[gomp-nvptx 04/13] nvptx backend: add support for placing variables in shared memory

[Alexander Monakov]

This patch allows to use __attribute__((shared)) to place non-automatic
variables in shared memory.

        * config/nvptx/nvptx.c (nvptx_encode_section_info): Handle "shared"
        attribute.
        (nvptx_handle_shared_attribute): New.  Use it...
        (nvptx_attribute_table): ... here (new entry).
---
 gcc/ChangeLog.gomp-nvptx |  7 +++++++
 gcc/config/nvptx/nvptx.c | 33 ++++++++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index f63f840..5c8c28b 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -228,9 +228,12 @@ nvptx_encode_section_info (tree decl, rtx rtl, int first)
       if (TREE_CONSTANT (decl))
        area = DATA_AREA_CONST;
       else if (TREE_CODE (decl) == VAR_DECL)
-       /* TODO: This would be a good place to check for a .shared or
-          other section name.  */
-       area = TREE_READONLY (decl) ? DATA_AREA_CONST : DATA_AREA_GLOBAL;
+       {
+         if (lookup_attribute ("shared", DECL_ATTRIBUTES (decl)))
+           area = DATA_AREA_SHARED;
+         else
+           area = TREE_READONLY (decl) ? DATA_AREA_CONST : DATA_AREA_GLOBAL;
+       }
 
       SET_SYMBOL_DATA_AREA (XEXP (rtl, 0), area);
     }
@@ -4047,12 +4050,36 @@ nvptx_handle_kernel_attribute (tree *node, tree name, 
tree ARG_UNUSED (args),
   return NULL_TREE;
 }
 
+/* Handle a "shared" attribute; arguments as in
+   struct attribute_spec.handler.  */
+
+static tree
+nvptx_handle_shared_attribute (tree *node, tree name, tree ARG_UNUSED (args),
+                              int ARG_UNUSED (flags), bool *no_add_attrs)
+{
+  tree decl = *node;
+
+  if (TREE_CODE (decl) != VAR_DECL)
+    {
+      error ("%qE attribute only applies to variables", name);
+      *no_add_attrs = true;
+    }
+  else if (current_function_decl && !TREE_STATIC (decl))
+    {
+      error ("%qE attribute only applies to non-stack variables", name);
+      *no_add_attrs = true;
+    }
+
+  return NULL_TREE;
+}
+
 /* Table of valid machine attributes.  */
 static const struct attribute_spec nvptx_attribute_table[] =
 {
   /* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler,
        affects_type_identity } */
   { "kernel", 0, 0, true, false,  false, nvptx_handle_kernel_attribute, false 
},
+  { "shared", 0, 0, true, false,  false, nvptx_handle_shared_attribute, false 
},
   { NULL, 0, 0, false, false, false, NULL, false }
 };