Commit Graph

50 Commits

Author SHA1 Message Date
Snehasish Kumar 50713461d4 Reland "[memprof] Introduce a wrapper around MemInfoBlock."
This reverts commit e6999040f5.

Update test to fix signed int comparison warning, fix whitespace in
compiler-rt MIBEntryDef.inc file.

Differential Revision: https://reviews.llvm.org/D117256
2022-02-14 19:04:36 -08:00
Snehasish Kumar f89319b841 Reland "[memprof] Refactor out the MemInfoBlock into a macro based def."
This reverts commit 857ec0d01f.

Fixes -DLLVM_ENABLE_MODULES=On build by adding the new textual
header to the modulemap file.

Reviewed in https://reviews.llvm.org/D117722
2022-02-14 16:05:05 -08:00
Snehasish Kumar 857ec0d01f Revert "[memprof] Refactor out the MemInfoBlock into a macro based def."
This reverts commit 9def83c6d0. [4/4]
2022-02-14 11:42:58 -08:00
Snehasish Kumar 85355a560a Revert "Reland "[memprof] Extend the index prof format to include memory profiles.""
This reverts commit de54e4ab78 [1/4]
2022-02-14 11:42:58 -08:00
Snehasish Kumar de54e4ab78 Reland "[memprof] Extend the index prof format to include memory profiles."
This reverts commit 0f73fb18ca.

Use llvm/Profile/MIBEntryDef.inc instead of relative path.

Generated the raw profile data with `-mllvm
-enable-name-compression=false` so that builbots where the reader is
built without zlib do not fail.

Also updated the test build instructions.
2022-02-14 10:52:13 -08:00
Snehasish Kumar 0f73fb18ca Revert "[memprof] Extend the index prof format to include memory profiles."
This reverts commit 43c2348c5b.

Buildbots are failing with an error on reading memprof testdata.
"Inputs/basic.profraw: profile uses zlib
compression but the profile reader was built without zlib support"

https://lab.llvm.org/buildbot/#/builders/16/builds/24490
2022-02-14 10:25:01 -08:00
Snehasish Kumar 43c2348c5b [memprof] Extend the index prof format to include memory profiles.
This patch adds support for optional memory profile information to be
included with and indexed profile. The indexed profile header adds a new
field which points to the offset of the memory profile section (if
present) in the indexed profile. For users who do not utilize this
feature the only overhead is a 64-bit offset in the header.

The memory profile section contains (1) profile metadata describing the
information recorded for each entry (2) an on-disk hashtable containing
the profile records indexed via llvm::md5(function_name). We chose to
introduce a separate hash table instead of the existing one since the
indexing for the instrumented fdo hash table is based on a CFG hash
which itself is perturbed by memprof instrumentation.

Differential Revision: https://reviews.llvm.org/D118653
2022-02-14 09:53:45 -08:00
Snehasish Kumar 9def83c6d0 [memprof] Refactor out the MemInfoBlock into a macro based def.
This patch refactors out the MemInfoBlock definition into a macro based
header which can be included to generate enums, structus and code for
each field recorded by the memprof profiling runtime.

Differential Revision: https://reviews.llvm.org/D117722
2022-02-14 09:53:45 -08:00
Snehasish Kumar 8306968b59 [memprof] Move the meminfo block struct to MemProfData.inc.
The definition of the MemInfoBlock is shared between the memprof
compiler-rt runtime and llvm/lib/ProfileData/. This change removes the
memprof_meminfoblock header and moves the struct to the shared include
file. To enable this sharing, the Print method is moved to the
memprof_allocator (the only place it is used) and the remaining uses are
updated to refer to the MemInfoBlock defined in the MemProfData.inc
file.

Also a couple of other minor changes which improve usability of the
types in MemProfData.inc.
* Update the PACKED macro to handle commas.
* Add constructors and equality operators.
* Don't initialize the buildid field.

Differential Revision: https://reviews.llvm.org/D116780
2022-01-31 15:04:41 -08:00
Ellis Hoag 11d3074267 [InstrProf] Add single byte coverage mode
Use the llvm flag `-pgo-function-entry-coverage` to create single byte "counters" to track functions coverage. This mode has significantly less size overhead in both code and data because
  * We mark a function as "covered" with a store instead of an increment which generally requires fewer assembly instructions
  * We use a single byte per function rather than 8 bytes per block

The trade off of course is that this mode only tells you if a function has been covered. This is useful, for example, to detect dead code.

