On Fri, May 10, 2019 at 11:03 PM Iain Sandoe <idsan...@googlemail.com> wrote:
>
> Hi!
>
> PR82920 is about CET fails on Darwin.
>
> Initially, this was expected to be just a testsuite issue, however it turns
> out that the indirection thunks code has inconsistent handling of the output
> of labels. Thus some of the output is missing the leading “_” on Darwin,
> which breaks ABI and won’t link.
>
> Since most of the tests are scan-asms that check for what’s expected, they
> currently pass on Darwin but will begin failing when the codegen is fixed.
> Thus there is larger, but mechanical, testsuite change needed to deal with
> this. I will post that if anyone’s interested, but otherwise will just
> apply it once the codgen fix is agreed.
>
> The patch factors out some common code that writes out the jumps and uses the
> regular output scheme that accounts for __USER_LABEL_PREFIX__.
>
> I will note in passing that there’s very little PIC test coverage for the
> indirection thunks code, although Darwin is PIC-only for m64 - Linux has only
> a few tests.
>
> OK for trunk?
OK for trunk if the patch doesn't regress x86_64-linux.
> Backports?
Also OK for backports after a couple of days of soaking in the trunk
without problems (so autotesters will test the patched compiler from
the trunk).
Thanks,
Uros.
> Iain
>
> gcc/
>
> * config/i386/i386.c (ix86_output_jmp_thunk_or_indirect): New.
> (ix86_output_indirect_branch_via_reg): Use output mechanism
> accounting for
> __USR_LABEL_PREFIX.
> (ix86_output_indirect_branch_via_push): Likewise.
> (ix86_output_function_return): Likewise.
> (ix86_output_indirect_function_return): Likewise.
>
> From 4da5837cd7bbe61b6d2687e552e3afb5bfdb2765 Mon Sep 17 00:00:00 2001
> From: Iain Sandoe <i...@sandoe.co.uk>
> Date: Tue, 7 May 2019 07:27:19 -0400
> Subject: [PATCH] [Darwin] Fix PR82920 - code changes.
>
> Emit labels using machinery that includes the __USER_LABEL_PREFIX__
> ---
> gcc/config/i386/i386.c | 48 ++++++++++++++++++++++++------------------
> 1 file changed, 27 insertions(+), 21 deletions(-)
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index c51d775b89..08aa9d9475 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -15130,6 +15130,20 @@ ix86_nopic_noplt_attribute_p (rtx call_op)
> return false;
> }
>
> +/* Helper to output the jmp/call. */
> +static void
> +ix86_output_jmp_thunk_or_indirect (const char *thunk_name, const int regno)
> +{
> + if (thunk_name != NULL)
> + {
> + fprintf (asm_out_file, "\tjmp\t");
> + assemble_name (asm_out_file, thunk_name);
> + putc ('\n', asm_out_file);
> + }
> + else
> + output_indirect_thunk (regno);
> +}
> +
> /* Output indirect branch via a call and return thunk. CALL_OP is a
> register which contains the branch target. XASM is the assembly
> template for CALL_OP. Branch is a tail call if SIBCALL_P is true.
> @@ -15168,17 +15182,14 @@ ix86_output_indirect_branch_via_reg (rtx call_op,
> bool sibcall_p)
> thunk_name = NULL;
>
> if (sibcall_p)
> - {
> - if (thunk_name != NULL)
> - fprintf (asm_out_file, "\tjmp\t%s\n", thunk_name);
> - else
> - output_indirect_thunk (regno);
> - }
> + ix86_output_jmp_thunk_or_indirect (thunk_name, regno);
> else
> {
> if (thunk_name != NULL)
> {
> - fprintf (asm_out_file, "\tcall\t%s\n", thunk_name);
> + fprintf (asm_out_file, "\tcall\t");
> + assemble_name (asm_out_file, thunk_name);
> + putc ('\n', asm_out_file);
> return;
> }
>
> @@ -15199,10 +15210,7 @@ ix86_output_indirect_branch_via_reg (rtx call_op,
> bool sibcall_p)
>
> ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, indirectlabel1);
>
> - if (thunk_name != NULL)
> - fprintf (asm_out_file, "\tjmp\t%s\n", thunk_name);
> - else
> - output_indirect_thunk (regno);
> + ix86_output_jmp_thunk_or_indirect (thunk_name, regno);
>
> ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, indirectlabel2);
>
> @@ -15259,10 +15267,7 @@ ix86_output_indirect_branch_via_push (rtx call_op,
> const char *xasm,
> if (sibcall_p)
> {
> output_asm_insn (push_buf, &call_op);
> - if (thunk_name != NULL)
> - fprintf (asm_out_file, "\tjmp\t%s\n", thunk_name);
> - else
> - output_indirect_thunk (regno);
> + ix86_output_jmp_thunk_or_indirect (thunk_name, regno);
> }
> else
> {
> @@ -15318,10 +15323,7 @@ ix86_output_indirect_branch_via_push (rtx call_op,
> const char *xasm,
>
> output_asm_insn (push_buf, &call_op);
>
> - if (thunk_name != NULL)
> - fprintf (asm_out_file, "\tjmp\t%s\n", thunk_name);
> - else
> - output_indirect_thunk (regno);
> + ix86_output_jmp_thunk_or_indirect (thunk_name, regno);
>
> ASM_OUTPUT_INTERNAL_LABEL (asm_out_file, indirectlabel2);
>
> @@ -15420,7 +15422,9 @@ ix86_output_function_return (bool long_p)
> indirect_thunk_name (thunk_name, INVALID_REGNUM, need_prefix,
> true);
> indirect_return_needed |= need_thunk;
> - fprintf (asm_out_file, "\tjmp\t%s\n", thunk_name);
> + fprintf (asm_out_file, "\tjmp\t");
> + assemble_name (asm_out_file, thunk_name);
> + putc ('\n', asm_out_file);
> }
> else
> output_indirect_thunk (INVALID_REGNUM);
> @@ -15460,7 +15464,9 @@ ix86_output_indirect_function_return (rtx ret_op)
> indirect_return_via_cx = true;
> indirect_thunks_used |= 1 << CX_REG;
> }
> - fprintf (asm_out_file, "\tjmp\t%s\n", thunk_name);
> + fprintf (asm_out_file, "\tjmp\t");
> + assemble_name (asm_out_file, thunk_name);
> + putc ('\n', asm_out_file);
> }
> else
> output_indirect_thunk (regno);
> --
> 2.17.1
>
>
