The following fixes and ICE in the LTO streamer by releasing 
non-gimple-val sizepos values in free-lang-data.  This works around(?)
the C++ FE leaving non-gimplified abstract origins around.

LTO bootstrapped & tested on x86_64-unknown-linux-gnu, applied to trunk 
sofar.

Richard.

>From f7ddb8be8a059b084a1d46bde9a33ba365886b6e Mon Sep 17 00:00:00 2001
From: Richard Guenther <rguent...@suse.de>
Date: Mon, 19 Nov 2018 09:28:24 +0100
Subject: [PATCH] fix-pr87229

2018-11-19  Richard Biener  <rguent...@suse.de>

        PR lto/87229
        * tree.c (free_lang_data_in_one_sizepos): Free non-gimple-val
        sizepos values.

        * g++.dg/lto/pr87229_0.C: New testcase.

diff --git a/gcc/testsuite/g++.dg/lto/pr87229_0.C 
b/gcc/testsuite/g++.dg/lto/pr87229_0.C
new file mode 100644
index 00000000000..1c20e805291
--- /dev/null
+++ b/gcc/testsuite/g++.dg/lto/pr87229_0.C
@@ -0,0 +1,7 @@
+// { dg-lto-do assemble }
+
+struct Main { Main(char* x); };
+
+Main::Main(char* x) {
+    char cfg[__builtin_strlen(x)];
+}
diff --git a/gcc/tree.c b/gcc/tree.c
index be89897d43a..48de9cf350f 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -5254,6 +5254,13 @@ free_lang_data_in_one_sizepos (tree *expr_p)
   tree expr = *expr_p;
   if (CONTAINS_PLACEHOLDER_P (expr))
     *expr_p = build0 (PLACEHOLDER_EXPR, TREE_TYPE (expr));
+  /* ???  We have to reset all non-GIMPLE sizepos because those eventually
+     refer to trees we cannot stream.  See for example PR87229 which
+     shows an example with non-gimplified abstract origins in C++.
+     Note this should only happen for abstract copies so setting sizes
+     to NULL is OK (but we cannot easily assert this).  */
+  else if (expr && !is_gimple_val (expr))
+    *expr_p = NULL_TREE;
 }
 
 

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