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[isolate-data] Move hot fields closer to isolate_root

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In generated code, we access fields inside IsolateData through the
root-register. On some platforms it is significantly cheaper to access
things that are close to the root-register value than things that are
located far away. The motivation for this CL was a 5% difference in
Octane/Mandreel scores between

// Part of the stack check.
cmpq rsp,[r13+0x9ea8]

and

cmpq rsp,[r13-0x30]  // Mandreel score improved by 5%.

This moves the StackGuard up to fix Mandreel. As a drive-by, also move
two more fields up that are accessed by each CallCFunction.

Tbr: yangguo@chromium.org
Bug: v8:9534,chromium:993264
Change-Id: I5418b63d40274a138e285fa3c99b96e33a814fb1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1751345
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Auto-Submit: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63187}
This commit is contained in:
Jakob Gruber 2019-08-13 12:37:59 +02:00 committed by Commit Bot
parent a1982f0b8c
commit fb698cec37
3 changed files with 37 additions and 16 deletions
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9
include/v8-internal.h
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@ -152,6 +152,7 @@ class Internals {
static const uint32_t kNumIsolateDataSlots = 4;
// IsolateData layout guarantees.
static const int kIsolateEmbedderDataOffset = 0;
static const int kExternalMemoryOffset =
kNumIsolateDataSlots * kApiSystemPointerSize;
@ -159,8 +160,14 @@ class Internals {
kExternalMemoryOffset + kApiInt64Size;
static const int kExternalMemoryAtLastMarkCompactOffset =
kExternalMemoryLimitOffset + kApiInt64Size;
static const int kIsolateRootsOffset =
static const int kIsolateFastCCallCallerFpOffset =
kExternalMemoryAtLastMarkCompactOffset + kApiInt64Size;
static const int kIsolateFastCCallCallerPcOffset =
kIsolateFastCCallCallerFpOffset + kApiSystemPointerSize;
static const int kIsolateStackGuardOffset =
kIsolateFastCCallCallerPcOffset + kApiSystemPointerSize;
static const int kIsolateRootsOffset =
kIsolateStackGuardOffset + 7 * kApiSystemPointerSize;
static const int kUndefinedValueRootIndex = 4;
static const int kTheHoleValueRootIndex = 5;

36
src/execution/isolate-data.h
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@ -111,21 +111,27 @@ class IsolateData final {
Address* builtins() { return builtins_; }
private:
// Static layout definition.
// Static layout definition.
//
// Note: The location of fields within IsolateData is significant. The
// closer they are to the value of kRootRegister (i.e.: isolate_root()), the
// cheaper it is to access them. See also: https://crbug.com/993264.
// The recommend guideline is to put frequently-accessed fields close to the
// beginning of IsolateData.
#define FIELDS(V) \
V(kEmbedderDataOffset, Internals::kNumIsolateDataSlots* kSystemPointerSize) \
V(kExternalMemoryOffset, kInt64Size) \
V(kExternalMemoryLlimitOffset, kInt64Size) \
V(kExternalMemoryAtLastMarkCompactOffset, kInt64Size) \
V(kFastCCallCallerFPOffset, kSystemPointerSize) \
V(kFastCCallCallerPCOffset, kSystemPointerSize) \
V(kStackGuardOffset, StackGuard::kSizeInBytes) \
V(kRootsTableOffset, RootsTable::kEntriesCount* kSystemPointerSize) \
V(kExternalReferenceTableOffset, ExternalReferenceTable::kSizeInBytes) \
V(kThreadLocalTopOffset, ThreadLocalTop::kSizeInBytes) \
V(kBuiltinEntryTableOffset, Builtins::builtin_count* kSystemPointerSize) \
V(kBuiltinsTableOffset, Builtins::builtin_count* kSystemPointerSize) \
V(kVirtualCallTargetRegisterOffset, kSystemPointerSize) \
V(kFastCCallCallerFPOffset, kSystemPointerSize) \
V(kFastCCallCallerPCOffset, kSystemPointerSize) \
V(kStackGuardOffset, StackGuard::kSizeInBytes) \
V(kStackIsIterableOffset, kUInt8Size) \
/* This padding aligns IsolateData size by 8 bytes. */ \
V(kPaddingOffset, \
@ -153,6 +159,17 @@ class IsolateData final {
// Caches the amount of external memory registered at the last MC.
int64_t external_memory_at_last_mark_compact_ = 0;
// Stores the state of the caller for TurboAssembler::CallCFunction so that
// the sampling CPU profiler can iterate the stack during such calls. These
// are stored on IsolateData so that they can be stored to with only one move
// instruction in compiled code.
Address fast_c_call_caller_fp_ = kNullAddress;
Address fast_c_call_caller_pc_ = kNullAddress;
// Fields related to the system and JS stack. In particular, this contains the
// stack limit used by stack checks in generated code.
StackGuard stack_guard_;
RootsTable roots_;
ExternalReferenceTable external_reference_table_;
@ -172,17 +189,6 @@ class IsolateData final {
// ia32 (otherwise the arguments adaptor call runs out of registers).
void* virtual_call_target_register_ = nullptr;
// Stores the state of the caller for TurboAssembler::CallCFunction so that
// the sampling CPU profiler can iterate the stack during such calls. These
// are stored on IsolateData so that they can be stored to with only one move
// instruction in compiled code.
Address fast_c_call_caller_fp_ = kNullAddress;
Address fast_c_call_caller_pc_ = kNullAddress;
// Fields related to the system and JS stack. In particular, this contains the
// stack limit used by stack checks in generated code.
StackGuard stack_guard_;
// Whether the SafeStackFrameIterator can successfully iterate the current
// stack. Only valid values are 0 or 1.
uint8_t stack_is_iterable_ = 1;

8
src/execution/isolate.cc
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@ -2926,6 +2926,14 @@ void Isolate::CheckIsolateLayout() {
CHECK_EQ(OFFSET_OF(Isolate, isolate_data_), 0);
CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, isolate_data_.embedder_data_)),
Internals::kIsolateEmbedderDataOffset);
CHECK_EQ(static_cast<int>(
OFFSET_OF(Isolate, isolate_data_.fast_c_call_caller_fp_)),
Internals::kIsolateFastCCallCallerFpOffset);
CHECK_EQ(static_cast<int>(
OFFSET_OF(Isolate, isolate_data_.fast_c_call_caller_pc_)),
Internals::kIsolateFastCCallCallerPcOffset);
CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, isolate_data_.stack_guard_)),
Internals::kIsolateStackGuardOffset);
CHECK_EQ(static_cast<int>(OFFSET_OF(Isolate, isolate_data_.roots_)),
Internals::kIsolateRootsOffset);
CHECK_EQ(Internals::kExternalMemoryOffset % 8, 0);