re PR c++/84704 (internal compiler error: gimplification failed)

	PR c++/84704
	* tree.c (stabilize_reference_1): Return save_expr (e) for
	STATEMENT_LIST even if it doesn't have side-effects.

	* g++.dg/debug/pr84704.C: New test.

From-SVN: r258470

4 files changed, 27 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6af8d2f..e6fb95b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-03-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/84704
+	* tree.c (stabilize_reference_1): Return save_expr (e) for
+	STATEMENT_LIST even if it doesn't have side-effects.
+
 2018-03-12  Jonathan Wakely  <jwakely@redhat.com>
 
 	* doc/invoke.texi (-mclflushopt): Fix spelling of option.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 5880171..da617c7 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-03-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/84704
+	* g++.dg/debug/pr84704.C: New test.
+
 2018-03-12  Renlin Li  <renlin.li@arm.com>
 
 	* gcc.target/aarch64/movi_hf.c: New.
diff --git a/gcc/testsuite/g++.dg/debug/pr84704.C b/gcc/testsuite/g++.dg/debug/pr84704.C
new file mode 100644
index 0000000..3043edb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/debug/pr84704.C
@@ -0,0 +1,11 @@
+// PR c++/84704
+// { dg-do compile }
+// { dg-options "-g -fcompare-debug -O2" }
+
+int a[1] = { 0 };
+
+void
+foo ()
+{
+  a[({ 0; })] %= 5;
+}
diff --git a/gcc/tree.c b/gcc/tree.c
index 63a29f4..1e1a1be 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -4352,6 +4352,11 @@ stabilize_reference_1 (tree e)
   switch (TREE_CODE_CLASS (code))
     {
     case tcc_exceptional:
+      /* Always wrap STATEMENT_LIST into SAVE_EXPR, even if it doesn't
+	 have side-effects.  */
+      if (code == STATEMENT_LIST)
+	return save_expr (e);
+      /* FALLTHRU */
     case tcc_type:
     case tcc_declaration:
     case tcc_comparison: