cg_binary_bytes_to_bits(T, [{integer,8*N}|Acc]);
cg_binary_bytes_to_bits([{8,{byte_size,Reg}}|T], Acc) ->
    cg_binary_bytes_to_bits(T, [{bit_size,Reg}|Acc]);
cg_binary_bytes_to_bits([{8,Reg}|T], Acc) ->
    cg_binary_bytes_to_bits(T, [{'*',Reg,8}|Acc]);
cg_binary_bytes_to_bits([{1,Sz}|T], Acc) ->
    cg_binary_bytes_to_bits(T, [Sz|Acc]);
cg_binary_bytes_to_bits([], Acc) ->
    cg_binary_bytes_to_bits_1(sort(Acc)).

cg_binary_bytes_to_bits_1([{integer,I},{integer,J}|T]) ->
    cg_binary_bytes_to_bits_1([{integer,I+J}|T]);
cg_binary_bytes_to_bits_1([H|T]) ->
    [H|cg_binary_bytes_to_bits_1(T)];
cg_binary_bytes_to_bits_1([]) -> [].

cg_gen_binsize([{'*',{bs_utf8_size,Src},B}|T], Target, Temp, Fail, Live, Acc) ->
    Size = {bs_utf8_size,Fail,Src,Temp},
    Add = {bs_add,Fail,[Target,Temp,B],Target},
    cg_gen_binsize(T, Target, Temp, Fail, Live,
		   [Add,Size|Acc]);
cg_gen_binsize([{'*',{bs_utf16_size,Src},B}|T], Target, Temp, Fail, Live, Acc) ->
    Size = {bs_utf16_size,Fail,Src,Temp},
    Add = {bs_add,Fail,[Target,Temp,B],Target},
    cg_gen_binsize(T, Target, Temp, Fail, Live,
		   [Add,Size|Acc]);
cg_gen_binsize([{'*',A,B}|T], Target, Temp, Fail, Live, Acc) ->
    cg_gen_binsize(T, Target, Temp, Fail, Live,
		   [{bs_add,Fail,[Target,A,B],Target}|Acc]);
cg_gen_binsize([{bit_size,B}|T], Target, Temp, Fail, Live, Acc) ->
    cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
		   [{gc_bif,bit_size,Fail,Live,[B],Temp}|Acc]);
cg_gen_binsize([{byte_size,B}|T], Target, Temp, Fail, Live, Acc) ->
    cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
		   [{gc_bif,byte_size,Fail,Live,[B],Temp}|Acc]);
cg_gen_binsize([{bs_utf8_size,B}|T], Target, Temp, Fail, Live, Acc) ->
    cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
		   [{bs_utf8_size,Fail,B,Temp}|Acc]);
cg_gen_binsize([{bs_utf16_size,B}|T], Target, Temp, Fail, Live, Acc) ->
    cg_gen_binsize([Temp|T], Target, Temp, Fail, Live,
		   [{bs_utf16_size,Fail,B,Temp}|Acc]);
cg_gen_binsize([E0|T], Target, Temp, Fail, Live, Acc) ->
    cg_gen_binsize(T, Target, Temp, Fail, Live,
		   [{bs_add,Fail,[Target,E0,1],Target}|Acc]);
cg_gen_binsize([], _, _, _, _, Acc) -> Acc.


%% cg_bin_opt(Code0) -> Code
%%  Optimize the size calculations for binary construction.

