hipe: Add pseudo_spill_f?move instructions

These pseudo instructions are added to all backends and allow spill slot
to spill slot move coalescing in a clean way.

They have regular move semantics, but contain an additional scratch
register to be used if both source and destination are spilled, and can
not be move coalesced.

Additionally, a register allocator callback
Target:is_spill_move(Instr, Context) is added which allows the spill
slot allocators to check for these instructions and try to coalesce the
spill slots the two temporaries are allocated to.

1 files changed, 13 insertions, 5 deletions

diff --git a/lib/hipe/sparc/hipe_sparc_ra_postconditions_fp.erl b/lib/hipe/sparc/hipe_sparc_ra_postconditions_fp.erl
index 751e91425c..5fa3a5fc59 100644
--- a/lib/hipe/sparc/hipe_sparc_ra_postconditions_fp.erl
+++ b/lib/hipe/sparc/hipe_sparc_ra_postconditions_fp.erl
@@ -43,6 +43,7 @@ do_insn(I, TempMap) ->
     #pseudo_fload{} -> do_pseudo_fload(I, TempMap);
     #pseudo_fmove{} -> do_pseudo_fmove(I, TempMap);
     #pseudo_fstore{} -> do_pseudo_fstore(I, TempMap);
+    #pseudo_spill_fmove{} -> do_pseudo_spill_fmove(I, TempMap);
     _ -> {[I], false}
   end.
 
@@ -67,11 +68,13 @@ do_pseudo_fload(I=#pseudo_fload{dst=Dst}, TempMap) ->
   {[NewI | FixDst], DidSpill}.
 
 do_pseudo_fmove(I=#pseudo_fmove{src=Src,dst=Dst}, TempMap) ->
-  case temp_is_spilled(Dst, TempMap) of
-    true ->
-      {FixSrc,NewSrc,DidSpill} = fix_src(Src, TempMap),
-      NewI = I#pseudo_fmove{src=NewSrc},
-      {FixSrc ++ [NewI], DidSpill};
+  case temp_is_spilled(Src, TempMap)
+    andalso temp_is_spilled(Dst, TempMap)
+  of
+    true -> % Turn into pseudo_spill_fmove
+      Temp = clone(Src),
+      NewI = #pseudo_spill_fmove{src=Src,temp=Temp,dst=Dst},
+      {[NewI], true};
     _ ->
       {[I], false}
   end.
@@ -81,6 +84,11 @@ do_pseudo_fstore(I=#pseudo_fstore{src=Src}, TempMap) ->
   NewI = I#pseudo_fstore{src=NewSrc},
   {FixSrc ++ [NewI], DidSpill}.
 
+do_pseudo_spill_fmove(I=#pseudo_spill_fmove{temp=Temp}, TempMap) ->
+  %% Temp is above the low water mark and must not have been spilled
+  false = temp_is_spilled(Temp, TempMap),
+  {[I], false}.
+
 %%% Fix Dst and Src operands.
 
 fix_src(Src, TempMap) ->