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[embedded] Share a single RelocInfo between all trampolines

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Creates a single RelocInfo to be used by all builtin trampolines and
stores it as a root. All trampolines then substitute this for their
trampoline at generation time with DCHECKs to make sure it is
identical.

Also forces all non-trampoline RelocInfo ByteArrays for builtins to be
generated into RO_SPACE.

On x64, this results in the OLD_SPACE part of the startup snapshot
decreasing in size from 166096 to 131248 (-34848) bytes and RO_SPACE
(in the read-only snapshot) increasing from 31176 to 31248 (+72) bytes.

Bug: v8:8295
Change-Id: I69f4a899b738f2023ed42501c2b9797d34305b06
Reviewed-on: https://chromium-review.googlesource.com/c/1276468
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56811}
This commit is contained in:
Dan Elphick 2018-10-19 10:09:09 +01:00 committed by Commit Bot
parent c7a1743115
commit 1bf6e73553
9 changed files with 134 additions and 53 deletions
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63
src/builtins/builtins.cc
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@ -12,6 +12,7 @@
#include "src/isolate.h"
#include "src/macro-assembler.h"
#include "src/objects-inl.h"
#include "src/objects/fixed-array.h"
#include "src/visitors.h"
namespace v8 {
@ -364,6 +365,39 @@ bool Builtins::IsWasmRuntimeStub(int index) {
UNREACHABLE();
}
namespace {
class OffHeapTrampolineGenerator {
public:
explicit OffHeapTrampolineGenerator(Isolate* isolate)
: isolate_(isolate),
masm_(isolate, buffer, kBufferSize, CodeObjectRequired::kYes) {}
CodeDesc Generate(Address off_heap_entry) {
// Generate replacement code that simply tail-calls the off-heap code.
DCHECK(!masm_.has_frame());
{
FrameScope scope(&masm_, StackFrame::NONE);
masm_.JumpToInstructionStream(off_heap_entry);
}
CodeDesc desc;
masm_.GetCode(isolate_, &desc);
return desc;
}
Handle<HeapObject> CodeObject() { return masm_.CodeObject(); }
private:
Isolate* isolate_;
// Enough to fit the single jmp.
static constexpr size_t kBufferSize = 256;
byte buffer[kBufferSize];
MacroAssembler masm_;
};
} // namespace
// static
Handle<Code> Builtins::GenerateOffHeapTrampolineFor(Isolate* isolate,
Address off_heap_entry) {
@ -371,21 +405,26 @@ Handle<Code> Builtins::GenerateOffHeapTrampolineFor(Isolate* isolate,
DCHECK_NOT_NULL(isolate->embedded_blob());
DCHECK_NE(0, isolate->embedded_blob_size());
constexpr size_t buffer_size = 256; // Enough to fit the single jmp.
byte buffer[buffer_size]; // NOLINT(runtime/arrays)
OffHeapTrampolineGenerator generator(isolate);
CodeDesc desc = generator.Generate(off_heap_entry);
// Generate replacement code that simply tail-calls the off-heap code.
MacroAssembler masm(isolate, buffer, buffer_size, CodeObjectRequired::kYes);
DCHECK(!masm.has_frame());
{
FrameScope scope(&masm, StackFrame::NONE);
masm.JumpToInstructionStream(off_heap_entry);
}
return isolate->factory()->NewCode(desc, Code::BUILTIN,
generator.CodeObject());
}
CodeDesc desc;
masm.GetCode(isolate, &desc);
// static
Handle<ByteArray> Builtins::GenerateOffHeapTrampolineRelocInfo(
Isolate* isolate) {
OffHeapTrampolineGenerator generator(isolate);
// Generate a jump to a dummy address as we're not actually interested in the
// generated instruction stream.
CodeDesc desc = generator.Generate(kNullAddress);
return isolate->factory()->NewCode(desc, Code::BUILTIN, masm.CodeObject());
Handle<ByteArray> reloc_info =
isolate->factory()->NewByteArray(desc.reloc_size, TENURED_READ_ONLY);
Code::CopyRelocInfoToByteArray(*reloc_info, desc);
return reloc_info;
}
// static

