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Date: Sat, 11 Jul 2009 00:06:00 -0000
Subject: [Bug middle-end/40718]  New: Invalid code produced with -foptimize-sibling-calls
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The following program will fail.

gcc -S -O1 -foptimize-sibling-calls bug.c

bug.c:
============================================
#define stdcall __attribute__((__stdcall__))

struct S {
    void (stdcall *f)(struct S *);
    int i;
};

void stdcall foo(struct S *s)
{
    s->i++;
}

void stdcall bar(struct S *s)
{
    foo(s);
    s->f(s);
}

int main(void)
{
    struct S s = { foo, 0 };
    bar(&s);
}
============================================

This is what the compiler produces:

bar:
        pushl   %ebp
        movl    %esp, %ebp
        pushl   %ebx
        subl    $20, %esp
        movl    8(%ebp), %ebx
        movl    %ebx, (%esp)
        call    foo
        subl    $4, %esp
        movl    %ebx, 8(%ebp)
        movl    -4(%ebp), %ebx
        leave
        jmp     *(%ebx)


-- 
           Summary: Invalid code produced with -foptimize-sibling-calls
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: d dot g dot gorbachev at gmail dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40718