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+ peephole optimizer: change jmp .L1 ... .L1: ret into ret

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git-svn-id: trunk@33523 -
This commit is contained in:
florian 2016-04-15 19:11:43 +00:00
parent e566fe1938
commit 2dbcdbe466
1 changed files with 48 additions and 18 deletions
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66
compiler/i386/popt386.pas
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@ -470,6 +470,24 @@ begin
end;
end;
{ skips all labels and returns the next "real" instruction }
function SkipLabels(hp: tai; var hp2: tai): boolean;
begin
while assigned(hp.next) and
(tai(hp.next).typ in SkipInstr + [ait_label,ait_align]) Do
hp := tai(hp.next);
if assigned(hp.next) then
begin
SkipLabels := True;
hp2 := tai(hp.next)
end
else
begin
hp2 := hp;
SkipLabels := False
end;
end;
{ First pass of peephole optimizations }
procedure PeepHoleOptPass1(Asml: TAsmList; BlockStart, BlockEnd: tai);
@ -503,24 +521,6 @@ var
TmpBool1, TmpBool2: Boolean;
function SkipLabels(hp: tai; var hp2: tai): boolean;
{skips all labels and returns the next "real" instruction}
begin
while assigned(hp.next) and
(tai(hp.next).typ in SkipInstr + [ait_label,ait_align]) Do
hp := tai(hp.next);
if assigned(hp.next) then
begin
SkipLabels := True;
hp2 := tai(hp.next)
end
else
begin
hp2 := hp;
SkipLabels := False
end;
end;
function GetFinalDestination(asml: TAsmList; hp: taicpu; level: longint): boolean;
{traces sucessive jumps to their final destination and sets it, e.g.
je l1 je l3
@ -2152,6 +2152,36 @@ begin
hp1.free;
end;
end;
A_JMP:
{
change
jmp .L1
...
.L1:
ret
into
ret
}
if (taicpu(p).oper[0]^.typ=top_ref) and (taicpu(p).oper[0]^.ref^.refaddr=addr_full) then
begin
hp1:=dfa.getlabelwithsym(tasmlabel(taicpu(p).oper[0]^.ref^.symbol));
if assigned(hp1) and SkipLabels(hp1,hp1) and (hp1.typ=ait_instruction) and (taicpu(hp1).opcode=A_RET) and (taicpu(p).condition=C_None) then
begin
tasmlabel(taicpu(p).oper[0]^.ref^.symbol).decrefs;
taicpu(p).opcode:=A_RET;
taicpu(p).is_jmp:=false;
taicpu(p).ops:=taicpu(hp1).ops;
case taicpu(hp1).ops of
0:
taicpu(p).clearop(0);
1:
taicpu(p).loadconst(0,taicpu(hp1).oper[0]^.val);
else
internalerror(2016041301);
end;
continue;
end;
end;
A_MOV:
begin
if (taicpu(p).oper[0]^.typ = top_reg) and