The common profile usage is to collect profile from a target and then use the profile to guide the optimized build for the same target. There are some cases that no profile can be collected for a target. In those cases, although no full profile is available, it is possible to have some partial profile collected from other targets to optimize common libraries and utilities. A flag is needed to tell the partial profile from the full profile apart, so compiler can use different strategy for them.
Differential Revision: https://reviews.llvm.org/D77426
Compbinary format uses MD5 to represent strings in name table. That gives smaller profile without the need of compression/decompression when writing/reading the profile. The patch adds the support in extbinary format. It is off by default but user can choose to enable it.
Note the feature of using MD5 in name table can bring very small chance of name conflict leading to profile mismatch. Besides, profile using the feature won't have the profile remapping support.
Differential Revision: https://reviews.llvm.org/D76255
After the format change from D69471, there can be more than one section
in an object that contains coverage function records. Look up each of
these sections and concatenate all the records together.
This re-enables the instrprof-merging.cpp test, which previously was
failing on OSes which use comdats.
Thanks to Jeremy Morse, who very kindly provided object files from the
bot I broke to help me debug.
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
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
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.
This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.
This doesn't actually modify StringRef yet, I'll do that in a follow-up.
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
Summary:
Most libraries are defined in the lib/ directory but there are also a
few libraries defined in tools/ e.g. libLLVM, libLTO. I'm defining
"Component Libraries" as libraries defined in lib/ that may be included in
libLLVM.so. Explicitly marking the libraries in lib/ as component
libraries allows us to remove some fragile checks that attempt to
differentiate between lib/ libraries and tools/ libraires:
1. In tools/llvm-shlib, because
llvm_map_components_to_libnames(LIB_NAMES "all") returned a list of
all libraries defined in the whole project, there was custom code
needed to filter out libraries defined in tools/, none of which should
be included in libLLVM.so. This code assumed that any library
defined as static was from lib/ and everything else should be
excluded.
With this change, llvm_map_components_to_libnames(LIB_NAMES, "all")
only returns libraries that have been added to the LLVM_COMPONENT_LIBS
global cmake property, so this custom filtering logic can be removed.
Doing this also fixes the build with BUILD_SHARED_LIBS=ON
and LLVM_BUILD_LLVM_DYLIB=ON.
2. There was some code in llvm_add_library that assumed that
libraries defined in lib/ would not have LLVM_LINK_COMPONENTS or
ARG_LINK_COMPONENTS set. This is only true because libraries
defined lib lib/ use LLVMBuild.txt and don't set these values.
This code has been fixed now to check if the library has been
explicitly marked as a component library, which should now make it
easier to remove LLVMBuild at some point in the future.
I have tested this patch on Windows, MacOS and Linux with release builds
and the following combinations of CMake options:
- "" (No options)
- -DLLVM_BUILD_LLVM_DYLIB=ON
- -DLLVM_LINK_LLVM_DYLIB=ON
- -DBUILD_SHARED_LIBS=ON
- -DBUILD_SHARED_LIBS=ON -DLLVM_BUILD_LLVM_DYLIB=ON
- -DBUILD_SHARED_LIBS=ON -DLLVM_LINK_LLVM_DYLIB=ON
Reviewers: beanz, smeenai, compnerd, phosek
Reviewed By: beanz
Subscribers: wuzish, jholewinski, arsenm, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, mgorny, mehdi_amini, sbc100, jgravelle-google, hiraditya, aheejin, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, steven_wu, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, PkmX, jocewei, jsji, dang, Jim, lenary, s.egerton, pzheng, sameer.abuasal, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70179
Add support for continuously syncing profile counter updates to a file.
The motivation for this is that programs do not always exit cleanly. On
iOS, for example, programs are usually killed via a signal from the OS.
Running atexit() handlers after catching a signal is unreliable, so some
method for progressively writing out profile data is necessary.
