[PATCH][OpenACC] Don't error on implicitly private induction variables in gfortran

[Cesar Philippidis]

At present, the fortran FE reports an error if the user adds an explicit
private clause to an induction variable used by an acc loop. This patch
teaches the fortran acc block resolver how to cope with "duplicate"
private clauses, so that it doesn't error anymore.

Is this patch OK for trunk? I bootstrapped and regression tested it for
x86_64 with nvptx offloading.

Thanks,
Cesar

>From 576b2a7d5574400f067ec309929b38b324d8c6f6 Mon Sep 17 00:00:00 2001
From: Cesar Philippidis <ce...@codesourcery.com>
Date: Fri, 27 Jan 2017 14:58:16 +0000
Subject: [PATCH] [OpenACC] Don't error on implicitly private induction
 variables in gfortran

2018-XX-YY  Cesar Philippidis  <ce...@codesourcery.com>

	gcc/fortran/
	* openmp.c (gfc_resolve_oacc_blocks): Populate list of private
	variables.

	gcc/testsuite/
	* gfortran.dg/goacc/implicitly-private.f90: New test.

---
 gcc/fortran/openmp.c                                   |  5 +++++
 gcc/testsuite/gfortran.dg/goacc/implicitly-private.f90 | 12 ++++++++++++
 2 files changed, 17 insertions(+)
 create mode 100644 gcc/testsuite/gfortran.dg/goacc/implicitly-private.f90

diff --git a/gcc/fortran/openmp.c b/gcc/fortran/openmp.c
index b346b51..798c5fa 100644
--- a/gcc/fortran/openmp.c
+++ b/gcc/fortran/openmp.c
@@ -5951,6 +5951,7 @@ void
 gfc_resolve_oacc_blocks (gfc_code *code, gfc_namespace *ns)
 {
   fortran_omp_context ctx;
+  gfc_omp_namelist *n;
 
   resolve_oacc_loop_blocks (code);
 
@@ -5961,6 +5962,10 @@ gfc_resolve_oacc_blocks (gfc_code *code, gfc_namespace *ns)
   ctx.is_openmp = false;
   omp_current_ctx = &ctx;
 
+  if (code->ext.omp_clauses)
+    for (n = code->ext.omp_clauses->lists[OMP_LIST_PRIVATE]; n; n = n->next)
+      ctx.private_iterators->add (n->sym);
+
   gfc_resolve_blocks (code->block, ns);
 
   omp_current_ctx = ctx.previous;
diff --git a/gcc/testsuite/gfortran.dg/goacc/implicitly-private.f90 b/gcc/testsuite/gfortran.dg/goacc/implicitly-private.f90
new file mode 100644
index 0000000..a687d8a
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/goacc/implicitly-private.f90
@@ -0,0 +1,12 @@
+! Ensure that implicitly private variables do not clash with those
+! that are explicitly private.
+
+program main
+  implicit none
+
+  integer i
+
+  !$acc parallel loop private(i)
+  do i = 1, 100
+  end do
+end program main
-- 
2.7.4