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From: "mikpe at it dot uu.se" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c/52734] Incorrect optimization of uClibc sbrk()
Date: Tue, 27 Mar 2012 07:54:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52734

Mikael Pettersson <mikpe at it dot uu.se> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikpe at it dot uu.se

--- Comment #3 from Mikael Pettersson <mikpe at it dot uu.se> 2012-03-27 07:45:49 UTC ---
Here's the bogus assembly code for ccc() with gcc-4.7 and -Os:

        .globl  ccc
        .type   ccc, @function
ccc:
.LFB1:
        .cfi_startproc
        call    aaa
        testl   %eax, %eax
        je      .L3
.L5:
        movl    bbb(%rip), %eax
        ret
.L3:
        call    aaa
        testl   %eax, %eax
        je      .L5
        xorl    %eax, %eax
        ret
        .cfi_endproc
.LFE1:
        .size   ccc, .-ccc

Note how it fails to read bbb into a local before the second call to aaa.