[Bug c++/108626] New: GCC doesn't combine string literals for const char*const and const char b[]

["marat at slonopotamus dot org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108626

            Bug ID: 108626
           Summary: GCC doesn't combine string literals for const
                    char*const and const char b[]
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marat at slonopotamus dot org
  Target Milestone: ---

Given the following code


----
#include <stdio.h>

static const char* const a = "bla";
static const char b[] = "bla";

int main() {
    puts(a);
    puts(b);
}
----

GCC 12.2 with -O2 produces

----
.LC0:
        .string "bla"
main:
        sub     rsp, 8
        mov     edi, OFFSET FLAT:.LC0
        call    puts
        mov     edi, OFFSET FLAT:_ZL1b
        call    puts
        xor     eax, eax
        add     rsp, 8
        ret
_ZL1b:
        .string "bla"
----

On the other hand, clang 15.0 with -O1 and higher produces

----
main:                                   # @main
        push    rbx
        lea     rbx, [rip + .L.str]
        mov     rdi, rbx
        call    puts@PLT
        mov     rdi, rbx
        call    puts@PLT
        xor     eax, eax
        pop     rbx
        ret
.L.str:
        .asciz  "bla"
----

For some reason, GCC doesn't want to combine readonly data for these two string
literals.

Godbolt playground: https://godbolt.org/z/WaeazezE6