commit 420b64d2fa291a02bc915f36c46776912f862a03
author Nicolas Capens <capn@google.com> Fri Jul 07 17:01:16 2017 -0400
committer Nicolas Capens <capn@google.com> Mon Jul 10 16:42:15 2017 +0000
tree dacf6a48262aa2193fc72accb846352c77bf9cdb
parent a781af7d5a1930d82d20c0cbc9d66fc8a42391e0

Fix TLS for platforms without library constructors.

Some platforms don't support constructors that get called when the
shared library gets loaded. This results in the thread-local-storage
key to never be allocated. Instead we can check if it was allocated on
each use. Also prevent creating new 'current' state if it already
exists, and avoid pthreads undefined behavior.

Bug b/25629882

Change-Id: I5e2486f88185150b976d88d0144e4d13a349eb79
Reviewed-on: https://swiftshader-review.googlesource.com/10451
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <capn@google.com>
Tested-by: Nicolas Capens <capn@google.com>

src/Common/Thread.hpp

diff --git a/src/Common/Thread.hpp b/src/Common/Thread.hpp
index 8f6443e..f59a0d4 100644
--- a/src/Common/Thread.hpp
+++ b/src/Common/Thread.hpp
@@ -135,7 +135,7 @@
 			return TlsAlloc();
 		#else
 			LocalStorageKey key;
-			pthread_key_create(&key, 0);
+			pthread_key_create(&key, NULL);
 			return key;
 		#endif
 	}
@@ -145,7 +145,7 @@
 		#if defined(_WIN32)
 			TlsFree(key);
 		#else
-			pthread_key_delete(key);
+			pthread_key_delete(key);   // Using an invalid key is an error but not undefined behavior.
 		#endif
 	}
 
@@ -154,7 +154,10 @@
 		#if defined(_WIN32)
 			TlsSetValue(key, value);
 		#else
-			pthread_setspecific(key, value);
+			if(key != TLS_OUT_OF_INDEXES)   // Avoid undefined behavior.
+			{
+				pthread_setspecific(key, value);
+			}
 		#endif
 	}
 
@@ -163,6 +166,11 @@
 		#if defined(_WIN32)
 			return TlsGetValue(key);
 		#else
+			if(key == TLS_OUT_OF_INDEXES)   // Avoid undefined behavior.
+			{
+				return nullptr;
+			}
+
 			return pthread_getspecific(key);
 		#endif
 	}

src/OpenGL/libEGL/main.cpp

diff --git a/src/OpenGL/libEGL/main.cpp b/src/OpenGL/libEGL/main.cpp
index 1df31c5..7f024d0 100644
--- a/src/OpenGL/libEGL/main.cpp
+++ b/src/OpenGL/libEGL/main.cpp
@@ -39,22 +39,31 @@
 
 namespace egl
 {
-void attachThread()
+Current *attachThread()
 {
 	TRACE("()");
 
-	Current *current = new Current;
-
-	if(current)
+	if(currentTLS == TLS_OUT_OF_INDEXES)
 	{
-		sw::Thread::setLocalStorage(currentTLS, current);
-
-		current->error = EGL_SUCCESS;
-		current->API = EGL_OPENGL_ES_API;
-		current->context = nullptr;
-		current->drawSurface = nullptr;
-		current->readSurface = nullptr;
+		currentTLS = sw::Thread::allocateLocalStorageKey();
 	}
+
+	Current *current = (Current*)sw::Thread::getLocalStorage(currentTLS);
+
+	if(!current)
+	{
+		current = new Current;
+
+		sw::Thread::setLocalStorage(currentTLS, current);
+	}
+
+	current->error = EGL_SUCCESS;
+	current->API = EGL_OPENGL_ES_API;
+	current->context = nullptr;
+	current->drawSurface = nullptr;
+	current->readSurface = nullptr;
+
+	return current;
 }
 
 void detachThread()
@@ -82,13 +91,6 @@
 		}
 	#endif
 
-	currentTLS = sw::Thread::allocateLocalStorageKey();
-
-	if(currentTLS == TLS_OUT_OF_INDEXES)
-	{
-		return;
-	}
-
 	attachThread();
 }
 
@@ -176,10 +178,10 @@
 
 	if(!current)
 	{
-		attachThread();
+		current = attachThread();
 	}
 
-	return (Current*)sw::Thread::getLocalStorage(currentTLS);
+	return current;
 }
 
 void setCurrentError(EGLint error)