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* Improvement to TEST/JNE/TEST/JNE code to be more accurate where register deallocations are concerned

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J. Gareth "Curious Kit" Moreton 2023-07-27 19:24:03 +01:00 committed by J. Gareth "Kit" Moreton
parent 699db16fe4
commit dde19c0144
1 changed files with 19 additions and 5 deletions
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24
compiler/x86/aoptx86.pas
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@ -5501,15 +5501,29 @@ unit aoptx86;
if IsJumpToLabel(taicpu(hp1_dist)) then
TAsmLabel(taicpu(hp1_dist).oper[0]^.ref^.symbol).DecRefs;
DebugMsg(SPeepholeOptimization + 'TEST/JNE/TEST/JNE merged', p);
RemoveInstruction(hp1_dist);
{ Only remove the second test if no jumps or other conditional instructions follow }
TransferUsedRegs(TmpUsedRegs);
UpdateUsedRegs(TmpUsedRegs, tai(p.Next));
UpdateUsedRegs(TmpUsedRegs, tai(hp1.Next));
if not RegUsedAfterInstruction(NR_DEFAULTFLAGS, p_dist, TmpUsedRegs) then
RemoveInstruction(p_dist);
UpdateUsedRegs(TmpUsedRegs, tai(p_dist.Next));
if not RegUsedAfterInstruction(NR_DEFAULTFLAGS, hp1_dist, TmpUsedRegs) then
begin
DebugMsg(SPeepholeOptimization + 'TEST/JNE/TEST/JNE merged', p);
RemoveInstruction(p_dist);
{ Remove the first jump, not the second, to keep
any register deallocations between the second
TEST/JNE pair in the same place. Aids future
optimisation. }
RemoveInstruction(hp1);
end
else
begin
DebugMsg(SPeepholeOptimization + 'TEST/JNE/TEST/JNE merged (second TEST preserved)', p);
{ Remove second jump in this instance }
RemoveInstruction(hp1_dist);
end;
Result := True;
Exit;