cg_bin_opt([{move,Size,D},{bs_append,Fail,D,Extra,Regs0,U,Bin,Flags,D}|Is]) ->
    Regs = cg_bo_newregs(Regs0, D),
    cg_bin_opt([{bs_append,Fail,Size,Extra,Regs,U,Bin,Flags,D}|Is]);
cg_bin_opt([{move,Size,D},{bs_private_append,Fail,D,U,Bin,Flags,D}|Is]) ->
    cg_bin_opt([{bs_private_append,Fail,Size,U,Bin,Flags,D}|Is]);
cg_bin_opt([{move,{integer,0},D},{bs_add,_,[D,{integer,_}=S,1],Dst}|Is]) ->
    cg_bin_opt([{move,S,Dst}|Is]);
cg_bin_opt([{move,{integer,0},D},{bs_add,Fail,[D,S,U],Dst}|Is]) ->
    cg_bin_opt([{bs_add,Fail,[{integer,0},S,U],Dst}|Is]);
cg_bin_opt([{move,{integer,Bytes},D},{Op,Fail,D,Extra,Regs0,Flags,D}|Is])
  when Op =:= bs_init2; Op =:= bs_init_bits ->
    Regs = cg_bo_newregs(Regs0, D),
    cg_bin_opt([{Op,Fail,Bytes,Extra,Regs,Flags,D}|Is]);
cg_bin_opt([{move,Src1,Dst},{bs_add,Fail,[Dst,Src2,U],Dst}|Is]) ->
    cg_bin_opt([{bs_add,Fail,[Src1,Src2,U],Dst}|Is]);
cg_bin_opt([I|Is]) ->
    [I|cg_bin_opt(Is)];
cg_bin_opt([]) -> [].

cg_bo_newregs(R, {x,X}) when R-1 =:= X -> R-1;
cg_bo_newregs(R, _) -> R.

%% Common for new and old binary code generation.

cg_bin_put({bin_seg,[],S0,U,T,Fs,[E0,Next]}, Fail, Bef) ->
    S1 = case S0 of
	     {var,Sv} -> fetch_var(Sv, Bef);
	     _ -> S0
	 end,
    E1 = case E0 of
	     {var,V} -> fetch_var(V, Bef);
	     Other ->   Other
	 end,
    {Format,Op} = case T of
		      integer -> {plain,bs_put_integer};
		      utf8 ->    {utf,bs_put_utf8};
		      utf16 ->   {utf,bs_put_utf16};
		      utf32 ->   {utf,bs_put_utf32};
		      binary  -> {plain,bs_put_binary};
		      float   -> {plain,bs_put_float}
		  end,
    case Format of
	plain ->
	    [{Op,Fail,S1,U,{field_flags,Fs},E1}|cg_bin_put(Next, Fail, Bef)];
	utf ->
	    [{Op,Fail,{field_flags,Fs},E1}|cg_bin_put(Next, Fail, Bef)]
    end;
cg_bin_put({bin_end,[]}, _, _) -> [].

cg_build_args(As, Bef) ->
    map(fun ({var,V}) -> {put,fetch_var(V, Bef)};
	    (Other) -> {put,Other}
	end, As).

%% return_cg([Val], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%% break_cg([Val], Le, Vdb, Bef, St) -> {[Ainstr],Aft,St}.
%%  These are very simple, just put return/break values in registers
%%  from 0, then return/break.  Use the call setup to clean up stack,
%%  but must clear registers to ensure sr_merge works correctly.

return_cg(Rs, Le, Vdb, Bef, St) ->
    {Ms,Int} = cg_setup_call(Rs, Bef, Le#l.i, Vdb),
    {Ms ++ [return],Int#sr{reg=clear_regs(Int#sr.reg)},St}.

break_cg(Bs, Le, Vdb, Bef, St) ->
    {Ms,Int} = cg_setup_call(Bs, Bef, Le#l.i, Vdb),
    {Ms ++ [{jump,{f,St#cg.break}}],
     Int#sr{reg=clear_regs(Int#sr.reg)},St}.

