re PR c/87387 (trunk/gcc/builtins.c:585:7: warning: -Wself-assign problem)

	PR c/87387
        * builtins.c (unterminated_array): Simplify.
	* expr.c (string_constant): Handle SSA_NAME.  Add more exceptions
	where pointer arithmetic is safe.

	* gcc.dg/warn-stpcpy-no-nul.c: Drop unnecessary xfails.
	* gcc.dg/warn-stplen-no-nul.c: Likewise.

From-SVN: r264585

1 files changed, 36 insertions, 1 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index b8782b9..583c7f0 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -11372,7 +11372,10 @@ string_constant (tree arg, tree *ptr_offset, tree *mem_size, tree *decl)
 	  /* Avoid pointers to arrays (see bug 86622).  */
 	  if (POINTER_TYPE_P (TREE_TYPE (arg))
 	      && TREE_CODE (TREE_TYPE (TREE_TYPE (arg))) == ARRAY_TYPE
-	      && TREE_CODE (TREE_OPERAND (arg0, 0)) == ARRAY_REF)
+	      && !(decl && !*decl)
+	      && !(decl && tree_fits_uhwi_p (DECL_SIZE_UNIT (*decl))
+		   && mem_size && tree_fits_uhwi_p (*mem_size)
+		   && tree_int_cst_equal (*mem_size, DECL_SIZE_UNIT (*decl))))
 	    return NULL_TREE;
 
 	  tree type = TREE_TYPE (arg1);
@@ -11381,6 +11384,38 @@ string_constant (tree arg, tree *ptr_offset, tree *mem_size, tree *decl)
 	}
       return NULL_TREE;
     }
+  else if (TREE_CODE (arg) == SSA_NAME)
+    {
+      gimple *stmt = SSA_NAME_DEF_STMT (arg);
+      if (!is_gimple_assign (stmt))
+	return NULL_TREE;
+
+      tree rhs1 = gimple_assign_rhs1 (stmt);
+      tree_code code = gimple_assign_rhs_code (stmt);
+      if (code == ADDR_EXPR)
+	return string_constant (rhs1, ptr_offset, mem_size, decl);
+      else if (code != POINTER_PLUS_EXPR)
+	return NULL_TREE;
+
+      tree offset;
+      if (tree str = string_constant (rhs1, &offset, mem_size, decl))
+	{
+	  /* Avoid pointers to arrays (see bug 86622).  */
+	  if (POINTER_TYPE_P (TREE_TYPE (rhs1))
+	      && TREE_CODE (TREE_TYPE (TREE_TYPE (rhs1))) == ARRAY_TYPE
+	      && !(decl && !*decl)
+	      && !(decl && tree_fits_uhwi_p (DECL_SIZE_UNIT (*decl))
+		   && mem_size && tree_fits_uhwi_p (*mem_size)
+		   && tree_int_cst_equal (*mem_size, DECL_SIZE_UNIT (*decl))))
+	    return NULL_TREE;
+
+	  tree rhs2 = gimple_assign_rhs2 (stmt);
+	  tree type = TREE_TYPE (rhs2);
+	  *ptr_offset = fold_build2 (PLUS_EXPR, type, offset, rhs2);
+	  return str;
+	}
+      return NULL_TREE;
+    }
   else if (DECL_P (arg))
     array = arg;
   else