When combined with debug info correlation [0] we are able to create an instrumented Clang binary that is only 150M (the vanilla Clang binary is 143M). That is an overhead of 7M (4.9%) compared to the default instrumentation (without value profiling) which has an overhead of 31M (21.7%).

[0] https://groups.google.com/g/llvm-dev/c/r03Z6JoN7d4

Reviewed By: kyulee

Differential Revision: https://reviews.llvm.org/D116180
2022-01-27 17:38:55 -08:00
Ellis Hoag ccb09a4889 Fix broken comment in InstrProfData.inc
This comment was introduced in https://reviews.llvm.org/D117631

Differential Revision: https://reviews.llvm.org/D117705
2022-01-19 10:38:13 -08:00
Ellis Hoag 88d81770f1 [InstrProf] Restore InstrProfData.inc to fix Fuchsia builds
https://reviews.llvm.org/D116179 introduced some changes to
`InstrProfData.inc` which broke some downstream builds. This commit
reverts those changes since they only changes two field names.

Reviewed By: phosek

Differential Revision: https://reviews.llvm.org/D117631
2022-01-19 10:10:58 -08:00
Ellis Hoag f21473752b [InstrProf][NFC] Do not assume size of counter type
Existing code tended to assume that counters had type `uint64_t` and
computed size from the number of counters. Fix this code to directly
compute the counters size in number of bytes where possible. When the
number of counters is needed, use `__llvm_profile_counter_entry_size()`
or `getCounterTypeSize()`. In a later diff these functions will depend
on the profile mode.

Change the meaning of `DataSize` and `CountersSize` to make them more clear.
* `DataSize` (`CountersSize`) - the size of the data (counter) section in bytes.
* `NumData` (`NumCounters`) - the number of data (counter) entries.

Reviewed By: kyulee

Differential Revision: https://reviews.llvm.org/D116179
2022-01-14 11:29:11 -08:00
Ellis Hoag 58d9c1aec8 [Try2][InstrProf] Attach debug info to counters
Add the llvm flag `-debug-info-correlate` to attach debug info to instrumentation counters so we can correlate raw profile data to their functions. Raw profiles are dumped as `.proflite` files. The next diff enables `llvm-profdata` to consume `.proflite` and debug info files to produce a normal `.profdata` profile.

Part of the "lightweight instrumentation" work: https://groups.google.com/g/llvm-dev/c/r03Z6JoN7d4

The original diff https://reviews.llvm.org/D114565 was reverted because of the `Instrumentation/InstrProfiling/debug-info-correlate.ll` test, which is fixed in this commit.

Reviewed By: kyulee

Differential Revision: https://reviews.llvm.org/D115693
2021-12-16 14:20:30 -08:00
Ellis Hoag c809da7d9c Revert "[InstrProf] Attach debug info to counters"
This reverts commit 800bf8ed29.

The `Instrumentation/InstrProfiling/debug-info-correlate.ll` test was
failing because I forgot the `llc` commands are architecture specific.
I'll follow up with a fix.

Differential Revision: https://reviews.llvm.org/D115689
2021-12-13 18:15:17 -08:00
Ellis Hoag 800bf8ed29 [InstrProf] Attach debug info to counters
Add the llvm flag `-debug-info-correlate` to attach debug info to instrumentation counters so we can correlate raw profile data to their functions. Raw profiles are dumped as `.proflite` files. The next diff enables `llvm-profdata` to consume `.proflite` and debug info files to produce a normal `.profdata` profile.

Part of the "lightweight instrumentation" work: https://groups.google.com/g/llvm-dev/c/r03Z6JoN7d4

Reviewed By: kyulee

Differential Revision: https://reviews.llvm.org/D114565
2021-12-13 17:51:22 -08:00
Snehasish Kumar 7cca33b40f [memprof] Extend llvm-profdata to display MemProf profile summaries.
This commit adds initial support to llvm-profdata to read and print
summaries of raw memprof profiles.
Summary of changes:
* Refactor shared defs to MemProfData.inc
* Extend show_main to display memprof profile summaries.
* Add a simple raw memprof profile reader.
* Add a couple of tests to tools/llvm-profdata.

