re PR tree-optimization/87940 (FAIL: gcc.dg/warn-strlen-no-nul.c)

2018-11-09  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR tree-optimization/87940
        * expr.c (string_constant): Don't strip NOPS in subexpressions.
        Fold PLUS_EXPR correctly.

From-SVN: r265992

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6d1b40d1e946a84380c2fc2b49c2e9185675115f..1535fe51b1524a2931649ae17e40ae0fdc893ced 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-11-09  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+       PR tree-optimization/87940
+       * expr.c (string_constant): Don't strip NOPS in subexpressions.
+       Fold PLUS_EXPR correctly.
+
 2018-11-09  Ilya Leoshkevich  <iii@linux.ibm.com>
 
        PR target/87762

diff --git a/gcc/expr.c b/gcc/expr.c
index 6341c5a0bdb6539f93006ca4197cec12f80c65a5..7ae3e37378c5afbc6bb59b064ded4afb3e0e8673 100644 (file)
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -11358,18 +11358,15 @@ string_constant (tree arg, tree *ptr_offset, tree *mem_size, tree *decl)
       tree arg0 = TREE_OPERAND (arg, 0);
       tree arg1 = TREE_OPERAND (arg, 1);
 
-      STRIP_NOPS (arg0);
-      STRIP_NOPS (arg1);
-
-      if (TREE_CODE (arg0) == ADDR_EXPR)
-       ;   /* Do nothing.  */
-      else if (TREE_CODE (arg1) == ADDR_EXPR)
-       std::swap (arg0, arg1);
-      else
-       return NULL_TREE;
-
       tree offset;
-      if (tree str = string_constant (arg0, &offset, mem_size, decl))
+      tree str = string_constant (arg0, &offset, mem_size, decl);
+      if (!str)
+       {
+          str = string_constant (arg1, &offset, mem_size, decl);
+          arg1 = arg0;
+       }
+
+      if (str)
        {
          /* Avoid pointers to arrays (see bug 86622).  */
          if (POINTER_TYPE_P (TREE_TYPE (arg))
@@ -11380,7 +11377,8 @@ string_constant (tree arg, tree *ptr_offset, tree *mem_size, tree *decl)
                   && tree_int_cst_equal (*mem_size, DECL_SIZE_UNIT (*decl))))
            return NULL_TREE;
 
-         tree type = TREE_TYPE (arg1);
+         tree type = TREE_TYPE (offset);
+         arg1 = fold_convert (type, arg1);
          *ptr_offset = fold_build2 (PLUS_EXPR, type, offset, arg1);
          return str;
        }
@@ -11412,7 +11410,8 @@ string_constant (tree arg, tree *ptr_offset, tree *mem_size, tree *decl)
            return NULL_TREE;
 
          tree rhs2 = gimple_assign_rhs2 (stmt);
-         tree type = TREE_TYPE (rhs2);
+         tree type = TREE_TYPE (offset);
+         rhs2 = fold_convert (type, rhs2);
          *ptr_offset = fold_build2 (PLUS_EXPR, type, offset, rhs2);
          return str;
        }