5
src/builtins/builtins.h
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@ -12,6 +12,7 @@
namespace v8 {
namespace internal {
class ByteArray;
class Callable;
template <typename T>
class Handle;
@ -188,6 +189,10 @@ class Builtins {
static Handle<Code> GenerateOffHeapTrampolineFor(Isolate* isolate,
Address off_heap_entry);
// Generate the RelocInfo ByteArray that would be generated for an offheap
// trampoline.
static Handle<ByteArray> GenerateOffHeapTrampolineRelocInfo(Isolate* isolate);
private:
static void Generate_CallFunction(MacroAssembler* masm,
ConvertReceiverMode mode);

23
src/heap/factory.cc
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@ -2575,7 +2575,9 @@ MaybeHandle<Code> Factory::TryNewCode(
uint32_t stub_key, bool is_turbofanned, int stack_slots,
int safepoint_table_offset, int handler_table_offset) {
// Allocate objects needed for code initialization.
Handle<ByteArray> reloc_info = NewByteArray(desc.reloc_size, TENURED);
Handle<ByteArray> reloc_info = NewByteArray(
desc.reloc_size,
Builtins::IsBuiltinId(builtin_index) ? TENURED_READ_ONLY : TENURED);
Handle<CodeDataContainer> data_container = NewCodeDataContainer(0);
Handle<ByteArray> source_position_table =
maybe_source_position_table.is_null()
@ -2625,7 +2627,9 @@ Handle<Code> Factory::NewCode(
uint32_t stub_key, bool is_turbofanned, int stack_slots,
int safepoint_table_offset, int handler_table_offset) {
// Allocate objects needed for code initialization.
Handle<ByteArray> reloc_info = NewByteArray(desc.reloc_size, TENURED);
Handle<ByteArray> reloc_info = NewByteArray(
desc.reloc_size,
Builtins::IsBuiltinId(builtin_index) ? TENURED_READ_ONLY : TENURED);
Handle<CodeDataContainer> data_container = NewCodeDataContainer(0);
Handle<ByteArray> source_position_table =
maybe_source_position_table.is_null()
@ -2709,6 +2713,21 @@ Handle<Code> Factory::NewOffHeapTrampolineFor(Handle<Code> code,
result->set_safepoint_table_offset(code->safepoint_table_offset());
}
// Replace the newly generated trampoline's RelocInfo ByteArray with the
// canonical one stored in the roots to avoid duplicating it for every single
// builtin.
ByteArray* canonical_reloc_info =
ReadOnlyRoots(isolate()).off_heap_trampoline_relocation_info();
#ifdef DEBUG
// Verify that the contents are the same.
ByteArray* reloc_info = result->relocation_info();
DCHECK_EQ(reloc_info->length(), canonical_reloc_info->length());
for (int i = 0; i < reloc_info->length(); ++i) {
DCHECK_EQ(reloc_info->get(i), canonical_reloc_info->get(i));
}
#endif
result->set_relocation_info(canonical_reloc_info);
return result;
}

3
src/heap/setup-heap-internal.cc
View File

@ -896,6 +896,9 @@ void Heap::CreateInitialObjects() {
set_noscript_shared_function_infos(roots.empty_weak_array_list());
set_off_heap_trampoline_relocation_info(
*Builtins::GenerateOffHeapTrampolineRelocInfo(isolate_));
// Evaluate the hash values which will then be cached in the strings.
isolate()->factory()->zero_string()->Hash();
isolate()->factory()->one_string()->Hash();

4
src/objects.cc
View File

@ -14397,9 +14397,7 @@ void Code::CopyFromNoFlush(Heap* heap, const CodeDesc& desc) {
}
// Copy reloc info.
CopyBytes(relocation_start(),
desc.buffer + desc.buffer_size - desc.reloc_size,
static_cast<size_t>(desc.reloc_size));
CopyRelocInfoToByteArray(unchecked_relocation_info(), desc);
// Unbox handles and relocate.
Assembler* origin = desc.origin;

8
src/objects/code-inl.h
View File

@ -341,6 +341,14 @@ int Code::ExecutableSize() const {
return raw_instruction_size() + Code::kHeaderSize;
}
// static
void Code::CopyRelocInfoToByteArray(ByteArray* dest, const CodeDesc& desc) {
DCHECK_EQ(dest->length(), desc.reloc_size);
CopyBytes(dest->GetDataStartAddress(),
desc.buffer + desc.buffer_size - desc.reloc_size,
static_cast<size_t>(desc.reloc_size));
}
int Code::CodeSize() const { return SizeFor(body_size()); }
Code::Kind Code::kind() const {

