[PATCH] tree-optimization/114048 - ICE in copy_reference_ops_from_ref

[Richard Biener]

The following adds another omission to the assert verifying we're
not running into spurious off == -1.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

        PR tree-optimization/114048
        * tree-ssa-sccvn.cc (copy_reference_ops_from_ref): MEM_REF
        can also produce -1 off.

        * gcc.dg/torture/pr114048.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr114048.c | 25 +++++++++++++++++++++++++
 gcc/tree-ssa-sccvn.cc                   |  2 ++
 2 files changed, 27 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr114048.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr114048.c 
b/gcc/testsuite/gcc.dg/torture/pr114048.c
new file mode 100644
index 00000000000..338000b3006
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr114048.c
@@ -0,0 +1,25 @@
+/* { dg-do compile } */
+
+typedef struct {
+  void *child[2];
+  char otherbits;
+} critbit0_node;
+
+int allprefixed_traverse(char *top)
+{
+  if (top)
+    {
+      critbit0_node *q = (void *)top - 1;
+      int direction = 0;
+      for (;; ++direction)
+       switch (allprefixed_traverse(q->child[direction]))
+         {
+         case 1:
+           break;
+         case 0:
+           return 0;
+         default:
+           return 1;
+         }
+    }
+}
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 3e93685e80a..2587eb1c505 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -1185,6 +1185,8 @@ copy_reference_ops_from_ref (tree ref, 
vec<vn_reference_op_s> *result)
              else
                {
                  gcc_assert (known_ne (op.off, -1)
+                             /* The constant offset can be -1.  */
+                             || op.opcode == MEM_REF
                              /* Out-of-bound indices can compute to
                                 a known -1 offset.  */
                              || ((op.opcode == ARRAY_REF
-- 
2.35.3