[libc] Add macro LIBC_THREAD_LOCAL.

It resolves to thread_local on all platform except for the GPUs on which
it resolves to nothing. The use of thread_local in the source code has been
replaced with the new macro.

Reviewed By: jhuber6

Differential Revision: https://reviews.llvm.org/D151486

Author: Siva Chandra Reddy

Diff for: libc/src/__support/StringUtil/CMakeLists.txt

@@ -44,6 +44,7 @@ add_object_library(
   DEPENDS
     .message_mapper
     .platform_errors
+    libc.src.__support.common
     libc.src.__support.CPP.span
     libc.src.__support.CPP.string_view
     libc.src.__support.CPP.stringstream
@@ -60,6 +61,7 @@ add_object_library(
     .message_mapper
     .platform_signals
     libc.include.signal
+    libc.src.__support.common
     libc.src.__support.CPP.span
     libc.src.__support.CPP.string_view
     libc.src.__support.CPP.stringstream

Diff for: libc/src/__support/StringUtil/error_to_string.cpp

@@ -14,6 +14,7 @@
 #include "src/__support/CPP/stringstream.h"
 #include "src/__support/StringUtil/message_mapper.h"
 #include "src/__support/integer_to_string.h"
+#include "src/__support/macros/attributes.h"
 
 #include <stddef.h>
 
@@ -31,7 +32,7 @@ constexpr size_t max_buff_size() {
 // This is to hold error strings that have to be custom built. It may be
 // rewritten on every call to strerror (or other error to string function).
 constexpr size_t ERR_BUFFER_SIZE = max_buff_size();
-thread_local char error_buffer[ERR_BUFFER_SIZE];
+LIBC_THREAD_LOCAL char error_buffer[ERR_BUFFER_SIZE];
 
 constexpr size_t TOTAL_STR_LEN = total_str_len(PLATFORM_ERRORS);
 

Diff for: libc/src/__support/StringUtil/signal_to_string.cpp

@@ -14,6 +14,7 @@
 #include "src/__support/CPP/stringstream.h"
 #include "src/__support/StringUtil/message_mapper.h"
 #include "src/__support/integer_to_string.h"
+#include "src/__support/macros/attributes.h"
 
 #include <signal.h>
 #include <stddef.h>
@@ -32,7 +33,7 @@ constexpr size_t max_buff_size() {
 // This is to hold signal strings that have to be custom built. It may be
 // rewritten on every call to strsignal (or other signal to string function).
 constexpr size_t SIG_BUFFER_SIZE = max_buff_size();
-thread_local char signal_buffer[SIG_BUFFER_SIZE];
+LIBC_THREAD_LOCAL char signal_buffer[SIG_BUFFER_SIZE];
 
 constexpr size_t TOTAL_STR_LEN = total_str_len(PLATFORM_SIGNALS);
 

Diff for: libc/src/__support/macros/attributes.h

@@ -17,8 +17,16 @@
 #ifndef LLVM_LIBC_SUPPORT_MACROS_ATTRIBUTES_H
 #define LLVM_LIBC_SUPPORT_MACROS_ATTRIBUTES_H
 
+#include "properties/architectures.h"
+
 #define LIBC_INLINE inline
 #define LIBC_INLINE_ASM __asm__ __volatile__
 #define LIBC_UNUSED __attribute__((unused))
 
+#ifdef LIBC_TARGET_ARCH_IS_GPU
+#define LIBC_THREAD_LOCAL
+#else
+#define LIBC_THREAD_LOCAL thread_local
+#endif
+
 #endif // LLVM_LIBC_SUPPORT_MACROS_ATTRIBUTES_H

Diff for: libc/src/__support/threads/CMakeLists.txt

@@ -48,6 +48,7 @@ if(TARGET libc.src.__support.threads.${LIBC_TARGET_OS}.thread)
     DEPENDS
       .mutex
       .${LIBC_TARGET_OS}.thread
+      libc.src.__support.common
       libc.src.__support.fixedvector
       libc.src.__support.CPP.array
       libc.src.__support.CPP.optional

Diff for: libc/src/__support/threads/thread.cpp

@@ -12,10 +12,11 @@
 #include "src/__support/CPP/array.h"
 #include "src/__support/CPP/optional.h"
 #include "src/__support/fixedvector.h"
+#include "src/__support/macros/attributes.h"
 
 namespace __llvm_libc {
 
-thread_local Thread self;
+LIBC_THREAD_LOCAL Thread self;
 
 namespace {
 
@@ -99,7 +100,7 @@ struct TSSValueUnit {
       : active(true), payload(p), dtor(d) {}
 };
 
-static thread_local cpp::array<TSSValueUnit, TSS_KEY_COUNT> tss_values;
+static LIBC_THREAD_LOCAL cpp::array<TSSValueUnit, TSS_KEY_COUNT> tss_values;
 
 } // anonymous namespace
 
@@ -128,7 +129,7 @@ class ThreadAtExitCallbackMgr {
   }
 };
 
