[Bug target/47253] Conditional jump to tail function is not generated

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47253

--- Comment #14 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 60458
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60458&action=edit
A patch to fold jump table with tests

I got

[hjl@gnu-tgl-3 pr47253]$ cat j.c
void bar0 (void);
void bar1 (void);
void bar2 (void);
void bar3 (void);
void bar4 (void);

void
foo (int i)
{
  switch (i)
    {
    case 0: bar0 (); break;
    case 1: bar1 (); break;
    case 2: bar2 (); break;
    case 3: bar3 (); break;
    case 4: bar4 (); break;
    }
}
[hjl@gnu-tgl-3 pr47253]$ cat j.s
        .file   "j.c"
        .text
        .p2align 4
        .globl  foo
        .type   foo, @function
foo:
.LFB0:
        .cfi_startproc
        cmpl    $4, %edi
        ja      .L1
        movl    %edi, %edi
        jmp     *.L4(,%rdi,8)
        .section        .rodata
        .align 8
        .align 4
.L4:
        .quad   bar0
        .quad   bar1
        .quad   bar2
        .quad   bar3
        .quad   bar4
        .text
.L1:
        ret
        .cfi_endproc
.LFE0:
        .size   foo, .-foo
        .ident  "GCC: (GNU) 15.0.1 20250211 (experimental)"
        .section        .note.GNU-stack,"",@progbits
[hjl@gnu-tgl-3 pr47253]$