diff options
Diffstat (limited to 'lib/hipe/x86/hipe_x86_postpass.erl')
| -rw-r--r-- | lib/hipe/x86/hipe_x86_postpass.erl | 39 |
1 files changed, 26 insertions, 13 deletions
diff --git a/lib/hipe/x86/hipe_x86_postpass.erl b/lib/hipe/x86/hipe_x86_postpass.erl index 4515822a34..f88a841cca 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 %% ----------- @@ -187,6 +183,18 @@ peep([B = #alu{aluop=Op,src=#x86_imm{value=Val},dst=Dst}|Insns], Res, Lst) -> peep(Insns, [B|Res], Lst) end; +%% LeaToAdd +%% This rule transforms lea into add when the destination is the same as one of +%% the operands. Sound because lea is never used where the condition codes are +%% live (and would be clobbered by add). +%% ---------- +peep([#lea{mem=#x86_mem{base=#x86_temp{reg=DstR},off=Src}, + temp=Dst=#x86_temp{reg=DstR}}|Insns], Res, Lst) -> + peep(Insns, [#alu{aluop='add',src=Src,dst=Dst}|Res], [leaToAdd|Lst]); +peep([#lea{mem=#x86_mem{base=Src,off=#x86_temp{reg=DstR}}, + temp=Dst=#x86_temp{reg=DstR}}|Insns], Res, Lst) -> + peep(Insns, [#alu{aluop='add',src=Src,dst=Dst}|Res], [leaToAdd|Lst]); + %% SubToDec %% This rule turns "subl $1,Dst; jl Lab" into "decl Dst; jl Lab", which %% changes reduction counter tests to use decl instead of subl. @@ -209,6 +217,11 @@ trivial_goto_elimination(Insns) -> goto_elim(Insns, []). goto_elim([#jmp_label{label=Label}, I = #label{label=Label}|Insns], Res) -> goto_elim([I|Insns], Res); +goto_elim([#jcc{cc=CC, label=Label} = IJCC, + #jmp_label{label=BranchTgt}, + #label{label=Label} = ILBL|Insns], Res) -> + goto_elim([IJCC#jcc{cc=hipe_x86:neg_cc(CC), label=BranchTgt}, + ILBL|Insns], Res); goto_elim([I | Insns], Res) -> goto_elim(Insns, [I|Res]); goto_elim([], Res) -> |