5
src/objects/code.h
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@ -308,6 +308,11 @@ class Code : public HeapObject, public NeverReadOnlySpaceObject {
// Migrate code from desc without flushing the instruction cache.
void CopyFromNoFlush(Heap* heap, const CodeDesc& desc);
// Copy the RelocInfo portion of |desc| to |dest|. The ByteArray must be
// exactly the same size as the RelocInfo in |desc|.
static inline void CopyRelocInfoToByteArray(ByteArray* dest,
const CodeDesc& desc);
// Flushes the instruction cache for the executable instructions of this code
// object.
void FlushICache() const;

5
src/roots.h
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@ -211,7 +211,10 @@ class RootVisitor;
V(HeapNumber*, minus_zero_value, MinusZeroValue) \
V(HeapNumber*, minus_infinity_value, MinusInfinityValue) \
/* Marker for self-references during code-generation */ \
V(HeapObject*, self_reference_marker, SelfReferenceMarker)
V(HeapObject*, self_reference_marker, SelfReferenceMarker) \
/* Canonical trampoline RelocInfo */ \
V(ByteArray*, off_heap_trampoline_relocation_info, \
OffHeapTrampolineRelocationInfo)
// Mutable roots that are known to be immortal immovable, for which we can
// safely skip write barriers.

71
tools/v8heapconst.py
View File

@ -296,41 +296,41 @@ KNOWN_MAPS = {
("RO_SPACE", 0x02699): (171, "Tuple2Map"),
("RO_SPACE", 0x02739): (173, "ArrayBoilerplateDescriptionMap"),
("RO_SPACE", 0x02a79): (161, "InterceptorInfoMap"),
("RO_SPACE", 0x05031): (153, "AccessCheckInfoMap"),
("RO_SPACE", 0x05081): (154, "AccessorInfoMap"),
("RO_SPACE", 0x050d1): (155, "AccessorPairMap"),
("RO_SPACE", 0x05121): (156, "AliasedArgumentsEntryMap"),
("RO_SPACE", 0x05171): (157, "AllocationMementoMap"),
("RO_SPACE", 0x051c1): (158, "AsyncGeneratorRequestMap"),
("RO_SPACE", 0x05211): (159, "DebugInfoMap"),
("RO_SPACE", 0x05261): (160, "FunctionTemplateInfoMap"),
("RO_SPACE", 0x052b1): (162, "InterpreterDataMap"),
("RO_SPACE", 0x05301): (163, "ModuleInfoEntryMap"),
("RO_SPACE", 0x05351): (164, "ModuleMap"),
("RO_SPACE", 0x053a1): (165, "ObjectTemplateInfoMap"),
("RO_SPACE", 0x053f1): (166, "PromiseCapabilityMap"),
("RO_SPACE", 0x05441): (167, "PromiseReactionMap"),
("RO_SPACE", 0x05491): (168, "PrototypeInfoMap"),
("RO_SPACE", 0x054e1): (169, "ScriptMap"),
("RO_SPACE", 0x05531): (170, "StackFrameInfoMap"),
("RO_SPACE", 0x05581): (172, "Tuple3Map"),
("RO_SPACE", 0x055d1): (174, "WasmDebugInfoMap"),
("RO_SPACE", 0x05621): (175, "WasmExportedFunctionDataMap"),
("RO_SPACE", 0x05671): (176, "CallableTaskMap"),
("RO_SPACE", 0x056c1): (177, "CallbackTaskMap"),
("RO_SPACE", 0x05711): (178, "PromiseFulfillReactionJobTaskMap"),
("RO_SPACE", 0x05761): (179, "PromiseRejectReactionJobTaskMap"),
("RO_SPACE", 0x057b1): (180, "PromiseResolveThenableJobTaskMap"),
("RO_SPACE", 0x05801): (181, "MicrotaskQueueMap"),
