[Bug target/96479] New: AArch64: return SIMD register with -mgeneral-regs-only

[Bug target/96479] New: AArch64: return SIMD register with -mgeneral-regs-only

[qiaopeixin at huawei dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96479

            Bug ID: 96479
           Summary: AArch64: return SIMD register with -mgeneral-regs-only
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: qiaopeixin at huawei dot com
  Target Milestone: ---

Created attachment 49001
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49001&action=edit
aarch64: vector incompatible with -mgeneral-regs-only

Hi,

When compiling the test case of vector extraction and insertion with
-mgeneral-regs-only option, which is
gcc/testsuite/c-c++-common/torture/vector-subscript-2.c, GCC reports the ice,
which should not be. It uses the vector with the length of four integers, which
is defined in test case. The start funciton of expand pass will figure out the
mode of eventual return register to store the vector. At this time, GCC will
check if it can be returned in simd/fp register(s), and return v4si register.
Unfortunately, -mgeneral-regs-only prevent the use of simd/fp register(s).

I proposed to add one if statement when entering into the if statement of
checking that the mode of return register is simd/fp. If TARGET_FLOAT is false,
which is enabled by -mgeneral-regs-only option, it will report the error that
'-mgeneral-regs-only' is incompatiable with the use of vector types.

Is it the solution to solve the problem?

All the best

[Bug target/96479] AArch64: return SIMD register with -mgeneral-regs-only

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96479

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-invalid-code
             Target|                            |aarch64

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
If -mgeneral-regs-only is not supposed to be an ABI changing option then the
compiler has to reject code using non-general regs.  With a diagnostic
preferably, not by ICEing.

[Bug target/96479] AArch64: return SIMD register with -mgeneral-regs-only

[qiaopeixin at huawei dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96479

--- Comment #2 from qiaopeixin at huawei dot com ---
(In reply to Richard Biener from comment #1)
> If -mgeneral-regs-only is not supposed to be an ABI changing option then the
> compiler has to reject code using non-general regs.  With a diagnostic
> preferably, not by ICEing.

For now, the compiler report the diagnostic information as following

../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c: In function
‘myfunc2’:
../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c:17:1: error:
‘-mgeneral-regs-only’ is incompatible with the use of vector types
../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c: In function
‘modify’:
../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c:28:10: error:
‘-mgeneral-regs-only’ is incompatible with the use of vector types
../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c:28:10: error:
‘-mgeneral-regs-only’ is incompatible with the use of vector types
../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c: In function
‘myfunc2’:
../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c:16:20: error:
‘-mgeneral-regs-only’ is incompatible with the use of vector types
../gcc/gcc/testsuite/c-c++-common/torture/vector-subscript-2.c:23:12: error:
‘-mgeneral-regs-only’ is incompatible with the use of vector types

[Bug target/96479] AArch64: return SIMD register with -mgeneral-regs-only

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96479

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
                 CC|                            |rsandifo at gcc dot gnu.org
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #3 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Fix committed.

[Bug target/96479] AArch64: return SIMD register with -mgeneral-regs-only

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96479

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-08-13
             Status|RESOLVED                    |REOPENED
     Ever confirmed|0                           |1
         Resolution|FIXED                       |---

--- Comment #4 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Patch was reverted due to a glibc build failure.
See https://gcc.gnu.org/pipermail/gcc-patches/2020-August/551903.html

[Bug target/96479] AArch64: return SIMD register with -mgeneral-regs-only

[rsandifo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96479

rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from rsandifo at gcc dot gnu.org <rsandifo at gcc dot gnu.org> ---
Now fixed.

[Bug target/96479] AArch64: return SIMD register with -mgeneral-regs-only

[qiaopeixin at huawei dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96479

--- Comment #6 from qiaopeixin at huawei dot com ---
Fix on
https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=a5a635fc4331b6d5f1a1e688e1153abd2ff194a5