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

[Martin Liška]

On 4/2/20 7:17 PM, Christophe Lyon wrote:

On Thu, 2 Apr 2020 at 17:16, Martin Liška <mli...@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  <mli...@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(+)