The approach taken here is to mmap() the `__llvm_prf_cnts` section onto
a raw profile. To do this, the linker must page-align the counter and
data sections, and the runtime must ensure that counters are mapped to a
page-aligned offset within a raw profile.
Continuous mode is (for the moment) incompatible with the online merging
mode. This limitation is lifted in https://reviews.llvm.org/D69586.
Continuous mode is also (for the moment) incompatible with value
profiling, as I'm not sure whether there is interest in this and the
implementation may be tricky.
As I have not been able to test extensively on non-Darwin platforms,
only Darwin support is included for the moment. However, continuous mode
may "just work" without modification on Linux and some UNIX-likes. AIUI
the default value for the GNU linker's `--section-alignment` flag is set
to the page size on many systems. This appears to be true for LLD as
well, as its `no_nmagic` option is on by default. Continuous mode will
not "just work" on Fuchsia or Windows, as it's not possible to mmap() a
section on these platforms. There is a proposal to add a layer of
indirection to the profile instrumentation to support these platforms.
rdar://54210980
Differential Revision: https://reviews.llvm.org/D68351
by ExtBinary format profile
Profile on-demand loading was added for ExtBinary format profile in rL374233,
but currently profile on-demand loading doesn't work well with profile
remapping. The patch adds the support.
Suppose a function in the current module has outline instance in the profile.
The function name in the module is different from the name of the outline
instance, but remapper knows the two names are equal. When loading profile
on-demand, the outline instance has to be loaded with remapper's help.
At the same time SampleProfileReaderItaniumRemapper is changed from a proxy
of SampleProfileReader to a helper member in SampleProfileReader.
Differential Revision: https://reviews.llvm.org/D68901
llvm-svn: 375295
in ExtBinary format
Currently for Text, Binary and ExtBinary format profiles, when we compile a
module with samplefdo, even if there is no function showing up in the profile,
we have to load all the function profiles from the profile input. That is a
waste of compile time.
CompactBinary format profile has already had the support of loading function
profiles on demand. In this patch, we add the support to load profile on
demand for ExtBinary format. It will work no matter the sections in ExtBinary
format profile are compressed or not. Experiment shows it reduces the time to
compile a server benchmark by 30%.
When profile remapping and loading function profiles on demand are both used,
extra work needs to be done so that the loading on demand process will take
the name remapping into consideration. It will be addressed in a follow-up
patch.
Differential Revision: https://reviews.llvm.org/D68601
llvm-svn: 374233
Previously ExtBinary profile format only supports compression using zlib for
profile symbol list. In this patch, we extend the compression support to any
section. User can select some or all of the sections to compress. In an
experiment, for a 45M profile in ExtBinary format, compressing name table
reduced its size to 24M, and compressing all the sections reduced its size
to 11M.
Differential Revision: https://reviews.llvm.org/D68253
llvm-svn: 373914
The static analyzer is warning about a potential null dereference, as we're already earlying-out for a null Constant pointer I've just folded this into a dyn_cast_or_null<ConstantInt>.
No test case, this is by inspection only.
llvm-svn: 373322
or the size of the profile for profile in ExtBinary format.
Fix a test failure on Mac.
[SampleFDO] Expose an interface to return the size of a section or the
size of the profile for profile in ExtBinary format.
Sometimes we want to limit the size of the profile by stripping some functions
with low sample count or by stripping some function names with small text size
from profile symbol list. That requires the profile reader to have the
interfaces returning the size of a section or the size of total profile. The
patch add those interfaces.
At the same time, add some dump facility to show the size of each section.
Differential revision: https://reviews.llvm.org/D67726
llvm-svn: 372478
of the profile for profile in ExtBinary format.
Sometimes we want to limit the size of the profile by stripping some functions
with low sample count or by stripping some function names with small text size
from profile symbol list. That requires the profile reader to have the
interfaces returning the size of a section or the size of total profile. The
patch add those interfaces.