guard_break_cg(Bs, Locked, #l{i=I}, Vdb, #sr{reg=Reg0}=Bef, St) ->
    RegLocked = get_locked_regs(Reg0, Locked),
    #sr{reg=Reg1} = Int = clear_dead(Bef#sr{reg=RegLocked}, I, Vdb),
    Reg2 = trim_free(Reg1),
    NumLocked = length(Reg2),
    Moves0 = gen_moves(Bs, Bef, NumLocked, []),
    Moves = order_moves(Moves0, find_scratch_reg(RegLocked)),
    {BreakVars,_} = mapfoldl(fun(_, RegNum) ->
				     {{RegNum,gbreakvar},RegNum+1}
			     end, length(Reg2), Bs),
    Reg = Reg2 ++ BreakVars,
    Aft = Int#sr{reg=Reg},
    {Moves ++ [{jump,{f,St#cg.break}}],Aft,St}.

get_locked_regs([R|Rs0], Preserve) ->
    case {get_locked_regs(Rs0, Preserve),R} of
	{[],{_,V}} ->
	    case lists:member(V, Preserve) of
		true -> [R];
		false -> []
	    end;
	{[],_} ->
	    [];
	{Rs,_} ->
	    [R|Rs]
    end;
get_locked_regs([], _) -> [].

%% cg_reg_arg(Arg0, Info) -> Arg
%% cg_reg_args([Arg0], Info) -> [Arg]
%%  Convert argument[s] into registers. Literal values are returned unchanged.

cg_reg_args(As, Bef) -> [cg_reg_arg(A, Bef) || A <- As].

cg_reg_arg({var,V}, Bef) -> fetch_var(V, Bef);
cg_reg_arg(Literal, _) -> Literal.

%% cg_setup_call([Arg], Bef, Cur, Vdb) -> {[Instr],Aft}.
%%  Do the complete setup for a call/enter.

cg_setup_call(As, Bef, I, Vdb) ->
    {Ms,Int0} = cg_call_args(As, Bef, I, Vdb),
    %% Have set up arguments, can now clean up, compress and save to stack.
    Int1 = Int0#sr{stk=clear_dead_stk(Int0#sr.stk, I, Vdb),res=[]},
    {Sis,Int2} = adjust_stack(Int1, I, I+1, Vdb),
    {Ms ++ Sis,Int2}.

%% cg_call_args([Arg], SrState) -> {[Instr],SrState}.
%%  Setup the arguments to a call/enter/bif. Put the arguments into
%%  consecutive registers starting at {x,0} moving any data which
%%  needs to be saved. Return a modified SrState structure with the
%%  new register contents.  N.B. the resultant register info will
%%  contain non-variable values when there are non-variable values.
%%
%%  This routine is complicated by unsaved values in x registers.
%%  We'll move away any unsaved values that are in the registers
%%  to be overwritten by the arguments.

cg_call_args(As, Bef, I, Vdb) ->
    Regs0 = load_arg_regs(Bef#sr.reg, As),
    Unsaved = unsaved_registers(Regs0, Bef#sr.stk, I, I+1, Vdb),
    {UnsavedMoves,Regs} = move_unsaved(Unsaved, Bef#sr.reg, Regs0),
    Moves0 = gen_moves(As, Bef),
    Moves = order_moves(Moves0, find_scratch_reg(Regs)),
    {UnsavedMoves ++ Moves,Bef#sr{reg=Regs}}.

%% load_arg_regs([Reg], Arguments) -> [Reg]
%%  Update the register descriptor to include the arguments (from {x,0}
%%  and upwards). Values in argument register are overwritten.
%%  Values in x registers above the arguments are preserved.

load_arg_regs(Regs, As) -> load_arg_regs(Regs, As, 0).

load_arg_regs([_|Rs], [{var,V}|As], I) -> [{I,V}|load_arg_regs(Rs, As, I+1)];
load_arg_regs([_|Rs], [A|As], I) -> [{I,A}|load_arg_regs(Rs, As, I+1)];
load_arg_regs([], [{var,V}|As], I) -> [{I,V}|load_arg_regs([], As, I+1)];
load_arg_regs([], [A|As], I) -> [{I,A}|load_arg_regs([], As, I+1)];
load_arg_regs(Rs, [], _) -> Rs.

