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* a64: New movz reg,#0 -> mov reg,xzr (or wzr) optimisation

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This commit is contained in:
J. Gareth "Curious Kit" Moreton 2022-05-15 18:16:39 +01:00 committed by FPK
parent 6c47f8f4d7
commit 637645b6d6
1 changed files with 53 additions and 4 deletions

57
compiler/aarch64/aoptcpu.pas
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@ -59,6 +59,7 @@ Interface
function OptPass1FData(var p: tai): Boolean;
function OptPass1STP(var p: tai): boolean;
function OptPass1Mov(var p: tai): boolean;
function OptPass1MOVZ(var p: tai): boolean;
function OptPass1FMov(var p: tai): Boolean;
function OptPass2LDRSTR(var p: tai): boolean;
@ -530,11 +531,13 @@ Implementation
end
else if GetNextInstruction(p, hp1) and
MatchInstruction(hp1,[A_ADD,A_SUB],[taicpu(p).condition], [PF_None,PF_S]) and
(taicpu(p).ops=2) and
(taicpu(hp1).ops=3) and
else if (taicpu(p).ops=2) and
(getsubreg(taicpu(p).oper[0]^.reg)=R_SUBD) and
GetNextInstruction(p, hp1) and
{ Faster to get it out of the way than go through MatchInstruction }
(hp1.typ=ait_instruction) and
(taicpu(hp1).ops=3) and
MatchInstruction(hp1,[A_ADD,A_SUB],[taicpu(p).condition], [PF_None,PF_S]) and
(getsubreg(taicpu(hp1).oper[2]^.reg)=R_SUBQ) and
(getsupreg(taicpu(p).oper[0]^.reg)=getsupreg(taicpu(hp1).oper[2]^.reg)) and
RegEndOfLife(taicpu(hp1).oper[2]^.reg,taicpu(hp1)) then
@ -566,6 +569,50 @@ Implementation
end;
function TCpuAsmOptimizer.OptPass1MOVZ(var p: tai): boolean;
var
hp1: tai;
ZeroReg: TRegister;
begin
Result := False;
hp1 := nil;
if (taicpu(p).oppostfix = PF_None) and (taicpu(p).condition = C_None) then
begin
if
{ Check next instruction first so hp1 gets set to something, then
if it remains nil, we know for sure that there's no valid next
instruction. }
not GetNextInstruction(p, hp1) or
{ MOVZ and MOVK/MOVN instructions undergo macro-fusion. }
not MatchInstruction(hp1, [A_MOVK, A_MOVN], [C_None], [PF_None]) or
(taicpu(hp1).oper[0]^.reg <> taicpu(p).oper[0]^.reg) then
begin
if (taicpu(p).oper[1]^.val = 0) then
begin
{ Change;
movz reg,#0
(no movk or movn)
To:
mov reg,xzr (or wzr)
Easier to perform other optimisations with registers
}
DebugMsg(SPeepholeOptimization + 'Movz0ToMovZeroReg', p);
{ Make sure the zero register is the correct size }
ZeroReg := taicpu(p).oper[0]^.reg;
setsupreg(ZeroReg, RS_XZR);
taicpu(p).opcode := A_MOV;
taicpu(p).loadreg(1, ZeroReg);
Result := True;
Exit;
end;
end;
end;
end;
function TCpuAsmOptimizer.OptPass1FMov(var p: tai): Boolean;
var
hp1: tai;
@ -910,6 +957,8 @@ Implementation
Result:=OptPass1STR(p);
A_MOV:
Result:=OptPass1Mov(p);
A_MOVZ:
Result:=OptPass1MOVZ(p);
A_STP:
Result:=OptPass1STP(p);
A_LSR,