Differential Revision: https://reviews.llvm.org/D114286
2021-11-30 10:45:26 -08:00
Petr Hosek 24c615fa6b [InstrProfData] Bump the raw profile version to 8
This is to account for the change that made CountersPtr in __profd_
relative which landed in a1532ed275.
That change hasn't updated the raw profile version, and while the
profile layout stayed the same, profiles generated by tip-of-tree
LLVM are incompatible with 13.x tooling.

Differential Revision: https://reviews.llvm.org/D111123
2021-10-05 09:57:56 -07:00
Petr Hosek 83302c8489 [profile] Fix profile merging with binary IDs
This fixes support for merging profiles which broke as a consequence
of e50a38840d. The issue was missing
adjustment in merge logic to account for the binary IDs which are
now included in the raw profile just after header.

In addition, this change also:
* Includes the version in module signature that's used for merging
to avoid accidental attempts to merge incompatible profiles.
* Moves the binary IDs size field after version field in the header
as was suggested in the review.

Differential Revision: https://reviews.llvm.org/D107143
2021-07-30 18:54:27 -07:00
Petr Hosek d3dd07e3d0 Revert "[profile] Fix profile merging with binary IDs"
This reverts commit dcadd64986.
2021-07-30 18:53:48 -07:00
Petr Hosek dcadd64986 [profile] Fix profile merging with binary IDs
This fixes support for merging profiles which broke as a consequence
of e50a38840d. The issue was missing
adjustment in merge logic to account for the binary IDs which are
now included in the raw profile just after header.

In addition, this change also:
* Includes the version in module signature that's used for merging
to avoid accidental attempts to merge incompatible profiles.
* Moves the binary IDs size field after version field in the header
as was suggested in the review.

Differential Revision: https://reviews.llvm.org/D107143
2021-07-30 17:38:53 -07:00
Petr Hosek 6ea2f31f3d Revert "[profile] Fix profile merging with binary IDs"
This reverts commit 89d6eb6f8c, this
seemed to have break a few builders.
2021-07-30 14:32:52 -07:00
Petr Hosek 89d6eb6f8c [profile] Fix profile merging with binary IDs
This fixes support for merging profiles which broke as a consequence
of e50a38840d. The issue was missing
adjustment in merge logic to account for the binary IDs which are
now included in the raw profile just after header.

In addition, this change also:
* Includes the version in module signature that's used for merging
to avoid accidental attempts to merge incompatible profiles.
* Moves the binary IDs size field after version field in the header
as was suggested in the review.

Differential Revision: https://reviews.llvm.org/D107143
2021-07-30 13:30:30 -07:00
Fangrui Song a1532ed275 [InstrProfiling] Make CountersPtr in __profd_ relative
Change `CountersPtr` in `__profd_` to a label difference, which is a link-time
constant. On ELF, when linking a shared object, this requires that `__profc_` is
either private or linkonce/linkonce_odr hidden. On COFF, we need D104564 so that
`.quad a-b` (64-bit label difference) can lower to a 32-bit PC-relative relocation.

```
# ELF: R_X86_64_PC64 (PC-relative)
.quad .L__profc_foo-.L__profd_foo

# Mach-O: a pair of 8-byte X86_64_RELOC_UNSIGNED and X86_64_RELOC_SUBTRACTOR
.quad l___profc_foo-l___profd_foo

# COFF: we actually use IMAGE_REL_AMD64_REL32/IMAGE_REL_ARM64_REL32 so
# the high 32-bit value is zero even if .L__profc_foo < .L__profd_foo
# As compensation, we truncate CountersDelta in the header so that
# __llvm_profile_merge_from_buffer and llvm-profdata reader keep working.
.quad .L__profc_foo-.L__profd_foo
```

(Note: link.exe sorts `.lprfc` before `.lprfd` even if the object writer
has `.lprfd` before `.lprfc`, so we cannot work around by reordering
`.lprfc` and `.lprfd`.)

