Revert "Fix a few issues found when testing an MSVC build locally."

This reverts commit 436e5b7.

Reason for revert:  Win10 Tests x64 (dbg) base_unittests failures:
https://ci.chromium.org/ui/p/chromium/builders/ci/Win10%20Tests%20x64%20(dbg)/27879/overview

Original change's description:
> Fix a few issues found when testing an MSVC build locally.
>
> These won't get MSVC compiling, but seemed reasonably low-effort to
> carry.  I think if I want to pursue much further, I need C++20.
>
> Bug: none
> Change-Id: If3879f9862c38f2a365d075ef43463d2b39f79c4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3615250
> Reviewed-by: Behdad Bakhshinategh <behdadb@chromium.org>
> Commit-Queue: Peter Kasting <pkasting@chromium.org>
> Auto-Submit: Peter Kasting <pkasting@chromium.org>
> Reviewed-by: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
> Reviewed-by: Daniel Cheng <dcheng@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1001751}

Bug: none
Change-Id: I98abc04eade6c7e665a652e816699e449a24c1d2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3641530
Reviewed-by: Aya Elsayed <ayaelattar@chromium.org>
Auto-Submit: Sergey Poromov <poromov@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Sergey Poromov <poromov@chromium.org>
Owners-Override: Sergey Poromov <poromov@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1002027}

base/allocator/allocator_shim_default_dispatch_to_partition_alloc.cc

@@ -586,7 +586,7 @@ void ConfigurePartitions(
     }
     PA_DCHECK(!enable_brp);
     PA_DCHECK(!use_dedicated_aligned_partition);
-    PA_DCHECK(!current_root->flags.with_thread_cache);
+    PA_DCHECK(!current_root->with_thread_cache);
     return;
   }
 

base/allocator/partition_allocator/extended_api.cc

@@ -17,11 +17,11 @@ namespace {
 void DisableThreadCacheForRootIfEnabled(ThreadSafePartitionRoot* root) {
   // Some platforms don't have a thread cache, or it could already have been
   // disabled.
-  if (!root || !root->flags.with_thread_cache)
+  if (!root || !root->with_thread_cache)
     return;
 
   ThreadCacheRegistry::Instance().PurgeAll();
-  root->flags.with_thread_cache = false;
+  root->with_thread_cache = false;
   // Doesn't destroy the thread cache object(s). For background threads, they
   // will be collected (and free cached memory) at thread destruction
   // time. For the main thread, we leak it.
@@ -31,7 +31,7 @@ void EnablePartitionAllocThreadCacheForRootIfDisabled(
     ThreadSafePartitionRoot* root) {
   if (!root)
     return;
-  root->flags.with_thread_cache = true;
+  root->with_thread_cache = true;
 }
 
 #if BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)

base/allocator/partition_allocator/partition_page.h

@@ -117,9 +117,8 @@ using AllocationStateMap =
 //   booted out of the active list. If there are no suitable active slot spans
 //   found, an empty or decommitted slot spans (if one exists) will be pulled
 //   from the empty/decommitted list on to the active list.
-#pragma pack(push, 1)
 template <bool thread_safe>
-struct SlotSpanMetadata {
+struct __attribute__((packed)) SlotSpanMetadata {
  private:
   PartitionFreelistEntry* freelist_head = nullptr;
 
@@ -303,7 +302,6 @@ struct SlotSpanMetadata {
         empty_cache_index_(0),
         unused2_(0) {}
 };
-#pragma pack(pop)
 static_assert(sizeof(SlotSpanMetadata<ThreadSafe>) <= kPageMetadataSize,
               "SlotSpanMetadata must fit into a Page Metadata slot.");
 
@@ -326,12 +324,11 @@ struct SubsequentPageMetadata {
 // first page of a slot span, describes that slot span. If a slot span spans
 // more than 1 page, the page metadata may contain rudimentary additional
 // information.
-// "Pack" the union so that common page metadata still fits within
-// kPageMetadataSize. (SlotSpanMetadata is also "packed".)
-#pragma pack(push, 1)
 template <bool thread_safe>
-struct PartitionPage {
-  union {
+struct __attribute__((packed)) PartitionPage {
+  // "Pack" the union so that common page metadata still fits within
+  // kPageMetadataSize. (SlotSpanMetadata is also "packed".)
+  union __attribute__((packed)) {
     SlotSpanMetadata<thread_safe> slot_span_metadata;
 
     SubsequentPageMetadata subsequent_page_metadata;
@@ -369,7 +366,7 @@ struct PartitionPage {
 
   ALWAYS_INLINE static PartitionPage* FromAddr(uintptr_t address);
 };
-#pragma pack(pop)
+
 static_assert(sizeof(PartitionPage<ThreadSafe>) == kPageMetadataSize,
               "PartitionPage must be able to fit in a metadata slot");
 
