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[ptr-cage] Better support sharing CodeRange with re-embedded builtins

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If a shared CodeRange is already allocated when creating an Isolate in
jitless mode, the CodeRange will be used. This is to better support the
following use pattern:

```
FLAG_jitless = false;
v8::Isolate::New();
FLAG_jitless = true;
v8::Isolate::New();
```

Note that the other direction of toggling jitless from true to false is
unsupported and may have undefined behavior.

Bug: v8:11460
Change-Id: I1c451c53bc160be4122056d8b309323a94d4b8b6
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2890591
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74535}
This commit is contained in:
Shu-yu Guo 2021-05-12 08:42:06 -07:00 committed by V8 LUCI CQ
parent 73b9a84755
commit a61aa4919f
2 changed files with 48 additions and 3 deletions
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8
src/execution/isolate.cc
View File

@ -3657,8 +3657,7 @@ bool Isolate::Init(SnapshotData* startup_snapshot_data,
is_short_builtin_calls_enabled_ = (heap_.MaxOldGenerationSize() >=
kShortBuiltinCallsOldSpaceSizeThreshold);
if (COMPRESS_POINTERS_IN_SHARED_CAGE_BOOL) {
std::shared_ptr<CodeRange> code_range =
CodeRange::GetProcessWideCodeRange();
CodeRange* code_range = CodeRange::GetProcessWideCodeRange().get();
if (code_range && code_range->embedded_blob_code_copy() != nullptr) {
is_short_builtin_calls_enabled_ = true;
}
@ -4974,7 +4973,10 @@ void Isolate::AddCodeRange(Address begin, size_t length_in_bytes) {
}
bool Isolate::RequiresCodeRange() const {
return kPlatformRequiresCodeRange && !jitless_;
if (kPlatformRequiresCodeRange && !jitless_) return true;
return COMPRESS_POINTERS_IN_SHARED_CAGE_BOOL &&
CodeRange::GetProcessWideCodeRange().get() != nullptr;
}
v8::metrics::Recorder::ContextId Isolate::GetOrRegisterRecorderContextId(

43
test/cctest/test-ptr-compr-cage.cc
View File

@ -101,6 +101,49 @@ UNINITIALIZED_TEST(SharedPtrComprCageCodeRange) {
isolate2->Dispose();
}
UNINITIALIZED_TEST(SharedPtrComprCageRemappedBuiltinsJitlessFalseToTrue) {
// Testing that toggling jitless from false to true use the same re-embedded
// builtins. Toggling jitless from false to true with shared pointer
// compression cage is not supported.
if (!V8_SHORT_BUILTIN_CALLS_BOOL) return;
FLAG_short_builtin_calls = true;
FLAG_jitless = false;
constexpr uint64_t kMemoryGB = 4;
v8::Isolate::CreateParams create_params;
create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
create_params.constraints.ConfigureDefaults(kMemoryGB * GB, kMemoryGB * GB);
v8::Isolate* isolate1 = v8::Isolate::New(create_params);
Isolate* i_isolate1 = reinterpret_cast<Isolate*>(isolate1);
v8::Isolate* isolate2 = v8::Isolate::New(create_params);
Isolate* i_isolate2 = reinterpret_cast<Isolate*>(isolate2);
CHECK_EQ(i_isolate1->embedded_blob_code(), i_isolate2->embedded_blob_code());
CodeRange* shared_code_range = CodeRange::GetProcessWideCodeRange().get();
if (shared_code_range &&
shared_code_range->embedded_blob_code_copy() != nullptr) {
CHECK_EQ(shared_code_range->embedded_blob_code_copy(),
i_isolate1->embedded_blob_code());
CHECK_EQ(shared_code_range->embedded_blob_code_copy(),
i_isolate2->embedded_blob_code());
}
FLAG_jitless = true;
v8::Isolate* isolate3 = v8::Isolate::New(create_params);
Isolate* i_isolate3 = reinterpret_cast<Isolate*>(isolate3);
if (shared_code_range &&
shared_code_range->embedded_blob_code_copy() != nullptr) {
CHECK_EQ(shared_code_range->embedded_blob_code_copy(),
i_isolate3->embedded_blob_code());
}
isolate1->Dispose();
isolate2->Dispose();
isolate3->Dispose();
}
namespace {
constexpr int kIsolatesToAllocate = 25;