With this change, a stage 2 (`-DLLVM_TARGETS_TO_BUILD=X86 -DLLVM_BUILD_INSTRUMENTED=IR`)
`ld -pie` linked clang is 1.74% smaller due to fewer R_X86_64_RELATIVE relocations.
```
% readelf -r pie | awk '$3~/R.*/{s[$3]++} END {for (k in s) print k, s[k]}'
R_X86_64_JUMP_SLO 331
R_X86_64_TPOFF64 2
R_X86_64_RELATIVE 476059  # was: 607712
R_X86_64_64 2616
R_X86_64_GLOB_DAT 31
```

The absolute function address (used by llvm-profdata to collect indirect call
targets) can be converted to relative as well, but is not done in this patch.

Differential Revision: https://reviews.llvm.org/D104556
2021-07-30 11:52:18 -07:00
Gulfem Savrun Yeniceri e50a38840d [profile] Add binary id into profiles
This patch adds binary id into profiles to easily associate binaries
with the corresponding profiles. There is an RFC that discusses
the motivation, design and implementation in more detail:
https://lists.llvm.org/pipermail/llvm-dev/2021-June/151154.html

Differential Revision: https://reviews.llvm.org/D102039
2021-07-23 00:19:12 +00:00
Gulfem Savrun Yeniceri fd895bc81b Revert "[profile] Add binary id into profiles"
Revert "[profile] Change linkage type of a compiler-rt func"
This reverts commits f984ac2715 and
467c719124 because it broke some builds.
2021-07-21 19:15:18 +00:00
Gulfem Savrun Yeniceri f984ac2715 [profile] Add binary id into profiles
This patch adds binary id into profiles to easily associate binaries
with the corresponding profiles. There is an RFC that discusses
the motivation, design and implementation in more detail:
https://lists.llvm.org/pipermail/llvm-dev/2021-June/151154.html

Differential Revision: https://reviews.llvm.org/D102039
2021-07-21 17:55:43 +00:00
Petr Hosek 54902e00d1 [InstrProfiling] Use weak alias for bias variable
We need the compiler generated variable to override the weak symbol of
the same name inside the profile runtime, but using LinkOnceODRLinkage
results in weak symbol being emitted in which case the symbol selected
by the linker is going to depend on the order of inputs which can be
fragile.

This change replaces the use of weak definition inside the runtime with
a weak alias. We place the compiler generated symbol inside a COMDAT
group so dead definition can be garbage collected by the linker.

We also disable the use of runtime counter relocation on Darwin since
Mach-O doesn't support weak external references, but Darwin already uses
a different continous mode that relies on overmapping so runtime counter
relocation isn't needed there.

Differential Revision: https://reviews.llvm.org/D105176
2021-07-19 12:23:51 -07:00
Hiroshi Yamauchi 365b225d46 [PGO] Fix two issues in PGOMemOPSizeOpt.
1. PGOMemOPSizeOpt grabs only the first, up to five (by default) entries from
the value profile metadata and preserves the remaining entries for the fallback
memop call site. If there are more than five entries, the rest of the entries
would get dropped. This is fine for PGOMemOPSizeOpt itself as it only promotes
up to 3 (by default) values, but potentially not for other downstream passes
that may use the value profile metadata.

2. PGOMemOPSizeOpt originally assumed that only values 0 through 8 are kept
track of. When the range buckets were introduced, it was changed to skip the
range buckets, but since it does not grab all entries (only five), if some range
buckets exist in the first five entries, it could potentially cause fewer
promotion opportunities (eg. if 4 out of 5 were range buckets, it may be able to
promote up to one non-range bucket, as opposed to 3.) Also, combined with 1, it
means that wrong entries may be preserved, as it didn't correctly keep track of
which were entries were skipped.

To fix this, PGOMemOPSizeOpt now grabs all the entries (up to the maximum number
of value profile buckets), keeps track of which entries were skipped, and
preserves all the remaining entries.

Differential Revision: https://reviews.llvm.org/D97592
2021-03-11 09:53:05 -08:00
Fangrui Song 27ddcd51d3 [profile] Fix InstrProfGetRangeRepValue to use UINT64_C
This is a minor issue because the TargetValue parameter of `__llvm_profile_instrument_memop`
is usually small and cannot exceed 2**31 at all.

