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* Do not promote integer comparison operations to native size if one side is a constant and its value is within range of opposite side. Instead, cast the constant to type of the opposite side.

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Comparisons are already not promoted if sides are equally signed, but this wasn't true for "unsigned vs constant" case, because constants are preferably parsed as signed.
The change considerably improves generated code for i386 and even more considerably for m68k. Tested on i386-win32.

git-svn-id: trunk@28266 -
This commit is contained in:
sergei 2014-07-25 21:40:22 +00:00
parent a0934e897e
commit 0d96963459
1 changed files with 20 additions and 0 deletions
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20
compiler/nadd.pas
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@ -1013,6 +1013,14 @@ implementation
change : boolean;
{$endif}
function maybe_cast_ordconst(var n: tnode; adef: tdef): boolean;
begin
result:=(tordconstnode(n).value>=torddef(adef).low) and
(tordconstnode(n).value<=torddef(adef).high);
if result then
inserttypeconv(n,adef);
end;
begin
result:=nil;
rlow:=0;
@ -1420,6 +1428,18 @@ implementation
inserttypeconv(right,nd);
end;
end
{ don't extend (sign-mismatched) comparisons if either side is a constant
whose value is within range of opposite side }
else if is_integer(ld) and is_integer(rd) and
(nodetype in [equaln,unequaln,gtn,gten,ltn,lten]) and
(is_signed(ld)<>is_signed(rd)) and
(
((lt=ordconstn) and maybe_cast_ordconst(left,rd)) or
((rt=ordconstn) and maybe_cast_ordconst(right,ld))
) then
begin
{ done here }
end
{ is there a signed 64 bit type ? }
else if ((torddef(rd).ordtype=s64bit) or (torddef(ld).ordtype=s64bit)) then
begin