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authorMagnus Lång <[email protected]>2016-11-15 13:37:19 +0100
committerMagnus Lång <[email protected]>2016-11-15 14:58:59 +0100
commitbd898fab5d86ff44ce3129db9a06a5c709719392 (patch)
tree7aca352682b8d1add3e30f716dd42d52d1f803f8 /lib
parent3579a706ea0c0081d7dd01291990cd8d3669f195 (diff)
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hipe_x86: Fix&activate ElimCmp0 peephole rule
Diffstat (limited to 'lib')
-rw-r--r--lib/hipe/x86/hipe_x86_postpass.erl22
1 files changed, 9 insertions, 13 deletions
diff --git a/lib/hipe/x86/hipe_x86_postpass.erl b/lib/hipe/x86/hipe_x86_postpass.erl
index 4515822a34..bd232041b6 100644
--- a/lib/hipe/x86/hipe_x86_postpass.erl
+++ b/lib/hipe/x86/hipe_x86_postpass.erl
@@ -120,19 +120,15 @@ peep([#move{src=Src1, dst=Dst},
%% ElimCmp0
%% --------
-peep([C=#cmp{src=Src, dst=Dst},J=#jcc{cc=Cond, label=Lab}|Insns],Res,Lst) ->
- case (((Src =:= #x86_imm{value=0}) or (Dst =:= #x86_imm{value=0})) and
- ((Cond =:= 'eq') or (Cond =:= 'neq'))) of
- true ->
- Src2 = case Src of #x86_imm{value=0} -> Src; _ -> Dst end,
- Cond2 = case Cond of 'eq' -> 'z'; 'neq' -> 'nz' end,
- Test = #test{src=Src2, dst=#x86_imm{value=0}},
- Jump = #jcc{cc=Cond2, label=Lab},
- peep(Insns, [Jump, Test|Res], [elimCmp0|Lst]);
- _ ->
- peep(Insns, [J,C|Res], Lst)
- end;
-
+peep([#cmp{src=#x86_imm{value=0}, dst=Dst=#x86_temp{}}|Insns],Res,Lst) ->
+ %% TEST leaves the adjust flag undefined, whereas CMP sets it properly (in
+ %% this case to 0). However, since HiPE does not use any instructions that
+ %% read the adjust flag, we can do this transform safely.
+ peep(Insns, [#test{src=Dst, dst=Dst} | Res], [elimCmp0_1|Lst]);
+peep([#cmp{src=Src=#x86_temp{}, dst=#x86_imm{value=0}},
+ J=#jcc{cc=Cond}|Insns],Res,Lst)
+ when Cond =:= 'e'; Cond =:= 'ne' -> % We're commuting the comparison
+ peep(Insns, [J, #test{src=Src, dst=Src} | Res], [elimCmp0_2|Lst]);
%% ElimCmpTest
%% -----------