[v2] match: Fix `!a?b:c` and `a?~t:t` patterns for signed 1 bit types [PR114666]

Message ID 20240412045218.3794143-1-quic_apinski@quicinc.com
State Committed
Commit 245595d72818526e2ca857848831e8afa87ae2de
Headers
Series [v2] match: Fix `!a?b:c` and `a?~t:t` patterns for signed 1 bit types [PR114666] |

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Commit Message

Andrew Pinski (QUIC) April 12, 2024, 4:52 a.m. UTC
  The problem is `!a?b:c` pattern will create a COND_EXPR with an 1bit signed integer
which breaks patterns like `a?~t:t`. This rejects when we have a signed operand for
both patterns.

Note for GCC 15, I am going to look at the canonicalization of `a?~t:t` where t
was a constant since I think keeping it a COND_EXPR might be more canonical and
is what VPR produces from the same IR; if anything expand should handle which one
is better.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

	PR tree-optimization/114666

gcc/ChangeLog:

	* match.pd (`!a?b:c`): Reject signed types for the condition.
	(`a?~t:t`): Likewise.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/execute/bitfld-signed1-1.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
---
 gcc/match.pd                                        |  6 +++++-
 .../gcc.c-torture/execute/bitfld-signed1-1.c        | 13 +++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c
  

Comments

Richard Biener April 12, 2024, 7:26 a.m. UTC | #1
On Fri, Apr 12, 2024 at 6:53 AM Andrew Pinski <quic_apinski@quicinc.com> wrote:
>
> The problem is `!a?b:c` pattern will create a COND_EXPR with an 1bit signed integer
> which breaks patterns like `a?~t:t`. This rejects when we have a signed operand for
> both patterns.
>
> Note for GCC 15, I am going to look at the canonicalization of `a?~t:t` where t
> was a constant since I think keeping it a COND_EXPR might be more canonical and
> is what VPR produces from the same IR; if anything expand should handle which one
> is better.
>
> Bootstrapped and tested on x86_64-linux-gnu with no regressions.

OK.

>         PR tree-optimization/114666
>
> gcc/ChangeLog:
>
>         * match.pd (`!a?b:c`): Reject signed types for the condition.
>         (`a?~t:t`): Likewise.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.c-torture/execute/bitfld-signed1-1.c: New test.
>
> Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
> ---
>  gcc/match.pd                                        |  6 +++++-
>  .../gcc.c-torture/execute/bitfld-signed1-1.c        | 13 +++++++++++++
>  2 files changed, 18 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 15a1e7350d4..d401e7503e6 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -5895,7 +5895,10 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>   /* !A ? B : C -> A ? C : B.  */
>   (simplify
>    (cnd (logical_inverted_value truth_valued_p@0) @1 @2)
> -  (cnd @0 @2 @1)))
> +  /* For CONDs, don't handle signed values here. */
> +  (if (cnd == VEC_COND_EXPR
> +       || TYPE_UNSIGNED (TREE_TYPE (@0)))
> +   (cnd @0 @2 @1))))
>
>  /* abs/negative simplifications moved from fold_cond_expr_with_comparison.
>
> @@ -7095,6 +7098,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>   (cond @0 @1 @2)
>   (with { bool wascmp; }
>    (if (INTEGRAL_TYPE_P (type)
> +       && TYPE_UNSIGNED (TREE_TYPE (@0))
>         && bitwise_inverted_equal_p (@1, @2, wascmp)
>         && (!wascmp || TYPE_PRECISION (type) == 1))
>     (if ((!TYPE_UNSIGNED (type) && TREE_CODE (type) == BOOLEAN_TYPE)
> diff --git a/gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c b/gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c
> new file mode 100644
> index 00000000000..b0ff120ea51
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c
> @@ -0,0 +1,13 @@
> +/* PR tree-optimization/114666 */
> +/* We used to miscompile this to be always aborting
> +   due to the use of the signed 1bit into the COND_EXPR. */
> +
> +struct {
> +  signed a : 1;
> +} b = {-1};
> +char c;
> +int main()
> +{
> +  if ((b.a ^ 1UL) < 3)
> +    __builtin_abort();
> +}
> --
> 2.43.0
>
  

Patch

diff --git a/gcc/match.pd b/gcc/match.pd
index 15a1e7350d4..d401e7503e6 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5895,7 +5895,10 @@  DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  /* !A ? B : C -> A ? C : B.  */
  (simplify
   (cnd (logical_inverted_value truth_valued_p@0) @1 @2)
-  (cnd @0 @2 @1)))
+  /* For CONDs, don't handle signed values here. */
+  (if (cnd == VEC_COND_EXPR
+       || TYPE_UNSIGNED (TREE_TYPE (@0)))
+   (cnd @0 @2 @1))))
 
 /* abs/negative simplifications moved from fold_cond_expr_with_comparison.
 
@@ -7095,6 +7098,7 @@  DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (cond @0 @1 @2)
  (with { bool wascmp; }
   (if (INTEGRAL_TYPE_P (type)
+       && TYPE_UNSIGNED (TREE_TYPE (@0))
        && bitwise_inverted_equal_p (@1, @2, wascmp)
        && (!wascmp || TYPE_PRECISION (type) == 1))
    (if ((!TYPE_UNSIGNED (type) && TREE_CODE (type) == BOOLEAN_TYPE)
diff --git a/gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c b/gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c
new file mode 100644
index 00000000000..b0ff120ea51
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/bitfld-signed1-1.c
@@ -0,0 +1,13 @@ 
+/* PR tree-optimization/114666 */
+/* We used to miscompile this to be always aborting
+   due to the use of the signed 1bit into the COND_EXPR. */
+
+struct {
+  signed a : 1;
+} b = {-1};
+char c;
+int main()
+{
+  if ((b.a ^ 1UL) < 3)
+    __builtin_abort();
+}