re PR tree-optimization/92131 (incorrect assumption that (ao >= 0) is always false)

	PR tree-optimization/92131
	* tree-vrp.c (extract_range_from_plus_minus_expr): If the resulting
	range would be symbolic, drop to varying for any explicit overflow
	in the constant part or if neither range is a singleton.

From-SVN: r277314

1 files changed, 73 insertions, 0 deletions

diff --git a/gcc/testsuite/gcc.c-torture/execute/20191023-1.c b/gcc/testsuite/gcc.c-torture/execute/20191023-1.c
new file mode 100644
index 0000000..3811ebc
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20191023-1.c
@@ -0,0 +1,73 @@
+/* PR tree-optimization/92131 */
+/* Testcase by Armin Rigo <arigo@tunes.org> */
+
+long b, c, d, e, f, i;
+char g, h, j, k;
+int *aa;
+
+static void error (void) __attribute__((noipa));
+static void error (void) { __builtin_abort(); }
+
+static void see_me_here (void) __attribute__((noipa));
+static void see_me_here (void) {}
+
+static void aaa (void) __attribute__((noipa));
+static void aaa (void) {}
+
+static void a (void) __attribute__((noipa));
+static void a (void) {
+  long am, ao;
+  if (aa == 0) {
+    aaa();
+    if (j)
+      goto ay;
+  }
+  return;
+ay:
+  aaa();
+  if (k) {
+    aaa();
+    goto az;
+  }
+  return;
+az:
+  if (i)
+    if (g)
+      if (h)
+        if (e)
+          goto bd;
+  return;
+bd:
+  am = 0;
+  while (am < e) {
+    switch (c) {
+    case 8:
+      goto bh;
+    case 4:
+      return;
+    }
+  bh:
+    if (am >= 0)
+      b = -am;
+    ao = am + b;
+    f = ao & 7;
+    if (f == 0)
+      see_me_here();
+    if (ao >= 0)
+      am++;
+    else
+      error();
+  }
+}
+
+int main (void)
+{
+    j++;
+    k++;
+    i++;
+    g++;
+    h++;
+    e = 1;
+    a();
+    return 0;
+}