ruby: new atomics implementation

This patch changes the way that Ruby handles atomic RMW instructions. This implementation, unlike the prior one, is protocol independent. It works by locking an address from the sequencer immediately after the read portion of an RMW completes. When that address is locked, the coherence controller will only satisfy requests coming from one port (e.g., the mandatory queue) and will ignore all others. After the write portion completed, the line is unlocked. This should also work with multi-line atomics, as long as the blocks are always acquired in the same order.

1 files changed, 13 insertions, 2 deletions

diff --git a/src/mem/slicc/ast/PeekStatementAST.py b/src/mem/slicc/ast/PeekStatementAST.py
index 5186bf0d5..b63ce6516 100644
--- a/src/mem/slicc/ast/PeekStatementAST.py
+++ b/src/mem/slicc/ast/PeekStatementAST.py
@@ -29,8 +29,8 @@ from slicc.ast.StatementAST import StatementAST
 from slicc.symbols import Var
 
 class PeekStatementAST(StatementAST):
-    def __init__(self, slicc, queue_name, type_ast, statements, method):
-        super(PeekStatementAST, self).__init__(slicc)
+    def __init__(self, slicc, queue_name, type_ast, pairs, statements, method):
+        super(PeekStatementAST, self).__init__(slicc, pairs)
 
         self.queue_name = queue_name
         self.type_ast = type_ast
@@ -63,6 +63,17 @@ class PeekStatementAST(StatementAST):
     in_msg_ptr = dynamic_cast<const $mtid *>(($qcode).${{self.method}}());
     assert(in_msg_ptr != NULL);
 ''')
+        if self.pairs.has_key("block_on"):
+            address_field = self.pairs['block_on']
+            code('''
+    if ( (m_is_blocking == true) &&
+         (m_block_map.count(in_msg_ptr->m_$address_field) == 1) ) {
+         if (m_block_map[in_msg_ptr->m_$address_field] != &$qcode) {
+            $qcode.delayHead();
+            continue;
+         }
+    }
+            ''')
 
         # The other statements
         self.statements.generate(code, return_type)