Revert "[ios] Added stack_sample_profiler iOS flavor (x86_64 and ARM64)"

This reverts commit d281d7561e.

Reason for revert: Cronet failures

Original change's description:
> [ios] Added stack_sample_profiler iOS flavor (x86_64 and ARM64)
>
> Added iOS version of stack unwinder that relies on frames
> using pthread_stack_frame_decode_np.
>
> Bug: 1199722
> Change-Id: Ifce3fdccc20bb5104eb1516ae30d714eb7ba1f79
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2831597
> Reviewed-by: Mike Wittman <wittman@chromium.org>
> Commit-Queue: David Jean <djean@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#892015}

Bug: 1199722
Change-Id: I9290505fcf24e49b3bc51893d23f1bbfc41a8e8e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2961109
Owners-Override: Adam Trudeau-Arcaro <adamta@google.com>
Reviewed-by: Adam Trudeau-Arcaro <adamta@google.com>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#892091}

base/BUILD.gn

@@ -1195,11 +1195,7 @@ component("base") {
       "process/launch_ios.cc",
       "process/process_metrics_ios.cc",
       "profiler/module_cache_mac.cc",
-      "profiler/native_unwinder_ios.cc",
-      "profiler/native_unwinder_ios.h",
       "profiler/stack_sampler_ios.cc",
-      "profiler/suspendable_thread_delegate_mac.cc",
-      "profiler/suspendable_thread_delegate_mac.h",
     ]
   }
 

base/profiler/native_unwinder_ios.cc

@@ -1,61 +0,0 @@
-// Copyright 2021 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "base/profiler/native_unwinder_ios.h"
-
-#include <pthread/stack_np.h>
-
-#include "base/check_op.h"
-#include "base/notreached.h"
-#include "base/profiler/module_cache.h"
-#include "base/profiler/native_unwinder.h"
-#include "build/build_config.h"
-
-namespace base {
-
-NativeUnwinderIOS::NativeUnwinderIOS() {}
-
-bool NativeUnwinderIOS::CanUnwindFrom(const Frame& current_frame) const {
-  return current_frame.module && current_frame.module->IsNative();
-}
-
-UnwindResult NativeUnwinderIOS::TryUnwind(RegisterContext* thread_context,
-                                          uintptr_t stack_top,
-                                          std::vector<Frame>* stack) const {
-  // We expect the frame corresponding to the |thread_context| register state to
-  // exist within |stack|.
-  DCHECK_GT(stack->size(), 0u);
-
-#if defined(ARCH_CPU_ARM64)
-  const uintptr_t align_mask = 0x1;
-  const uintptr_t stack_bottom = thread_context->__sp;
-  uintptr_t next_frame = thread_context->__fp;
-#elif defined(ARCH_CPU_X86_64)
-  const uintptr_t align_mask = 0xf;
-  const uintptr_t stack_bottom = thread_context->__rsp;
-  uintptr_t next_frame = thread_context->__rbp;
-#endif
-
-  for (;;) {
-    uintptr_t retaddr;
-    uintptr_t frame = next_frame;
-    next_frame = pthread_stack_frame_decode_np(frame, &retaddr);
-
-    if (frame < stack_bottom || frame > stack_top ||
-        (frame & align_mask) != 0 || next_frame <= frame) {
-      return UnwindResult::COMPLETED;
-    }
-
-    stack->emplace_back(retaddr, module_cache()->GetModuleForAddress(retaddr));
-  }
-
-  NOTREACHED();
-  return UnwindResult::COMPLETED;
-}
-
-std::unique_ptr<Unwinder> CreateNativeUnwinder(ModuleCache* module_cache) {
-  return std::make_unique<NativeUnwinderIOS>();
-}
-
-}  // namespace base

base/profiler/native_unwinder_ios.h

@@ -1,29 +0,0 @@
-// Copyright 2021 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef BASE_PROFILER_NATIVE_UNWINDER_IOS_H_
-#define BASE_PROFILER_NATIVE_UNWINDER_IOS_H_
-
-#include "base/profiler/unwinder.h"
-
-namespace base {
-
-// Native unwinder implementation for iOS, ARM64 and X86_64.
-class NativeUnwinderIOS : public Unwinder {
- public:
-  NativeUnwinderIOS();
-
-  NativeUnwinderIOS(const NativeUnwinderIOS&) = delete;
-  NativeUnwinderIOS& operator=(const NativeUnwinderIOS&) = delete;
-
-  // Unwinder:
-  bool CanUnwindFrom(const Frame& current_frame) const override;
-  UnwindResult TryUnwind(RegisterContext* thread_context,
-                         uintptr_t stack_top,
-                         std::vector<Frame>* stack) const override;
-};
-
-}  // namespace base
-
-#endif  // BASE_PROFILER_NATIVE_UNWINDER_IOS_H_

base/profiler/register_context.h

@@ -69,7 +69,7 @@ inline uintptr_t& RegisterContextInstructionPointer(::CONTEXT* context) {
 #endif
 }
 