At the same time, add some dump facility to show the size of each section.
llvm-svn: 372439
Make the method MachOUniversalBinary::getObjectForArch return MachOUniversalBinary::ObjectForArch
and add helper methods MachOUniversalBinary::getMachOObjectForArch, MachOUniversalBinary::getArchiveForArch
for those who explicitly expect to get a MachOObjectFile or an Archive.
Differential revision: https://reviews.llvm.org/D67700
Test plan: make check-all
llvm-svn: 372278
Summary:
The PGO counter reading will add cold and inlinehint (hot) attributes
to functions that are very cold or hot. This was using hardcoded
thresholds, instead of the profile summary cutoffs which are used in
other hot/cold detection and are more dynamic and adaptable. Switch
to using the summary-based cold/hot detection.
The hardcoded limits were causing some code that had a medium level of
hotness (per the summary) to be incorrectly marked with a cold
attribute, blocking inlining.
Reviewers: davidxl
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67673
llvm-svn: 372189
Speed up queries for coverage info in a file by reducing the amount of
time spent determining whether a function record corresponds to a file.
This gives a 36% speedup when generating a coverage report for `llc`.
The reduction is entirely in user time.
rdar://54758110
Differential Revision: https://reviews.llvm.org/D67575
llvm-svn: 372025
The check needs to validate a counter offset before performing pointer
arithmetic with the (potentially corrupt) offset.
Found by UBSan's pointer overflow check.
rdar://54843625
Differential Revision: https://reviews.llvm.org/D66979
llvm-svn: 370826
1. zlib::compress accept &size_t but the param is an uint64_t.
2. Some systems don't have zlib installed. Don't use compression by default.
llvm-svn: 370564
cold versus function being newly added.
This is the second half of https://reviews.llvm.org/D66374.
Profile symbol list is the collection of function symbols showing up in
the binary which generates the current profile. It is used to discriminate
function being cold versus function being newly added. Profile symbol list
is only added for profile with ExtBinary format.
During profile use compilation, when profile-sample-accurate is enabled,
a function without profile will be regarded as cold only when it is
contained in that list.
Differential Revision: https://reviews.llvm.org/D66766
llvm-svn: 370563
Before this change, if multiple binary files were presented, all of them must have been instrumented or the load would fail with coverage_map_error::no_data_found.
Patch by Dean Sturtevant.
Differential Revision: https://reviews.llvm.org/D66763
llvm-svn: 370257
This is a followup of https://reviews.llvm.org/D66513. The code calling each
section reader should be put into a separate function (readOneSection), so
SampleProfileExtBinaryReader can override it. Otherwise, the base class
SampleProfileExtBinaryBaseReader will need to be aware of all different kinds
of section readers. That is not right.
Differential Revision: https://reviews.llvm.org/D66693
llvm-svn: 369919
This is a patch split from https://reviews.llvm.org/D66374. It tries to add
a new format of profile called ExtBinary. The format adds a section header
table to the profile and organize the profile in sections, so the future
extension like adding a new section or extending an existing section will be
easier while keeping backward compatiblity feasible.
Differential Revision: https://reviews.llvm.org/D66513
llvm-svn: 369798
Summary:
StringMap is used for storing call target to frequency map for AutoFDO. However the iterating order of StringMap is non-deterministic, which leads to non-determinism in AutoFDO profile output. Now new API getSortedCallTargets and SortCallTargets are added for deterministic ordering and output.
Roundtrip test for text profile and binary profile is added.
Reviewers: wmi, davidxl, danielcdh
Subscribers: hiraditya, mgrang, llvm-commits, twoh
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66191
llvm-svn: 369440
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
llvm-svn: 369013
Changes: no changes. A fix for the clang code will be landed right on top.
Original commit message:
SectionRef::getName() returns std::error_code now.
Returning Expected<> instead has multiple benefits.
For example, it forces user to check the error returned.
Also Expected<> may keep a valuable string error message,
what is more useful than having a error code.
