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* x86: TEST and CMP optimisations now perform jump optimisations prematurely to remove unnecessary TEST/CMPs

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This commit is contained in:
J. Gareth "Curious Kit" Moreton 2022-11-15 16:20:09 +00:00 committed by J. Gareth "Kit" Moreton
parent c1ec558d0a
commit e57ef24e37
1 changed files with 93 additions and 1 deletions
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94
compiler/x86/aoptx86.pas
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@ -5019,6 +5019,7 @@ unit aoptx86;
hp1, p_label, p_dist, hp1_dist: tai;
JumpLabel, JumpLabel_dist: TAsmLabel;
FirstValue, SecondValue: TCGInt;
TempBool: Boolean;
begin
Result := False;
if (taicpu(p).oper[0]^.typ = top_const) and
@ -5064,6 +5065,44 @@ unit aoptx86;
Exit;
end;
if MatchInstruction(hp1, A_Jcc, []) then
begin
TempBool := True;
if DoJumpOptimizations(hp1, TempBool) or
not TempBool then
begin
Result := True;
if Assigned(hp1) then
begin
if (hp1.typ in [ait_align]) then
SkipAligns(hp1, hp1);
{ CollapseZeroDistJump will be set to the label after the
jump if it optimises, whether or not it's live or dead }
if (hp1.typ in [ait_label]) and
not (tai_label(hp1).labsym.is_used) then
GetNextInstruction(hp1, hp1);
end;
TransferUsedRegs(TmpUsedRegs);
UpdateUsedRegs(TmpUsedRegs, tai(p.Next));
if not Assigned(hp1) or
(
not MatchInstruction(hp1, A_Jcc, A_SETcc, A_CMOVcc, []) and
not RegUsedAfterInstruction(NR_DEFAULTFLAGS, hp1, TmpUsedRegs)
) then
begin
{ No more conditional jumps; conditional statement is no longer required }
DebugMsg(SPeepholeOptimization + 'Removed unnecessary condition (Test2Nop)', p);
RemoveCurrentP(p);
end;
Exit;
end;
end;
{ Search for:
test $x,(reg/ref)
jne @lbl1
@ -7233,7 +7272,7 @@ unit aoptx86;
var
v: TCGInt;
hp1, hp2, p_dist, p_jump, hp1_dist, p_label, hp1_label: tai;
FirstMatch: Boolean;
FirstMatch, TempBool: Boolean;
NewReg: TRegister;
JumpLabel, JumpLabel_dist, JumpLabel_far: TAsmLabel;
begin
@ -7263,7 +7302,60 @@ unit aoptx86;
begin
if IsJumpToLabel(taicpu(p_jump)) then
begin
{ Do jump optimisations first in case the condition becomes
unnecessary }
TempBool := True;
if DoJumpOptimizations(p_jump, TempBool) or
not TempBool then
begin
if Assigned(p_jump) then
begin
hp1 := p_jump;
if (p_jump.typ in [ait_align]) then
SkipAligns(p_jump, p_jump);
{ CollapseZeroDistJump will be set to the label after the
jump if it optimises, whether or not it's live or dead }
if (p_jump.typ in [ait_label]) and
not (tai_label(p_jump).labsym.is_used) then
GetNextInstruction(p_jump, p_jump);
end;
TransferUsedRegs(TmpUsedRegs);
UpdateUsedRegs(TmpUsedRegs, tai(p.Next));
if not Assigned(p_jump) or
(
not MatchInstruction(p_jump, A_Jcc, A_SETcc, A_CMOVcc, []) and
not RegUsedAfterInstruction(NR_DEFAULTFLAGS, p_jump, TmpUsedRegs)
) then
begin
{ No more conditional jumps; conditional statement is no longer required }
DebugMsg(SPeepholeOptimization + 'Removed unnecessary condition (Cmp2Nop)', p);
RemoveCurrentP(p);
Result := True;
Exit;
end;
hp1 := p_jump;
Include(OptsToCheck, aoc_ForceNewIteration);
Continue;
end;
JumpLabel := TAsmLabel(taicpu(p_jump).oper[0]^.ref^.symbol);
if GetNextInstruction(p_jump, hp2) and
(
OptimizeConditionalJump(JumpLabel, p_jump, hp2, TempBool) or
not TempBool
) then
begin
hp1 := p_jump;
Include(OptsToCheck, aoc_ForceNewIteration);
Continue;
end;
p_label := nil;
if Assigned(JumpLabel) then
p_label := getlabelwithsym(JumpLabel);