%% Returns the variables must be saved and are currently in the
%% x registers that are about to be overwritten by the arguments.

unsaved_registers(Regs, Stk, Fb, Lf, Vdb) ->
    [V || {V,F,L} <- Vdb,
	  F < Fb,
	  L >= Lf,
	  not on_stack(V, Stk),
	  not in_reg(V, Regs)].

in_reg(V, Regs) -> keymember(V, 2, Regs).

%% Move away unsaved variables from the registers that are to be
%% overwritten by the arguments.
move_unsaved(Vs, OrigRegs, NewRegs) ->
    move_unsaved(Vs, OrigRegs, NewRegs, []).
    
move_unsaved([V|Vs], OrigRegs, NewRegs0, Acc) ->
    NewRegs = put_reg(V, NewRegs0),
    Src = fetch_reg(V, OrigRegs),
    Dst = fetch_reg(V, NewRegs),
    move_unsaved(Vs, OrigRegs, NewRegs, [{move,Src,Dst}|Acc]);
move_unsaved([], _, Regs, Acc) -> {Acc,Regs}.
    
%% gen_moves(As, Sr)
%%  Generate the basic move instruction to move the arguments
%%  to their proper registers. The list will be sorted on
%%  destinations. (I.e. the move to {x,0} will be first --
%%  see the comment to order_moves/2.)

gen_moves(As, Sr) -> gen_moves(As, Sr, 0, []).

gen_moves([{var,V}|As], Sr, I, Acc) ->
    case fetch_var(V, Sr) of
	{x,I} -> gen_moves(As, Sr, I+1, Acc);
	Reg -> gen_moves(As, Sr, I+1, [{move,Reg,{x,I}}|Acc])
    end;
gen_moves([A|As], Sr, I, Acc) ->
    gen_moves(As, Sr, I+1, [{move,A,{x,I}}|Acc]);
gen_moves([], _, _, Acc) -> lists:keysort(3, Acc).

%% order_moves([Move], ScratchReg) -> [Move]
%%  Orders move instruction so that source registers are not
%%  destroyed before they are used. If there are cycles
%%  (such as {move,{x,0},{x,1}}, {move,{x,1},{x,1}}),
%%  the scratch register is used to break up the cycle.
%%    If possible, the first move of the input list is placed
%%  last in the result list (to make the move to {x,0} occur
%%  just before the call to allow the Beam loader to coalesce
%%  the instructions).

order_moves(Ms, Scr) -> order_moves(Ms, Scr, []).

order_moves([{move,_,_}=M|Ms0], ScrReg, Acc0) ->
    {Chain,Ms} = collect_chain(Ms0, [M], ScrReg),
    Acc = reverse(Chain, Acc0),
    order_moves(Ms, ScrReg, Acc);
order_moves([], _, Acc) -> Acc.

collect_chain(Ms, Path, ScrReg) ->
    collect_chain(Ms, Path, [], ScrReg).

collect_chain([{move,Src,Same}=M|Ms0], [{move,Same,_}|_]=Path, Others, ScrReg) ->
    case lists:keyfind(Src, 3, Path) of
	false ->
	    collect_chain(reverse(Others, Ms0), [M|Path], [], ScrReg);
	_ ->	% We have a cycle.
	    {break_up_cycle(M, Path, ScrReg),reverse(Others, Ms0)}
    end;
collect_chain([M|Ms], Path, Others, ScrReg) ->
    collect_chain(Ms, Path, [M|Others], ScrReg);
collect_chain([], Path, Others, _) ->
    {Path,Others}.

break_up_cycle({move,Src,_}=M, Path, ScrReg) ->
    [{move,ScrReg,Src},M|break_up_cycle1(Src, Path, ScrReg)].

break_up_cycle1(Dst, [{move,Src,Dst}|Path], ScrReg) ->
    [{move,Src,ScrReg}|Path];
break_up_cycle1(Dst, [M|Path], LastMove) ->
    [M|break_up_cycle1(Dst, Path, LastMove)].

