[Bug middle-end/93536] New: -fpatchable-function-entries doesn't work with --gc-sections

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93536

            Bug ID: 93536
           Summary: -fpatchable-function-entries doesn't work with
                    --gc-sections
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hjl.tools at gmail dot com
            Blocks: 93195
  Target Milestone: ---

[hjl@gnu-cfl-2 pr93492]$ cat foo.i 
void
bar (void)
{
}

void
_start (void)
{
}
[hjl@gnu-cfl-2 pr93492]$ make foo.s
/export/build/gnu/tools-build/gcc-gitlab-debug/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/tools-build/gcc-gitlab-debug/build-x86_64-linux/gcc/
-fpatchable-function-entry=1 -ffunction-sections -O2 -S foo.i
[hjl@gnu-cfl-2 pr93492]$ cat foo.s
        .file   "foo.i"
        .text
        .section        .text.bar,"ax",@progbits
        .p2align 4
        .globl  bar
        .type   bar, @function
bar:
        .cfi_startproc
        .section        __patchable_function_entries,"aw",@progbits
        .align 8
        .quad   .LPFE1
        .section        .text.bar
.LPFE1:
        nop
.LFB0:
        ret
        .cfi_endproc
.LFE0:
        .size   bar, .-bar
        .section        .text._start,"ax",@progbits
        .p2align 4
        .globl  _start
        .type   _start, @function
_start:
        .cfi_startproc
        .section        __patchable_function_entries
        .align 8
        .quad   .LPFE2
        .section        .text._start
.LPFE2:
        nop
.LFB3:
        ret
        .cfi_endproc
.LFE3:
        .size   _start, .-_start
        .ident  "GCC: (GNU) 10.0.1 20200201 (experimental)"
        .section        .note.GNU-stack,"",@progbits
[hjl@gnu-cfl-2 pr93492]$ 

With --gc-sections, linker will discard bar and may leave a bad entry in
__patchable_function_entries.


Referenced Bugs:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93195
[Bug 93195] -fpatchable-function-entries : __patchable_function_entries should
consider comdat groups