Differential Revision: https://reviews.llvm.org/D97640
2021-03-09 12:46:13 -08:00
Petr Hosek 5fbd1a333a [Coverage] Store compilation dir separately in coverage mapping
We currently always store absolute filenames in coverage mapping.  This
is problematic for several reasons. It poses a problem for distributed
compilation as source location might vary across machines.  We are also
duplicating the path prefix potentially wasting space.

This change modifies how we store filenames in coverage mapping. Rather
than absolute paths, it stores the compilation directory and file paths
as given to the compiler, either relative or absolute. Later when
reading the coverage mapping information, we recombine relative paths
with the working directory. This approach is similar to handling
ofDW_AT_comp_dir in DWARF.

Finally, we also provide a new option, -fprofile-compilation-dir akin
to -fdebug-compilation-dir which can be used to manually override the
compilation directory which is useful in distributed compilation cases.

Differential Revision: https://reviews.llvm.org/D95753
2021-02-18 14:34:39 -08:00
Petr Hosek fbf8b957fd Revert "[Coverage] Store compilation dir separately in coverage mapping"
This reverts commit 97ec8fa5bb since
the test is failing on some bots.
2021-02-18 12:50:24 -08:00
Petr Hosek 97ec8fa5bb [Coverage] Store compilation dir separately in coverage mapping
We currently always store absolute filenames in coverage mapping.  This
is problematic for several reasons. It poses a problem for distributed
compilation as source location might vary across machines.  We are also
duplicating the path prefix potentially wasting space.

This change modifies how we store filenames in coverage mapping. Rather
than absolute paths, it stores the compilation directory and file paths
as given to the compiler, either relative or absolute. Later when
reading the coverage mapping information, we recombine relative paths
with the working directory. This approach is similar to handling
ofDW_AT_comp_dir in DWARF.

Finally, we also provide a new option, -fprofile-compilation-dir akin
to -fdebug-compilation-dir which can be used to manually override the
compilation directory which is useful in distributed compilation cases.

Differential Revision: https://reviews.llvm.org/D95753
2021-02-18 12:27:42 -08:00
Vitaly Buka fc05b2d9e5 [NFC][ProfileData] Improve language 2021-02-12 02:55:58 -08:00
Alan Phipps 9f2967bcfe [Coverage] Add support for Branch Coverage in LLVM Source-Based Code Coverage
This is an enhancement to LLVM Source-Based Code Coverage in clang to track how
many times individual branch-generating conditions are taken (evaluate to TRUE)
and not taken (evaluate to FALSE).  Individual conditions may comprise larger
boolean expressions using boolean logical operators.  This functionality is
very similar to what is supported by GCOV except that it is very closely
anchored to the ASTs.

Differential Revision: https://reviews.llvm.org/D84467
2021-01-05 09:51:51 -06:00
Hiroshi Yamauchi 1ebee7adf8 [PGO] Remove the old memop value profiling buckets.
Following up D81682 and D83903, remove the code for the old value profiling
buckets, which have been replaced with the new, extended buckets and disabled by
default.

Also syncing InstrProfData.inc between compiler-rt and llvm.

Differential Revision: https://reviews.llvm.org/D88838
2020-10-15 10:09:49 -07:00
Hiroshi Yamauchi f78f509c75 [PGO] Extend the value profile buckets for mem op sizes.
Extend the memop value profile buckets to be more flexible (could accommodate a
mix of individual values and ranges) and to cover more value ranges (from 11 to
22 buckets).

Disabled behind a flag (to be enabled separately) and the existing code to be
removed later.

Differential Revision: https://reviews.llvm.org/D81682
2020-08-03 11:04:32 -07:00
Fangrui Song 27650ec554 Revert D81682 "[PGO] Extend the value profile buckets for mem op sizes."
This reverts commit 4a539faf74.

