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[memprof][NFC] Free symbolizer memory eagerly #75849

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Merged
merged 2 commits into from
Dec 19, 2023
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[memprof][NFC] Free symbolizer memory eagerly #75849

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[memprof][NFC] Free symbolizer memory eagerly
teresajohnson Dec 18, 2023
a0927e0
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teresajohnson Dec 18, 2023
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11 changes: 5 additions & 6 deletions llvm/include/llvm/ProfileData/RawMemProfReader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -147,14 +147,14 @@ class RawMemProfReader final : public MemProfReader {
llvm::SmallVectorImpl<SegmentEntry> &Seg,
llvm::MapVector<uint64_t, MemInfoBlock> &Prof,
CallStackMap &SM, bool KeepName = false)
: Symbolizer(std::move(Sym)), SegmentInfo(Seg.begin(), Seg.end()),
CallstackProfileData(Prof), StackMap(SM), KeepSymbolName(KeepName) {
: SegmentInfo(Seg.begin(), Seg.end()), CallstackProfileData(Prof),
StackMap(SM), KeepSymbolName(KeepName) {
// We don't call initialize here since there is no raw profile to read. The
// test should pass in the raw profile as structured data.

// If there is an error here then the mock symbolizer has not been
// initialized properly.
if (Error E = symbolizeAndFilterStackFrames())
if (Error E = symbolizeAndFilterStackFrames(std::move(Sym)))
report_fatal_error(std::move(E));
if (Error E = mapRawProfileToRecords())
report_fatal_error(std::move(E));
Expand All @@ -173,7 +173,8 @@ class RawMemProfReader final : public MemProfReader {
// callstacks from the raw profile. Also prune callstack frames which we can't
// symbolize or those that belong to the runtime. For profile entries where
// the entire callstack is pruned, we drop the entry from the profile.
Error symbolizeAndFilterStackFrames();
Error symbolizeAndFilterStackFrames(
std::unique_ptr<llvm::symbolize::SymbolizableModule> Symbolizer);
// Construct memprof records for each function and store it in the
// `FunctionProfileData` map. A function may have allocation profile data or
// callsite data or both.
Expand All @@ -183,8 +184,6 @@ class RawMemProfReader final : public MemProfReader {

// The profiled binary.
object::OwningBinary<object::Binary> Binary;
// A symbolizer to translate virtual addresses to code locations.
std::unique_ptr<llvm::symbolize::SymbolizableModule> Symbolizer;
// The preferred load address of the executable segment.
uint64_t PreferredTextSegmentAddress = 0;
// The base address of the text segment in the process during profiling.
Expand Down
25 changes: 15 additions & 10 deletions llvm/lib/ProfileData/RawMemProfReader.cpp
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Expand Up @@ -336,6 +336,13 @@ Error RawMemProfReader::initialize(std::unique_ptr<MemoryBuffer> DataBuffer) {
inconvertibleErrorCode()),
FileName);

// Process the raw profile.
if (Error E = readRawProfile(std::move(DataBuffer)))
return E;

if (Error E = setupForSymbolization())
return E;

auto *Object = cast<object::ObjectFile>(Binary.getBinary());
std::unique_ptr<DIContext> Context = DWARFContext::create(
*Object, DWARFContext::ProcessDebugRelocations::Process);
Expand All @@ -344,16 +351,13 @@ Error RawMemProfReader::initialize(std::unique_ptr<MemoryBuffer> DataBuffer) {
Object, std::move(Context), /*UntagAddresses=*/false);
if (!SOFOr)
return report(SOFOr.takeError(), FileName);
Symbolizer = std::move(SOFOr.get());

// Process the raw profile.
if (Error E = readRawProfile(std::move(DataBuffer)))
return E;

if (Error E = setupForSymbolization())
return E;
auto Symbolizer = std::move(SOFOr.get());
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I wonder if it makes a difference to the peak memory usage if we move L343-L347 after the readRawRawProfile call. That would mean that we initialize the Symbolizer after we free the raw profile data buffer.

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Yeah that's a good idea. In fact, we can move it after setupForSymbolization(), although I don't think there is a memory savings from doing that.


if (Error E = symbolizeAndFilterStackFrames())
// The symbolizer ownership is moved into symbolizeAndFilterStackFrames so
// that it is freed automatically at the end, when it is no longer used. This
// reduces peak memory since it won't be live while also mapping the raw
// profile into records afterwards.
if (Error E = symbolizeAndFilterStackFrames(std::move(Symbolizer)))
return E;

return mapRawProfileToRecords();
Expand Down Expand Up @@ -469,7 +473,8 @@ Error RawMemProfReader::mapRawProfileToRecords() {
return Error::success();
}

Error RawMemProfReader::symbolizeAndFilterStackFrames() {
Error RawMemProfReader::symbolizeAndFilterStackFrames(
std::unique_ptr<llvm::symbolize::SymbolizableModule> Symbolizer) {
// The specifier to use when symbolization is requested.
const DILineInfoSpecifier Specifier(
DILineInfoSpecifier::FileLineInfoKind::RawValue,
Expand Down