@@ -620,7 +617,7 @@ SlotSpanMetadata<thread_safe>::FromObject(void* object) {
   PA_DCHECK((::partition_alloc::internal::UnmaskPtr(object_addr) -
              ::partition_alloc::internal::UnmaskPtr(slot_span_start)) %
                 slot_span->bucket->slot_size ==
-            root->flags.extras_offset);
+            root->extras_offset);
 #endif  // DCHECK_IS_ON()
   return slot_span;
 }
@@ -640,10 +637,10 @@ SlotSpanMetadata<thread_safe>::FromObjectInnerAddr(uintptr_t address) {
   auto* root = PartitionRoot<thread_safe>::FromSlotSpan(slot_span);
   uintptr_t shift_from_slot_start =
       (address - slot_span_start) % slot_span->bucket->slot_size;
-  PA_DCHECK(shift_from_slot_start >= root->flags.extras_offset);
+  PA_DCHECK(shift_from_slot_start >= root->extras_offset);
   // Use <= to allow an address immediately past the object.
   PA_DCHECK(shift_from_slot_start <=
-            root->flags.extras_offset + slot_span->GetUsableSize(root));
+            root->extras_offset + slot_span->GetUsableSize(root));
 #endif  // DCHECK_IS_ON()
   return slot_span;
 }

base/allocator/partition_allocator/partition_root.cc

@@ -631,7 +631,7 @@ void PartitionRoot<thread_safe>::DestructForTesting() {
   // We need to destruct the thread cache before we unreserve any of the super
   // pages below, which we currently are not doing. So, we should only call
   // this function on PartitionRoots without a thread cache.
-  PA_CHECK(!flags.with_thread_cache);
+  PA_CHECK(!with_thread_cache);
   auto pool_handle = ChoosePool();
   auto* curr = first_extent;
   while (curr != nullptr) {
@@ -674,24 +674,24 @@ void PartitionRoot<thread_safe>::Init(PartitionOptions opts) {
     internal::PartitionAddressSpace::Init();
 #endif
 
-    flags.allow_aligned_alloc =
+    allow_aligned_alloc =
         opts.aligned_alloc == PartitionOptions::AlignedAlloc::kAllowed;
-    flags.allow_cookie = opts.cookie == PartitionOptions::Cookie::kAllowed;
+    allow_cookie = opts.cookie == PartitionOptions::Cookie::kAllowed;
 #if BUILDFLAG(USE_BACKUP_REF_PTR)
-    flags.brp_enabled_ =
+    brp_enabled_ =
         opts.backup_ref_ptr == PartitionOptions::BackupRefPtr::kEnabled;
 #else
     PA_CHECK(opts.backup_ref_ptr == PartitionOptions::BackupRefPtr::kDisabled);
 #endif
-    flags.use_configurable_pool =
+    use_configurable_pool =
         (opts.use_configurable_pool ==
          PartitionOptions::UseConfigurablePool::kIfAvailable) &&
         IsConfigurablePoolAvailable();
-    PA_DCHECK(!flags.use_configurable_pool || IsConfigurablePoolAvailable());
+    PA_DCHECK(!use_configurable_pool || IsConfigurablePoolAvailable());
 
     // brp_enabled_() is not supported in the configurable pool because
     // BRP requires objects to be in a different Pool.
-    PA_CHECK(!(flags.use_configurable_pool && brp_enabled()));
+    PA_CHECK(!(use_configurable_pool && brp_enabled()));
 
     // Ref-count messes up alignment needed for AlignedAlloc, making this
     // option incompatible. However, except in the
@@ -701,28 +701,28 @@ void PartitionRoot<thread_safe>::Init(PartitionOptions opts) {
 #endif
 
 #if defined(PA_EXTRAS_REQUIRED)
-    flags.extras_size = 0;
-    flags.extras_offset = 0;
+    extras_size = 0;
+    extras_offset = 0;
 
-    if (flags.allow_cookie) {
-      flags.extras_size += internal::kPartitionCookieSizeAdjustment;
+    if (allow_cookie) {
+      extras_size += internal::kPartitionCookieSizeAdjustment;
     }
 
     if (brp_enabled()) {
       // TODO(tasak): In the PUT_REF_COUNT_IN_PREVIOUS_SLOT case, ref-count is
       // stored out-of-line for single-slot slot spans, so no need to
       // add/subtract its size in this case.
-      flags.extras_size += internal::kPartitionRefCountSizeAdjustment;
-      flags.extras_offset += internal::kPartitionRefCountOffsetAdjustment;
+      extras_size += internal::kPartitionRefCountSizeAdjustment;
+      extras_offset += internal::kPartitionRefCountOffsetAdjustment;
     }
 #endif  //  defined(PA_EXTRAS_REQUIRED)
 
