aarch64: Fix up RTL sharing bug in aarch64_load_symref_appropriately [PR104910]
Commit Message
Hi!
We unshare all RTL created during expansion, but when
aarch64_load_symref_appropriately is called after expansion like in the
following testcases, we use imm in both HIGH and LO_SUM operands.
If imm is some RTL that shouldn't be shared like a non-sharable CONST,
we get at least with --enable-checking=rtl a checking ICE, otherwise might
just get silently wrong code.
The following patch fixes that by copying it if it can't be shared.
Bootstrapped/regtested on aarch64-linux, ok for trunk?
2022-03-15 Jakub Jelinek <jakub@redhat.com>
PR target/104910
* config/aarch64/aarch64.cc (aarch64_load_symref_appropriately): Copy
imm rtx.
* gcc.dg/pr104910.c: New test.
Jakub
Comments
Jakub Jelinek <jakub@redhat.com> writes:
> Hi!
>
> We unshare all RTL created during expansion, but when
> aarch64_load_symref_appropriately is called after expansion like in the
> following testcases, we use imm in both HIGH and LO_SUM operands.
> If imm is some RTL that shouldn't be shared like a non-sharable CONST,
> we get at least with --enable-checking=rtl a checking ICE, otherwise might
> just get silently wrong code.
>
> The following patch fixes that by copying it if it can't be shared.
>
> Bootstrapped/regtested on aarch64-linux, ok for trunk?
>
> 2022-03-15 Jakub Jelinek <jakub@redhat.com>
>
> PR target/104910
> * config/aarch64/aarch64.cc (aarch64_load_symref_appropriately): Copy
> imm rtx.
>
> * gcc.dg/pr104910.c: New test.
OK, thanks. I guess the REG_EQUAL notes might need the same treatment,
but that's probably a separate patch.
Richard
--- gcc/config/aarch64/aarch64.cc.jj 2022-02-22 10:38:02.404689359 +0100
> +++ gcc/config/aarch64/aarch64.cc 2022-03-14 12:42:00.218975192 +0100
> @@ -3971,7 +3971,7 @@ aarch64_load_symref_appropriately (rtx d
> if (can_create_pseudo_p ())
> tmp_reg = gen_reg_rtx (mode);
>
> - emit_move_insn (tmp_reg, gen_rtx_HIGH (mode, imm));
> + emit_move_insn (tmp_reg, gen_rtx_HIGH (mode, copy_rtx (imm)));
> emit_insn (gen_add_losym (dest, tmp_reg, imm));
> return;
> }
> --- gcc/testsuite/gcc.dg/pr104910.c.jj 2022-03-14 12:46:20.983327114 +0100
> +++ gcc/testsuite/gcc.dg/pr104910.c 2022-03-14 12:46:06.064535794 +0100
> @@ -0,0 +1,14 @@
> +/* PR target/104910 */
> +/* { dg-do compile } */
> +/* { dg-options "-Os -fno-forward-propagate" } */
> +/* { dg-additional-options "-fstack-protector-all" { target fstack_protector } } */
> +
> +void
> +bar (void);
> +
> +void
> +foo (int x)
> +{
> + if (x)
> + bar ();
> +}
>
> Jakub
On Wed, Mar 16, 2022 at 09:10:35AM +0000, Richard Sandiford wrote:
> Jakub Jelinek <jakub@redhat.com> writes:
> > We unshare all RTL created during expansion, but when
> > aarch64_load_symref_appropriately is called after expansion like in the
> > following testcases, we use imm in both HIGH and LO_SUM operands.
> > If imm is some RTL that shouldn't be shared like a non-sharable CONST,
> > we get at least with --enable-checking=rtl a checking ICE, otherwise might
> > just get silently wrong code.
> >
> > The following patch fixes that by copying it if it can't be shared.
> >
> > Bootstrapped/regtested on aarch64-linux, ok for trunk?
> >
> > 2022-03-15 Jakub Jelinek <jakub@redhat.com>
> >
> > PR target/104910
> > * config/aarch64/aarch64.cc (aarch64_load_symref_appropriately): Copy
> > imm rtx.
> >
> > * gcc.dg/pr104910.c: New test.
>
> OK, thanks. I guess the REG_EQUAL notes might need the same treatment,
> but that's probably a separate patch.
If it can be invoked after expansion, yes. Though, I think e.g. having the
TLS related loads/stores done after expansion is unlikely.
Anyway, --enable-checking=rtl ought to catch this.
Jakub
@@ -3971,7 +3971,7 @@ aarch64_load_symref_appropriately (rtx d
if (can_create_pseudo_p ())
tmp_reg = gen_reg_rtx (mode);
- emit_move_insn (tmp_reg, gen_rtx_HIGH (mode, imm));
+ emit_move_insn (tmp_reg, gen_rtx_HIGH (mode, copy_rtx (imm)));
emit_insn (gen_add_losym (dest, tmp_reg, imm));
return;
}
@@ -0,0 +1,14 @@
+/* PR target/104910 */
+/* { dg-do compile } */
+/* { dg-options "-Os -fno-forward-propagate" } */
+/* { dg-additional-options "-fstack-protector-all" { target fstack_protector } } */
+
+void
+bar (void);
+
+void
+foo (int x)
+{
+ if (x)
+ bar ();
+}