commit 9637e7ea887e100f35d99b8d12101f9f8a9b94e3
Author: Julian Brown <julian@codesourcery.com>
Date:   Thu Aug 9 20:27:04 2018 -0700

    [OpenACC] Add support for gang local storage allocation in shared memory
    
    2018-08-10  Julian Brown  <julian@codesourcery.com>
    	    Chung-Lin Tang  <cltang@codesourcery.com>
    
    	gcc/
    	* config/nvptx/nvptx.c (tree-hash-traits.h): Include.
    	(gangprivate_shared_size): New global variable.
    	(gangprivate_shared_align): Likewise.
    	(gangprivate_shared_sym): Likewise.
    	(gangprivate_shared_hmap): Likewise.
    	(nvptx_option_override): Initialize gangprivate_shared_sym,
    	gangprivate_shared_align.
    	(nvptx_file_end): Output gangprivate_shared_sym.
    	(nvptx_goacc_expand_accel_var): New function.
    	(nvptx_set_current_function): New function.
    	(TARGET_SET_CURRENT_FUNCTION): Define hook.
    	(TARGET_GOACC_EXPAND_ACCEL): Likewise.
    	* doc/tm.texi (TARGET_GOACC_EXPAND_ACCEL_VAR): Document new hook.
    	* doc/tm.texi.in (TARGET_GOACC_EXPAND_ACCEL_VAR): Likewise.
    	* expr.c (expand_expr_real_1): Remap decls marked with the
    	"oacc gangprivate" atttribute.
    	* omp-low.c (omp_context): Add oacc_partitioning_level and oacc_decls
    	fields.
    	(new_omp_context): Initialize oacc_decls in new omp_context.
    	(delete_omp_context): Delete oacc_decls in old omp_context.
    	(lower_oacc_head_tail): Record partitioning-level count in omp context.
    	(oacc_record_private_var_clauses, oacc_record_vars_in_bind)
    	(mark_oacc_gangprivate): New functions.
    	(lower_omp_for): Call oacc_record_private_var_clauses with "for"
    	clauses.  Call mark_oacc_gangprivate for gang-partitioned loops.
    	(lower_omp_target): Call oacc_record_private_var_clauses with "target"
    	clauses.
    	Call mark_oacc_gangprivate for offloaded target regions.
    	(lower_omp_1): Call vars_in_bind for GIMPLE_BIND within OMP regions.
    	* target.def (expand_accel_var): New hook.
    
    	libgomp/
    	* testsuite/libgomp.oacc-c-c++-common/gang-private-1.c: New test.
    	* testsuite/libgomp.oacc-c-c++-common/loop-gwv-2.c: New test.
    	* testsuite/libgomp.oacc-c/pr85465.c: New test.

diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index c0b0a2e..14eb842 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -73,6 +73,7 @@
 #include "cfgloop.h"
 #include "fold-const.h"
 #include "intl.h"
+#include "tree-hash-traits.h"
 
 /* This file should be included last.  */
 #include "target-def.h"
@@ -137,6 +138,12 @@ static unsigned worker_red_size;
 static unsigned worker_red_align;
 static GTY(()) rtx worker_red_sym;
 
+/* Shared memory block for gang-private variables.  */
+static unsigned gangprivate_shared_size;
+static unsigned gangprivate_shared_align;
+static GTY(()) rtx gangprivate_shared_sym;
+static hash_map<tree_decl_hash, unsigned int> gangprivate_shared_hmap;
+
 /* Global lock variable, needed for 128bit worker & gang reductions.  */
 static GTY(()) tree global_lock_var;
 
@@ -210,6 +217,10 @@ nvptx_option_override (void)
   SET_SYMBOL_DATA_AREA (worker_red_sym, DATA_AREA_SHARED);
   worker_red_align = GET_MODE_ALIGNMENT (SImode) / BITS_PER_UNIT;
 
+  gangprivate_shared_sym = gen_rtx_SYMBOL_REF (Pmode, "__gangprivate_shared");
+  SET_SYMBOL_DATA_AREA (gangprivate_shared_sym, DATA_AREA_SHARED);
+  gangprivate_shared_align = GET_MODE_ALIGNMENT (SImode) / BITS_PER_UNIT;
+
   diagnose_openacc_conflict (TARGET_GOMP, "-mgomp");
   diagnose_openacc_conflict (TARGET_SOFT_STACK, "-msoft-stack");
   diagnose_openacc_conflict (TARGET_UNIFORM_SIMT, "-muniform-simt");
@@ -4968,6 +4979,10 @@ nvptx_file_end (void)
     write_worker_buffer (asm_out_file, worker_red_sym,
 			 worker_red_align, worker_red_size);
 