-#elif defined(OS_MAC) || defined(OS_IOS)  // #if defined(OS_WIN)
+#elif defined(OS_MAC)  // #if defined(OS_WIN)
 
 #if defined(ARCH_CPU_X86_64)
 using RegisterContext = x86_thread_state64_t;

base/profiler/stack_sampler_ios.cc

@@ -1,29 +1,14 @@
-// Copyright 2021 The Chromium Authors. All rights reserved.
+// Copyright 2019 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// Placeholder functions for the StackSampler on iOS, which is not currently
+// supported.
+
 #include "base/profiler/stack_sampler.h"
 
-#include "base/bind.h"
-#include "base/check.h"
-#include "base/profiler/native_unwinder_ios.h"
-#include "base/profiler/stack_copier_suspend.h"
-#include "base/profiler/stack_sampler_impl.h"
-#include "base/profiler/suspendable_thread_delegate_mac.h"
-#include "build/build_config.h"
-
 namespace base {
 
-namespace {
-
-std::vector<std::unique_ptr<Unwinder>> CreateUnwinders() {
-  std::vector<std::unique_ptr<Unwinder>> unwinders;
-  unwinders.push_back(std::make_unique<NativeUnwinderIOS>());
-  return unwinders;
-}
-
-}  // namespace
-
 // static
 std::unique_ptr<StackSampler> StackSampler::Create(
     SamplingProfilerThreadToken thread_token,
@@ -31,21 +16,12 @@ std::unique_ptr<StackSampler> StackSampler::Create(
     UnwindersFactory core_unwinders_factory,
     RepeatingClosure record_sample_callback,
     StackSamplerTestDelegate* test_delegate) {
-  DCHECK(!core_unwinders_factory);
+  return nullptr;
-  return std::make_unique<StackSamplerImpl>(
-      std::make_unique<StackCopierSuspend>(
-          std::make_unique<SuspendableThreadDelegateMac>(thread_token)),
-      BindOnce(&CreateUnwinders), module_cache,
-      std::move(record_sample_callback), test_delegate);
 }
 
 // static
 size_t StackSampler::GetStackBufferSize() {
-  size_t stack_size = PlatformThread::GetDefaultThreadStackSize();
+  return 0;
-
-  // If getrlimit somehow fails, return the default iOS main thread stack size
-  // of 1 MB with extra wiggle room.
-  return stack_size > 0 ? stack_size : 1536 * 1024;
 }
 
 }  // namespace base

base/profiler/stack_sampling_profiler_unittest.cc

@@ -47,8 +47,8 @@
 
 // STACK_SAMPLING_PROFILER_SUPPORTED is used to conditionally enable the tests
 // below for supported platforms (currently Win x64 and Mac x64).
-#if (defined(OS_WIN) && defined(ARCH_CPU_X86_64)) ||                      \
+#if (defined(OS_WIN) && defined(ARCH_CPU_X86_64)) || \
-    (defined(OS_MAC) && defined(ARCH_CPU_X86_64)) || (defined(OS_IOS)) || \
+    (defined(OS_MAC) && defined(ARCH_CPU_X86_64)) || \
     (defined(OS_ANDROID) && BUILDFLAG(ENABLE_ARM_CFI_TABLE))
 #define STACK_SAMPLING_PROFILER_SUPPORTED 1
 #endif
@@ -507,13 +507,12 @@ PROFILER_TEST_F(StackSamplingProfilerTest, MAYBE_Alloca) {
 // Checks that a stack that runs through another library produces a stack with
 // the expected functions.
 // macOS ASAN is not yet supported - crbug.com/718628.
-// iOS chrome doesn't support loading native libraries.
 // Android is not supported when EXCLUDE_UNWIND_TABLES |other_library| doesn't
 // have unwind tables.
 // TODO(https://crbug.com/1100175): Enable this test again for Android with
 // ASAN. This is now disabled because the android-asan bot fails.
-#if (defined(ADDRESS_SANITIZER) && defined(OS_APPLE)) || defined(OS_IOS) || \
+#if (defined(ADDRESS_SANITIZER) && defined(OS_APPLE)) ||         \
-    (defined(OS_ANDROID) && BUILDFLAG(EXCLUDE_UNWIND_TABLES)) ||            \
+    (defined(OS_ANDROID) && BUILDFLAG(EXCLUDE_UNWIND_TABLES)) || \
     (defined(OS_ANDROID) && defined(ADDRESS_SANITIZER))
 #define MAYBE_OtherLibrary DISABLED_OtherLibrary
 #else
@@ -553,8 +552,7 @@ PROFILER_TEST_F(StackSamplingProfilerTest, MAYBE_UnloadingLibrary) {
 // produces a stack, and doesn't crash.
 // macOS ASAN is not yet supported - crbug.com/718628.
 // Android is not supported since modules are found before unwinding.
-#if (defined(ADDRESS_SANITIZER) && defined(OS_APPLE)) || \
+#if (defined(ADDRESS_SANITIZER) && defined(OS_APPLE)) || defined(OS_ANDROID)
-    defined(OS_ANDROID) || defined(OS_IOS)
 #define MAYBE_UnloadedLibrary DISABLED_UnloadedLibrary
 #else
 #define MAYBE_UnloadedLibrary UnloadedLibrary