There is a __llvm_profile_instrument_range related crash in PGO-instrumented clang:

```
(gdb) bt
llvm::ConstantRange const&, llvm::APInt const&, unsigned int, bool) ()
llvm::ScalarEvolution::getRangeForAffineAR(llvm::SCEV const*, llvm::SCEV
const*, llvm::SCEV const*, unsigned int) ()
```

(The body of __llvm_profile_instrument_range is inlined, so we can only find__llvm_profile_instrument_target in the trace)

```
 23│    0x000055555dba0961 <+65>:    nopw   %cs:0x0(%rax,%rax,1)
 24│    0x000055555dba096b <+75>:    nopl   0x0(%rax,%rax,1)
 25│    0x000055555dba0970 <+80>:    mov    %rsi,%rbx
 26│    0x000055555dba0973 <+83>:    mov    0x8(%rsi),%rsi  # %rsi=-1 -> SIGSEGV
 27│    0x000055555dba0977 <+87>:    cmp    %r15,(%rbx)
 28│    0x000055555dba097a <+90>:    je     0x55555dba0a76 <__llvm_profile_instrument_target+342>
```
2020-07-22 16:08:25 -07:00
Hiroshi Yamauchi 4a539faf74 [PGO] Extend the value profile buckets for mem op sizes.
Extend the memop value profile buckets to be more flexible (could accommodate a
mix of individual values and ranges) and to cover more value ranges (from 11 to
22 buckets).

Disabled behind a flag (to be enabled separately) and the existing code to be
removed later.
2020-07-15 10:26:15 -07:00
Hiroshi Yamauchi 9878996c70 Revert "[PGO] Extend the value profile buckets for mem op sizes."
This reverts commit 63a89693f0.

Due to a build failure like http://lab.llvm.org:8011/builders/sanitizer-windows/builds/65386/steps/annotate/logs/stdio
2020-06-25 11:13:49 -07:00
Hiroshi Yamauchi 63a89693f0 [PGO] Extend the value profile buckets for mem op sizes.
Extend the memop value profile buckets to be more flexible (could accommodate a
mix of individual values and ranges) and to cover more value ranges (from 11 to
22 buckets).

Disabled behind a flag (to be enabled separately) and the existing code to be
removed later.

Differential Revision: https://reviews.llvm.org/D81682
2020-06-25 10:22:56 -07:00
Hiroshi Yamauchi 14bb6770f2 [profile] Sync InstrProfData.inc with llvm.
Reviewers: davidxl

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers

Differential Revision: https://reviews.llvm.org/D81038
2020-06-03 10:00:11 -07:00
Vedant Kumar dd1ea9de2e Reland: [Coverage] Revise format to reduce binary size
Try again with an up-to-date version of D69471 (99317124 was a stale
revision).

---

Revise the coverage mapping format to reduce binary size by:

1. Naming function records and marking them `linkonce_odr`, and
2. Compressing filenames.

This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB)
and speeds up end-to-end single-threaded report generation by 10%. For
reference the compressed name data in llc is 81MB (__llvm_prf_names).

Rationale for changes to the format:

- With the current format, most coverage function records are discarded.
  E.g., more than 97% of the records in llc are *duplicate* placeholders
  for functions visible-but-not-used in TUs. Placeholders *are* used to
  show under-covered functions, but duplicate placeholders waste space.

- We reached general consensus about giving (1) a try at the 2017 code
  coverage BoF [1]. The thinking was that using `linkonce_odr` to merge
  duplicates is simpler than alternatives like teaching build systems
  about a coverage-aware database/module/etc on the side.

- Revising the format is expensive due to the backwards compatibility
  requirement, so we might as well compress filenames while we're at it.
  This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB).

See CoverageMappingFormat.rst for the details on what exactly has
changed.

Fixes PR34533 [2], hopefully.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html
[2] https://bugs.llvm.org/show_bug.cgi?id=34533

Differential Revision: https://reviews.llvm.org/D69471
2020-02-28 18:12:04 -08:00
Vedant Kumar 3388871714 Revert "[Coverage] Revise format to reduce binary size"
This reverts commit 99317124e1. This is
still busted on Windows:

http://lab.llvm.org:8011/builders/lld-x86_64-win7/builds/40873

The llvm-cov tests report 'error: Could not load coverage information'.
2020-02-28 18:03:15 -08:00
Vedant Kumar 99317124e1 [Coverage] Revise format to reduce binary size
Revise the coverage mapping format to reduce binary size by:

1. Naming function records and marking them `linkonce_odr`, and
2. Compressing filenames.

This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB)
and speeds up end-to-end single-threaded report generation by 10%. For
reference the compressed name data in llc is 81MB (__llvm_prf_names).