-static thread_local ThreadAtExitCallbackMgr atexit_callback_mgr;
+static LIBC_THREAD_LOCAL ThreadAtExitCallbackMgr atexit_callback_mgr;
 
 // The function __cxa_thread_atexit is provided by C++ runtimes like libcxxabi.
 // It is used by thread local object runtime to register destructor calls. To

Diff for: libc/src/__support/threads/thread.h

@@ -13,6 +13,7 @@
 #include "src/__support/CPP/optional.h"
 #include "src/__support/CPP/string_view.h"
 #include "src/__support/CPP/stringstream.h"
+#include "src/__support/macros/attributes.h"
 #include "src/__support/macros/properties/architectures.h"
 
 #include <linux/param.h> // for exec_pagesize.
@@ -225,7 +226,7 @@ struct Thread {
   int get_name(cpp::StringStream &name) const;
 };
 
-extern thread_local Thread self;
+extern LIBC_THREAD_LOCAL Thread self;
 
 // Platforms should implement this function.
 [[noreturn]] void thread_exit(ThreadReturnValue retval, ThreadStyle style);

Diff for: libc/src/errno/CMakeLists.txt

@@ -6,4 +6,5 @@ add_entrypoint_object(
     libc_errno.h     # Include this
   DEPENDS
     libc.include.errno
+    libc.src.__support.common
 )

Diff for: libc/src/errno/libc_errno.cpp

@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "src/__support/macros/attributes.h"
 #include "src/__support/macros/properties/architectures.h"
 
 namespace __llvm_libc {
@@ -29,13 +30,13 @@ extern "C" {
 #ifdef LIBC_TARGET_ARCH_IS_GPU
 ErrnoConsumer __llvmlibc_errno;
 #else
-thread_local int __llvmlibc_errno;
+LIBC_THREAD_LOCAL int __llvmlibc_errno;
 #endif // LIBC_TARGET_ARCH_IS_GPU
 #else
 #ifdef LIBC_TARGET_ARCH_IS_GPU
 ErrnoConsumer __llvmlibc_internal_errno;
 #else
-thread_local int __llvmlibc_internal_errno;
+LIBC_THREAD_LOCAL int __llvmlibc_internal_errno;
 #endif // LIBC_TARGET_ARCH_IS_GPU
 #endif
 } // extern "C"

Diff for: libc/src/errno/libc_errno.h

@@ -9,6 +9,7 @@
 #ifndef LLVM_LIBC_SRC_ERRNO_LLVMLIBC_ERRNO_H
 #define LLVM_LIBC_SRC_ERRNO_LLVMLIBC_ERRNO_H
 
+#include "src/__support/macros/attributes.h"
 #include "src/__support/macros/properties/architectures.h"
 
 #include <errno.h>
@@ -42,7 +43,7 @@ namespace __llvm_libc {
 extern "C" ErrnoConsumer __llvmlibc_internal_errno;
 #else // LIBC_TARGET_ARCH_IS_GPU
 extern "C" {
-extern thread_local int __llvmlibc_internal_errno;
+extern LIBC_THREAD_LOCAL int __llvmlibc_internal_errno;
 } // extern "C"
 #endif
 

Diff for: libc/src/stdlib/CMakeLists.txt

@@ -218,6 +218,8 @@ add_object_library(
     rand_util.cpp
   HDRS
     rand_util.h
+  DEPENDS
+    libc.src.__support.common
 )
 
 add_entrypoint_object(

Diff for: libc/src/stdlib/rand_util.cpp

@@ -7,9 +7,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/stdlib/rand_util.h"
+#include "src/__support/macros/attributes.h"
 
 namespace __llvm_libc {
 
-thread_local unsigned long rand_next;
+LIBC_THREAD_LOCAL unsigned long rand_next;
 
 } // namespace __llvm_libc

Diff for: libc/src/stdlib/rand_util.h

@@ -9,9 +9,11 @@
 #ifndef LLVM_LIBC_SRC_STDLIB_RAND_UTIL_H
 #define LLVM_LIBC_SRC_STDLIB_RAND_UTIL_H
 
+#include "src/__support/macros/attributes.h"
+
 namespace __llvm_libc {
 
-extern thread_local unsigned long rand_next;
+extern LIBC_THREAD_LOCAL unsigned long rand_next;
 
 } // namespace __llvm_libc
 

Diff for: utils/bazel/llvm-project-overlay/libc/BUILD.bazel

@@ -93,7 +93,10 @@ libc_support_library(
 libc_support_library(
     name = "__support_macros_attributes",
     hdrs = ["src/__support/macros/attributes.h"],
-    deps = [":libc_root"],
+    deps = [
+        ":__support_macros_properties_architectures",
+        ":libc_root"
+    ],
 )
 
 libc_support_library(
@@ -827,6 +830,7 @@ libc_function(
     hdrs = ["src/errno/libc_errno.h"],
     deps = [
         ":__support_common",
+        ":__support_macros_attributes",
         ":__support_macros_properties_architectures",
     ],
 )