[PATCH] c++: Fix ICE on complex constant with -frounding-math [PR103114]

Jakub Jelinek jakub@redhat.com
Tue Nov 9 09:38:43 GMT 2021


Hi!

The FE uses build_complex which assumes that fold_convert will fold
value to a constant.  With -frounding-math that isn't guaranteed though.
So, the patch instead fold_build2s COMPLEX_EXPR, which will result
in build_complex if both arguments are constants, and otherwise
will build COMPLEX_EXPR.
build_zero_cst is an optimization for fold_convert (type, integer_zero_node).

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2021-11-09  Jakub Jelinek  <jakub@redhat.com>

	PR c++/103114
	* parser.c (cp_parser_userdef_numeric_literal): Use fold_build2
	with COMPLEX_EXPR arg instead of build_complex, use build_zero_cst
	instead of fold_convert from integer_zero_node.

	* g++.dg/ext/complex10.C: New test.

--- gcc/cp/parser.c.jj	2021-10-28 20:07:48.571193189 +0200
+++ gcc/cp/parser.c	2021-11-08 23:10:14.623106858 +0100
@@ -4804,9 +4804,8 @@ cp_parser_userdef_numeric_literal (cp_pa
       else /* if (id_equal (suffix_id, "il")) */
 	type = long_double_type_node;
 
-      value = build_complex (build_complex_type (type),
-			     fold_convert (type, integer_zero_node),
-			     fold_convert (type, value));
+      value = fold_build2 (COMPLEX_EXPR, build_complex_type (type),
+			   build_zero_cst (type), fold_convert (type, value));
     }
 
   if (cp_parser_uncommitted_to_tentative_parse_p (parser))
--- gcc/testsuite/g++.dg/ext/complex10.C.jj	2021-11-08 23:09:58.826331001 +0100
+++ gcc/testsuite/g++.dg/ext/complex10.C	2021-11-08 23:09:21.847855693 +0100
@@ -0,0 +1,5 @@
+// PR c++/103114
+// { dg-do compile }
+// { dg-options "-frounding-math" }
+
+_Complex double d = 10.1i;

	Jakub



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