Fix matching with huge binaries

In certain cases of matching with very big binaries, the HiPE compiler
generated code that would fail the match, even in cases that the matching
was successful.  The problem was more quite noticeable on 32-bit platforms
where certain integer quantities would be represented as bignums.

Brief summary of changes:

 * gen_rtl({bs_skip_bits, ...}, ...) could not handle too large constants.
   Previously the constants were truncated to word size.

 * hipe_rtl_binary_match:make_size/3 erroneously assumed that the output
   of first_part/3 would not overflow when multiplied by 8, which is no
   longer true. To maintain full performance, the overflow test is only
   performed when BitsVar was a bignum. Thus, the fast path is identical
   to before.

 * hipe_rtl_binary_match:set_high/2 was assuming that only bits below
   bit 27 were ever set in arguments to bs_skip_bits, which is not only
   false when the arguments are bignums, but also on 64-bit platforms.

The commit includes a test taken from the bs_match_bin_SUITE.

Most of the credit for finding these HiPE compiler errors and for
creating appropriate fixes for them should go to Magnus Lång.

1 files changed, 59 insertions, 22 deletions

diff --git a/lib/hipe/rtl/hipe_rtl_binary_match.erl b/lib/hipe/rtl/hipe_rtl_binary_match.erl
index 37263a951a..51213b71d1 100644
--- a/lib/hipe/rtl/hipe_rtl_binary_match.erl
+++ b/lib/hipe/rtl/hipe_rtl_binary_match.erl
@@ -233,14 +233,26 @@ gen_rtl({bs_skip_bits_all, Unit, _Flags}, Dst, [Ms],
     skip_bits_all(Unit, Ms, TrueLblName, FalseLblName);
 %% ----- bs_skip_bits -----
 gen_rtl({bs_skip_bits, Bits}, Dst, [Ms|Args], TrueLblName, FalseLblName) ->
+  MaxValue = (1 bsl (hipe_rtl_arch:word_size() * ?BYTE_SIZE)),
   opt_update_ms(Dst, Ms) ++
-    case Args of
-      [] ->
-	skip_bits2(Ms, hipe_rtl:mk_imm(Bits), TrueLblName, FalseLblName);
-      [Arg] ->
-	{SizeCode, SizeReg} = make_size(Bits, Arg, FalseLblName),
-	InCode = skip_bits2(Ms, SizeReg, TrueLblName, FalseLblName),
-	SizeCode ++ InCode
+    case Bits < MaxValue of
+      true ->
+	case Args of
+	  [] ->
+	    skip_bits2(Ms, hipe_rtl:mk_imm(Bits), TrueLblName, FalseLblName);
+	  [Arg] ->
+	    {SizeCode, SizeReg} = make_size(Bits, Arg, FalseLblName),
+	    InCode = skip_bits2(Ms, SizeReg, TrueLblName, FalseLblName),
+	    SizeCode ++ InCode
+	end;
+      false -> % handle overflow case
+	case Args of
+	  [] ->
+	    [hipe_rtl:mk_goto(FalseLblName)];
+	  [Arg] ->
+	    [hipe_rtl:mk_branch(Arg, 'eq', hipe_tagscheme:mk_fixnum(0),
+				TrueLblName, FalseLblName, 0.5)]
+	end
     end;
 %% ----- bs_restore -----
 gen_rtl({bs_restore, Slot}, [NewMs], [Ms], TrueLblName, _FalseLblName) ->
@@ -1089,23 +1101,47 @@ create_gcsafe_regs(0) ->
   [].
 
