[gcc r12-4187] Allow more kinds of invariant addresses in GIMPLE FE

[Richard Biener <rguenth@gcc.gnu.org>]

https://gcc.gnu.org/g:d4f6dbe18374385b8199ca3d6121e37a1189b589

commit r12-4187-gd4f6dbe18374385b8199ca3d6121e37a1189b589
Author: Richard Biener <rguenther@suse.de>
Date:   Tue Oct 5 14:18:09 2021 +0200

    Allow more kinds of invariant addresses in GIMPLE FE
    
    The gimple FE is too restrictive in what it accepts as
    literals, the following makes it also accept &a[10] for example.
    
    2021-10-05  Richard Biener  <rguenther@suse.de>
    
            PR c/102605
    gcc/c/
            * gimple-parser.c (c_parser_gimple_postfix_expression):
            Accept more address _Literals.
    
    gcc/testsuite/
            * gcc.dg/gimplefe-46.c: New testcase.

Diff:
---
 gcc/c/gimple-parser.c              | 14 +++++++++-----
 gcc/testsuite/gcc.dg/gimplefe-46.c | 23 +++++++++++++++++++++++
 2 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/gcc/c/gimple-parser.c b/gcc/c/gimple-parser.c
index c8d9db61f0a..c43ee38a2cf 100644
--- a/gcc/c/gimple-parser.c
+++ b/gcc/c/gimple-parser.c
@@ -1622,16 +1622,20 @@ c_parser_gimple_postfix_expression (gimple_parser &parser)
 		  tree val = c_parser_gimple_postfix_expression (parser).value;
 		  if (! val
 		      || val == error_mark_node
-		      || (!CONSTANT_CLASS_P (val)
-			  && !(addr_p
-			       && (TREE_CODE (val) == STRING_CST
-				   || DECL_P (val)))))
+		      || (!CONSTANT_CLASS_P (val) && !addr_p))
 		    {
 		      c_parser_error (parser, "invalid _Literal");
 		      return expr;
 		    }
 		  if (addr_p)
-		    val = build1 (ADDR_EXPR, type, val);
+		    {
+		      val = build1 (ADDR_EXPR, type, val);
+		      if (!is_gimple_invariant_address (val))
+			{
+			  c_parser_error (parser, "invalid _Literal");
+			  return expr;
+			}
+		    }
 		  if (neg_p)
 		    {
 		      val = const_unop (NEGATE_EXPR, TREE_TYPE (val), val);
diff --git a/gcc/testsuite/gcc.dg/gimplefe-46.c b/gcc/testsuite/gcc.dg/gimplefe-46.c
new file mode 100644
index 00000000000..fb91f7d2a90
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/gimplefe-46.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-fgimple" } */
+
+char global[10];
+
+void bar (void);
+
+void __GIMPLE (ssa)
+foo (char * p)
+{
+  __BB(2):
+  if (p_2(D) == _Literal (char *)&global[2])
+    goto __BB3;
+  else
+    goto __BB4;
+
+  __BB(3):
+  bar ();
+  goto __BB4;
+
+  __BB(4):
+  return;
+}