+  if (gangprivate_shared_size)
+    write_worker_buffer (asm_out_file, gangprivate_shared_sym,
+			 gangprivate_shared_align, gangprivate_shared_size);
+
   if (need_softstack_decl)
     {
       write_var_marker (asm_out_file, false, true, "__nvptx_stacks");
@@ -5915,6 +5930,47 @@ nvptx_can_change_mode_class (machine_mode, machine_mode, reg_class_t)
   return false;
 }
 
+static rtx
+nvptx_goacc_expand_accel_var (tree var)
+{
+  if (TREE_CODE (var) == VAR_DECL
+      && lookup_attribute ("oacc gangprivate", DECL_ATTRIBUTES (var)))
+    {
+      unsigned int offset, *poffset;
+      poffset = gangprivate_shared_hmap.get (var);
+      if (poffset)
+	offset = *poffset;
+      else
+	{
+	  unsigned HOST_WIDE_INT align = DECL_ALIGN (var);
+	  gangprivate_shared_size =
+	    (gangprivate_shared_size + align - 1) & ~(align - 1);
+	  if (gangprivate_shared_align < align)
+	    gangprivate_shared_align = align;
+
+	  offset = gangprivate_shared_size;
+	  bool existed = gangprivate_shared_hmap.put (var, offset);
+	  gcc_assert (!existed);
+	  gangprivate_shared_size += tree_to_uhwi (DECL_SIZE_UNIT (var));
+	}
+      rtx addr = plus_constant (Pmode, gangprivate_shared_sym, offset);
+      return gen_rtx_MEM (TYPE_MODE (TREE_TYPE (var)), addr);
+    }
+  return NULL_RTX;
+}
+
+static GTY(()) tree nvptx_previous_fndecl;
+
+static void
+nvptx_set_current_function (tree fndecl)
+{
+  if (!fndecl || fndecl == nvptx_previous_fndecl)
+    return;
+
+  gangprivate_shared_hmap.empty ();
+  nvptx_previous_fndecl = fndecl;
+}
+
 #undef TARGET_OPTION_OVERRIDE
 #define TARGET_OPTION_OVERRIDE nvptx_option_override
 
@@ -6051,6 +6107,12 @@ nvptx_can_change_mode_class (machine_mode, machine_mode, reg_class_t)
 #undef TARGET_HAVE_SPECULATION_SAFE_VALUE
 #define TARGET_HAVE_SPECULATION_SAFE_VALUE speculation_safe_value_not_needed
 
+#undef TARGET_GOACC_EXPAND_ACCEL_VAR
+#define TARGET_GOACC_EXPAND_ACCEL_VAR nvptx_goacc_expand_accel_var
+
+#undef TARGET_SET_CURRENT_FUNCTION
+#define TARGET_SET_CURRENT_FUNCTION nvptx_set_current_function
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-nvptx.h"
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index a40f45a..fb87f67 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -6064,6 +6064,14 @@ like @code{cond_add@var{m}}.  The default implementation returns a zero
 constant of type @var{type}.
 @end deftypefn
 
+@deftypefn {Target Hook} rtx TARGET_GOACC_EXPAND_ACCEL_VAR (tree @var{var})
+This hook, if defined, is used by accelerator target back-ends to expand
+specially handled kinds of VAR_DECL expressions.  A particular use is to
+place variables with specific attributes inside special accelarator
+memories.  A return value of NULL indicates that the target does not
+handle this VAR_DECL, and normal RTL expanding is resumed.
+@end deftypefn
+
 @node Anchored Addresses
 @section Anchored Addresses
 @cindex anchored addresses
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 39a214e..beace61 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -4151,6 +4151,8 @@ address;  but often a machine-dependent strategy can generate better code.
 
