From: Andrew Pinski <apinski@marvell.com>
Date: Sun, 17 Sep 2023 18:20:36 +0000 (-0700)
Subject: MATCH: Make zero_one_valued_p non-recursive fully
X-Git-Tag: basepoints/gcc-15~6025
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7ea501d3ea698e1c845fb61e3487f4cd949e6253;p=thirdparty%2Fgcc.git

MATCH: Make zero_one_valued_p non-recursive fully

So it turns out VN can't handle any kind of recursion for match. In this
case we have `b = a & -1` and we try to match a as being zero_one_valued_p
and VN returns b as being the value and we just go into an infinite loop at
this point.

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

Note genmatch should warn (or error out) if this gets detected so I filed PR 111446
which I will be looking into next week or the week after so we don't run into
this issue again.

	PR tree-optimization/111442

gcc/ChangeLog:

	* match.pd (zero_one_valued_p): Have the bit_and match not be
	recursive.

gcc/testsuite/ChangeLog:

	* gcc.c-torture/compile/pr111442-1.c: New test.
---

diff --git a/gcc/match.pd b/gcc/match.pd
index a405c9ff6f82..bef513aaa3f0 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2183,8 +2183,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 
 /* (a&1) is always [0,1] too. This is useful again when
    the range is not known. */
+/* Note this can't be recursive due to VN handling of equivalents,
+   VN and would cause an infinite recursion. */
 (match zero_one_valued_p
- (bit_and:c@0 @1 zero_one_valued_p))
+ (bit_and:c@0 @1 integer_onep)
+ (if (INTEGRAL_TYPE_P (type))))
 
 /* A conversion from an zero_one_valued_p is still a [0,1].
    This is useful when the range of a variable is not known */
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr111442-1.c b/gcc/testsuite/gcc.c-torture/compile/pr111442-1.c
new file mode 100644
index 000000000000..5814ee938de0
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr111442-1.c
@@ -0,0 +1,13 @@
+
+int *a, b;
+int main() {
+  int d = 1, e;
+  if (d)
+    e = a ? 0 % 0 : 0;
+  if (d)
+    a = &d;
+  d = -1;
+  b = d & e;
+  b = 2 * e ^ 1;
+  return 0;
+}