From: Thomas Preudhomme <thomas.preudhomme@linaro.org>
To: "Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com>
Cc: "kyrylo.tkachov@foss.arm.com" <kyrylo.tkachov@foss.arm.com>,
Ramana Radhakrishnan <ramana.radhakrishnan@arm.com>,
"gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH, ARM] Fix PR77904 testcase failure
Date: Mon, 31 Dec 2018 19:14:00 -0000 [thread overview]
Message-ID: <CAKnkMGssbo7iEUMsRwoTnLRTnaa2FHf8MLrV0Pn_O2KHSjf2qA@mail.gmail.com> (raw)
In-Reply-To: <c3793a32-fe4d-0f13-7e9e-52dfad399b92@arm.com>
Hi Richard,
On Thursday, 20 December 2018, Richard Earnshaw (lists) <
Richard.Earnshaw@arm.com> wrote:
> 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.
Bernd suggested in [1] that the behaviour tested by pr77904.c might
actually be a behaviour we can allow with a patch to add a dg-warning to
the decade. I'll wait for a resolution on that suggestion before deciding
whether to commit this.
Best regards,
Thomas
>
>>
>> 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;
>> -}
>>
>
>
next prev parent reply other threads:[~2018-12-31 17:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-14 23:28 Thomas Preudhomme
2018-12-20 10:35 ` Richard Earnshaw (lists)
2018-12-31 19:14 ` Thomas Preudhomme [this message]
2018-12-31 21:58 ` Thomas Preudhomme
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAKnkMGssbo7iEUMsRwoTnLRTnaa2FHf8MLrV0Pn_O2KHSjf2qA@mail.gmail.com \
--to=thomas.preudhomme@linaro.org \
--cc=Richard.Earnshaw@arm.com \
--cc=gcc-patches@gcc.gnu.org \
--cc=kyrylo.tkachov@foss.arm.com \
--cc=ramana.radhakrishnan@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).