[Bug other/95779] New: Unnecessary dispatch function for static target_clones function.

[yyc1992 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95779

            Bug ID: 95779
           Summary: Unnecessary dispatch function for static target_clones
                    function.
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yyc1992 at gmail dot com
  Target Milestone: ---

Using the code in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95778 the full
assembly generated (the version with both noinline) is (disabled unwind info),

```
        .file   "b.c"
        .text
        .p2align 4
        .type   f2.default.1, @function
f2.default.1:
        movl    (%rdi), %eax
        ret
        .size   f2.default.1, .-f2.default.1
        .p2align 4
        .type   g2.default.1, @function
g2.default.1:
        jmp     f2.default.1
        .size   g2.default.1, .-g2.default.1
        .p2align 4
        .type   f2.avx2.0, @function
f2.avx2.0:
        movl    (%rdi), %eax
        ret
        .size   f2.avx2.0, .-f2.avx2.0
        .p2align 4
        .type   g2.avx2.0, @function
g2.avx2.0:
        jmp     f2.avx2.0
        .size   g2.avx2.0, .-g2.avx2.0
        .section        .text.g2.resolver,"axG",@progbits,g2.resolver,comdat
        .p2align 4
        .weak   g2.resolver
        .type   g2.resolver, @function
g2.resolver:
        subq    $8, %rsp
        call    __cpu_indicator_init@PLT
        movq    __cpu_model@GOTPCREL(%rip), %rax
        leaq    g2.avx2.0(%rip), %rdx
        testb   $4, 13(%rax)
        leaq    g2.default.1(%rip), %rax
        cmovne  %rdx, %rax
        addq    $8, %rsp
        ret
        .size   g2.resolver, .-g2.resolver
        .globl  g2
        .type   g2, @gnu_indirect_function
        .set    g2,g2.resolver
        .text
        .p2align 4
        .type   f2.resolver, @function
f2.resolver:
        subq    $8, %rsp
        call    __cpu_indicator_init@PLT
        movq    __cpu_model@GOTPCREL(%rip), %rax
        leaq    f2.avx2.0(%rip), %rdx
        testb   $4, 13(%rax)
        leaq    f2.default.1(%rip), %rax
        cmovne  %rdx, %rax
        addq    $8, %rsp
        ret
        .size   f2.resolver, .-f2.resolver
        .ident  "GCC: (GNU) 10.1.0"
        .section        .note.GNU-stack,"",@progbits
```

AFAICT the `f2.resolver` is never used anywhere and can be omitted (all caller
of `f2` are statically dispatched).