PING^2: [PATCH] x86: Add UNSPECV_PATCHABLE_AREA

[Jakub Jelinek]

On Tue, Jun 09, 2020 at 09:34:01AM -0700, H.J. Lu via Gcc-patches wrote:
> > >         * gcc.target/i386/pr93492-3.c: Likewise.
> > >         * gcc.target/i386/pr93492-5.c: Likewise.

These tests FAIL on i686-linux.
E.g. in the first one I see
        .file   "pr93492-3.c"
        .text
        .globl  f10_endbr
        .type   f10_endbr, @function
f10_endbr:
.LFB0:
        .cfi_startproc
        endbr32
        .section        __patchable_function_entries,"aw",@progbits
        .align 4
        .long   .LPFE1
        .text
.LPFE1:
        nop
1:      call    __fentry__
        pushl   %ebp
        .cfi_def_cfa_offset 8
        .cfi_offset 5, -8
        movl    %esp, %ebp
        .cfi_def_cfa_register 5
        popl    %ebp
        .cfi_restore 5
        .cfi_def_cfa 4, 4
        ret
        .cfi_endproc
.LFE0:
        .size   f10_endbr, .-f10_endbr
so it doesn't match the scan regexp, because
	call	__fentry__
is not immediately followed by
	ret
As -pg is incompatible with -fomit-frame-pointer, I don't see anything wrong
on that.

Another thing in the test is that I don't think you can rely on
.cfi_startproc actually being printed, you should add an effective target
that will either check __GCC_HAVE_DWARF2_CFI_ASM macro definition, or check
for presence of .cfi_startproc on some trivial function compiled with
-fasynchronous-unwind-tables.

	Jakub