[gcc r11-9260] tree-optimization/103204 - fix missed valueization in VN

[gcc r11-9260] tree-optimization/103204 - fix missed valueization in VN

[Richard Biener]

https://gcc.gnu.org/g:5571c2719269687ad518d5aadf248a7500f11f85

commit r11-9260-g5571c2719269687ad518d5aadf248a7500f11f85
Author: Richard Biener <rguenther@suse.de>
Date:   Fri Nov 12 09:09:29 2021 +0100

    tree-optimization/103204 - fix missed valueization in VN
    
    The following fixes a missed valueization when simplifying
    a MEM[&...] combination during valueization.
    
    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.
    
    (cherry picked from commit 140346fa246dc2476c5c2bf2ecadebd18a3af5d0)

Diff:
---
 gcc/testsuite/gcc.dg/torture/pr103204.c | 16 ++++++++++++++++
 gcc/tree-ssa-sccvn.c                    | 13 ++++++++-----
 2 files changed, 24 insertions(+), 5 deletions(-)

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 07a52887b6b..3723d326c03 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1612,13 +1612,12 @@ 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))
 	{
@@ -1666,7 +1665,11 @@ 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.  */