("RO_SPACE", 0x05851): (182, "AllocationSiteWithWeakNextMap"),
("RO_SPACE", 0x058a1): (182, "AllocationSiteWithoutWeakNextMap"),
("RO_SPACE", 0x058f1): (214, "LoadHandler1Map"),
("RO_SPACE", 0x05941): (214, "LoadHandler2Map"),
("RO_SPACE", 0x05991): (214, "LoadHandler3Map"),
("RO_SPACE", 0x059e1): (221, "StoreHandler0Map"),
("RO_SPACE", 0x05a31): (221, "StoreHandler1Map"),
("RO_SPACE", 0x05a81): (221, "StoreHandler2Map"),
("RO_SPACE", 0x05ad1): (221, "StoreHandler3Map"),
("RO_SPACE", 0x05049): (153, "AccessCheckInfoMap"),
("RO_SPACE", 0x05099): (154, "AccessorInfoMap"),
("RO_SPACE", 0x050e9): (155, "AccessorPairMap"),
("RO_SPACE", 0x05139): (156, "AliasedArgumentsEntryMap"),
("RO_SPACE", 0x05189): (157, "AllocationMementoMap"),
("RO_SPACE", 0x051d9): (158, "AsyncGeneratorRequestMap"),
("RO_SPACE", 0x05229): (159, "DebugInfoMap"),
("RO_SPACE", 0x05279): (160, "FunctionTemplateInfoMap"),
("RO_SPACE", 0x052c9): (162, "InterpreterDataMap"),
("RO_SPACE", 0x05319): (163, "ModuleInfoEntryMap"),
("RO_SPACE", 0x05369): (164, "ModuleMap"),
("RO_SPACE", 0x053b9): (165, "ObjectTemplateInfoMap"),
("RO_SPACE", 0x05409): (166, "PromiseCapabilityMap"),
("RO_SPACE", 0x05459): (167, "PromiseReactionMap"),
("RO_SPACE", 0x054a9): (168, "PrototypeInfoMap"),
("RO_SPACE", 0x054f9): (169, "ScriptMap"),
("RO_SPACE", 0x05549): (170, "StackFrameInfoMap"),
("RO_SPACE", 0x05599): (172, "Tuple3Map"),
("RO_SPACE", 0x055e9): (174, "WasmDebugInfoMap"),
("RO_SPACE", 0x05639): (175, "WasmExportedFunctionDataMap"),
("RO_SPACE", 0x05689): (176, "CallableTaskMap"),
("RO_SPACE", 0x056d9): (177, "CallbackTaskMap"),
("RO_SPACE", 0x05729): (178, "PromiseFulfillReactionJobTaskMap"),
("RO_SPACE", 0x05779): (179, "PromiseRejectReactionJobTaskMap"),
("RO_SPACE", 0x057c9): (180, "PromiseResolveThenableJobTaskMap"),
("RO_SPACE", 0x05819): (181, "MicrotaskQueueMap"),
("RO_SPACE", 0x05869): (182, "AllocationSiteWithWeakNextMap"),
("RO_SPACE", 0x058b9): (182, "AllocationSiteWithoutWeakNextMap"),
("RO_SPACE", 0x05909): (214, "LoadHandler1Map"),
("RO_SPACE", 0x05959): (214, "LoadHandler2Map"),
("RO_SPACE", 0x059a9): (214, "LoadHandler3Map"),
("RO_SPACE", 0x059f9): (221, "StoreHandler0Map"),
("RO_SPACE", 0x05a49): (221, "StoreHandler1Map"),
("RO_SPACE", 0x05a99): (221, "StoreHandler2Map"),
("RO_SPACE", 0x05ae9): (221, "StoreHandler3Map"),
("MAP_SPACE", 0x00139): (1057, "ExternalMap"),
("MAP_SPACE", 0x00189): (1073, "JSMessageObjectMap"),
}
@ -384,6 +384,7 @@ KNOWN_OBJECTS = {
("RO_SPACE", 0x02af1): "MinusZeroValue",
("RO_SPACE", 0x02b01): "MinusInfinityValue",
("RO_SPACE", 0x02b11): "SelfReferenceMarker",
("RO_SPACE", 0x02b69): "OffHeapTrampolineRelocationInfo",
("OLD_SPACE", 0x00139): "ArgumentsIteratorAccessor",
("OLD_SPACE", 0x001a9): "ArrayLengthAccessor",
("OLD_SPACE", 0x00219): "BoundFunctionLengthAccessor",