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* Disabled mov reg,0 -> xor reg,reg optimization

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daniel 2003-02-26 13:24:59 +00:00
parent 8cb2ac6714
commit 49849a0b86
1 changed files with 8 additions and 1 deletions
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9
compiler/i386/popt386.pas
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@ -1934,6 +1934,9 @@ Begin
continue;
end;
End;
(*
Optimization is not safe; xor clears the carry flag.
See test/tgadint64 in the test suite.
A_MOV:
if (Taicpu(p).oper[0].typ = Top_Const) And
(Taicpu(p).oper[0].val = 0) And
@ -1943,6 +1946,7 @@ Begin
Taicpu(p).opcode := A_XOR;
Taicpu(p).LoadReg(0,Taicpu(p).oper[1].reg);
End;
*)
A_MOVZX:
{ if register vars are on, it's possible there is code like }
{ "cmpl $3,%eax; movzbl 8(%ebp),%ebx; je .Lxxx" }
@ -2054,7 +2058,10 @@ End.
{
$Log$
Revision 1.40 2003-02-25 07:41:54 daniel
Revision 1.41 2003-02-26 13:24:59 daniel
* Disabled mov reg,0 -> xor reg,reg optimization
Revision 1.40 2003/02/25 07:41:54 daniel
* Properly fixed reversed operands bug
Revision 1.39 2003/02/24 21:27:01 daniel