From: Brian Norris <banorris@uci.edu>
Date: Sat, 7 Jul 2012 00:09:17 +0000 (-0700)
Subject: action: support ATOMIC_INIT
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c0182a11fd62cc38f9f5cbe49960d7a9bce8d381;p=cdsspec-compiler.git

action: support ATOMIC_INIT

For now, atomic_init() will be supported as simply a relaxed write. This
doesn't quite match the spec exactly [1, 2], but it is expedient for supporting
the common case of checking proper initialization.

[1] From C++ N3242, Section 29.6.5, Statement 8:

       Non-atomically initializes *object with value desired.

       Note: Concurrent access from another thread, even via an atomic
       operation, constitutes a data race.

[2] Note that for now, my implementation will not flag concurrent atomic_init()
    and atomic_store() as data races.
---

diff --git a/action.cc b/action.cc
index 68a34aa..d5131f0 100644
--- a/action.cc
+++ b/action.cc
@@ -33,7 +33,7 @@ bool ModelAction::is_read() const
 
 bool ModelAction::is_write() const
 {
-	return type == ATOMIC_WRITE;
+	return type == ATOMIC_WRITE || type == ATOMIC_INIT;
 }
 
 bool ModelAction::is_rmw() const
@@ -41,6 +41,11 @@ bool ModelAction::is_rmw() const
 	return type == ATOMIC_RMW;
 }
 
+bool ModelAction::is_initialization() const
+{
+	return type == ATOMIC_INIT;
+}
+
 bool ModelAction::is_acquire() const
 {
 	switch (order) {
@@ -166,6 +171,9 @@ void ModelAction::print(void) const
 	case ATOMIC_RMW:
 		type_str = "atomic rmw";
 		break;
+	case ATOMIC_INIT:
+		type_str = "init atomic";
+		break;
 	default:
 		type_str = "unknown type";
 	}
diff --git a/action.h b/action.h
index 4903f37..f9c6d41 100644
--- a/action.h
+++ b/action.h
@@ -21,7 +21,8 @@ typedef enum action_type {
 	THREAD_JOIN,
 	ATOMIC_READ,
 	ATOMIC_WRITE,
-	ATOMIC_RMW
+	ATOMIC_RMW,
+	ATOMIC_INIT
 } action_type_t;
 
 /* Forward declaration */
@@ -51,6 +52,7 @@ public:
 	bool is_read() const;
 	bool is_write() const;
 	bool is_rmw() const;
+	bool is_initialization() const;
 	bool is_acquire() const;
 	bool is_release() const;
 	bool is_seqcst() const;
diff --git a/libatomic.cc b/libatomic.cc
index 507f685..a076533 100644
--- a/libatomic.cc
+++ b/libatomic.cc
@@ -19,5 +19,7 @@ int atomic_load_explicit(struct atomic_object *obj, memory_order order)
 
 void atomic_init(struct atomic_object *obj, int value)
 {
+	DBG();
 	obj->value = value;
+	model->switch_to_master(new ModelAction(ATOMIC_INIT, memory_order_relaxed, obj, value));
 }