     // Re-confirm the above PA_CHECKs, by making sure there are no
     // pre-allocation extras when AlignedAlloc is allowed. Post-allocation
     // extras are ok.
-    PA_CHECK(!flags.allow_aligned_alloc || !flags.extras_offset);
+    PA_CHECK(!allow_aligned_alloc || !extras_offset);
 
-    flags.quarantine_mode =
+    quarantine_mode =
 #if defined(PA_ALLOW_PCSCAN)
         (opts.quarantine == PartitionOptions::Quarantine::kDisallowed
              ? QuarantineMode::kAlwaysDisabled
@@ -763,10 +763,10 @@ void PartitionRoot<thread_safe>::Init(PartitionOptions opts) {
     with_thread_cache = false;
 #else
     ThreadCache::EnsureThreadSpecificDataInitialized();
-    flags.with_thread_cache =
+    with_thread_cache =
         (opts.thread_cache == PartitionOptions::ThreadCache::kEnabled);
 
-    if (flags.with_thread_cache)
+    if (with_thread_cache)
       ThreadCache::Init(this);
 #endif  // !defined(PA_THREAD_CACHE_SUPPORTED)
 
@@ -786,7 +786,7 @@ void PartitionRoot<thread_safe>::Init(PartitionOptions opts) {
 template <bool thread_safe>
 PartitionRoot<thread_safe>::~PartitionRoot() {
 #if BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
-  PA_CHECK(!flags.with_thread_cache)
+  PA_CHECK(!with_thread_cache)
       << "Must not destroy a partition with a thread cache";
 #endif  // BUILDFLAG(USE_PARTITION_ALLOC_AS_MALLOC)
 
@@ -800,7 +800,7 @@ template <bool thread_safe>
 void PartitionRoot<thread_safe>::EnableThreadCacheIfSupported() {
 #if defined(PA_THREAD_CACHE_SUPPORTED)
   ::partition_alloc::internal::ScopedGuard guard{lock_};
-  PA_CHECK(!flags.with_thread_cache);
+  PA_CHECK(!with_thread_cache);
   // By the time we get there, there may be multiple threads created in the
   // process. Since `with_thread_cache` is accessed without a lock, it can
   // become visible to another thread before the effects of
@@ -815,7 +815,7 @@ void PartitionRoot<thread_safe>::EnableThreadCacheIfSupported() {
   PA_CHECK(before == 0);
   ThreadCache::Init(this);
   thread_caches_being_constructed_.fetch_sub(1, std::memory_order_release);
-  flags.with_thread_cache = true;
+  with_thread_cache = true;
 #endif  // defined(PA_THREAD_CACHE_SUPPORTED)
 }
 
@@ -916,7 +916,7 @@ bool PartitionRoot<thread_safe>::TryReallocInPlaceForDirectMap(
 
 #if DCHECK_IS_ON()
   // Write a new trailing cookie.
-  if (flags.allow_cookie) {
+  if (allow_cookie) {
     auto* object =
         reinterpret_cast<unsigned char*>(SlotStartToObject(slot_start));
     internal::PartitionCookieWriteValue(object +
@@ -965,7 +965,7 @@ bool PartitionRoot<thread_safe>::TryReallocInPlaceForNormalBuckets(
 #if DCHECK_IS_ON()
     // Write a new trailing cookie only when it is possible to keep track
     // raw size (otherwise we wouldn't know where to look for it later).
-    if (flags.allow_cookie) {
+    if (allow_cookie) {
       internal::PartitionCookieWriteValue(
           reinterpret_cast<unsigned char*>(address) +
           slot_span->GetUsableSize(this));
@@ -1204,7 +1204,7 @@ void PartitionRoot<thread_safe>::DumpStats(const char* partition_name,
     stats.total_active_bytes += direct_mapped_allocations_total_size;
     stats.total_active_count += num_direct_mapped_allocations;
 
-    stats.has_thread_cache = flags.with_thread_cache;
+    stats.has_thread_cache = with_thread_cache;
     if (stats.has_thread_cache) {
       ThreadCacheRegistry::Instance().DumpStats(
           true, &stats.current_thread_cache_stats);
@@ -1241,9 +1241,9 @@ void PartitionRoot<thread_safe>::DumpStats(const char* partition_name,
 template <bool thread_safe>
 void PartitionRoot<thread_safe>::DeleteForTesting(
     PartitionRoot* partition_root) {
-  if (partition_root->flags.with_thread_cache) {
+  if (partition_root->with_thread_cache) {
     ThreadCache::SwapForTesting(nullptr);
-    partition_root->flags.with_thread_cache = false;
+    partition_root->with_thread_cache = false;
   }
 
   delete partition_root;