 first_part(Var, Register, FalseLblName) ->
-  [SuccessLbl1, SuccessLbl2] = create_lbls(2),
-  [hipe_tagscheme:test_fixnum(Var, hipe_rtl:label_name(SuccessLbl1),
-			      FalseLblName, 0.99),
-  SuccessLbl1,
-  hipe_tagscheme:fixnum_ge(Var, hipe_rtl:mk_imm(hipe_tagscheme:mk_fixnum(0)), 
-			   hipe_rtl:label_name(SuccessLbl2), FalseLblName, 0.99),
-  SuccessLbl2,
-  hipe_tagscheme:untag_fixnum(Register, Var)].
+  [EndLbl] = create_lbls(1),
+  EndName = hipe_rtl:label_name(EndLbl),
+  first_part(Var, Register, FalseLblName, EndName, EndName, [EndLbl]).
+
+first_part(Var, Register, FalseLblName, TrueLblName, BigLblName, Tail) ->
+  [FixnumLbl, NotFixnumLbl, BignumLbl, SuccessLbl] = create_lbls(4),
+  [hipe_tagscheme:test_fixnum(Var, hipe_rtl:label_name(FixnumLbl),
+			      hipe_rtl:label_name(NotFixnumLbl), 0.99),
+   FixnumLbl,
+   hipe_tagscheme:fixnum_ge(Var, hipe_rtl:mk_imm(hipe_tagscheme:mk_fixnum(0)),
+			    hipe_rtl:label_name(SuccessLbl), FalseLblName,
+			    0.99),
+   SuccessLbl,
+   hipe_tagscheme:untag_fixnum(Register, Var),
+   hipe_rtl:mk_goto(TrueLblName),
+   NotFixnumLbl,
+   %% Since binaries are not allowed to be larger than 2^wordsize bits
+   %% and since bignum digits are words, we know that a bignum with an
+   %% arity larger than one can't match.
+   hipe_tagscheme:test_pos_bignum_arity(Var, 1, hipe_rtl:label_name(BignumLbl),
+					FalseLblName, 0.99),
+   BignumLbl,
+   hipe_tagscheme:unsafe_get_one_word_pos_bignum(Register, Var),
+   hipe_rtl:mk_goto(BigLblName) | Tail].
 
 make_size(1, BitsVar, FalseLblName) ->
   [DstReg] = create_regs(1),
   {first_part(BitsVar, DstReg, FalseLblName), DstReg};
 make_size(?BYTE_SIZE, BitsVar, FalseLblName) ->
   [DstReg] = create_regs(1),
-  Code = 
-    first_part(BitsVar, DstReg, FalseLblName) ++
-    [hipe_rtl:mk_alu(DstReg, DstReg, sll, hipe_rtl:mk_imm(?BYTE_SHIFT))],
+  [FixnumLbl, BignumLbl] = create_lbls(2),
+  WordBits = hipe_rtl_arch:word_size() * ?BYTE_SIZE,
+  FixnumLblName = hipe_rtl:label_name(FixnumLbl),
+  Tail = [BignumLbl,
+	  hipe_rtl:mk_branch(DstReg, 'ltu',
+			     hipe_rtl:mk_imm(1 bsl (WordBits - ?BYTE_SHIFT)),
+			     FixnumLblName, FalseLblName, 0.99),
+	  FixnumLbl,
+	  hipe_rtl:mk_alu(DstReg, DstReg, sll, hipe_rtl:mk_imm(?BYTE_SHIFT))],
+  Code = first_part(BitsVar, DstReg, FalseLblName, FixnumLblName,
+		    hipe_rtl:label_name(BignumLbl), Tail),
   {Code, DstReg};
 make_size(UnitImm, BitsVar, FalseLblName) ->
   [DstReg] = create_regs(1),
@@ -1154,12 +1190,13 @@ floorlog2(X) ->
   round(math:log(X)/math:log(2)-0.5). 
 
 set_high(X) ->
-  set_high(X, 0).
+  WordBits = hipe_rtl_arch:word_size() * ?BYTE_SIZE,
+  set_high(min(X, WordBits), WordBits, 0).
 
-set_high(0, Y) ->
+set_high(0, _, Y) ->
   Y;
-set_high(X, Y) ->
-  set_high(X-1, Y+(1 bsl (27-X))).
+set_high(X, WordBits, Y) ->
+  set_high(X-1, WordBits, Y+(1 bsl (WordBits-X))).
 
 is_illegal_const(Const) ->
   Const >=  1 bsl (hipe_rtl_arch:word_size() * ?BYTE_SIZE) orelse Const < 0.