Hello!
The problem was with the ordering of vzeroupper removal pass and
pad-return pass, both in mach pass. Attached patch changes pass
ordering so vzeroupper removal is run before pad-return pass.
Pad-return pass then (correctly) finds empty function and emits long
return.
2011-05-04 Uros Bizjak <ubiz...@gmail.com>
* config/i386/i386.c (ix86_reorg): Run move_or_delete_vzeroupper first.
Tested on x86_64-pc-linux-gnu {,-m32} AVX target, committed to mainline SVN.
Uros.
Index: i386.c
===================================================================
--- i386.c (revision 173376)
+++ i386.c (working copy)
@@ -30444,6 +30444,10 @@ ix86_reorg (void)
with old MDEP_REORGS that are not CFG based. Recompute it now. */
compute_bb_for_insn ();
+ /* Run the vzeroupper optimization if needed. */
+ if (TARGET_VZEROUPPER)
+ move_or_delete_vzeroupper ();
+
if (optimize && optimize_function_for_speed_p (cfun))
{
if (TARGET_PAD_SHORT_FUNCTION)
@@ -30455,10 +30459,6 @@ ix86_reorg (void)
ix86_avoid_jump_mispredicts ();
#endif
}
-
- /* Run the vzeroupper optimization if needed. */
- if (TARGET_VZEROUPPER)
- move_or_delete_vzeroupper ();
}
/* Return nonzero when QImode register that must be represented via REX prefix
