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+ Add nice little peephole trick

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git-svn-id: trunk@2602 -
This commit is contained in:
daniel 2006-02-15 22:03:07 +00:00
parent 6974105177
commit e138c9c081
1 changed files with 38 additions and 0 deletions
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38
compiler/i386/popt386.pas
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@ -409,6 +409,7 @@ var
l : longint;
p,hp1,hp2 : tai;
hp3,hp4: tai;
v:aint;
TmpRef: TReference;
@ -695,6 +696,43 @@ begin
end;
A_CMP:
begin
{ cmp register,$8000 neg register
je target --> jo target
.... only if register is deallocated before jump.}
case Taicpu(p).opsize of
S_B: v:=$80;
S_W: v:=$8000;
S_L: v:=$80000000;
end;
if (taicpu(p).oper[0]^.typ=Top_const) and
(taicpu(p).oper[0]^.val=v) and
(Taicpu(p).oper[1]^.typ=top_reg) and
GetNextInstruction(p, hp1) and
(hp1.typ=ait_instruction) and
(taicpu(hp1).opcode=A_Jcc) and
(Taicpu(hp1).condition in [C_E,C_NE]) and
not(getsupreg(Taicpu(p).oper[1]^.reg) in usedregs) then
begin
Taicpu(p).opcode:=A_NEG;
Taicpu(p).loadoper(0,Taicpu(p).oper[1]^);
Taicpu(p).clearop(1);
Taicpu(p).ops:=1;
if Taicpu(hp1).condition=C_E then
Taicpu(hp1).condition:=C_O
else
Taicpu(hp1).condition:=C_NO;
continue;
end;
{
@@2: @@2:
.... ....
cmp operand1,0
jle/jbe @@1
dec operand1 --> sub operand1,1
jmp @@2 jge/jae @@2
@@1: @@1:
... ....}
if (taicpu(p).oper[0]^.typ = top_const) and
(taicpu(p).oper[1]^.typ in [top_reg,top_ref]) and
(taicpu(p).oper[0]^.val = 0) and