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Re: [PATCH, ARM] Fix PR77904 testcase failure


On 14/12/2018 23:28, Thomas Preudhomme wrote:
> Hi,
> 
> Commit r242693 forced fp to be saved/restored when needed due to an
> instance of GCC using fp as a scratch register to save sp while it's
> being clobbered by an inline asm. The normal path in
> thumb1_compute_save_reg_mask saving callee-saved registers which are
> live in the function does not work in that case because fp is chosen to
> hold sp after that function is called.
> 
> Since clobbering sp is now errored out by the compiler and this was the
> only case reported where fp was live but not marked as such when
> thumb1_compute_save_reg_mask is called, I believe the whole commit
> r242693 should be reverted.
> 
> ChangeLog entries are as follows:
> 
> *** gcc/ChangeLog ***
> 
> 2018-12-14  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     Revert:
>     2016-11-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     PR target/77904
>     * config/arm/arm.c (thumb1_compute_save_reg_mask): Mark frame pointer
>     in save register mask if it is needed.
> 
> *** gcc/testsuite/ChangeLog ***
> 
> 2018-12-14  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     Revert:
>     2016-11-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     PR target/77904
>     * gcc.target/arm/pr77904.c: New test.
> 
> Testing: Built an arm-none-eabi GCC cross-compiler targeting Armv6S-M
> and regression testsuite does not show any regression.
> 
> Ok for stage3?

OK.

R.

> 
> Best regards,
> 
> Thomas
> 
> 
> fix_pr77904_test_failure.patch
> 
> From 63c52e7bf932947be7122cdc63f6cdc913479259 Mon Sep 17 00:00:00 2001
> From: Thomas Preud'homme <thomas.preudhomme@linaro.org>
> Date: Fri, 14 Dec 2018 16:02:59 +0000
> Subject: [PATCH] [PATCH, ARM] Fix PR77904 testcase failure
> 
> Hi,
> 
> Commit r242693 forced fp to be saved/restored when needed due to an
> instance of GCC using fp as a scratch register to save sp while it's
> being clobbered by an inline asm. The normal path in
> thumb1_compute_save_reg_mask saving callee-saved registers which are
> live in the function does not work in that case because fp is chosen to
> hold sp after that function is called.
> 
> Since clobbering sp is now errored out by the compiler and this was the
> only case reported where fp was live but not marked as such when
> thumb1_compute_save_reg_mask is called, I believe the whole commit
> r242693 should be reverted.
> 
> ChangeLog entries are as follows:
> 
> *** gcc/ChangeLog ***
> 
> 2018-12-14  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     Revert:
>     2016-11-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     PR target/77904
>     * config/arm/arm.c (thumb1_compute_save_reg_mask): Mark frame pointer
>     in save register mask if it is needed.
> 
> *** gcc/testsuite/ChangeLog ***
> 
> 2018-12-14  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     Revert:
>     2016-11-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> 
>     PR target/77904
>     * gcc.target/arm/pr77904.c: New test.
> 
> Testing: Built an arm-none-eabi GCC cross-compiler targeting Armv6S-M
> and regression testsuite does not show any regression.
> 
> Ok for stage3?
> 
> Best regards,
> 
> Thomas
> ---
>  gcc/ChangeLog                          |  9 ++++++
>  gcc/config/arm/arm.c                   |  4 ---
>  gcc/testsuite/ChangeLog                |  8 +++++
>  gcc/testsuite/gcc.target/arm/pr77904.c | 45 --------------------------
>  4 files changed, 17 insertions(+), 49 deletions(-)
>  delete mode 100644 gcc/testsuite/gcc.target/arm/pr77904.c
> 
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index d8e374fb15f..9caeb1d5e18 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,12 @@
> +2018-12-14  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> +
> +	Revert:
> +	2016-11-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> +
> +	PR target/77904
> +	* config/arm/arm.c (thumb1_compute_save_reg_mask): Mark frame pointer
> +	in save register mask if it is needed.
> +
>  2018-11-27  Alan Modra  <amodra@gmail.com>
>  
>  	* config/rs6000/aix71.h (ASM_SPEC): Don't select default -maix64
> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
> index 40f0574e32e..2ab5d8abc33 100644
> --- a/gcc/config/arm/arm.c
> +++ b/gcc/config/arm/arm.c
> @@ -19553,10 +19553,6 @@ thumb1_compute_save_core_reg_mask (void)
>      if (df_regs_ever_live_p (reg) && callee_saved_reg_p (reg))
>        mask |= 1 << reg;
>  
> -  /* Handle the frame pointer as a special case.  */
> -  if (frame_pointer_needed)
> -    mask |= 1 << HARD_FRAME_POINTER_REGNUM;
> -
>    if (flag_pic
>        && !TARGET_SINGLE_PIC_BASE
>        && arm_pic_register != INVALID_REGNUM
> diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
> index 9e1f6d05a45..4e58c8940da 100644
> --- a/gcc/testsuite/ChangeLog
> +++ b/gcc/testsuite/ChangeLog
> @@ -1,3 +1,11 @@
> +2018-12-14  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> +
> +	Revert:
> +	2016-11-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
> +
> +	PR target/77904
> +	* gcc.target/arm/pr77904.c: New test.
> +
>  2018-11-27  Jozef Lawrynowicz  <jozef.l@mittosystems.com>
>  
>  	* lib/target-supports.exp
> diff --git a/gcc/testsuite/gcc.target/arm/pr77904.c b/gcc/testsuite/gcc.target/arm/pr77904.c
> deleted file mode 100644
> index 76728c07e73..00000000000
> --- a/gcc/testsuite/gcc.target/arm/pr77904.c
> +++ /dev/null
> @@ -1,45 +0,0 @@
> -/* { dg-do run } */
> -/* { dg-options "-O2" } */
> -
> -__attribute__ ((noinline, noclone)) void
> -clobber_sp (void)
> -{
> -  __asm volatile ("" : : : "sp");
> -}
> -
> -int
> -main (void)
> -{
> -  int ret;
> -
> -  __asm volatile ("mov\tr4, #0xf4\n\t"
> -		  "mov\tr5, #0xf5\n\t"
> -		  "mov\tr6, #0xf6\n\t"
> -		  "mov\tr7, #0xf7\n\t"
> -		  "mov\tr0, #0xf8\n\t"
> -		  "mov\tr8, r0\n\t"
> -		  "mov\tr0, #0xfa\n\t"
> -		  "mov\tr10, r0"
> -		  : : : "r0", "r4", "r5", "r6", "r7", "r8", "r10");
> -  clobber_sp ();
> -
> -  __asm volatile ("cmp\tr4, #0xf4\n\t"
> -		  "bne\tfail\n\t"
> -		  "cmp\tr5, #0xf5\n\t"
> -		  "bne\tfail\n\t"
> -		  "cmp\tr6, #0xf6\n\t"
> -		  "bne\tfail\n\t"
> -		  "cmp\tr7, #0xf7\n\t"
> -		  "bne\tfail\n\t"
> -		  "mov\tr0, r8\n\t"
> -		  "cmp\tr0, #0xf8\n\t"
> -		  "bne\tfail\n\t"
> -		  "mov\tr0, r10\n\t"
> -		  "cmp\tr0, #0xfa\n\t"
> -		  "bne\tfail\n\t"
> -		  "mov\t%0, #1\n"
> -		  "fail:\n\t"
> -		  "sub\tr0, #1"
> -		  : "=r" (ret) : :);
> -  return ret;
> -}
> 


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