 @hook TARGET_PREFERRED_ELSE_VALUE
 
+@hook TARGET_GOACC_EXPAND_ACCEL_VAR
+
 @node Anchored Addresses
 @section Anchored Addresses
 @cindex anchored addresses
diff --git a/gcc/expr.c b/gcc/expr.c
index de6709d..2c62bf9 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9854,8 +9854,19 @@ expand_expr_real_1 (tree exp, rtx target, machine_mode tmode,
       exp = SSA_NAME_VAR (ssa_name);
       goto expand_decl_rtl;
 
-    case PARM_DECL:
     case VAR_DECL:
+      /* Allow accel compiler to handle specific cases of variables,
+	 specifically those tagged with the "oacc gangprivate" attribute,
+	 which may intended to be placed in special memory in GPUs.  */
+      if (flag_openacc && targetm.goacc.expand_accel_var)
+	{
+	  temp = targetm.goacc.expand_accel_var (exp);
+	  if (temp)
+	    return temp;
+	}
+      /* ... fall through ...  */
+
+    case PARM_DECL:
       /* If a static var's type was incomplete when the decl was written,
 	 but the type is complete now, lay out the decl now.  */
       if (DECL_SIZE (exp) == 0
diff --git a/gcc/omp-low.c b/gcc/omp-low.c
index 843c66f..354e182 100644
--- a/gcc/omp-low.c
+++ b/gcc/omp-low.c
@@ -124,6 +124,12 @@ struct omp_context
 
   /* True if this construct can be cancelled.  */
   bool cancellable;
+
+  /* The number of levels of OpenACC partitioning invoked in this context.  */
+  int oacc_partitioning_levels;
+
+  /* Decls in this context.  */
+  vec<tree> *oacc_decls;
 };
 
 static splay_tree all_contexts;
@@ -850,6 +856,7 @@ new_omp_context (gimple *stmt, omp_context *outer_ctx)
     }
 
   ctx->cb.decl_map = new hash_map<tree, tree>;
+  ctx->oacc_decls = new vec<tree> ();
 
   return ctx;
 }
@@ -925,6 +932,8 @@ delete_omp_context (splay_tree_value value)
   if (is_task_ctx (ctx))
     finalize_task_copyfn (as_a <gomp_task *> (ctx->stmt));
 
+  delete ctx->oacc_decls;
+
   XDELETE (ctx);
 }
 
@@ -5716,6 +5725,9 @@ lower_oacc_head_tail (location_t loc, tree clauses,
   tree join_kind = build_int_cst (unsigned_type_node, IFN_UNIQUE_OACC_JOIN);
 
   gcc_assert (count);
+
+  ctx->oacc_partitioning_levels = count;
+
   for (unsigned done = 1; count; count--, done++)
     {
       gimple_seq fork_seq = NULL;
@@ -6732,6 +6744,66 @@ lower_omp_for_lastprivate (struct omp_for_data *fd, gimple_seq *body_p,
     }
 }
 
+/* Record vars listed in private clauses in CLAUSES in CTX.  This information
+   is used to mark up variables that should be made private per-gang.  */
+
+static void
+oacc_record_private_var_clauses (omp_context *ctx, tree clauses)
+{
+  tree c;
+
+  if (!ctx)
+    return;
+
+  for (c = clauses; c; c = OMP_CLAUSE_CHAIN (c))
+    switch (OMP_CLAUSE_CODE (c))
+      {
+      case OMP_CLAUSE_PRIVATE:
+	{
+	  tree decl = OMP_CLAUSE_DECL (c);
+	  ctx->oacc_decls->safe_push (decl);
+	}
+	break;
+
+      default:
+	/* Empty.  */;
+      }
+}
+
+/* Record vars declared in BINDVARS in CTX.  This information is used to mark
+   up variables that should be made private per-gang.  */
+
+static void
+oacc_record_vars_in_bind (omp_context *ctx, tree bindvars)
+{
+  if (!ctx)
+    return;
+
+  for (tree v = bindvars; v; v = DECL_CHAIN (v))
+    ctx->oacc_decls->safe_push (v);
+}
+
+/* Mark variables which are declared implicitly or explicitly as gang private
+   with a special attribute.  These may need to have their declarations altered
+   later on in compilation (e.g. in execute_oacc_device_lower or the backend,
+   depending on how the OpenACC execution model is implemented on a given
+   target) to ensure that sharing semantics are correct.
+   Only variables which have their address taken need to be considered.  */
+
+static void
+mark_oacc_gangprivate (vec<tree> *decls)
+{
+  int i;
+  tree decl;
+
+  FOR_EACH_VEC_ELT (*decls, i, decl)
+    {
+      if (TREE_CODE (decl) == VAR_DECL && TREE_ADDRESSABLE (decl))
+	DECL_ATTRIBUTES (decl)
+	  = tree_cons (get_identifier ("oacc gangprivate"),
+		       NULL, DECL_ATTRIBUTES (decl));
+    }
+}
 
 /* Lower code for an OMP loop directive.  */
 
@@ -6748,6 +6820,8 @@ lower_omp_for (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 
   push_gimplify_context ();
 
+  oacc_record_private_var_clauses (ctx, gimple_omp_for_clauses (stmt));
+
   lower_omp (gimple_omp_for_pre_body_ptr (stmt), ctx);
 
   block = make_node (BLOCK);
@@ -6878,7 +6952,20 @@ lower_omp_for (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 
   /* Add OpenACC partitioning and reduction markers just before the loop.  */
   if (oacc_head)
-    gimple_seq_add_seq (&body, oacc_head);
+    {
+      gimple_seq_add_seq (&body, oacc_head);
+
+      int level_total = 0;
+      omp_context *thisctx;
+
+      for (thisctx = ctx; thisctx; thisctx = thisctx->outer)
+        level_total += thisctx->oacc_partitioning_levels;
+
+      /* If the current context and parent contexts are distributed over a
+	 total of one parallelism level, we have gang partitioning.  */
+      if (level_total == 1)
+        mark_oacc_gangprivate (ctx->oacc_decls);
+    }
 
   lower_omp_for_lastprivate (&fd, &body, &dlist, ctx);
 
@@ -7511,6 +7598,8 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 
   clauses = gimple_omp_target_clauses (stmt);
 
+  oacc_record_private_var_clauses (ctx, clauses);
+
   gimple_seq dep_ilist = NULL;
   gimple_seq dep_olist = NULL;
   if (omp_find_clause (clauses, OMP_CLAUSE_DEPEND))
@@ -7761,6 +7850,8 @@ lower_omp_target (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 
   if (offloaded)
     {
+      mark_oacc_gangprivate (ctx->oacc_decls);
+
       /* Declare all the variables created by mapping and the variables
 	 declared in the scope of the target body.  */
       record_vars_into (ctx->block_vars, child_fn);
@@ -8755,6 +8846,7 @@ lower_omp_1 (gimple_stmt_iterator *gsi_p, omp_context *ctx)
 		 ctx);
       break;
     case GIMPLE_BIND:
+      oacc_record_vars_in_bind (ctx, gimple_bind_vars (as_a <gbind *> (stmt)));
       lower_omp (gimple_bind_body_ptr (as_a <gbind *> (stmt)), ctx);
       maybe_remove_omp_member_access_dummy_vars (as_a <gbind *> (stmt));
       break;
diff --git a/gcc/target.def b/gcc/target.def
index c570f38..b3b24b8 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -1701,6 +1701,16 @@ for allocating any storage for reductions when necessary.",
 void, (gcall *call),
 default_goacc_reduction)
 
+DEFHOOK
+(expand_accel_var,
+"This hook, if defined, is used by accelerator target back-ends to expand\n\
+specially handled kinds of VAR_DECL expressions.  A particular use is to\n\
+place variables with specific attributes inside special accelarator\n\
+memories.  A return value of NULL indicates that the target does not\n\
+handle this VAR_DECL, and normal RTL expanding is resumed.",
+rtx, (tree var),
+NULL)
+
 HOOK_VECTOR_END (goacc)
 
 /* Functions relating to vectorization.  */
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/gang-private-1.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/gang-private-1.c
new file mode 100644
index 0000000..f378346
--- /dev/null
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/gang-private-1.c
@@ -0,0 +1,38 @@
+#include <assert.h>
+
+int main (void)
+{
+  int ret;
+
+  #pragma acc parallel num_gangs(1) num_workers(32) copyout(ret)
+  {
+    int w = 0;
+
+    #pragma acc loop worker
+    for (int i = 0; i < 32; i++)
+      {
+        #pragma acc atomic update
+	w++;
+      }
+
+    ret = (w == 32);
+  }
+  assert (ret);
+
+  #pragma acc parallel num_gangs(1) vector_length(32) copyout(ret)
+  {
+    int v = 0;
+
+    #pragma acc loop vector
+    for (int i = 0; i < 32; i++)
+      {
+        #pragma acc atomic update
+	v++;
+      }
+
+    ret = (v == 32);
+  }
+  assert (ret);
+
+  return 0;
+}
diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/loop-gwv-2.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/loop-gwv-2.c
new file mode 100644
index 0000000..2fa708a
--- /dev/null
+++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/loop-gwv-2.c
@@ -0,0 +1,106 @@
+/* { dg-xfail-run-if "gangprivate failure" { openacc_nvidia_accel_selected } { "-O0" } { "" } } */
+
+#include <stdio.h>
+#include <openacc.h>
+#include <alloca.h>
+#include <string.h>
+#include <gomp-constants.h>
+#include <stdlib.h>
+
+#if 0
+#define DEBUG(DIM, IDX, VAL) \
+  fprintf (stderr, "%sdist[%d] = %d\n", (DIM), (IDX), (VAL))
+#else
+#define DEBUG(DIM, IDX, VAL)
+#endif
+
+#define N (32*32*32)
+
+int
+check (const char *dim, int *dist, int dimsize)
+{
+  int ix;
+  int exit = 0;
+
+  for (ix = 0; ix < dimsize; ix++)
+    {
+      DEBUG(dim, ix, dist[ix]);
+      if (dist[ix] < (N) / (dimsize + 0.5)
+	  || dist[ix] > (N) / (dimsize - 0.5))
+	{
+	  fprintf (stderr, "did not distribute to %ss (%d not between %d "
+		   "and %d)\n", dim, dist[ix], (int) ((N) / (dimsize + 0.5)),
+		   (int) ((N) / (dimsize - 0.5)));
+	  exit |= 1;
+	}
+    }
+
+  return exit;
+}
+
+int main ()
+{
+  int ary[N];
+  int ix;
+  int exit = 0;
+  int ondev = 0;
+  int gangsize = 0, workersize = 0, vectorsize = 0;
+  int *gangdist, *workerdist, *vectordist;
+
+  for (ix = 0; ix < N;ix++)
+    ary[ix] = -1;
+
+#pragma acc parallel num_gangs(32) num_workers(32) vector_length(32) copy(ary) copy(ondev) copyout(gangsize, workersize, vectorsize)
+  {
+#pragma acc loop gang worker vector
+    for (unsigned ix = 0; ix < N; ix++)
+      {
+	if (acc_on_device (acc_device_not_host))
+	  {
+	    int g, w, v;
+
+	    g = __builtin_goacc_parlevel_id (GOMP_DIM_GANG);
+	    w = __builtin_goacc_parlevel_id (GOMP_DIM_WORKER);
+	    v = __builtin_goacc_parlevel_id (GOMP_DIM_VECTOR);
+
+	    ary[ix] = (g << 16) | (w << 8) | v;
+	    ondev = 1;
+	  }
+	else
+	  ary[ix] = ix;
+      }
+
+    gangsize = __builtin_goacc_parlevel_size (GOMP_DIM_GANG);
+    workersize = __builtin_goacc_parlevel_size (GOMP_DIM_WORKER);
+    vectorsize = __builtin_goacc_parlevel_size (GOMP_DIM_VECTOR);
+  }
+
+  gangdist = (int *) alloca (gangsize * sizeof (int));
+  workerdist = (int *) alloca (workersize * sizeof (int));
+  vectordist = (int *) alloca (vectorsize * sizeof (int));
+  memset (gangdist, 0, gangsize * sizeof (int));
+  memset (workerdist, 0, workersize * sizeof (int));
+  memset (vectordist, 0, vectorsize * sizeof (int));
+
+  /* Test that work is shared approximately equally amongst each active
+     gang/worker/vector.  */
+  for (ix = 0; ix < N; ix++)
+    {
+      if (ondev)
+	{
+	  int g = (ary[ix] >> 16) & 255;
+	  int w = (ary[ix] >> 8) & 255;
+	  int v = ary[ix] & 255;
+
+	  gangdist[g]++;
+	  workerdist[w]++;
+	  vectordist[v]++;
+	}
+    }
+
+  exit = check ("gang", gangdist, gangsize);
+  exit |= check ("worker", workerdist, workersize);
+  exit |= check ("vector", vectordist, vectorsize);
+
+  return exit;
+}
diff --git a/libgomp/testsuite/libgomp.oacc-c/pr85465.c b/libgomp/testsuite/libgomp.oacc-c/pr85465.c
new file mode 100644
index 0000000..329e8a0
--- /dev/null
+++ b/libgomp/testsuite/libgomp.oacc-c/pr85465.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-additional-options "-w" } */
+
+int
+main (void)
+{
+#pragma acc parallel
+  foo ();
+
+  return 0;
+}