%% clear_dead(Sr, Until, Vdb) -> Aft.
%%  Remove all variables in Sr which have died AT ALL so far.

clear_dead(Sr, Until, Vdb) ->
    Sr#sr{reg=clear_dead_reg(Sr, Until, Vdb),
	  stk=clear_dead_stk(Sr#sr.stk, Until, Vdb)}.

clear_dead_reg(Sr, Until, Vdb) ->
    Reg = map(fun ({_I,V} = IV) ->
		      case vdb_find(V, Vdb) of
			  {V,_,L} when L > Until -> IV;
			  _ -> free		%Remove anything else
		      end;
		  ({reserved,_I,_V} = Reserved) -> Reserved;
		  (free) -> free
	      end, Sr#sr.reg),
    reserve(Sr#sr.res, Reg, Sr#sr.stk).

clear_dead_stk(Stk, Until, Vdb) ->
    map(fun ({V} = T) ->
		case vdb_find(V, Vdb) of
		    {V,_,L} when L > Until -> T;
		    _ -> dead			%Remove anything else
		end;
	    (free) -> free;
	    (dead) -> dead
	end, Stk).

%% sr_merge(Sr1, Sr2) -> Sr.
%%  Merge two stack/register states keeping the longest of both stack
%%  and register. Perform consistency check on both, elements must be
%%  the same.  Allow frame size 'void' to make easy creation of
%%  "empty" frame.

sr_merge(#sr{reg=R1,stk=S1,res=[]}, #sr{reg=R2,stk=S2,res=[]}) ->
    #sr{reg=longest(R1, R2),stk=longest(S1, S2),res=[]};
sr_merge(void, S2) -> S2#sr{res=[]}.

longest([H|T1], [H|T2]) -> [H|longest(T1, T2)];
longest([dead|T1], [free|T2]) -> [dead|longest(T1, T2)];
longest([free|T1], [dead|T2]) -> [dead|longest(T1, T2)];
longest([dead|_] = L, []) -> L;
longest([], [dead|_] = L) -> L;
longest([free|_] = L, []) -> L;
longest([], [free|_] = L) -> L;
longest([], []) -> [].

trim_free([R|Rs0]) ->
    case {trim_free(Rs0),R} of
	{[],free} -> [];
	{Rs,R} -> [R|Rs]
    end;
trim_free([]) -> [].

%% adjust_stack(Bef, FirstBefore, LastFrom, Vdb) -> {[Ainstr],Aft}.
%%  Do complete stack adjustment by compressing stack and adding
%%  variables to be saved.  Try to optimise ordering on stack by
%%  having reverse order to their lifetimes.
%%
%%  In Beam, there is a fixed stack frame and no need to do stack compression.

adjust_stack(Bef, Fb, Lf, Vdb) ->
    Stk0 = Bef#sr.stk,
    {Stk1,Saves} = save_stack(Stk0, Fb, Lf, Vdb),
    {saves(Saves, Bef#sr.reg, Stk1),
     Bef#sr{stk=Stk1}}.

%% save_stack(Stack, FirstBefore, LastFrom, Vdb) -> {[SaveVar],NewStack}.
%%  Save variables which are used past current point and which are not
%%  already on the stack.

save_stack(Stk0, Fb, Lf, Vdb) ->
    %% New variables that are in use but not on stack.
    New = [VFL || {V,F,L} = VFL <- Vdb,
		  F < Fb,
		  L >= Lf,
		  not on_stack(V, Stk0)],
    %% Add new variables that are not just dropped immediately.
    %% N.B. foldr works backwards from the end!!
    Saves = [V || {V,_,_} <- keysort(3, New)],
    Stk1 = foldr(fun (V, Stk) -> put_stack(V, Stk) end, Stk0, Saves),
    {Stk1,Saves}.

%% saves([SaveVar], Reg, Stk) -> [{move,Reg,Stk}].
%%  Generate move instructions to save variables onto stack.  The
%%  stack/reg info used is that after the new stack has been made.

saves(Ss, Reg, Stk) ->
    [{move,fetch_reg(V, Reg),fetch_stack(V, Stk)} || V <- Ss].

