[Bug c++/59071] New: sse2 intrinsics and constant expressions

[Bug c++/59071] New: sse2 intrinsics and constant expressions

[vermaelen.wouter at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59071

            Bug ID: 59071
           Summary: sse2 intrinsics and constant expressions
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vermaelen.wouter at gmail dot com

gcc-4.8.2 with -O0 rejects the following code. With -O1 it works fine. Gcc-4.6,
4.7 and clang also work fine. I *believe* the stuff below is a constant
expression, so it should compile (even without optimizations enabled).

-------

#include "emmintrin.h"

template<int N> __m128i foo(__m128i x) {
    return _mm_slli_si128(x, sizeof(__m128i) - N);
}

void bar(__m128i x) { foo<4>(x); }

--------

> g++ test.cc
In file included from test.cc:1:0:
test.cc: In function ‘__m128i foo(__m128i) [with int N = 4; __m128i =
__vector(2) long long int]’:
test.cc:4:9: error: the last argument must be an 8-bit immediate
  return _mm_slli_si128(x, sizeof(__m128i) - N);
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Subject: [Bug middle-end/50643] Suppress cc1: warnings being treated as errors
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idP643

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |4.8.0

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
In GCC 4.8.0 and above, it shows what option enabled the error (in most cases)
including the warning option that enabled it.

[Bug c++/59071] sse2 intrinsics and constant expressions

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59071

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Target|                            |x86_64-*-*, i?86-*-*
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2013-11-11
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.

[Bug c++/59071] sse2 intrinsics and constant expressions

[mark.j.abraham at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59071

Mark Abraham <mark.j.abraham at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mark.j.abraham at gmail dot com

--- Comment #2 from Mark Abraham <mark.j.abraham at gmail dot com> ---
The same error message with 4.8.2 is provoked by

_mm_srli_si128((x), sizeof(int) * (i))

and is fixed by

_mm_srli_si128((x), 4 * (i))

[Bug c++/59071] sse2 intrinsics and constant expressions

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59071

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
You would need constexpr int n = sizeof(__i128i) - N;
to guarantee it is folded into a constant, otherwise there is no guarantee it
will be, it is normal expression and it is purely an optimization issue (which
you've requested not to be performed through -O0) whether it is evaluated as
constant or not.