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Date: Sun, 08 Jul 2007 20:26:00 -0000
Subject: [Bug c/32680]  New: unneeded movsbl
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From: "romikb at mail dot ru" <gcc-bugzilla@gcc.gnu.org>
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Code compiled with -O2 -fomit-frame-pointer

char function1(){ return 10; }
char (*pfunc)() = function1;
char function2(){ return pfunc(); }

produce unneeded movsbl instruction:

_function2:
        subl    $12, %esp << unneeded
        call    *_pfunc
        addl    $12, %esp << unneeded
        movsbl  %al,%eax << unneeded
        ret

eax register allready contains char and don't need to be converted.

Code for

long function1(){ return 10; }
long (*pfunc)() = function1;
lonf function2(){ return pfunc(); }

looks fine.


-- 
           Summary: unneeded movsbl
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: romikb at mail dot ru


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32680