Warn about inconsistent OpenACC nested reduction clauses

	OpenACC (cf. OpenACC 2.7, section 2.9.11. "reduction clause";
	this was first clarified by OpenACC 2.6) requires that, if a
	variable is used in reduction clauses on two nested loops, then
	there must be reduction clauses for that variable on all loops
	that are nested in between the two loops and all these reduction
	clauses must use the same operator.
	This commit introduces a check for that property which reports
	warnings if it is violated.

	2019-11-06  Gergö Barany  <gergo@codesourcery.com>
	            Frederik Harwath  <frederik@codesourcery.com>
	            Thomas Schwinge  <thomas@codesourcery.com>

	gcc/
	* omp-low.c (struct omp_context): New fields
	local_reduction_clauses, outer_reduction_clauses.
	(new_omp_context): Initialize these.
	(scan_sharing_clauses): Record reduction clauses on OpenACC constructs.
	(scan_omp_for): Check reduction clauses for incorrect nesting.
	gcc/testsuite/
	* c-c++-common/goacc/nested-reductions-warn.c: New test.
	* c-c++-common/goacc/nested-reductions.c: New test.
	* gfortran.dg/goacc/nested-reductions-warn.f90: New test.
	* gfortran.dg/goacc/nested-reductions.f90: New test.
	libgomp/
	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-1.c:
	Add expected warnings about missing reduction clauses.
	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-2.c:
	Likewise.
	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-3.c:
	Likewise.
	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-4.c:
	Likewise.

	Reviewed-by: Thomas Schwinge <thomas@codesourcery.com>



git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@277875 138bc75d-0d04-0410-961f-82ee72b054a4

5 files changed, 15 insertions, 4 deletions

diff --git a/libgomp/ChangeLog b/libgomp/ChangeLog
index 15521b48bd8..067d247da9a 100644
--- a/libgomp/ChangeLog
+++ b/libgomp/ChangeLog
@@ -1,3 +1,14 @@
+2019-11-06  Thomas Schwinge  <thomas@codesourcery.com>
+
+	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-1.c:
+	Add expected warnings about missing reduction clauses.
+	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-2.c:
+	Likewise.
+	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-3.c:
+	Likewise.
+	* testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-4.c:
+	Likewise.
+
 2019-11-04  Tobias Burnus  <tobias@codesourcery.com>
 
 	* testsuite/libgomp.fortran/pr66199-1.f90: Remove
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-1.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-1.c
index 5e82e1d350c..8c08717fdf2 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-1.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-1.c
@@ -15,7 +15,7 @@ main (int argc, char *argv[])
   #pragma acc parallel num_gangs(32) num_workers(32) vector_length(32) \
     reduction(+:res) copy(res)
   {
-    #pragma acc loop gang
+    #pragma acc loop gang /* { dg-warning "nested loop in reduction needs reduction clause for 'res'" "TODO" } */
     for (j = 0; j < 32; j++)
       {
 	#pragma acc loop worker reduction(+:res)
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-2.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-2.c
index a339f327956..41042accbde 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-2.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-2.c
@@ -14,7 +14,7 @@ main (int argc, char *argv[])
   #pragma acc parallel num_gangs(32) num_workers(32) vector_length(32) \
 		       reduction(^:res)
   {
-    #pragma acc loop gang
+    #pragma acc loop gang /* { dg-warning "nested loop in reduction needs reduction clause for 'res'" "TODO" } */
     for (j = 0; j < 32; j++)
       {
 	#pragma acc loop worker vector reduction(^:res)
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-3.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-3.c
index 6369d7fbb33..ace1e005e2e 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-3.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-3.c
@@ -16,7 +16,7 @@ main (int argc, char *argv[])
   #pragma acc parallel num_gangs(32) num_workers(32) vector_length(32) \
     reduction(+:res) copy(res)
   {
-    #pragma acc loop gang
+    #pragma acc loop gang /* { dg-warning "nested loop in reduction needs reduction clause for 'res'" "TODO" } */
     for (j = 0; j < 32; j++)
       {
 	#pragma acc loop worker vector reduction(+:res)
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-4.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-4.c
index 140c3226327..c3cc12fa953 100644
--- a/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-4.c
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/par-loop-comb-reduction-4.c
@@ -16,7 +16,7 @@ main (int argc, char *argv[])
   #pragma acc parallel num_gangs(32) num_workers(32) vector_length(32) \
     reduction(+:res) reduction(max:mres) copy(res, mres)
   {
-    #pragma acc loop gang
+    #pragma acc loop gang /* { dg-warning "nested loop in reduction needs reduction clause for 'm\?res'" "TODO" } */
     for (j = 0; j < 32; j++)
       {
 	#pragma acc loop worker vector reduction(+:res) reduction(max:mres)