From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 30 May 2017 08:25:50 +0000 (+0200)
Subject: backport: re PR libgomp/80394 (Empty OpenMP task is wrongly removed when optimizing)
X-Git-Tag: releases/gcc-5.5.0~242
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=da086d5e0c0e96189d45aa80b9456d9f3ace6103;p=thirdparty%2Fgcc.git

backport: re PR libgomp/80394 (Empty OpenMP task is wrongly removed when optimizing)

	Backported from mainline
	2017-04-11  Jakub Jelinek  <jakub@redhat.com>

	PR libgomp/80394
	* omp-low.c (scan_omp_task): Don't optimize away empty tasks
	if they have any depend clauses.

	* testsuite/libgomp.c/pr80394.c: New test.

From-SVN: r248671
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 32e6d75a790f..24ddc3397a5c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,12 @@
 2017-05-30  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2017-04-11  Jakub Jelinek  <jakub@redhat.com>
+
+	PR libgomp/80394
+	* omp-low.c (scan_omp_task): Don't optimize away empty tasks
+	if they have any depend clauses.
+
 	2017-04-04  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/80286
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 945b9c733d6a..907a728417b8 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -2378,9 +2378,11 @@ scan_omp_task (gimple_stmt_iterator *gsi, omp_context *outer_ctx)
   tree name, t;
   gomp_task *stmt = as_a <gomp_task *> (gsi_stmt (*gsi));
 
-  /* Ignore task directives with empty bodies.  */
+  /* Ignore task directives with empty bodies, unless they have depend
+     clause.  */
   if (optimize > 0
-      && empty_body_p (gimple_omp_body (stmt)))
+      && empty_body_p (gimple_omp_body (stmt))
+      && !find_omp_clause (gimple_omp_task_clauses (stmt), OMP_CLAUSE_DEPEND))
     {
       gsi_replace (gsi, gimple_build_nop (), false);
       return;
diff --git a/libgomp/ChangeLog b/libgomp/ChangeLog
index bae1441dabf1..b602cf16998e 100644
--- a/libgomp/ChangeLog
+++ b/libgomp/ChangeLog
@@ -1,6 +1,11 @@
 2017-05-30  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2017-04-11  Jakub Jelinek  <jakub@redhat.com>
+
+	PR libgomp/80394
+	* testsuite/libgomp.c/pr80394.c: New test.
+
 	2017-03-30  Jakub Jelinek  <jakub@redhat.com>
 
 	* env.c (initialize_env): Initialize stacksize to 0.
diff --git a/libgomp/testsuite/libgomp.c/pr80394.c b/libgomp/testsuite/libgomp.c/pr80394.c
new file mode 100644
index 000000000000..6c5a74018515
--- /dev/null
+++ b/libgomp/testsuite/libgomp.c/pr80394.c
@@ -0,0 +1,22 @@
+/* PR libgomp/80394 */
+
+int
+main ()
+{
+  int x = 0;
+  #pragma omp parallel shared(x)
+  #pragma omp single
+  {
+    #pragma omp task depend(inout: x)
+    {
+      for (int i = 0; i < 100000; i++)
+        asm volatile ("" : : : "memory");
+      x += 5;
+    }
+    #pragma omp task if (0) depend(inout: x)
+    ;
+    if (x != 5)
+      __builtin_abort ();
+  }
+  return 0;
+}