%% fetch_var(VarName, StkReg) -> r{R} | sp{Sp}.
%% find_var(VarName, StkReg) -> ok{r{R} | sp{Sp}} | error.
%%  Fetch/find a variable in either the registers or on the
%%  stack. Fetch KNOWS it's there.

fetch_var(V, Sr) ->
    case find_reg(V, Sr#sr.reg) of
	{ok,R} -> R;
	error -> fetch_stack(V, Sr#sr.stk)
    end.

% find_var(V, Sr) ->
%     case find_reg(V, Sr#sr.reg) of
% 	{ok,R} -> {ok,R};
% 	error ->
% 	    case find_stack(V, Sr#sr.stk) of
% 		{ok,S} -> {ok,S};
% 		error -> error
% 	    end
%     end.

load_vars(Vs, Regs) ->
    foldl(fun ({var,V}, Rs) -> put_reg(V, Rs) end, Regs, Vs).

%% put_reg(Val, Regs) -> Regs.
%% free_reg(Val, Regs) -> Regs.
%% find_reg(Val, Regs) -> ok{r{R}} | error.
%% fetch_reg(Val, Regs) -> r{R}.
%%  Functions to interface the registers.
%%  put_reg puts a value into a free register,
%%  load_reg loads a value into a fixed register
%%  free_reg frees a register containing a specific value.

% put_regs(Vs, Rs) -> foldl(fun put_reg/2, Rs, Vs).

put_reg(V, Rs) -> put_reg_1(V, Rs, 0).

put_reg_1(V, [free|Rs], I) -> [{I,V}|Rs];
put_reg_1(V, [{reserved,I,V}|Rs], I) -> [{I,V}|Rs];
put_reg_1(V, [R|Rs], I) -> [R|put_reg_1(V, Rs, I+1)];
put_reg_1(V, [], I) -> [{I,V}].

% free_reg(V, [{I,V}|Rs]) -> [free|Rs];
% free_reg(V, [R|Rs]) -> [R|free_reg(V, Rs)];
% free_reg(V, []) -> [].

fetch_reg(V, [{I,V}|_]) -> {x,I};
fetch_reg(V, [_|SRs]) -> fetch_reg(V, SRs).

find_reg(V, [{I,V}|_]) -> {ok,{x,I}};
find_reg(V, [_|SRs]) -> find_reg(V, SRs);
find_reg(_, []) -> error.

%% For the bit syntax, we need a scratch register if we are constructing
%% a binary that will not be used.

find_scratch_reg(Rs) -> find_scratch_reg(Rs, 0).
    
find_scratch_reg([free|_], I) -> {x,I};
find_scratch_reg([_|Rs], I) -> find_scratch_reg(Rs, I+1);
find_scratch_reg([], I) -> {x,I}.

%%copy_reg(Val, R, Regs) -> load_reg(Val, R, Regs).
%%move_reg(Val, R, Regs) -> load_reg(Val, R, free_reg(Val, Regs)).

replace_reg_contents(Old, New, [{I,Old}|Rs]) -> [{I,New}|Rs];
replace_reg_contents(Old, New, [R|Rs]) -> [R|replace_reg_contents(Old, New, Rs)].

%%clear_regs(Regs) -> map(fun (R) -> free end, Regs).
clear_regs(_) -> [].

max_reg(Regs) ->
    foldl(fun ({I,_}, _) -> I;
	      (_, Max) -> Max end,
	  -1, Regs) + 1.

