[Bug tree-optimization/59413] [4.9 Regression] wrong code at -Os on x86_64-linux-gnu in both 32-bit and 64-bit modes

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59413

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hjl.tools at gmail dot com

--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> ---
[hjl@gnu-mic-2 gcc-regression]$ cat pr59413.c
typedef unsigned int uint32_t;

uint32_t a;
int b;

int
main ()
{
  uint32_t c;
  for (a = 7; a <= 1; a++)
    {
      char d = a;
      c = d;
      b = a == c;
    }
  if (a != 7)
    __builtin_abort ();
  return 0;
}
[hjl@gnu-mic-2 gcc-regression]$
/export/project/git/gcc-regression/master/205883/usr/bin/gcc -S pr59413.c -Os
-o bad.s
[hjl@gnu-mic-2 gcc-regression]$
/export/project/git/gcc-regression/master/205887/usr/bin/gcc -S pr59413.c -Os
-o good.s
[hjl@gnu-mic-2 gcc-regression]$ diff -up bad.s good.s
--- bad.s    2013-12-20 04:38:57.810620352 -0800
+++ good.s    2013-12-20 04:39:12.476337299 -0800
@@ -8,20 +8,9 @@
 main:
 .LFB0:
     .cfi_startproc
-    movl    b(%rip), %edx
-    movl    $7, %eax
-.L2:
-    incl    %eax
-    cmpl    $3, %eax
-    je    .L6
-    movl    $1, %edx
-    jmp    .L2
-.L6:
-    pushq    %rax
-    .cfi_def_cfa_offset 16
-    movl    %edx, b(%rip)
-    movl    $2, a(%rip)
-    call    abort
+    movl    $7, a(%rip)
+    xorl    %eax, %eax
+    ret
     .cfi_endproc
 .LFE0:
     .size    main, .-main
@@ -31,5 +20,5 @@ main:
 .LHOTE0:
     .comm    b,4,4
     .comm    a,4,4
-    .ident    "GCC: (GNU) 4.9.0 20131211 (experimental) [trunk revision
205883]"
+    .ident    "GCC: (GNU) 4.9.0 20131211 (experimental) [trunk revision
205887]"
     .section    .note.GNU-stack,"",@progbits
[hjl@gnu-mic-2 gcc-regression]$