base/profiler/suspendable_thread_delegate_mac.cc

@@ -24,22 +24,17 @@ namespace base {
 
 namespace {
 
-#if defined(ARCH_CPU_X86_64)
-constexpr mach_msg_type_number_t kThreadStateCount = x86_THREAD_STATE64_COUNT;
-constexpr thread_state_flavor_t kThreadStateFlavor = x86_THREAD_STATE64;
-#elif defined(ARCH_CPU_ARM64)
-constexpr mach_msg_type_number_t kThreadStateCount = ARM_THREAD_STATE64_COUNT;
-constexpr thread_state_flavor_t kThreadStateFlavor = ARM_THREAD_STATE64;
-#endif
-
 // Fills |state| with |target_thread|'s context. NO HEAP ALLOCATIONS.
 bool GetThreadContextImpl(thread_act_t target_thread, RegisterContext* state) {
-  auto count = kThreadStateCount;
+  // TODO(wittman): Implement the unwinder for Mac arm.
-  return thread_get_state(target_thread, kThreadStateFlavor,
+#if !defined(ARCH_CPU_ARM64)
+  auto count = static_cast<mach_msg_type_number_t>(x86_THREAD_STATE64_COUNT);
+  return thread_get_state(target_thread, x86_THREAD_STATE64,
                           reinterpret_cast<thread_state_t>(state),
                           &count) == KERN_SUCCESS;
-
+#else   // !defined(ARCH_CPU_ARM64)
   return false;
+#endif  // !defined(ARCH_CPU_ARM64)
 }
 
 }  // namespace
@@ -112,28 +107,15 @@ bool SuspendableThreadDelegateMac::CanCopyStack(uintptr_t stack_pointer) {
 
 std::vector<uintptr_t*> SuspendableThreadDelegateMac::GetRegistersToRewrite(
     RegisterContext* thread_context) {
-#if defined(ARCH_CPU_X86_64)
+#if !defined(ARCH_CPU_ARM64)
   return {
       &AsUintPtr(&thread_context->__rbx), &AsUintPtr(&thread_context->__rbp),
       &AsUintPtr(&thread_context->__rsp), &AsUintPtr(&thread_context->__r12),
       &AsUintPtr(&thread_context->__r13), &AsUintPtr(&thread_context->__r14),
       &AsUintPtr(&thread_context->__r15)};
-#elif defined(ARCH_CPU_ARM64)  // defined(ARCH_CPU_X86_64)
+#else   // !defined(ARCH_CPU_ARM64)
-  return {
+  return {};
-      &AsUintPtr(&thread_context->__fp),
+#endif  // !defined(ARCH_CPU_ARM64)
-      &AsUintPtr(&thread_context->__sp),
-      &AsUintPtr(&thread_context->__x[19]),
-      &AsUintPtr(&thread_context->__x[20]),
-      &AsUintPtr(&thread_context->__x[21]),
-      &AsUintPtr(&thread_context->__x[22]),
-      &AsUintPtr(&thread_context->__x[23]),
-      &AsUintPtr(&thread_context->__x[24]),
-      &AsUintPtr(&thread_context->__x[25]),
-      &AsUintPtr(&thread_context->__x[26]),
-      &AsUintPtr(&thread_context->__x[27]),
-      &AsUintPtr(&thread_context->__x[28]),
-  };
-#endif                         // defined(ARCH_CPU_ARM64)
 }
 
 }  // namespace base

base/profiler/suspendable_thread_delegate_mac.h

@@ -17,7 +17,7 @@
 namespace base {
 
 // Platform- and thread-specific implementation in support of stack sampling on
-// Mac (X86_64) and iOS (X86_64 and ARM64).
+// Mac.
 class BASE_EXPORT SuspendableThreadDelegateMac
     : public SuspendableThreadDelegate {
  public: