[Bug c++/107358] New: [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[Bug c++/107358] New: [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

            Bug ID: 107358
           Summary: [13 Regression] i686-linux: Since
                    r13-3290-g98e341130f8798 code fails to build
                    libjxl-0/7.0 (vector float code)
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: slyfox at gcc dot gnu.org
                CC: jakub at gcc dot gnu.org, jakub at redhat dot com
  Target Milestone: ---

Initially observed build failure on libjxl-0.7.0 on i686-linux target.

Seems to happen only on i686-unknown-linux-gnu and only on -std=c++11.

PR107295 does not seem to be enough to fix it. Here is the minimal example:

// $ cat skcms.cc
// this works:
float approx_scal(float e) {
    return e - 124.225514990f;
}

typedef float __attribute__((vector_size(4*sizeof(float)))) F;

// this fails:
//   error: conversion of scalar 'long double' to vector 'F' {aka '__vector(4)
float'} involves truncation
F approx_vec(F e) {
    return e - 124.225514990f;
    //return e - 1.0f; // this works, does 'f' get ignored when float does not
fit?
}


$ g++-13 -fPIC -std=c++11 -o skcms.cc.o -c skcms.cc
skcms.cc: In function 'F approx_vec(F)':
skcms.cc:10:17: warning: SSE vector return without SSE enabled changes the ABI
[-Wpsabi]
   10 | F approx_vec(F e) {
      |                 ^
skcms.cc:11:14: error: conversion of scalar 'long double' to vector 'F' {aka
'__vector(4) float'} involves truncation
   11 |     return e - 124.225514990f;
      |            ~~^~~~~~~~~~~~~~~~

$ g++-12 -fPIC -std=c++11 -o skcms.cc.o -c skcms.cc
skcms.cc: In function 'F approx_vec(F)':
skcms.cc:10:17: warning: SSE vector return without SSE enabled changes the ABI
[-Wpsabi]
   10 | F approx_vec(F e) {
      |                 ^
skcms.cc:10:3: note: the ABI for passing parameters with 16-byte alignment has
changed in GCC 4.6
   10 | F approx_vec(F e) {
      |   ^~~~~~~~~~
skcms.cc:10:3: warning: SSE vector argument without SSE enabled changes the ABI 

Note: gcc-12 works, gcc-13 fails.

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|jakub at redhat dot com            |

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
I think that is the preexisting C issue I've talked about in
https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603265.html
typedef float __attribute__((vector_size (16))) float32x4_t;
float32x4_t foo(float32x4_t x, float y) { return x + y; }
where C also fails for years with -fexcess-precision=standard.

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-10-22
             Status|UNCONFIRMED                 |ASSIGNED
     Ever confirmed|0                           |1
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 53757
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53757&action=edit
gcc13-pr107358.patch

Untested fix.

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

--- Comment #3 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
(In reply to Jakub Jelinek from comment #2)
> Created attachment 53757 [details]
> gcc13-pr107358.patch
> 
> Untested fix.

The proposed patch fixes libjxl-0.7.0 build for me.

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
   Target Milestone|---                         |13.0

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:65e3274e363cb2c6bfe6b5e648916eb7696f7e2f

commit r13-3461-g65e3274e363cb2c6bfe6b5e648916eb7696f7e2f
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Oct 24 17:53:16 2022 +0200

    c, c++: Fix up excess precision handling of scalar_to_vector conversion
[PR107358]

    As mentioned earlier in the C++ excess precision support mail, the
following
    testcase is broken with excess precision both in C and C++ (though just in
C++
    it was triggered in real-world code).
    scalar_to_vector is called in both FEs after the excess precision
promotions
    (or stripping of EXCESS_PRECISION_EXPR), so we can then get invalid
    diagnostics that say float vector + float involves truncation (on ia32
    from long double to float).

    The following patch fixes that by calling scalar_to_vector on the operands
    before the excess precision promotions, let scalar_to_vector just do the
    diagnostics (it does e.g. fold_for_warn so it will fold
    EXCESS_PRECISION_EXPR around REAL_CST to constants etc.) but will then
    do the actual conversions using the excess precision promoted operands
    (so say if we have vector double + (float + float) we don't actually do
    vector double + (float) ((long double) float + (long double) float)
    but
    vector double + (double) ((long double) float + (long double) float)

    2022-10-24  Jakub Jelinek  <jakub@redhat.com>

            PR c++/107358
    gcc/c/
            * c-typeck.cc (build_binary_op): Pass operands before excess
precision
            promotions to scalar_to_vector call.
    gcc/cp/
            * typeck.cc (cp_build_binary_op): Pass operands before excess
precision
            promotions to scalar_to_vector call.
    gcc/testsuite/
            * c-c++-common/pr107358.c: New test.
            * g++.dg/cpp1y/pr68180.C: Remove -fexcess-precision=fast from
            dg-options.

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Should be fixed now on the trunk.
I'll backport the C part later.

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:31f25cf4ef9a0a0ccc0b0f9158773c5a71e74cc5

commit r12-8889-g31f25cf4ef9a0a0ccc0b0f9158773c5a71e74cc5
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Oct 24 17:53:16 2022 +0200

    c, c++: Fix up excess precision handling of scalar_to_vector conversion
[PR107358]

    As mentioned earlier in the C++ excess precision support mail, the
following
    testcase is broken with excess precision both in C and C++ (though just in
C++
    it was triggered in real-world code).
    scalar_to_vector is called in both FEs after the excess precision
promotions
    (or stripping of EXCESS_PRECISION_EXPR), so we can then get invalid
    diagnostics that say float vector + float involves truncation (on ia32
    from long double to float).

    The following patch fixes that by calling scalar_to_vector on the operands
    before the excess precision promotions, let scalar_to_vector just do the
    diagnostics (it does e.g. fold_for_warn so it will fold
    EXCESS_PRECISION_EXPR around REAL_CST to constants etc.) but will then
    do the actual conversions using the excess precision promoted operands
    (so say if we have vector double + (float + float) we don't actually do
    vector double + (float) ((long double) float + (long double) float)
    but
    vector double + (double) ((long double) float + (long double) float)

    2022-10-24  Jakub Jelinek  <jakub@redhat.com>

            PR c++/107358
    gcc/c/
            * c-typeck.cc (build_binary_op): Pass operands before excess
precision
            promotions to scalar_to_vector call.
    gcc/testsuite/
            * c-c++-common/pr107358.c: New test.

    (cherry picked from commit 65e3274e363cb2c6bfe6b5e648916eb7696f7e2f)

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:57da0797a73f32c879bca77e121a4f55fcc57ce1

commit r11-10363-g57da0797a73f32c879bca77e121a4f55fcc57ce1
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Oct 24 17:53:16 2022 +0200

    c, c++: Fix up excess precision handling of scalar_to_vector conversion
[PR107358]

    As mentioned earlier in the C++ excess precision support mail, the
following
    testcase is broken with excess precision both in C and C++ (though just in
C++
    it was triggered in real-world code).
    scalar_to_vector is called in both FEs after the excess precision
promotions
    (or stripping of EXCESS_PRECISION_EXPR), so we can then get invalid
    diagnostics that say float vector + float involves truncation (on ia32
    from long double to float).

    The following patch fixes that by calling scalar_to_vector on the operands
    before the excess precision promotions, let scalar_to_vector just do the
    diagnostics (it does e.g. fold_for_warn so it will fold
    EXCESS_PRECISION_EXPR around REAL_CST to constants etc.) but will then
    do the actual conversions using the excess precision promoted operands
    (so say if we have vector double + (float + float) we don't actually do
    vector double + (float) ((long double) float + (long double) float)
    but
    vector double + (double) ((long double) float + (long double) float)

    2022-10-24  Jakub Jelinek  <jakub@redhat.com>

            PR c++/107358
    gcc/c/
            * c-typeck.c (build_binary_op): Pass operands before excess
precision
            promotions to scalar_to_vector call.
    gcc/testsuite/
            * c-c++-common/pr107358.c: New test.

    (cherry picked from commit 65e3274e363cb2c6bfe6b5e648916eb7696f7e2f)

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

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

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed for 11.4+/12.3+ in C too.

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:16bdaf29ff9df3c3c70ecc07bb37511d456d05c6

commit r10-11341-g16bdaf29ff9df3c3c70ecc07bb37511d456d05c6
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Mon Oct 24 17:53:16 2022 +0200

    c, c++: Fix up excess precision handling of scalar_to_vector conversion
[PR107358]

    As mentioned earlier in the C++ excess precision support mail, the
following
    testcase is broken with excess precision both in C and C++ (though just in
C++
    it was triggered in real-world code).
    scalar_to_vector is called in both FEs after the excess precision
promotions
    (or stripping of EXCESS_PRECISION_EXPR), so we can then get invalid
    diagnostics that say float vector + float involves truncation (on ia32
    from long double to float).

    The following patch fixes that by calling scalar_to_vector on the operands
    before the excess precision promotions, let scalar_to_vector just do the
    diagnostics (it does e.g. fold_for_warn so it will fold
    EXCESS_PRECISION_EXPR around REAL_CST to constants etc.) but will then
    do the actual conversions using the excess precision promoted operands
    (so say if we have vector double + (float + float) we don't actually do
    vector double + (float) ((long double) float + (long double) float)
    but
    vector double + (double) ((long double) float + (long double) float)

    2022-10-24  Jakub Jelinek  <jakub@redhat.com>

            PR c++/107358
    gcc/c/
            * c-typeck.c (build_binary_op): Pass operands before excess
precision
            promotions to scalar_to_vector call.
    gcc/testsuite/
            * c-c++-common/pr107358.c: New test.

    (cherry picked from commit 65e3274e363cb2c6bfe6b5e648916eb7696f7e2f)

[Bug c++/107358] [13 Regression] i686-linux: Since r13-3290-g98e341130f8798 code fails to build libjxl-0/7.0 (vector float code)

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107358

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed for 10.5 too.