Changing the type of Frame::SymbolName from std::optional<std::string>
to std::unique<std::string> reduces sizeof(Frame) from 64 to 32.
The smaller type reduces the cycle and instruction counts by 23% and
4.4%, respectively, with "llvm-profdata show" modified to deserialize
all MemProfRecords in a MemProf V2 profile. The peak memory usage is
cut down nearly by half.
I'm planning to remove StringRef::equals in favor of
StringRef::operator==.
- StringRef::operator==/!= outnumber StringRef::equals by a factor of
70 under llvm/ in terms of their usage.
- The elimination of StringRef::equals brings StringRef closer to
std::string_view, which has operator== but not equals.
- S == "foo" is more readable than S.equals("foo"), especially for
!Long.Expression.equals("str") vs Long.Expression != "str".
We are in the process of referring to call stacks with CallStackId in
IndexedMemProfRecord and IndexedAllocationInfo instead of holding call
stacks inline (both in memory and the serialized format). Doing so
deduplicates call stacks and reduces the MemProf profile file size.
Before we can eliminate the two fields holding call stacks inline:
- IndexedAllocationInfo::CallStack
- IndexedMemProfRecord::CallSites
we need to eliminate all the read operations on them.
This patch is a step toward that direction. Specifically, we
eliminate the read operations in the context of MemProfReader and
RawMemProfReader. A subsequent patch will eliminate the read
operations during the serialization.
This patch renames RawMemProfReader.{cpp,h} to MemProfReader.{cpp,h},
respectively. Also, it re-creates RawMemProfReader.h just to include
MemProfReader.h for compatibility with out-of-tree users.
