On Fri, Apr 12, 2024 at 6:53 AM Andrew Pinski <quic_apin...@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_apin...@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
>
