On Mon, Apr 11, 2022 at 6:50 PM Jakub Jelinek <ja...@redhat.com> wrote:
>
> Hi!
>
> The following testcase ICEs, because ix86_emit_i387_log1p attempts to
> emit something like
> if (cond)
> some_code1;
> else
> some_code2;
> and emits a conditional jump using emit_jump_insn (standard way in
> the file) and an unconditional jump using emit_jump.
> The problem with that is that if there is pending stack adjustment,
> it isn't emitted before the conditional jump, but is before the
> unconditional jump and therefore stack is adjusted only conditionally
> (at the end of some_code1 above), which makes dwarf2 pass unhappy about it
> but is a serious wrong-code even if it doesn't ICE.
>
> This can be fixed either by emitting pending stack adjust before the
> conditional jump as the following patch does, or by not using
> emit_jump (label2);
> and instead hand inlining what that function does except for the
> pending stack adjustment, like:
> emit_jump_insn (targetm.gen_jump (label2));
> emit_barrier ();
> In that case there will be no stack adjustment in the sequence and
> it will be done later on somewhere else.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> Or do you prefer the other version?
No, this looks like the correct approach to me. Perhaps a small
comment should be added, since the reason to call
do_pending_stack_adjust is not that obvious.
> 2022-04-11 Jakub Jelinek <ja...@redhat.com>
>
> PR target/105214
> * config/i386/i386-expand.cc (ix86_emit_i387_log1p): Call
> do_pending_stack_adjust.
>
> * gcc.dg/asan/pr105214.c: New test.
OK with the comment.
Thanks,
Uros.
>
> --- gcc/config/i386/i386-expand.cc.jj 2022-04-03 21:50:36.001635947 +0200
> +++ gcc/config/i386/i386-expand.cc 2022-04-11 15:17:43.943430658 +0200
> @@ -17291,6 +17291,8 @@ void ix86_emit_i387_log1p (rtx op0, rtx
> rtx cst, cstln2, cst1;
> rtx_insn *insn;
>
> + do_pending_stack_adjust ();
> +
> cst = const_double_from_real_value
> (REAL_VALUE_ATOF ("0.29289321881345247561810596348408353", XFmode),
> XFmode);
> cstln2 = force_reg (XFmode, standard_80387_constant_rtx (4)); /* fldln2 */
> --- gcc/testsuite/gcc.dg/asan/pr105214.c.jj 2022-04-11 15:21:05.467608711
> +0200
> +++ gcc/testsuite/gcc.dg/asan/pr105214.c 2022-04-11 15:22:10.559697224
> +0200
> @@ -0,0 +1,16 @@
> +/* PR target/105214 */
> +/* { dg-do compile } */
> +/* { dg-skip-if "" { *-*-* } { "*" } { "-O2" } } */
> +/* { dg-options "-Ofast -fnon-call-exceptions -fexceptions
> -fstack-check=generic -fsanitize=address -fno-finite-math-only
> -fsignaling-nans -fno-associative-math" } */
> +
> +float f;
> +void bar (int *);
> +
> +void
> +foo (void)
> +{
> + int a[1600], b[1];
> + f += __builtin_log1pf (f);
> + bar (a);
> + bar (b);
> +}
>
> Jakub
>
