While the PR is about an ICE during debug stmt expansion
it shows a missed optimization ultimatively leading to a
debug stmt refering to VIEW_CONVERT_EXPR<int>({}) which isn't
handled.
The following fixes the missed optimization and thus also
the ICE by instead producing a debug stmt refering to 0.
Bootstrap / regtest running on x86_64-unknown-linux-gnu.
OK for GCC 9? The ICE would be a checking-only ICE.
Richard.
2019-04-24 Richard Biener <rguent...@suse.de>
PR middle-end/90194
* match.pd: Add pattern to simplify view-conversion of an
empty constructor.
* g++.dg/torture/pr90194.C: New testcase.
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 270537)
+++ gcc/match.pd (working copy)
@@ -2596,6 +2596,13 @@ (define_operator_list COND_TERNARY
&& TYPE_UNSIGNED (TREE_TYPE (@1)))))
(view_convert @1)))
+/* Simplify a view-converted empty constructor. */
+(simplify
+ (view_convert CONSTRUCTOR@0)
+ (if (TREE_CODE (@0) != SSA_NAME
+ && CONSTRUCTOR_NELTS (@0) == 0)
+ { build_zero_cst (type); }))
+
/* Re-association barriers around constants and other re-association
barriers can be removed. */
(simplify
Index: gcc/testsuite/g++.dg/torture/pr90194.C
===================================================================
--- gcc/testsuite/g++.dg/torture/pr90194.C (nonexistent)
+++ gcc/testsuite/g++.dg/torture/pr90194.C (working copy)
@@ -0,0 +1,18 @@
+// { dg-do compile }
+// { dg-additional-options "-g" }
+
+struct cb {
+ int yr;
+};
+
+void *
+operator new (__SIZE_TYPE__, void *nq)
+{
+ return nq;
+}
+
+void
+af (int xn)
+{
+ new (&xn) cb { };
+}
