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+ optimize rol(0, x) and ror(0, x) to 0; also optimize the case with all ones,

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e.g. rol32(ffffffff, x) = ffffffff, etc.

git-svn-id: trunk@36042 -
This commit is contained in:
nickysn 2017-05-01 18:19:49 +00:00
parent de1e0c405e
commit 855cd616f0
1 changed files with 29 additions and 0 deletions
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29
compiler/ninl.pas
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@ -2107,6 +2107,35 @@ implementation
else
internalerror(2011061901);
end;
end
else if (left.nodetype=callparan) and assigned(tcallparanode(left).right) and
(tcallparanode(tcallparanode(left).right).left.nodetype=ordconstn) then
begin
def:=tcallparanode(tcallparanode(left).right).left.resultdef;
vl2:=tordconstnode(tcallparanode(tcallparanode(left).right).left).value;
{ rol/ror are unsigned operations, so cut off upper bits }
case resultdef.size of
1:
vl2:=vl2 and byte($ff);
2:
vl2:=vl2 and word($ffff);
4:
vl2:=vl2 and dword($ffffffff);
8:
vl2:=vl2 and qword($ffffffffffffffff);
else
internalerror(2017050101);
end;
{ rol(0,x) and ror(0,x) are 0 }
{ rol32(ffffffff,x) and ror32(ffffffff,x) are ffffffff, etc. }
if ((vl2=0) or
((resultdef.size=1) and (vl2=$ff)) or
((resultdef.size=2) and (vl2=$ffff)) or
((resultdef.size=4) and (vl2=$ffffffff)) or
((resultdef.size=8) and (vl2=$ffffffffffffffff))) and
((cs_opt_level4 in current_settings.optimizerswitches) or
not might_have_sideeffects(tcallparanode(left).left)) then
result:=cordconstnode.create(vl2,resultdef,true);
end;
end;