From: Jason Merrill <jason@redhat.com>
Date: Sun, 4 Mar 2018 05:32:39 +0000 (-0500)
Subject: PR c++/84686 - missing volatile loads.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=38946ea192bf484cc854dd407d34cce4de6b698b;p=gcc.git

PR c++/84686 - missing volatile loads.

	* cvt.c (convert_to_void): Call maybe_undo_parenthesized_ref.

From-SVN: r258231
---

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 391aa5f11fe..942b7e89aae 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2018-03-03  Jason Merrill  <jason@redhat.com>
+
+	PR c++/84686 - missing volatile loads.
+	* cvt.c (convert_to_void): Call maybe_undo_parenthesized_ref.
+
 2018-03-03  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/71464
diff --git a/gcc/cp/cvt.c b/gcc/cp/cvt.c
index f5da08bbee2..40e7576f23c 100644
--- a/gcc/cp/cvt.c
+++ b/gcc/cp/cvt.c
@@ -1063,6 +1063,8 @@ convert_to_void (tree expr, impl_conv_void implicit, tsubst_flags_t complain)
       || TREE_TYPE (expr) == error_mark_node)
     return error_mark_node;
 
+  expr = maybe_undo_parenthesized_ref (expr);
+
   expr = mark_discarded_use (expr);
   if (implicit == ICV_CAST)
     /* An explicit cast to void avoids all -Wunused-but-set* warnings.  */
diff --git a/gcc/testsuite/g++.dg/tree-ssa/volatile2.C b/gcc/testsuite/g++.dg/tree-ssa/volatile2.C
new file mode 100644
index 00000000000..bec60442477
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/volatile2.C
@@ -0,0 +1,20 @@
+// PR c++/84686
+// { dg-additional-options -fdump-tree-gimple }
+// { dg-final { scan-tree-dump-times "= i" 10 "gimple" } }
+
+volatile int i;
+
+int main()
+{
+  i; //evaluated (a load is performed)
+  (i); //unevaluated => the load shall be performed
+
+  (void)i; //evaluated (a load is performed)
+  (void)(i); //unevaluated => the load shall be performed
+
+  (void)i; //evaluated (a load is performed)
+  (void)(i); //unevaluated => the load shall be performed
+
+  (i,i); // the two subexpression are evaluated
+  ((i),(i)); // no evaluation, => two loads shall happen
+}