(Object\invalid.test was updated to show the new messages printed.)
This patch makes a change for all users to switch to Expected<> version.
Note: in a few places the error returned was ignored before my changes.
In such places I left them ignored. My intention was to convert the interface
used, and not to improve and/or the existent users in this patch.
(Though I think this is good idea for a follow-ups to revisit such places
and either remove consumeError calls or comment each of them to clarify why
it is OK to have them).
Differential revision: https://reviews.llvm.org/D66089
llvm-svn: 368826
SectionRef::getName() returns std::error_code now.
Returning Expected<> instead has multiple benefits.
For example, it forces user to check the error returned.
Also Expected<> may keep a valuable string error message,
what is more useful than having a error code.
(Object\invalid.test was updated to show the new messages printed.)
This patch makes a change for all users to switch to Expected<> version.
Note: in a few places the error returned was ignored before my changes.
In such places I left them ignored. My intention was to convert the interface
used, and not to improve and/or the existent users in this patch.
(Though I think this is good idea for a follow-ups to revisit such places
and either remove consumeError calls or comment each of them to clarify why
it is OK to have them).
Differential revision: https://reviews.llvm.org/D66089
llvm-svn: 368812
Summary: Fix "llvm-profdata show" so it can work with compact binary format profile. The change is to mark all functions "used" so SampleProfileReaderCompactBinary::read will read in all profiles available for dumping. The function names will be MD5 hash for compact binary format.
Reviewers: wmi, davidxl, danielcdh
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65162
llvm-svn: 368731
Summary:
This commit fixed a race condition from multi-threaded thinLTO backends that causes non-deterministic memory corruption for a data structure used only by AutoFDO with compact binary profile.
GUIDToFuncNameMap, a static data member of type DenseMap in FunctionSamples is used as a per-module mapping from function name MD5 to name string when input AutoFDO profile is in compact binary format. However with ThinLTO, we can have parallel backends modifying and accessing the class static map concurrently. The fix is to make GUIDToFuncNameMap a member of SampleProfileLoader instead of a file static data.
Reviewers: wmi, davidxl, danielcdh
Subscribers: mehdi_amini, inglorion, hiraditya, dexonsmith, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65848
llvm-svn: 368596
It looks like an older version of gcc can't figure out that it needs to
move a unique_ptr while implicitly constructing an Expected object.
llvm-svn: 363342
Support loading code coverage data from regular archives, thin archives,
and from MachO universal binaries which contain archives.
Testing: check-llvm, check-profile (with {A,UB}San enabled)
rdar://51538999
Differential Revision: https://reviews.llvm.org/D63232
llvm-svn: 363325
r360876 didn't fix 2 call sites in clang.
Expected<ArrayRef<uint8_t>> may be better but use Expected<StringRef> for now.
Follow-up of D61781.
llvm-svn: 360892
It broke the Clang build, see llvm-commits thread.
> Expected<ArrayRef<uint8_t>> may be better but use Expected<StringRef> for now.
>
> Follow-up of D61781.
llvm-svn: 360878
Add overlap functionality to llvm-profdata tool to compute the similarity
between two profile files.
Differential Revision: https://reviews.llvm.org/D60977
llvm-svn: 359612
Summary: Currently ProfileSummaryBuilder doesn't count into callsite samples when computing total samples. Considering that ProfileSummaryInfo is used to checked the hotness of not only body samples but also callsite samples (from SampleProfileLoader), I think the callsite sample counts should be considered when computing total samples.
Reviewers: eraman, danielcdh, wmi
Subscribers: hiraditya, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59835
llvm-svn: 357627
Summary:
Add hooks for determining the policy used to decide whether/how
to chop off symbol 'suffixes' when locating a given function
in a sample profile.
Prior to this change, any function symbols of the form "X.Y" were
elided/truncated into just "X" when looking up things in a sample
profile data file.
With this change, the policy on suffixes can be changed by adding a
new attribute "sample-profile-suffix-elision-policy" to the function:
this attribute can have the value "all" (the default), "selected", or
"none". A value of "all" preserves the previous behavior (chop off
everything after the first "." character, then treat that as the
symbol name). A value of "selected" chops off only the rightmost
".llvm.XXXX" suffix (where "XXX" is any string not containing a "."
char). A value of "none" indicates that names should be left as is.
Subscribers: jdoerfert, wmi, mtrofin, danielcdh, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D58832
llvm-svn: 356146
Part 4 of CSPGO changes:
(1) add support in cmake for cspgo build.
(2) fix an issue in big endian.
(3) test cases.
Differential Revision: https://reviews.llvm.org/D54175
llvm-svn: 355541
Part 2 of CSPGO changes (mostly related to ProfileSummary).
Note that I use a default parameter in setProfileSummary() and getSummary().
This is to break the dependency in clang. I will make the parameter explicit
after changing clang in a separated patch.
Differential Revision: https://reviews.llvm.org/D54175
llvm-svn: 355131
Current PGO profile counts are not context sensitive. The branch probabilities
for the inlined functions are kept the same for all call-sites, and they might
be very different from the actual branch probabilities. These suboptimal
profiles can greatly affect some downstream optimizations, in particular for
the machine basic block placement optimization.
In this patch, we propose to have a post-inline PGO instrumentation/use pass,
which we called Context Sensitive PGO (CSPGO). For the users who want the best
possible performance, they can perform a second round of PGO instrument/use on
the top of the regular PGO. They will have two sets of profile counts. The
first pass profile will be manly for inline, indirect-call promotion, and
CGSCC simplification pass optimizations. The second pass profile is for
post-inline optimizations and code-gen optimizations.
A typical usage:
// Regular PGO instrumentation and generate pass1 profile.
> clang -O2 -fprofile-generate source.c -o gen
> ./gen
> llvm-profdata merge default.*profraw -o pass1.profdata
// CSPGO instrumentation.
> clang -O2 -fprofile-use=pass1.profdata -fcs-profile-generate -o gen2
> ./gen2
// Merge two sets of profiles
> llvm-profdata merge default.*profraw pass1.profdata -o profile.profdata
// Use the combined profile. Pass manager will invoke two PGO use passes.
> clang -O2 -fprofile-use=profile.profdata -o use
This change touches many components in the compiler. The reviewed patch
(D54175) will committed in phrases.
Differential Revision: https://reviews.llvm.org/D54175
llvm-svn: 354930
Summary:
The llvm-cov tool needs to be able to find coverage names in the
executable, so the .lprfn and .lcovmap sections cannot be merged into
.rdata.
Also, the linker merges .lprfn$M into .lprfn, so llvm-cov needs to
handle that when looking up sections. It has to support running on both
relocatable object files and linked PE files.
Lastly, when loading .lprfn from a PE file, llvm-cov needs to skip the
leading zero byte added by the profile runtime.
Reviewers: vsk
Subscribers: hiraditya, #sanitizers, llvm-commits
Tags: #sanitizers, #llvm
Differential Revision: https://reviews.llvm.org/D58661
llvm-svn: 354840
The patch adds support for --hash-filenames to llvm-cov. This option adds md5
hash of the source path to the name of the generated .gcov file. The option is
crucial for cases where you have multiple files with the same name but can't
use --preserve-paths as resulting filenames exceed the limit.
from gcov(1):
```
-x
--hash-filenames
By default, gcov uses the full pathname of the source files to to
create an output filename. This can lead to long filenames that
can overflow filesystem limits. This option creates names of the
form source-file##md5.gcov, where the source-file component is
the final filename part and the md5 component is calculated from
the full mangled name that would have been used otherwise.
```
Patch by Igor Ignatev!
Differential Revision: https://reviews.llvm.org/D58370
llvm-svn: 354379
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
In LTO or Thin-lto mode (though linker plugin), the module
names are of temp file names which are different for
different compilations. Using SourceFileName avoids the issue.
This should not change any functionality for current PGO as
all the current callers of getPGOFuncName() is before LTO.
Differential Revision: https://reviews.llvm.org/D56327
llvm-svn: 350671
In LTO or Thin-lto mode (though linker plugin), the module
names are of temp file names which are different for
different compilations. Using SourceFileName avoids the issue.
This should not change any functionality for current PGO as
all the current callers of getPGOFuncName() is before LTO.
llvm-svn: 350442
Summary:
The goal of this patch is to have the same behaviour than gcc-gcov.
Currently the hit counts for a line is the sum of the counts for each block on that line.
The idea is to detect the cycles in the graph of blocks in using the algorithm by Hawick & James.
The count for a cycle is the min of the counts for each edge in the cycle.
Once we've the count for each cycle, we can sum them and add the transition counts of those cycles.
Fix both https://bugs.llvm.org/show_bug.cgi?id=38065 and https://bugs.llvm.org/show_bug.cgi?id=38066
Reviewers: marco-c, davidxl
Reviewed By: marco-c
Subscribers: vsk, lebedev.ri, sylvestre.ledru, dblaikie, llvm-commits
Differential Revision: https://reviews.llvm.org/D49659
llvm-svn: 342657
The patch saves a function offset table which maps function name index to the
offset of its function profile to the start of the binary profile. By using
the function offset table, for those function profiles which will not be used
when compiling a module, the profile reader does't have to read them. For
profile size around 10~20M, it saves ~10% compile time.
Differential Revision: https://reviews.llvm.org/D51863
llvm-svn: 342283
The patch tries to make sample profile loader independent of profile format
change. It moves compact format related code into FunctionSamples and
SampleProfileReader classes, and sample profile loader only has to interact
with those two classes and will be unaware of profile format changes.
The cleanup also contain some fixes to further remove the difference between
compactbinary format and binary format. After the cleanup using different
formats originated from the same profile will generate the same binaries,
which we verified by compiling two large server benchmarks w/wo thinlto.
Differential Revision: https://reviews.llvm.org/D51643
llvm-svn: 341591
Frontends emit 'unused' coverage mapping records for functions which are
provably unused in a TU. These unused records contain a single counter
with CounterKind::Zero. However, a function may be unused in one TU and
used in another. When this happens, prefer the records with a full set
of counters instead of arbitrarily picking the first loaded record.
There is no impact on the single-TU case. In the multiple-TU case, this
resolves issues causing a function to appear unused when it's not.
Testing: check-{llvm,clang,compiler-rt}
rdar://42981322
llvm-svn: 339194
Summary:
r262157 added ELF-specific logic to put a comdat on the __profc_*
globals created for available_externally functions. We should be able to
generalize that logic to all object file formats that support comdats,
i.e. everything other than MachO. This fixes duplicate symbol errors,
since on COFF, linkonce_odr doesn't make the symbol weak.
Fixes PR38251.
Reviewers: davidxl, xur
Subscribers: hiraditya, dmajor, llvm-commits, aheejin
Differential Revision: https://reviews.llvm.org/D49882
llvm-svn: 338082
The standard library functions ::isprint/std::isprint have platform-
and locale-dependent behavior which makes LLVM's output less
predictable. In particular, regression tests my fail depending on the
implementation of these functions.
Implement llvm::isPrint in StringExtras.h with a standard behavior and
replace all uses of ::isprint/std::isprint by a call it llvm::isPrint.
The function is inlined and does not look up language settings so it
should perform better than the standard library's version.
Such a replacement has already been done for isdigit, isalpha, isxdigit
in r314883. gtest does the same in gtest-printers.cc using the following
justification:
// Returns true if c is a printable ASCII character. We test the
// value of c directly instead of calling isprint(), which is buggy on
// Windows Mobile.
inline bool IsPrintableAscii(wchar_t c) {
return 0x20 <= c && c <= 0x7E;
}
Similar issues have also been encountered by Julia:
https://github.com/JuliaLang/julia/issues/7416
I noticed the problem myself when on Windows isprint('\t') started to
evaluate to true (see https://stackoverflow.com/questions/51435249) and
thus caused several unit tests to fail. The result of isprint doesn't
seem to be well-defined even for ASCII characters. Therefore I suggest
to replace isprint by a platform-independent version.
Differential Revision: https://reviews.llvm.org/D49680
llvm-svn: 338034
Name table occupies a big chunk of size in current binary format sample profile.
In order to reduce its size, the patch changes the sample writer/reader to
save/restore MD5Hash of names in the name table. Sample annotation phase will
also use MD5Hash of name to query samples accordingly.
Experiment shows compact binary format can reduce the size of sample profile by
2/3 compared with binary format generally.
Differential Revision: https://reviews.llvm.org/D47955
llvm-svn: 334447
Provide some free functions to reduce verbosity of endian-writing
a single value, and replace the endianness template parameter with
a field.
Part of PR37466.
Differential Revision: https://reviews.llvm.org/D47032
llvm-svn: 332757
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.
In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.
Differential Revision: https://reviews.llvm.org/D43624
llvm-svn: 332240
Summary:
Don't skip functions with the same name but from different files.
That change makes it possible to generate code coverage reports from
different binaries compiled from different sources even if there are functions
with non-unique names. Without that change, code coverage for such functions is
missing except of the first function processed.
Reviewers: vsk, morehouse
Reviewed By: vsk
Subscribers: llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D46478
llvm-svn: 331801
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.
Patch produced by
for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done
Differential Revision: https://reviews.llvm.org/D46290
llvm-svn: 331272
See r331124 for how I made a list of files missing the include.
I then ran this Python script:
for f in open('filelist.txt'):
f = f.strip()
fl = open(f).readlines()
found = False
for i in xrange(len(fl)):
p = '#include "llvm/'
if not fl[i].startswith(p):
continue
if fl[i][len(p):] > 'Config':
fl.insert(i, '#include "llvm/Config/llvm-config.h"\n')
found = True
break
if not found:
print 'not found', f
else:
open(f, 'w').write(''.join(fl))
and then looked through everything with `svn diff | diffstat -l | xargs -n 1000 gvim -p`
and tried to fix include ordering and whatnot.
No intended behavior change.
llvm-svn: 331184
Summary:
r327219 added wrappers to std::sort which randomly shuffle the container before sorting.
This will help in uncovering non-determinism caused due to undefined sorting
order of objects having the same key.
To make use of that infrastructure we need to invoke llvm::sort instead of std::sort.
Note: This patch is one of a series of patches to replace *all* std::sort to llvm::sort.
Refer the comments section in D44363 for a list of all the required patches.
Reviewers: bogner, vsk, eraman, ruiu
Reviewed By: ruiu
Subscribers: ruiu, llvm-commits
Differential Revision: https://reviews.llvm.org/D45139
llvm-svn: 330057
Summary:
This was originally part of rL328132, and led to the discovery
of the issues addressed in rL328987. Re-landing.
Reviewers: xur, davidxl, bkramer
Reviewed By: bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45545
llvm-svn: 330029
Summary:
This reverts commit 364eb09576a7667bc6d3ff80c52a83014ccac976 and separates out
the portion that was fixing binary reader error propagation - turns out, there
are production cases where that causes a regression.
Will re-introduce the error propagation fix separately.
The fix to the text reader error propagation is still "in".