Rationale for changes to the format:

- With the current format, most coverage function records are discarded.
  E.g., more than 97% of the records in llc are *duplicate* placeholders
  for functions visible-but-not-used in TUs. Placeholders *are* used to
  show under-covered functions, but duplicate placeholders waste space.

- We reached general consensus about giving (1) a try at the 2017 code
  coverage BoF [1]. The thinking was that using `linkonce_odr` to merge
  duplicates is simpler than alternatives like teaching build systems
  about a coverage-aware database/module/etc on the side.

- Revising the format is expensive due to the backwards compatibility
  requirement, so we might as well compress filenames while we're at it.
  This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB).

See CoverageMappingFormat.rst for the details on what exactly has
changed.

Fixes PR34533 [2], hopefully.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html
[2] https://bugs.llvm.org/show_bug.cgi?id=34533

Differential Revision: https://reviews.llvm.org/D69471
2020-02-28 17:33:25 -08:00
Vedant Kumar f208b70fbc Revert "[Coverage] Revise format to reduce binary size"
This reverts commit e18531595b.

On Windows, there is an error:

http://lab.llvm.org:8011/builders/sanitizer-windows/builds/54963/steps/stage%201%20check/logs/stdio

error: C:\b\slave\sanitizer-windows\build\stage1\projects\compiler-rt\test\profile\Profile-x86_64\Output\instrprof-merging.cpp.tmp.v1.o: Failed to load coverage: Malformed coverage data
2019-12-04 10:35:14 -08:00
Vedant Kumar e18531595b [Coverage] Revise format to reduce binary size
Revise the coverage mapping format to reduce binary size by:

1. Naming function records and marking them `linkonce_odr`, and
2. Compressing filenames.

This shrinks the size of llc's coverage segment by 82% (334MB -> 62MB)
and speeds up end-to-end single-threaded report generation by 10%. For
reference the compressed name data in llc is 81MB (__llvm_prf_names).

Rationale for changes to the format:

- With the current format, most coverage function records are discarded.
  E.g., more than 97% of the records in llc are *duplicate* placeholders
  for functions visible-but-not-used in TUs. Placeholders *are* used to
  show under-covered functions, but duplicate placeholders waste space.

- We reached general consensus about giving (1) a try at the 2017 code
  coverage BoF [1]. The thinking was that using `linkonce_odr` to merge
  duplicates is simpler than alternatives like teaching build systems
  about a coverage-aware database/module/etc on the side.

- Revising the format is expensive due to the backwards compatibility
  requirement, so we might as well compress filenames while we're at it.
  This shrinks the encoded filenames in llc by 86% (12MB -> 1.6MB).

See CoverageMappingFormat.rst for the details on what exactly has
changed.

Fixes PR34533 [2], hopefully.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118428.html
[2] https://bugs.llvm.org/show_bug.cgi?id=34533

Differential Revision: https://reviews.llvm.org/D69471
2019-12-04 10:10:55 -08:00
Petr Hosek f35032e03d Reland "[CMake] Support installation of InstrProfData.inc"
This header fragment is useful on its own for any consumer that wants
to use custom instruction profile runtime with the LLVM instrumentation.
The concrete use case is in Fuchsia's kernel where we want to use
instruction profile instrumentation, but we cannot use the compiler-rt
runtime because it's not designed for use in the kernel environment.
This change allows installing this header as part of compiler-rt.

Differential Revision: https://reviews.llvm.org/D64532
2019-11-22 14:09:46 -08:00
Petr Hosek 262b10ba1f Revert "[CMake] Support installation of InstrProfData.inc"
This reverts commit f11bc1776f since it's
failing to build on some bots.
2019-11-22 12:00:23 -08:00
Petr Hosek f11bc1776f [CMake] Support installation of InstrProfData.inc
This header fragment is useful on its own for any consumer that wants
to use custom instruction profile runtime with the LLVM instrumentation.
The concrete use case is in Fuchsia's kernel where we want to use
instruction profile instrumentation, but we cannot use the compiler-rt
runtime because it's not designed for use in the kernel environment.
This change allows installing this header as part of compiler-rt.

Differential Revision: https://reviews.llvm.org/D64532
2019-11-22 11:52:50 -08:00