diff mbox series

[committed] c++: Fix up handling of captured vars in lambdas in OpenMP clauses [PR93931]

Message ID 20200319113008.GQ2156@tucnak
State New
Headers show
Series [committed] c++: Fix up handling of captured vars in lambdas in OpenMP clauses [PR93931] | expand

Commit Message

Li, Pan2 via Gcc-patches March 19, 2020, 11:30 a.m. UTC 
Hi!

Without the parser.c change we were ICEing on the testcase, because while the
uses of the captured vars inside of the constructs were replaced with capture
proxy decls, we didn't do that for decls in OpenMP clauses.

With that fixed, we don't ICE anymore, but the testcase is miscompiled and FAILs
at runtime.  This is because the capture proxy decls have DECL_VALUE_EXPR and
during gimplification we were gimplifying those to their DECL_VALUE_EXPRs.
That is fine for shared vars, but for privatized ones we must not do that.
So that is what the cp-gimplify.c changes do.  Had to add a DECL_CONTEXT check
before calling is_capture_proxy because some VAR_DECLs don't have DECL_CONTEXT
set (yet) and is_capture_proxy relies on that being non-NULL always.

Bootstrapped/regtested on x86_64-linux and i686-linux, committed to trunk.

2020-03-19  Jakub Jelinek  <jakub@redhat.com>

	PR c++/93931
	* parser.c (cp_parser_omp_var_list_no_open): Call process_outer_var_ref
	on outer_automatic_var_p decls.
	* cp-gimplify.c (cxx_omp_disregard_value_expr): Return true also for
	capture proxy decls.

	* testsuite/libgomp.c++/pr93931.C: New test.


	Jakub
diff mbox series

Patch

--- gcc/cp/parser.c.jj	2020-03-19 10:20:28.621837665 +0100
+++ gcc/cp/parser.c	2020-03-19 11:17:25.204683731 +0100
@@ -34059,6 +34059,8 @@  cp_parser_omp_var_list_no_open (cp_parse
 					   token->location);
 	    }
 	}
+      if (outer_automatic_var_p (decl))
+	decl = process_outer_var_ref (decl, tf_warning_or_error);
       if (decl == error_mark_node)
 	;
       else if (kind != 0)
--- gcc/cp/cp-gimplify.c.jj	2020-03-19 10:20:28.276842716 +0100
+++ gcc/cp/cp-gimplify.c	2020-03-19 11:41:01.101925656 +0100
@@ -2260,12 +2260,17 @@  cxx_omp_finish_clause (tree c, gimple_se
 bool
 cxx_omp_disregard_value_expr (tree decl, bool shared)
 {
-  return !shared
-	 && VAR_P (decl)
-	 && DECL_HAS_VALUE_EXPR_P (decl)
-	 && DECL_ARTIFICIAL (decl)
-	 && DECL_LANG_SPECIFIC (decl)
-	 && DECL_OMP_PRIVATIZED_MEMBER (decl);
+  if (shared)
+    return false;
+  if (VAR_P (decl)
+      && DECL_HAS_VALUE_EXPR_P (decl)
+      && DECL_ARTIFICIAL (decl)
+      && DECL_LANG_SPECIFIC (decl)
+      && DECL_OMP_PRIVATIZED_MEMBER (decl))
+    return true;
+  if (VAR_P (decl) && DECL_CONTEXT (decl) && is_capture_proxy (decl))
+    return true;
+  return false;
 }
 
 /* Fold expression X which is used as an rvalue if RVAL is true.  */
--- libgomp/testsuite/libgomp.c++/pr93931.C.jj	2020-03-19 11:43:51.839420252 +0100
+++ libgomp/testsuite/libgomp.c++/pr93931.C	2020-03-19 11:38:22.097258893 +0100
@@ -0,0 +1,120 @@ 
+// PR c++/93931
+// { dg-do run }
+// { dg-options "-O2 -std=c++14" }
+
+extern "C" void abort ();
+
+void
+sink (int &x)
+{
+  int *volatile p;
+  p = &x;
+  (*p)++;
+}
+
+int
+foo ()
+{
+  int r = 0;
+  [&r] () {
+#pragma omp parallel for reduction(+ : r)
+    for (int i = 0; i < 1024; ++i)
+      r += i;
+  } ();
+  return r;
+}
+
+int
+bar ()
+{
+  int l = 0;
+  [&l] () {
+#pragma omp parallel for lastprivate (l)
+    for (int i = 0; i < 1024; ++i)
+      l = i;
+  } ();
+  return l;
+}
+
+void
+baz ()
+{
+  int f = 18;
+  [&f] () {
+#pragma omp parallel for firstprivate (f)
+    for (int i = 0; i < 1024; ++i)
+      {
+	sink (f);
+	f += 3;
+	sink (f);
+	if (f != 23)
+	  abort ();
+	sink (f);
+	f -= 7;
+	sink (f);
+      }
+  } ();
+  if (f != 18)
+    abort ();
+}
+
+int
+qux ()
+{
+  int r = 0;
+  [&] () {
+#pragma omp parallel for reduction(+ : r)
+    for (int i = 0; i < 1024; ++i)
+      r += i;
+  } ();
+  return r;
+}
+
+int
+corge ()
+{
+  int l = 0;
+  [&] () {
+#pragma omp parallel for lastprivate (l)
+    for (int i = 0; i < 1024; ++i)
+      l = i;
+  } ();
+  return l;
+}
+
+void
+garply ()
+{
+  int f = 18;
+  [&] () {
+#pragma omp parallel for firstprivate (f)
+    for (int i = 0; i < 1024; ++i)
+      {
+	sink (f);
+	f += 3;
+	sink (f);
+	if (f != 23)
+	  abort ();
+	sink (f);
+	f -= 7;
+	sink (f);
+      }
+  } ();
+  if (f != 18)
+    abort ();
+}
+
+int
+main ()
+{
+  if (foo () != 1024 * 1023 / 2)
+    abort ();
+  if (bar () != 1023)
+    abort ();
+  baz ();
+  if (qux () != 1024 * 1023 / 2)
+    abort ();
+  if (corge () != 1023)
+    abort ();
+  garply ();
+}