[Bug c/35762] New: wrong code emitted for loop with volatile induction variable

[regehr at cs dot utah dot edu]

This is for "gcc version 4.3.0 (GCC)" 

This is similar to bug 35729.  I'm filing a new report since the behavior seems
to be a different one.

This code:

volatile short g_10 = 0;
volatile int g_13 = 0;
int func_1 (void)
{
  for (g_10 = 0; g_10 > 10; g_10++)
    return g_13;
  return 0;
}

When compiled with:

  gcc -O1 -S foo.c

gives:

func_1:
        pushl   %ebp
        movl    %esp, %ebp
        movw    $0, g_10
        movzwl  g_10, %eax
        cmpw    $10, %ax
        setle   %al
        movzbl  %al, %eax
        subl    $1, %eax
        andl    g_13, %eax
        popl    %ebp
        ret

The output is not correct, it unconditionally returns the value from g_13.


-- 
           Summary: wrong code emitted for loop with volatile induction
                    variable
           Product: gcc
           Version: 4.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: regehr at cs dot utah dot edu
 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=35762