• d-bugmail puremagic.com (42/42) Dec 17 2023 https://issues.dlang.org/show_bug.cgi?id=24284

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=24284

          Issue ID: 24284
           Summary: [SIMD][CODEGEN] Bad codegen with comparison operator
                    of __vector(short[16])
           Product: D
           Version: D2
          Hardware: x86_64
                OS: All
            Status: NEW
          Severity: major
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: aliloko gmail.com

With DMD64 D Compiler v2.106.0-dirty on a computer with AVX2 instructions.
Consider the following program:

----------- repro.d ---------------

import core.simd;
import core.stdc.stdio;

void main()
{
    short16 sa        = [32767, 1, -4, -8, 9,     7, 0,-57, 1, 0, 0, 0, 1, 0,
0,  0];
    short16 sb        = [   -4,-8,  9,  7, 0,-32768, 0,  0, 0, 2, 0, 4, 2, 1,
2, -4];
    short16 greater = sa > sb;
    short16 R = (greater & sa) | (~greater & sb); // should return the maximum
of each int16
    short[16] correct = [32767, 1,  9,  7, 9,     7, 0,  0, 1, 2, 0, 4, 2, 1,
2,  0];

    printf("%d %d %d %d %d %d %d %d %d %d %d %d %d %d %d %d\n", 
           R[0], R[1], R[2], R[3],
           R[4], R[5], R[6], R[7],
           R[8], R[9], R[10], R[11],
           R[12], R[13], R[14], R[15]);

    assert(R.array == correct);
}

------------------------------------

Run with: dmd -m64 -mcpu=native repro.d
Second lane of R is wrong.

Looks similar to Issue 24283.

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