[PATCH] Fix PR77988

[Richard Biener]

Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.

Richard.

2016-10-17  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/77988
        * tree-vrp.c (remove_range_assertions): Use replace_uses_by.

        * gcc.dg/torture/pr77988.c: New testcase.

Index: gcc/testsuite/gcc.dg/torture/pr77988.c
===================================================================
--- gcc/testsuite/gcc.dg/torture/pr77988.c      (revision 0)
+++ gcc/testsuite/gcc.dg/torture/pr77988.c      (working copy)
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+
+static int a = 2;
+int b[1], c, d;
+
+int main ()
+{ 
+  int e = a, *f = &b[0];
+  if (d)
+    for (e = 0; e < 1; e++)
+      ;
+  if (e)
+    {
+L1:
+      if (b < f)
+       __builtin_abort ();
+      if (*f)
+       c++;
+      return 0;
+    }
+  f = 0;
+  goto L1;
+  return 0;
+}
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c      (revision 241227)
+++ gcc/tree-vrp.c      (working copy)
@@ -6882,7 +6882,6 @@ remove_range_assertions (void)
     for (si = gsi_after_labels (bb), is_unreachable = -1; !gsi_end_p (si);)
       {
        gimple *stmt = gsi_stmt (si);
-       gimple *use_stmt;
 
        if (is_gimple_assign (stmt)
            && gimple_assign_rhs_code (stmt) == ASSERT_EXPR)
@@ -6890,8 +6889,6 @@ remove_range_assertions (void)
            tree lhs = gimple_assign_lhs (stmt);
            tree rhs = gimple_assign_rhs1 (stmt);
            tree var;
-           use_operand_p use_p;
-           imm_use_iterator iter;
 
            var = ASSERT_EXPR_VAR (rhs);
 
@@ -6927,12 +6924,7 @@ remove_range_assertions (void)
              }
 
            /* Propagate the RHS into every use of the LHS.  */
-           FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
-             {
-               FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
-                 SET_USE (use_p, var);
-               update_stmt (use_stmt);
-             }
+           replace_uses_by (lhs, var);
 
            /* And finally, remove the copy, it is not needed.  */
            gsi_remove (&si, true);