MemInfoBlocks (MIB) with empty callstacks are erased prematurely from
the CallStackProfileData. This patch frees allocated histogram buffers
when the MIB is associated with an empty callstack.
This patch fixes:
llvm/lib/ProfileData/MemProfReader.cpp:685:1: error: non-void
function does not return a value in all con trol paths
[-Werror,-Wreturn-type]
While I am at it, this patch removes an else-after-return.
Adds compile time flag -mllvm -memprof-histogram and runtime flag
histogram=true|false to turn Histogram collection on and off. The
-memprof-histogram flag relies on -memprof-use-callbacks=true to work.
Updates shadow mapping logic in histogram mode from having one 8 byte
counter for 64 bytes, to 1 byte for 8 bytes, capped at 255. Only
supports this granularity as of now.
Updates the RawMemprofReader and serializing MemoryInfoBlocks to binary
format, including changing to a new version of the raw binary format
from version 3 to version 4.
Updates creating MemoryInfoBlocks with and without Histograms. When two
MemoryInfoBlocks are merged, AccessCounts are summed up and the shorter
Histogram is removed.
Adds a memprof_histogram test case.
Initial commit for adding AccessCountHistograms up until RawProfile for
memprof
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.
