[Bug other/78366] New: target_clones does not generate resovler function

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78366

            Bug ID: 78366
           Summary: target_clones does not generate resovler function
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tkoenig at gcc dot gnu.org
  Target Milestone: ---

The doc to target_clones says

#     For instance, on an x86, you could compile a function with
#     `target_clones("sse4.1,avx")'.  GCC creates two function clones,
#     one compiled with `-msse4.1' and another with `-mavx'.  It also
#     creates a resolver function (see the `ifunc' attribute above) that
#     dynamically selects a clone suitable for current architecture.

Gcc creates the three functions all right, but it does not create the
resolver function; or at least I am unable to find it in the assembly
code.

double foo(double *, double *, int) __attribute__
((target_clones("avx,default")));

double foo(double *a, double *b, int n)
{
  double s;
  int i;
  s = 0.0;
  for (i=0; i<n; i++)
    s += a[i] + b[i];

  return s;
}
ig25@linux-fd1f:~/Krempel/Target> gcc -O -S target.c
ig25@linux-fd1f:~/Krempel/Target> cat target.s
        .file   "target.c"
        .text
        .globl  foo
        .type   foo, @function
foo:
.LFB0:
        .cfi_startproc
        testl   %edx, %edx
        jle     .L4
        leal    -1(%rdx), %edx
        addq    $1, %rdx
        movl    $0, %eax
        pxor    %xmm0, %xmm0
.L3:
        movsd   (%rdi,%rax,8), %xmm1
        addsd   (%rsi,%rax,8), %xmm1
        addsd   %xmm1, %xmm0
        addq    $1, %rax
        cmpq    %rdx, %rax
        jne     .L3
        rep ret
.L4:
        pxor    %xmm0, %xmm0
        ret
        .cfi_endproc
.LFE0:
        .size   foo, .-foo
        .type   foo.avx.0, @function
foo.avx.0:
.LFB1:
        .cfi_startproc
        testl   %edx, %edx
        jle     .L9
        leal    -1(%rdx), %edx
        addq    $1, %rdx
        movl    $0, %eax
        vxorpd  %xmm0, %xmm0, %xmm0
.L8:
        vmovsd  (%rdi,%rax,8), %xmm1
        vaddsd  (%rsi,%rax,8), %xmm1, %xmm1
        vaddsd  %xmm1, %xmm0, %xmm0
        addq    $1, %rax
        cmpq    %rdx, %rax
        jne     .L8
        rep ret
.L9:
        vxorpd  %xmm0, %xmm0, %xmm0
        ret
        .cfi_endproc
.LFE1:
        .size   foo.avx.0, .-foo.avx.0
        .ident  "GCC: (GNU) 7.0.0 20161112 (experimental)"
        .section        .note.GNU-stack,"",@progbits