re PR middle-end/83415 (ICE during gimplification of assignment to read-only vector)

2017-12-14  Richard Biener  <rguenther@suse.de>

	PR c/83415
	c/
	* c-fold.c (c_fully_fold_internal): Treat VIEW_CONVERT_EXPR
	like REALPART_EXPR for the behavior of whether its operand
	is an lvalue.

	* gcc.dg/pr83415.c: New testcase.

From-SVN: r255629

gcc/c/ChangeLog

+2017-12-14  Richard Biener  <rguenther@suse.de>
+
+	PR c/83415
+	* c-fold.c (c_fully_fold_internal): Treat VIEW_CONVERT_EXPR
+	like REALPART_EXPR for the behavior of whether its operand
+	is an lvalue.
+
 2017-12-12  Marek Polacek  <polacek@redhat.com>
 
 	PR c/82679

gcc/c/c-fold.c

@@ -434,6 +434,7 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
       goto unary;
     case REALPART_EXPR:
     case IMAGPART_EXPR:
+    case VIEW_CONVERT_EXPR:
       op0_lval = lval;
       /* FALLTHRU */
     case INDIRECT_REF:
@@ -441,7 +442,6 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
     case FLOAT_EXPR:
     CASE_CONVERT:
     case ADDR_SPACE_CONVERT_EXPR:
-    case VIEW_CONVERT_EXPR:
     case NON_LVALUE_EXPR:
     case NEGATE_EXPR:
     case BIT_NOT_EXPR:

gcc/testsuite/ChangeLog

 2017-12-14  Richard Biener  <rguenther@suse.de>
 
+	PR c/83415
+	* gcc.dg/pr83415.c: New testcase.
+
+2017-12-14  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/83418
 	* gcc.dg/torture/pr83418.c: New testcase.
 

gcc/testsuite/gcc.dg/pr83415.c

+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+const short __attribute__((vector_size(16))) y = { 0, 1, 2, 3, 4, 5, 6, 7 };
+
+int
+main (int argc, short *argv[])
+{
+  int i = argc;
+  y[i] = 7 - i; /* { dg-warning "read-only" } */
+  return 0;
+}