Revert "[build, vm] Access TLS with less code."

This reverts commit aa79cf2708.

Reason for revert: -fPIC is needed in more places than the CL adds it to, see CI builds at https://ci.chromium.org/ui/p/dart-internal/builders/ci/dart-sdk-linux-riscv64-dev/405/overview

Original change's description:
> [build, vm] Access TLS with less code.
>
> - Avoid TLS initialization checks by using inline initialization.
> - Avoid global offset table indirection by reducing -fPIC to -fPIE.
>
> out/ReleaseXARM64/exe.stripped/dart_precompiled_runtime
> 11137992 -> 11274776 (-1.21%)
>
> We still need -fPIC in some places because we build a few shared libraries for FFI, so copy some of Fuchsia's GN setup to use -fPIE or -fPIC as appropriate.
>
> TEST=ci
> Change-Id: I6402fce3366a9c4b2741ffb4811562292b8ecb71
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/285704
> Commit-Queue: Ryan Macnak <rmacnak@google.com>
> Reviewed-by: Daco Harkes <dacoharkes@google.com>

Change-Id: Idacb7869e9fa9ad0f7ed7b0caa2bae19deece7d0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/286144
Reviewed-by: Martin Kustermann <kustermann@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: William Hesse <whesse@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>

build/config/BUILD.gn

@@ -18,17 +18,3 @@ config("product") {
     "PRODUCT",
   ]
 }
-
-config("shared_library_config") {
-  if (current_os == "android" || current_os == "fuchsia" ||
-      current_os == "linux" || current_os == "mac") {
-    cflags = [ "-fPIC" ]
-  }
-}
-
-config("executable_config") {
-  if (current_os == "android" || current_os == "fuchsia" ||
-      current_os == "linux" || current_os == "mac") {
-    cflags = [ "-fPIE" ]
-  }
-}

build/config/BUILDCONFIG.gn

@@ -313,8 +313,7 @@ if (is_win) {
 }
 
 # Executable defaults.
-_executable_configs =
-    _native_compiler_configs + [ "//build/config:executable_config" ]
+_executable_configs = _native_compiler_configs
 if (is_win) {
   _executable_configs += _windows_linker_configs
 } else if (is_mac) {
@@ -343,8 +342,7 @@ set_defaults("static_library") {
 }
 
 # Shared library defaults (also for components in component mode).
-_shared_library_configs =
-    _native_compiler_configs + [ "//build/config:shared_library_config" ]
+_shared_library_configs = _native_compiler_configs
 if (is_win) {
   _shared_library_configs += _windows_linker_configs
 } else if (is_mac) {

build/config/compiler/BUILD.gn

@@ -249,6 +249,17 @@ config("compiler") {
     ]
   }
 
+  # We need -fPIC:
+  # 1. On ARM for tcmalloc.
+  # 2. On Android.
+  # 3. When using the sanitizers.
+  # Otherwise there is a performance hit, in particular on ia32.
+  if (is_android || is_asan || is_lsan || is_msan || is_tsan || is_ubsan ||
+      (is_linux && current_cpu != "x86") || is_fuchsia) {
+    cflags += [ "-fPIC" ]
+    ldflags += [ "-fPIC" ]
+  }
+
   # Linux-specific compiler flags setup.
   # ------------------------------------
   if (is_linux) {

runtime/bin/BUILD.gn

@@ -1036,6 +1036,9 @@ shared_library("entrypoints_verification_test") {
     # The only effect of DART_SHARED_LIB is to export the Dart API.
     "DART_SHARED_LIB",
   ]
+  if (is_linux || is_android) {
+    cflags = [ "-fPIC" ]
+  }
   if (is_win) {
     # TODO(dartbug.com/40579): This wrongly links in dart.exe on precompiled.
     libs = [ "dart.lib" ]
@@ -1052,6 +1055,9 @@ shared_library("ffi_test_dynamic_library") {
     # The only effect of DART_SHARED_LIB is to export the Dart API.
     "DART_SHARED_LIB",
   ]
+  if (is_linux || is_android) {
+    cflags = [ "-fPIC" ]
+  }
   if (is_win) {
     # TODO(dartbug.com/40579): This wrongly links in dart.exe on precompiled.
     libs = [ "dart.lib" ]
@@ -1085,6 +1091,9 @@ shared_library("ffi_test_functions") {
     # The only effect of DART_SHARED_LIB is to export the Dart API.
     "DART_SHARED_LIB",
   ]
+  if (is_linux || is_android) {
+    cflags = [ "-fPIC" ]
+  }
   if (is_win) {
     # TODO(dartbug.com/40579): This wrongly links in dart.exe on precompiled.
     libs = [ "dart.lib" ]

runtime/vm/os_thread.cc

@@ -20,6 +20,11 @@ OSThread* OSThread::thread_list_head_ = NULL;
 Mutex* OSThread::thread_list_lock_ = NULL;
 bool OSThread::creation_enabled_ = false;
 
+thread_local ThreadState* OSThread::current_vm_thread_ = NULL;
+#if defined(DEBUG)
+thread_local bool ThreadInterruptScope::in_thread_interrupt_scope_ = false;
+#endif
+
 #if defined(SUPPORT_TIMELINE)
 inline void UpdateTimelineTrackMetadata(const OSThread& thread) {
   RecorderSynchronizationLockScope ls;

runtime/vm/os_thread.h

@@ -306,9 +306,7 @@ class OSThread : public BaseThread {
   static OSThread* thread_list_head_;
   static bool creation_enabled_;
 
-  // Inline initialization is important for avoiding unnecessary TLS
-  // initialization checks at each use.
-  static inline thread_local ThreadState* current_vm_thread_ = nullptr;
+  static thread_local ThreadState* current_vm_thread_;
 
   friend class IsolateGroup;  // to access set_thread(Thread*).
   friend class OSThreadIterator;
@@ -414,7 +412,7 @@ class ThreadInterruptScope : public ValueObject {
 
  private:
   ThreadState* saved_current_vm_thread_;
-  static inline thread_local bool in_thread_interrupt_scope_ = false;
+  static thread_local bool in_thread_interrupt_scope_;
 #endif  // DEBUG
 };
 

tests/standalone/pie_test.dart

@@ -1,28 +0,0 @@
-// Copyright (c) 2023, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import "dart:io";
-
-// Mmmm... pie!
-main() {
-  if (!Platform.isLinux) return; // readelf is a Linux tool.
-  // Modern Mac and Android binaries are always PIE.
-  // Fuchsia binaries are always PIE.
-
-  var result = Process.runSync("readelf", ["-h", Platform.resolvedExecutable]);
-  print("stdout:");
-  print(result.stdout);
-  print("stderr:");
-  print(result.stderr);
-
-  if (result.exitCode != 0) {
-    throw "readelf failed";
-  }
-
-  // A position-dependent executable outputs "EXEC (Executable file)".
-  if (!result.stdout.contains("DYN (Position-Independent Executable file)") &&
-      !result.stdout.contains("DYN (Shared object file)")) {
-    throw "Standalone VM should be a position-independent executable";
-  }
-}