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[perf-jit] Fix unneeded memory allocation

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Instead of unconditionally copying the script name into a
heap-allocated char vector, use existing storage if possible. Also, try
to avoid materializing the script name for computing its length.

R=titzer@chromium.org

Change-Id: If0e8ac95ecbbb4e7463d9e4a4cdb5579270bcdaf
Reviewed-on: https://chromium-review.googlesource.com/1051230
Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53157}
This commit is contained in:
Clemens Hammacher 2018-05-14 15:31:03 +02:00 committed by Commit Bot
parent 58c3c22e17
commit cf4b5a999a
1 changed files with 38 additions and 17 deletions
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55
src/perf-jit.cc
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@ -272,22 +272,41 @@ void PerfJitLogger::WriteJitCodeLoadEntry(const uint8_t* code_pointer,
namespace {
// TODO(clemensh): The heap-allocated string returned from here is just used to
// invoke {strlen} on it or to output it directly. Refactor this to make it
// cheaper.
std::unique_ptr<char[]> GetScriptName(const SourcePositionInfo& info) {
constexpr char kUnknownScriptNameString[] = "<unknown>";
constexpr size_t kUnknownScriptNameStringLen =
arraysize(kUnknownScriptNameString) - 1;
size_t GetScriptNameLength(const SourcePositionInfo& info) {
if (!info.script.is_null()) {
Object* name_or_url = info.script->GetNameOrSourceURL();
if (name_or_url->IsString()) {
return String::cast(name_or_url)
->ToCString(DISALLOW_NULLS, FAST_STRING_TRAVERSAL);
String* str = String::cast(name_or_url);
if (str->IsOneByteRepresentation()) return str->length();
int length;
str->ToCString(DISALLOW_NULLS, FAST_STRING_TRAVERSAL, &length);
return static_cast<size_t>(length);
}
}
constexpr char kUnknownString[] = "<unknown>";
constexpr size_t kUnknownStringLen = arraysize(kUnknownString) - 1;
std::unique_ptr<char[]> name(NewArray<char>(kUnknownStringLen + 1));
memcpy(name.get(), kUnknownString, kUnknownStringLen + 1);
return name;
return kUnknownScriptNameStringLen;
}
Vector<const char> GetScriptName(const SourcePositionInfo& info,
std::unique_ptr<char[]>* storage) {
if (!info.script.is_null()) {
Object* name_or_url = info.script->GetNameOrSourceURL();
if (name_or_url->IsSeqOneByteString()) {
SeqOneByteString* str = SeqOneByteString::cast(name_or_url);
return {reinterpret_cast<char*>(str->GetChars()),
static_cast<size_t>(str->length())};
} else if (name_or_url->IsString()) {
int length;
*storage =
String::cast(name_or_url)
->ToCString(DISALLOW_NULLS, FAST_STRING_TRAVERSAL, &length);
return {storage->get(), static_cast<size_t>(length)};
}
}
return {kUnknownScriptNameString, kUnknownScriptNameStringLen};
}
SourcePositionInfo GetSourcePositionInfo(Handle<Code> code,
@ -333,8 +352,7 @@ void PerfJitLogger::LogWriteDebugInfo(Code* code, SharedFunctionInfo* shared) {
!iterator.done(); iterator.Advance()) {
SourcePositionInfo info(GetSourcePositionInfo(code_handle, function_handle,
iterator.source_position()));
std::unique_ptr<char[]> name_string = GetScriptName(info);
size += (static_cast<uint32_t>(strlen(name_string.get())) + 1);
size += GetScriptNameLength(info) + 1;
}
int padding = ((size + 7) & (~7)) - size;
@ -355,11 +373,14 @@ void PerfJitLogger::LogWriteDebugInfo(Code* code, SharedFunctionInfo* shared) {
entry.line_number_ = info.line + 1;
entry.column_ = info.column + 1;
LogWriteBytes(reinterpret_cast<const char*>(&entry), sizeof(entry));
std::unique_ptr<char[]> name_string = GetScriptName(info);
LogWriteBytes(name_string.get(),
static_cast<uint32_t>(strlen(name_string.get())) + 1);
// The extracted name may point into heap-objects, thus disallow GC.
DisallowHeapAllocation no_gc;
std::unique_ptr<char[]> name_storage;
Vector<const char> name_string = GetScriptName(info, &name_storage);
LogWriteBytes(name_string.start(),
static_cast<uint32_t>(name_string.size()) + 1);
}
char padding_bytes[] = "\0\0\0\0\0\0\0\0";
char padding_bytes[8] = {0};
LogWriteBytes(padding_bytes, padding);
}