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From: "dlong at cadence dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug sanitizer/103519] New: Address sanitizer check missing for
 AVX512 masked load
Date: Wed, 01 Dec 2021 14:43:36 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D103519

            Bug ID: 103519
           Summary: Address sanitizer check missing for AVX512 masked load
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dlong at cadence dot com
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxi=
n at gcc dot gnu.org
  Target Milestone: ---

Example with generated assembly available here: https://godbolt.org/z/WTo5s=
GThb

In this:

#include <x86intrin.h>

__m512d v;

void
access(float const *addr)
{
  __m512d val;
  __m256 val1;
  __mmask8 const k3 =3D 0x3f;
  val1=3D_mm256_maskz_loadu_ps(k3, addr);
  val=3D_mm512_cvtps_pd(val1);
  _mm512_storeu_pd((double *)&v, val);
}

when compiled with AVX512 instructions and -fsanitize=3Daddress, no address=
 check
is generated for the maskz_load.

(FWIW, if the mask is folded into the conversion using maskz_cvtps_pd inste=
ad
then a check is generated.  However it's a check for a full 32-byte access =
even
though the CPU will only actually access 24-bytes due to the mask.)=