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New Movz ###,%ecx, shift/rotate %cl,... optimisation

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J. Gareth "Curious Kit" Moreton 2021-12-04 08:06:25 +00:00 committed by FPK
parent f02b7508de
commit 4825d2d16c
1 changed files with 95 additions and 2 deletions
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97
compiler/x86/aoptx86.pas
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@ -7959,6 +7959,100 @@ unit aoptx86;
begin
Result := False;
p_removed := False;
ThisReg := taicpu(p).oper[1]^.reg;
{ Check for:
movs/z ###,%ecx (or %cx or %rcx)
...
shl/shr/sar/rcl/rcr/ror/rol %cl,###
(dealloc %ecx)
Change to:
mov ###,%cl (if ### = %cl, then remove completely)
...
shl/shr/sar/rcl/rcr/ror/rol %cl,###
}
if (getsupreg(ThisReg) = RS_ECX) and
GetNextInstructionUsingReg(p, hp1, NR_ECX) and
(hp1.typ = ait_instruction) and
(
{ Under -O1 and -O2, GetNextInstructionUsingReg may return an
instruction that doesn't actually contain ECX }
(cs_opt_level3 in current_settings.optimizerswitches) or
RegInInstruction(NR_ECX, hp1) or
(
{ It's common for the shift/rotate's read/write register to be
initialised in between, so under -O2 and under, search ahead
one more instruction
}
GetNextInstruction(hp1, hp1) and
(hp1.typ = ait_instruction) and
RegInInstruction(NR_ECX, hp1)
)
) and
MatchInstruction(hp1, [A_SHL, A_SHR, A_SAR, A_ROR, A_ROL, A_RCR, A_RCL], []) and
(taicpu(hp1).oper[0]^.typ = top_reg) { This is enough to determine that it's %cl } then
begin
TransferUsedRegs(TmpUsedRegs);
hp2 := p;
repeat
UpdateUsedRegs(TmpUsedRegs, tai(hp2.Next));
until not GetNextInstruction(hp2, hp2) or (hp2 = hp1);
if not RegUsedAfterInstruction(NR_CL, hp1, TmpUsedRegs) then
begin
case taicpu(p).opsize of
S_BW, S_BL{$ifdef x86_64}, S_BQ{$endif x86_64}:
if MatchOperand(taicpu(p).oper[0]^, NR_CL) then
begin
DebugMsg(SPeepholeOptimization + 'MovxOp2Op 3a', p);
RemoveCurrentP(p);
end
else
begin
taicpu(p).opcode := A_MOV;
taicpu(p).opsize := S_B;
taicpu(p).oper[1]^.reg := NR_CL;
DebugMsg(SPeepholeOptimization + 'MovxOp2MovOp 1', p);
end;
S_WL{$ifdef x86_64}, S_WQ{$endif x86_64}:
if MatchOperand(taicpu(p).oper[0]^, NR_CX) then
begin
DebugMsg(SPeepholeOptimization + 'MovxOp2Op 3b', p);
RemoveCurrentP(p);
end
else
begin
taicpu(p).opcode := A_MOV;
taicpu(p).opsize := S_W;
taicpu(p).oper[1]^.reg := NR_CX;
DebugMsg(SPeepholeOptimization + 'MovxOp2MovOp 2', p);
end;
{$ifdef x86_64}
S_LQ:
if MatchOperand(taicpu(p).oper[0]^, NR_ECX) then
begin
DebugMsg(SPeepholeOptimization + 'MovxOp2Op 3c', p);
RemoveCurrentP(p);
end
else
begin
taicpu(p).opcode := A_MOV;
taicpu(p).opsize := S_L;
taicpu(p).oper[1]^.reg := NR_ECX;
DebugMsg(SPeepholeOptimization + 'MovxOp2MovOp 3', p);
end;
{$endif x86_64}
else
InternalError(2021120401);
end;
Result := True;
Exit;
end;
end;
{ This is anything but quick! }
if not(cs_opt_level2 in current_settings.optimizerswitches) then
@ -7966,7 +8060,6 @@ unit aoptx86;
SetLength(InstrList, 0);
InstrMax := -1;
ThisReg := taicpu(p).oper[1]^.reg;
case taicpu(p).opsize of
S_BW, S_BL:
@ -9847,7 +9940,7 @@ unit aoptx86;
if not RegUsed then
begin
DebugMsg(SPeepholeOptimization + 'MovxOp2Op',p);
DebugMsg(SPeepholeOptimization + 'MovxOp2Op 1',p);
if taicpu(p).oper[0]^.typ=top_reg then
begin
case taicpu(hp1).opsize of