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-rw-r--r--lib/hipe/rtl/hipe_tagscheme.erl15
1 files changed, 10 insertions, 5 deletions
diff --git a/lib/hipe/rtl/hipe_tagscheme.erl b/lib/hipe/rtl/hipe_tagscheme.erl
index 8d9514ae82..305aacb571 100644
--- a/lib/hipe/rtl/hipe_tagscheme.erl
+++ b/lib/hipe/rtl/hipe_tagscheme.erl
@@ -510,21 +510,26 @@ unsafe_fixnum_sub(Arg1, Arg2, Res) ->
%%% (16X+tag)+((16Y+tag)-tag) = 16X+tag+16Y = 16(X+Y)+tag
%%% (16X+tag)-((16Y+tag)-tag) = 16X+tag-16Y = 16(X-Y)+tag
fixnum_addsub(AluOp, Arg1, Arg2, Res, OtherLab) ->
- Tmp = hipe_rtl:mk_new_reg_gcsafe(),
+ NoOverflowLab = hipe_rtl:mk_new_label(),
%% XXX: Consider moving this test to the users of fixnum_addsub.
case Arg1 =/= Res andalso Arg2 =/= Res of
true ->
%% Args differ from res.
- NoOverflowLab = hipe_rtl:mk_new_label(),
- [hipe_rtl:mk_alu(Tmp, Arg2, sub, hipe_rtl:mk_imm(?TAG_IMMED1_SMALL)),
- hipe_rtl:mk_alub(Res, Arg1, AluOp, Tmp, not_overflow,
+ %% Commute add to save a move on x86
+ {UntagFirst, Lhs, Rhs} =
+ case AluOp of
+ 'add' -> {Arg1, Res, Arg2};
+ 'sub' -> {Arg2, Arg1, Res}
+ end,
+ [hipe_rtl:mk_alu(Res, UntagFirst, sub, hipe_rtl:mk_imm(?TAG_IMMED1_SMALL)),
+ hipe_rtl:mk_alub(Res, Lhs, AluOp, Rhs, not_overflow,
hipe_rtl:label_name(NoOverflowLab),
hipe_rtl:label_name(OtherLab), 0.99),
NoOverflowLab];
false ->
%% At least one of the arguments is the same as Res.
+ Tmp = hipe_rtl:mk_new_reg_gcsafe(),
Tmp2 = hipe_rtl:mk_new_var(), % XXX: shouldn't this var be a reg?
- NoOverflowLab = hipe_rtl:mk_new_label(),
[hipe_rtl:mk_alu(Tmp, Arg2, sub, hipe_rtl:mk_imm(?TAG_IMMED1_SMALL)),
hipe_rtl:mk_alub(Tmp2, Arg1, AluOp, Tmp, not_overflow,
hipe_rtl:label_name(NoOverflowLab),