Address some review comments on TargetRegistry.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75753 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/Target/TargetRegistry.h b/include/llvm/Target/TargetRegistry.h
index ce1b281..cad49d3 100644
--- a/include/llvm/Target/TargetRegistry.h
+++ b/include/llvm/Target/TargetRegistry.h
@@ -32,7 +32,11 @@
///
/// For registration purposes, this is a POD type so that targets can be
/// registered without the use of static constructors.
- struct Target {
+ ///
+ /// Targets should implement a single global instance of this class (which
+ /// will be zero initialized), and pass that instance to the TargetRegistry as
+ /// part of their initialization.
+ class Target {
private:
typedef unsigned (*TripleMatchQualityFnTy)(const std::string &TT);
typedef unsigned (*ModuleMatchQualityFnTy)(const Module &M);
@@ -44,7 +48,7 @@
TargetMachine &,
bool);
- friend class TargetRegistry;
+ friend struct TargetRegistry;
/// Next - The next registered target in the linked list, maintained by the
/// TargetRegistry.
@@ -132,6 +136,10 @@
/// @{
/// RegisterTarget - Register the given target.
+ ///
+ /// Clients are responsible for ensuring that registration doesn't occur
+ /// while another thread is attempting to access the registry. Typically
+ /// this is done by initializing all targets at program startup.
///
/// @param T - The target being registered.
/// @param Name - The target name. This should be a static string.
@@ -153,6 +161,10 @@
/// RegisterTargetMachine - Register a TargetMachine implementation for the
/// given target.
///
+ /// Clients are responsible for ensuring that registration doesn't occur
+ /// while another thread is attempting to access the registry. Typically
+ /// this is done by initializing all targets at program startup.
+ ///
/// @param T - The target being registered.
/// @param Fn - A function to construct a TargetMachine for the target.
static void RegisterTargetMachine(Target &T,
@@ -164,6 +176,10 @@
/// RegisterAsmPrinter - Register an AsmPrinter implementation for the given
/// target.
///
+ /// Clients are responsible for ensuring that registration doesn't occur
+ /// while another thread is attempting to access the registry. Typically
+ /// this is done by initializing all targets at program startup.
+ ///
/// @param T - The target being registered.
/// @param Fn - A function to construct an AsmPrinter for the target.
static void RegisterAsmPrinter(Target &T, Target::AsmPrinterCtorTy Fn) {
diff --git a/lib/Support/TargetRegistry.cpp b/lib/Support/TargetRegistry.cpp
index 24f87ce..258431a 100644
--- a/lib/Support/TargetRegistry.cpp
+++ b/lib/Support/TargetRegistry.cpp
@@ -11,9 +11,7 @@
#include <cassert>
using namespace llvm;
-// FIXME: Worry about locking? In general everything should be registered at
-// startup.
-
+// Clients are responsible for avoid race conditions in registration.
static Target *FirstTarget = 0;
const Target *