Same thing on x86_64-apple-darwin14.

Thanks for the report. I can reproduce the FAIL on IA32. Since the patch does not impact on -O0, it seams some library functions are wrong. I will investigate it.

Root cause: r217646 enhances ifcvt to handle cbranchcc4 instruction. But ifcvt does not check whether an insn will clobber CC or not, when moving it before the cbranchcc4 instruction.

I will work out a patch to fix it.

On aarch64, I have noticed that the following tests FAIL after r217646:
  gcc.target/aarch64/test_frame_1.c scan-assembler-times ldr\tx30, \\[sp\\], [0-9]+ 3
  gcc.target/aarch64/test_frame_2.c scan-assembler-times ldp\tx19, x30, \\[sp\\], [0-9]+ 2
  gcc.target/aarch64/test_frame_4.c scan-assembler-times ldp\tx19, x30, \\[sp\\], [0-9]+ 2
  gcc.target/aarch64/test_frame_6.c scan-assembler-times ldr\tx30, \\[sp\\], [0-9]+ 3
  gcc.target/aarch64/test_frame_7.c scan-assembler-times ldp\tx19, x30, \\[sp\\], [0-9]+ 2

(tested on aarch64 and aarch64_be)

(In reply to clyon from comment #4)
> On aarch64, I have noticed that the following tests FAIL after r217646:

That is recorded as bug 63971 and just a testsuite issue. In that the return is no longer duplicated so the loads are not either. Anyways I have a fix which I will be posting this weekend. 


>   gcc.target/aarch64/test_frame_1.c scan-assembler-times ldr\tx30, \\[sp\\],
> [0-9]+ 3
>   gcc.target/aarch64/test_frame_2.c scan-assembler-times ldp\tx19, x30,
> \\[sp\\], [0-9]+ 2
>   gcc.target/aarch64/test_frame_4.c scan-assembler-times ldp\tx19, x30,
> \\[sp\\], [0-9]+ 2
>   gcc.target/aarch64/test_frame_6.c scan-assembler-times ldr\tx30, \\[sp\\],
> [0-9]+ 3
>   gcc.target/aarch64/test_frame_7.c scan-assembler-times ldp\tx19, x30,
> \\[sp\\], [0-9]+ 2
> 
> (tested on aarch64 and aarch64_be)

*** Bug 64007 has been marked as a duplicate of this bug. ***

also gmp-4.3.2/mpz/n_pow_ui.c is miscompiled because of this.

(In reply to Zhenqiang Chen from comment #3)
> Root cause: r217646 enhances ifcvt to handle cbranchcc4 instruction. But
> ifcvt does not check whether an insn will clobber CC or not, when moving it
> before the cbranchcc4 instruction.

This is a clear and important regression, miscompiling real-life code. Can we get this fixed, or should we ask to revert 217646 until this is fixed?

A patch has been submitted at https://gcc.gnu.org/ml/gcc-patches/2014-12/msg00478.html waiting for approval!-(

Author: zqchen
Date: Fri Dec 12 05:51:19 2014
New Revision: 218658

URL: https://gcc.gnu.org/viewcvs?rev=218658&root=gcc&view=rev
Log:
2014-12-12  Zhenqiang Chen  <zhenqiang.chen@arm.com>

	PR rtl-optimization/63917
	* ifcvt.c (cc_in_cond): New function.
	(end_ifcvt_sequence): Make sure new generated insns do not clobber CC.
	(noce_process_if_block, check_cond_move_block): Check CC references.

testsuite/ChangeLog:
2014-12-12  Zhenqiang Chen  <zhenqiang.chen@arm.com>

	* gcc.dg/pr64007.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr64007.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/ifcvt.c
    trunk/gcc/testsuite/ChangeLog

Fixed.

Author: yroux
Date: Tue Apr  7 13:24:05 2015
New Revision: 221894

URL: https://gcc.gnu.org/viewcvs?rev=221894&root=gcc&view=rev
Log:
gcc/
2015-04-07  Yvan Roux  <yvan.roux@linaro.org>

	Backport from trunk r217062, r217646, r218658.
	2014-12-12  Zhenqiang Chen  <zhenqiang.chen@arm.com>

	PR rtl-optimization/63917
	* ifcvt.c (cc_in_cond): New function.
	(end_ifcvt_sequence): Make sure new generated insns do not clobber CC.
	(noce_process_if_block, check_cond_move_block): Check CC references.

	2014-11-17  Zhenqiang Chen  <zhenqiang.chen@arm.com>

	* ifcvt.c (HAVE_cbranchcc4): Define.
	(noce_emit_cmove, noce_get_alt_condition, noce_get_condition):
	Use HAVE_cbranchcc4.

	2014-11-04  Zhenqiang Chen  <zhenqiang.chen@arm.com>

	Revert:
		2014-11-03  Zhenqiang Chen  <zhenqiang.chen@arm.com>
	* ifcvt.c (noce_emit_cmove, noce_get_alt_condition, noce_get_condition):
	Allow CC mode if HAVE_cbranchcc4.

gcc/testsuite/
2015-04-07  Yvan Roux  <yvan.roux@linaro.org>

	Backport from trunk r218658.
	2014-12-12  Zhenqiang Chen  <zhenqiang.chen@arm.com>

	* gcc.dg/pr64007.c: New test.


Added:
    branches/linaro/gcc-4_9-branch/gcc/testsuite/gcc.dg/pr64007.c
Modified:
    branches/linaro/gcc-4_9-branch/gcc/ChangeLog.linaro
    branches/linaro/gcc-4_9-branch/gcc/ifcvt.c
    branches/linaro/gcc-4_9-branch/gcc/testsuite/ChangeLog.linaro