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[wasm] Allow mixing tagged and untagged fields

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In WasmInstanceObject we want to reorder the fields such that fields
that are often accessed from generated code have a small offset (<128
bytes). This requires mixing tagged and untagged fields.
This CL prepares the existing GC support for WasmInstanceObject to only
visit the listed tagged fields.

R=titzer@chromium.org

Bug: chromium:839919
Change-Id: Ia85d7bcfff54af35785b6d573e7e682a26c39ae6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1538119
Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60468}
This commit is contained in:
Clemens Hammacher 2019-03-26 14:03:34 +01:00 committed by Commit Bot
parent a0c30858ff
commit 42127d825f
3 changed files with 44 additions and 8 deletions
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21
src/objects-body-descriptors-inl.h
View File

@ -5,8 +5,11 @@
#ifndef V8_OBJECTS_BODY_DESCRIPTORS_INL_H_
#define V8_OBJECTS_BODY_DESCRIPTORS_INL_H_
#include "src/feedback-vector.h"
#include "src/objects-body-descriptors.h"
#include <algorithm>
#include "src/feedback-vector.h"
#include "src/objects/cell.h"
#include "src/objects/data-handler.h"
#include "src/objects/foreign-inl.h"
@ -658,15 +661,25 @@ class SeqTwoByteString::BodyDescriptor final : public BodyDescriptorBase {
class WasmInstanceObject::BodyDescriptor final : public BodyDescriptorBase {
public:
static bool IsValidSlot(Map map, HeapObject obj, int offset) {
if (offset < kMemoryStartOffset) return true;
if (offset < kModuleObjectOffset) return false;
SLOW_DCHECK(std::is_sorted(std::begin(kTaggedFieldOffsets),
std::end(kTaggedFieldOffsets)));
STATIC_ASSERT(sizeof(*kTaggedFieldOffsets) == sizeof(uint16_t));
if (offset < int{8 * sizeof(*kTaggedFieldOffsets)} &&
std::binary_search(std::begin(kTaggedFieldOffsets),
std::end(kTaggedFieldOffsets),
static_cast<uint16_t>(offset))) {
return true;
}
return IsValidJSObjectSlotImpl(map, obj, offset);
}
template <typename ObjectVisitor>
static inline void IterateBody(Map map, HeapObject obj, int object_size,
ObjectVisitor* v) {
IteratePointers(obj, kPropertiesOrHashOffset, kEndOfTaggedFieldsOffset, v);
IteratePointer(obj, kPropertiesOrHashOffset, v);
for (uint16_t offset : kTaggedFieldOffsets) {
IteratePointer(obj, offset, v);
}
IterateJSObjectBodyImpl(map, obj, kSize, object_size, v);
}

4
src/wasm/wasm-objects.cc
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@ -1473,6 +1473,10 @@ Address ImportedFunctionEntry::target() {
return instance_->imported_function_targets()[index_];
}
// static
constexpr uint16_t WasmInstanceObject::kTaggedFieldOffsets[];
// static
bool WasmInstanceObject::EnsureIndirectFunctionTableWithMinimumSize(
Handle<WasmInstanceObject> instance, uint32_t minimum_size) {
uint32_t old_size = instance->indirect_function_table_size();

27
src/wasm/wasm-objects.h
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@ -497,12 +497,10 @@ class WasmInstanceObject : public JSObject {
V(kNullValueOffset, kTaggedSize) \
V(kCEntryStubOffset, kTaggedSize) \
V(kWasmExportedFunctionsOffset, kTaggedSize) \
V(kEndOfTaggedFieldsOffset, 0) \
/* Raw data. */ \
V(kIndirectFunctionTableSizeOffset, kUInt32Size) \
/* Optional padding to align system pointer size fields */ \
V(kOptionalPaddingOffset, POINTER_SIZE_PADDING(kOptionalPaddingOffset)) \
V(kFirstSystemPointerFieldOffset, 0) \
V(kMemoryStartOffset, kSystemPointerSize) \
V(kMemorySizeOffset, kSizetSize) \
V(kMemoryMaskOffset, kSizetSize) \
@ -524,10 +522,31 @@ class WasmInstanceObject : public JSObject {
DEFINE_FIELD_OFFSET_CONSTANTS(JSObject::kHeaderSize,
WASM_INSTANCE_OBJECT_FIELDS)
STATIC_ASSERT(IsAligned(kSize, kTaggedSize));
#define ASSERT_FIELD_ALIGNED(offset, size) \
STATIC_ASSERT(size == 0 || IsAligned(offset, size));
WASM_INSTANCE_OBJECT_FIELDS(ASSERT_FIELD_ALIGNED)
#undef ASSERT_FIELD_ALIGNED
#undef WASM_INSTANCE_OBJECT_FIELDS
STATIC_ASSERT(IsAligned(kFirstSystemPointerFieldOffset, kSystemPointerSize));
STATIC_ASSERT(IsAligned(kSize, kTaggedSize));
static constexpr uint16_t kTaggedFieldOffsets[] = {
kModuleObjectOffset,
kExportsObjectOffset,
kNativeContextOffset,
kMemoryObjectOffset,
kUntaggedGlobalsBufferOffset,
kTaggedGlobalsBufferOffset,
kImportedMutableGlobalsBuffersOffset,
kDebugInfoOffset,
kTablesOffset,
kImportedFunctionRefsOffset,
kIndirectFunctionTableRefsOffset,
kManagedNativeAllocationsOffset,
kExceptionsTableOffset,
kUndefinedValueOffset,
kNullValueOffset,
kCEntryStubOffset,
kWasmExportedFunctionsOffset};
V8_EXPORT_PRIVATE const wasm::WasmModule* module();