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

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>

diff --git a/gcc/match.pd b/gcc/match.pd
index 15a1e7350d4a896758204b00638b53e84045cb13..d401e7503e62cde441877f0a61511d3e97ad146f 100644 (file)
--- 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 (file)
index 0000000..b0ff120
--- /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();
+}