[PATCH] tree-optimization/103204 - fix missed valueization in VN

Richard Biener rguenther@suse.de
Fri Nov 12 09:05:28 GMT 2021


The following fixes a missed valueization when simplifying
a MEM[&...] combination during valueization.

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

2021-11-12  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/103204
	* tree-ssa-sccvn.c (valueize_refs_1): Re-valueize the
	top operand after folding in an address.

	* gcc.dg/torture/pr103204.c: New testcase.
---
 gcc/testsuite/gcc.dg/torture/pr103204.c | 16 ++++++++++++++++
 gcc/tree-ssa-sccvn.c                    | 13 ++++++++-----
 2 files changed, 24 insertions(+), 5 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/torture/pr103204.c

diff --git a/gcc/testsuite/gcc.dg/torture/pr103204.c b/gcc/testsuite/gcc.dg/torture/pr103204.c
new file mode 100644
index 00000000000..b08b6864691
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr103204.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+
+int a[1][1];
+int b, c;
+void d()
+{
+  int e;
+  int f[0];
+  int *g;
+  for (; e;)
+    c = b;
+  if (a[0][b] = (__UINTPTR_TYPE__)f != 3)
+    g = &f[b];
+  int h;
+  *g = *g = *g = h;
+}
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 7be5d4e406f..149674e6a16 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1640,13 +1640,12 @@ static void
 valueize_refs_1 (vec<vn_reference_op_s> *orig, bool *valueized_anything,
 		 bool with_avail = false)
 {
-  vn_reference_op_t vro;
-  unsigned int i;
-
   *valueized_anything = false;
 
-  FOR_EACH_VEC_ELT (*orig, i, vro)
+  for (unsigned i = 0; i < orig->length (); ++i)
     {
+re_valueize:
+      vn_reference_op_t vro = &(*orig)[i];
       if (vro->opcode == SSA_NAME
 	  || (vro->op0 && TREE_CODE (vro->op0) == SSA_NAME))
 	{
@@ -1694,7 +1693,11 @@ valueize_refs_1 (vec<vn_reference_op_s> *orig, bool *valueized_anything,
 	       && (*orig)[i - 1].opcode == MEM_REF)
 	{
 	  if (vn_reference_maybe_forwprop_address (orig, &i))
-	    *valueized_anything = true;
+	    {
+	      *valueized_anything = true;
+	      /* Re-valueize the current operand.  */
+	      goto re_valueize;
+	    }
 	}
       /* If it transforms a non-constant ARRAY_REF into a constant
 	 one, adjust the constant offset.  */
-- 
2.31.1


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