Re: [PATCH] ICF: compare type attributes for gimple_call_fntypes.

["Martin Liška" <mliska@suse.cz>]

On 4/2/20 7:17 PM, Christophe Lyon wrote:
> On Thu, 2 Apr 2020 at 17:16, Martin Liška <mliska@suse.cz> wrote:
>>
>> Hi.
>>
>> The patch compares type attributes for gimple_call_fntypes in IPA ICF.
>> Note that we were unable to find a generic function attribute that
>> can be used on a function type definition.
>>
>> For a one which is allowed assume_aligned(16) I get affects_type_identity == false
>> which seems suspicious to me.
>>
>> Note that we currently use comp_type_attributes in ICF for both variable and
>> function declarations.
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>>
>> Ready to be installed?
>> Thanks,
>> Martin
>>
> 
> Hi,
> 
> Thanks for the quick patch!

Hi.

Good!

> 
> I confirm it fixes the problem I noticed on arm with the cmse-15.c for
> -O2 and -O3.
> 
> However, the testcase still fails with -Os. I haven't looked at the
> details, so it may be a different cause.

I analyzed that slightly and there are still IPA ICF merged that happen
(this time valid transformations):

/home/marxin/Programming/gcc/gcc/testsuite/gcc.target/arm/cmse/cmse-15.c:14:5: optimized: Semantic equality hit:nonsecure0/4->nonsecure2/6
/home/marxin/Programming/gcc/gcc/testsuite/gcc.target/arm/cmse/cmse-15.c:14:5: optimized: Assembler symbol names:nonsecure0/4->nonsecure2/6

/home/marxin/Programming/gcc/gcc/testsuite/gcc.target/arm/cmse/cmse-15.c:33:5: optimized: Semantic equality hit:secure0/8->secure2/10
/home/marxin/Programming/gcc/gcc/testsuite/gcc.target/arm/cmse/cmse-15.c:33:5: optimized: Assembler symbol names:secure0/8->secure2/10

and with -Os nosecure2 -> mosecure0 call is not inlined bad again. That makes the scanning pattern to miss:

-Os version:
nonsecure2:
	@ args = 0, pretend = 0, frame = 0
	@ frame_needed = 0, uses_anonymous_args = 0
	@ link register save eliminated.
	b	nonsecure0

-O2 version:
nonsecure2:
	@ args = 0, pretend = 0, frame = 0
	@ frame_needed = 0, uses_anonymous_args = 0
	push	{r4, lr}
	lsrs	r0, r0, #1
	lsls	r0, r0, #1
	mov	r1, r0
	mov	r2, r0
	mov	r3, r0
	bl	__gnu_cmse_nonsecure_call

Martin

> 
> Thanks,
> 
> Christophe
> 
>> gcc/ChangeLog:
>>
>> 2020-04-02  Martin Liska  <mliska@suse.cz>
>>
>>          PR ipa/94445
>>          * ipa-icf-gimple.c (func_checker::compare_gimple_call):
>>            Compare type attributes for gimple_call_fntypes.
>> ---
>>    gcc/ipa-icf-gimple.c | 4 ++++
>>    1 file changed, 4 insertions(+)
>>
>>