%% put_stack(Val, [{Val}]) -> [{Val}].
%% fetch_stack(Var, Stk) -> sp{S}.
%% find_stack(Var, Stk) -> ok{sp{S}} | error.
%%  Functions to interface the stack.

put_stack(Val, []) -> [{Val}];
put_stack(Val, [dead|Stk]) -> [{Val}|Stk];
put_stack(Val, [free|Stk]) -> [{Val}|Stk];
put_stack(Val, [NotFree|Stk]) -> [NotFree|put_stack(Val, Stk)].

put_stack_carefully(Val, Stk0) ->
    case catch put_stack_carefully1(Val, Stk0) of
	error -> error;
	Stk1 when is_list(Stk1) -> Stk1
    end.

put_stack_carefully1(_, []) -> throw(error);
put_stack_carefully1(Val, [dead|Stk]) -> [{Val}|Stk];
put_stack_carefully1(Val, [free|Stk]) -> [{Val}|Stk];
put_stack_carefully1(Val, [NotFree|Stk]) ->
    [NotFree|put_stack_carefully1(Val, Stk)].

fetch_stack(Var, Stk) -> fetch_stack(Var, Stk, 0).

fetch_stack(V, [{V}|_], I) -> {yy,I};
fetch_stack(V, [_|Stk], I) -> fetch_stack(V, Stk, I+1).

% find_stack(Var, Stk) -> find_stack(Var, Stk, 0).

% find_stack(V, [{V}|Stk], I) -> {ok,{yy,I}};
% find_stack(V, [O|Stk], I) -> find_stack(V, Stk, I+1);
% find_stack(V, [], I) -> error.

on_stack(V, Stk) -> keymember(V, 1, Stk).

is_register({x,_}) -> true;
is_register({yy,_}) -> true;
is_register(_) -> false.

%% put_catch(CatchTag, Stack) -> Stack'
%% drop_catch(CatchTag, Stack) -> Stack'
%%  Special interface for putting and removing catch tags, to ensure that
%%  catches nest properly. Also used for try tags.

put_catch(Tag, Stk0) -> put_catch(Tag, reverse(Stk0), []).

put_catch(Tag, [], Stk) ->
    put_stack({catch_tag,Tag}, Stk);
put_catch(Tag, [{{catch_tag,_}}|_]=RevStk, Stk) ->
    reverse(RevStk, put_stack({catch_tag,Tag}, Stk));
put_catch(Tag, [Other|Stk], Acc) ->
    put_catch(Tag, Stk, [Other|Acc]).

drop_catch(Tag, [{{catch_tag,Tag}}|Stk]) -> [free|Stk];
drop_catch(Tag, [Other|Stk]) -> [Other|drop_catch(Tag, Stk)].

%% new_label(St) -> {L,St}.

new_label(#cg{lcount=Next}=St) ->
    {Next,St#cg{lcount=Next+1}}.

%% line(Le) -> {line,[] | {location,File,Line}}
%%  Create a line instruction, containing information about
%%  the current filename and line number. A line information
%%  instruction should be placed before any operation that could
%%  cause an exception.

line(#l{a=Anno}) ->
    line(Anno);
line([Line,{file,Name}]) when is_integer(Line) ->
    line_1(Name, Line);
line([_|_]=A) ->
    {Name,Line} = find_loc(A, no_file, 0),
    line_1(Name, Line);
line([]) ->
    {line,[]}.

line_1(no_file, _) ->
    {line,[]};
line_1(_, 0) ->
    %% Missing line number or line number 0.
    {line,[]};
line_1(Name, Line) ->
    {line,[{location,Name,Line}]}.

find_loc([Line|T], File, _) when is_integer(Line) ->
    find_loc(T, File, Line);
find_loc([{file,File}|T], _, Line) ->
    find_loc(T, File, Line);
find_loc([_|T], File, Line) ->
    find_loc(T, File, Line);
find_loc([], File, Line) -> {File,Line}.

flatmapfoldl(F, Accu0, [Hd|Tail]) ->
    {R,Accu1} = F(Hd, Accu0),
    {Rs,Accu2} = flatmapfoldl(F, Accu1, Tail),
    {R++Rs,Accu2};
flatmapfoldl(_, Accu, []) -> {[],Accu}.