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

This patch adds support for recording BuildIds usng the sanitizer
ListOfModules API. We add another entry to the SegmentEntry struct and
change the memprof raw version.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D145190

This reverts commit 287177a47a396ca6cc0bef7696108cdaa0c68e5f.

This patch adds support for recording BuildIds usng the sanitizer
ListOfModules API. We add another entry to the SegmentEntry struct and
change the memprof raw version.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D145190

The memprof profiles and binaries need to be updated in case of version
updates. This change adds three scripts for llvm-profdata, clang and
llvm tests where memprof profiles are used as inputs. Also update the
tests, profiles and binaries in this change. Change based on the review
suggestions in D145023.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D145644

This reverts commit 599b7690fa917ea4e9cd67275e34d0b5a0f51aa9. Since
adding a cross project dependency is a concern.

This change replaces the binary profiles and executables used for
testing the memprof profile reader with tests where the profiles are
generated on the fly. This reduces toil when the profile version
changes. The tests are moved from tools/llvm-profdata to
compiler-rt/test/memprof due to the following reasons:
1. Adding dependency on memprof lit.cfg.py for llvm-profdata is
   preferable to adding a dependency on compiler-rt for llvm/test.
2. All the tests can now be run with `ninja check-memprof`.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D145023

Track min/max/avg access density (accesses per byte and accesses per
byte per lifetime second) metrics directly during profiling. This allows
more accurate use of these metrics in profile analysis and use, instead
of trying to compute them from already aggregated data in the profile.

This required regenerating some of the raw profile and executable inputs
for a few tests. While here, make the llvm-profdata memprof tests more
resilient to differences in things like memory mapping, timestamps and
cpu ids to make future test updates easier.

Differential Revision: https://reviews.llvm.org/D141558

The driver option -no-pie is preferred: Clang selects different crt*.o files,
though the PIC one usually can replace the non-PIC one.

Until we have symbolization for position independent code lets update
this documentation since clang now defaults to position independent
code.

Reviewed By: tejohnson

Differential Revision: https://reviews.llvm.org/D127808