From 1f59bf44410889fc91c4acdfc5da21572ff6d3fa Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Mon, 15 Dec 2014 01:04:45 +0000
Subject: [PATCH] ThreadLocal: Return a mutable pointer if templated with a
 non-const type

It makes more sense for ThreadLocal<const T>::get to return a const T*
and ThreadLocal<T>::get to return a T*.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224225 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Support/ThreadLocal.h    |  2 +-
 lib/Support/ThreadLocal.cpp           |  4 ++--
 lib/Support/Unix/ThreadLocal.inc      |  2 +-
 lib/Support/Windows/ThreadLocal.inc   |  2 +-
 unittests/Support/ThreadLocalTest.cpp | 23 +++++++++++++++++++++--
 5 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/llvm/Support/ThreadLocal.h b/include/llvm/Support/ThreadLocal.h
index 7518626901e..427a67e2a96 100644
--- a/include/llvm/Support/ThreadLocal.h
+++ b/include/llvm/Support/ThreadLocal.h
@@ -36,7 +36,7 @@ namespace llvm {
       ThreadLocalImpl();
       virtual ~ThreadLocalImpl();
       void setInstance(const void* d);
-      const void* getInstance();
+      void *getInstance();
       void removeInstance();
     };
 
diff --git a/lib/Support/ThreadLocal.cpp b/lib/Support/ThreadLocal.cpp
index 2dec9eb417f..e0622192566 100644
--- a/lib/Support/ThreadLocal.cpp
+++ b/lib/Support/ThreadLocal.cpp
@@ -31,7 +31,7 @@ void ThreadLocalImpl::setInstance(const void* d) {
   void **pd = reinterpret_cast<void**>(&data);
   *pd = const_cast<void*>(d);
 }
-const void* ThreadLocalImpl::getInstance() {
+void *ThreadLocalImpl::getInstance() {
   void **pd = reinterpret_cast<void**>(&data);
   return *pd;
 }
@@ -72,7 +72,7 @@ void ThreadLocalImpl::setInstance(const void* d) {
   (void) errorcode;
 }
 
-const void* ThreadLocalImpl::getInstance() {
+void *ThreadLocalImpl::getInstance() {
   pthread_key_t* key = reinterpret_cast<pthread_key_t*>(&data);
   return pthread_getspecific(*key);
 }
diff --git a/lib/Support/Unix/ThreadLocal.inc b/lib/Support/Unix/ThreadLocal.inc
index f14d0fa3d52..fa746a628e3 100644
--- a/lib/Support/Unix/ThreadLocal.inc
+++ b/lib/Support/Unix/ThreadLocal.inc
@@ -21,6 +21,6 @@ using namespace sys;
 ThreadLocalImpl::ThreadLocalImpl() : data() { }
 ThreadLocalImpl::~ThreadLocalImpl() { }
 void ThreadLocalImpl::setInstance(const void* d) { data = const_cast<void*>(d);}
-const void* ThreadLocalImpl::getInstance() { return data; }
+void *ThreadLocalImpl::getInstance() { return data; }
 void ThreadLocalImpl::removeInstance() { setInstance(0); }
 }
diff --git a/lib/Support/Windows/ThreadLocal.inc b/lib/Support/Windows/ThreadLocal.inc
index 14ce61933cb..b9cb8ff9836 100644
--- a/lib/Support/Windows/ThreadLocal.inc
+++ b/lib/Support/Windows/ThreadLocal.inc
@@ -34,7 +34,7 @@ ThreadLocalImpl::~ThreadLocalImpl() {
   TlsFree(*tls);
 }
 
-const void* ThreadLocalImpl::getInstance() {
+void *ThreadLocalImpl::getInstance() {
   DWORD* tls = reinterpret_cast<DWORD*>(&data);
   return TlsGetValue(*tls);
 }
diff --git a/unittests/Support/ThreadLocalTest.cpp b/unittests/Support/ThreadLocalTest.cpp
index ea751be230c..e71c7dba22f 100644
--- a/unittests/Support/ThreadLocalTest.cpp
+++ b/unittests/Support/ThreadLocalTest.cpp
@@ -1,6 +1,6 @@
-//===- llvm/unittest/Support/ThreadLocalTest.cpp - Therad Local tests   ---===//
+//===- llvm/unittest/Support/ThreadLocalTest.cpp - ThreadLocal tests ------===//
 //
-//		       The LLVM Compiler Infrastructure
+//                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
@@ -9,6 +9,7 @@
 
 #include "llvm/Support/ThreadLocal.h"
 #include "gtest/gtest.h"
+#include <type_traits>
 
 using namespace llvm;
 using namespace sys;
@@ -25,6 +26,10 @@ struct S {
 TEST_F(ThreadLocalTest, Basics) {
   ThreadLocal<const S> x;
 
+  static_assert(
+      std::is_const<std::remove_pointer<decltype(x.get())>::type>::value,
+      "ThreadLocal::get didn't return a pointer to const object");
+
   EXPECT_EQ(nullptr, x.get());
 
   S s;
@@ -33,6 +38,20 @@ TEST_F(ThreadLocalTest, Basics) {
 
   x.erase();
   EXPECT_EQ(nullptr, x.get());
+
+  ThreadLocal<S> y;
+
+  static_assert(
+      !std::is_const<std::remove_pointer<decltype(y.get())>::type>::value,
+      "ThreadLocal::get returned a pointer to const object");
+
+  EXPECT_EQ(nullptr, y.get());
+
+  y.set(&s);
+  EXPECT_EQ(&s, y.get());
+
+  y.erase();
+  EXPECT_EQ(nullptr, y.get());
 }
 
 }
-- 
2.34.1