Reviewers: bkramer
Reviewed By: bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D44807
llvm-svn: 328244
Summary:
This fixes a unittest failure introduced by D44717
D44717 introduced lazy sorting of the internal data structures of the
symbol table. The AddrToMD5Map getter was potentially exposing
inconsistent (unsorted) state. We could sort in the accessor, however,
a client may store the pointer and thus bypass the internal state
management of the symbol table. The alternative in this CL blocks
direct access to the state, thus ensuring consistent
externally-observable state.
Reviewers: davidxl, xur, eraman
Reviewed By: xur
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D44757
llvm-svn: 328163
Summary:
External functions appearing as indirect call targets could not be
found in the SymTab, and the value:counter record was represented,
in the text format, using an empty string for the name. This would
then cause a silent parsing error when reading.
This CL:
- adds explicit support for such functions
- fixes the places where we would not propagate errors when reading
- addresses a performance issue due to eager resorting of the SymTab.
Reviewers: xur, eraman, davidxl
Reviewed By: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D44717
llvm-svn: 328132
SampleProfReader assumes function names in the profile are all mangled names.
However, there are cases that few demangled names are somehow contained in
the profile (usually because of debug info problems), which may trigger parsing
error in SampleProfReader and cause the whole profile to be unusable. The patch
extends SampleProfReader to handle profiles with demangled names, so that those
profiles can still be useful.
Differential revision: https://reviews.llvm.org/D44161
llvm-svn: 326905
Summary:
Exposing getOffset and findFunctionSamples as members of
SampleProfile. They are intimately tied to design choices of the
sample profile format - using offsets instead of line numbers, and
traversing inlined functions stack, respectively.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D43605
llvm-svn: 325747
Most of the -Wsign-compare warnings are due to the fact that
enums are signed by default in the MS ABI, while the
tautological comparison warnings trigger on x86 builds where
sizeof(size_t) is 4 bytes, so N > numeric_limits<unsigned>::max()
is always false.
Differential Revision: https://reviews.llvm.org/D41256
llvm-svn: 320750
This extends r319391. It teaches the segment builder to emit the right
completed segment when more than one region ends at the same location.
Fixes PR35495.
llvm-svn: 319990
These command line options are not intended for public use, and often
don't even make sense in the context of a particular tool anyway. About
90% of them are already hidden, but when people add new options they
forget to hide them, so if you were to make a brand new tool today, link
against one of LLVM's libraries, and run tool -help you would get a
bunch of junk that doesn't make sense for the tool you're writing.
This patch hides these options. The real solution is to not have
libraries defining command line options, but that's a much larger effort
and not something I'm prepared to take on.
Differential Revision: https://reviews.llvm.org/D40674
llvm-svn: 319505
This is a fix for the coverage segment builder.
If multiple regions must be popped off the active stack at once, and
more than one of them end at the same location, emit a segment using the
count from the most-recent completed region.
Fixes PR35437, rdar://35760630
Testing: invoked llvm-cov on a stage2 build of clang, additional unit
tests, check-profile
llvm-svn: 319391
We've worked around bugs in the frontend by ignoring the count from
wrapped segments when a line has at least one region entry segment.
Those frontend bugs are now fixed, so it's time to regenerate the
checked-in covmapping files and remove the workaround.
llvm-svn: 317761
This class was split between libIR and libSupport, which breaks under
modular code generation. Move it into the one library that uses it,
ProfileData, to resolve this issue.
llvm-svn: 317366
LineCoverageIterator makes it easy for clients of coverage data to
determine line execution counts for a file or function. The coverage
iteration logic is tricky enough that it really pays not to have
multiple copies of it. Hopefully having just one implementation in LLVM
will make the iteration logic easier to test, reuse, and update.
This commit is NFC but I've added a unit test to go along with it just
because it's easy to do now.
llvm-svn: 316141
Summary:
Add LLVM_FORCE_ENABLE_DUMP cmake option, and use it along with
LLVM_ENABLE_ASSERTIONS to set LLVM_ENABLE_DUMP.
Remove NDEBUG and only use LLVM_ENABLE_DUMP to enable dump methods.
Move definition of LLVM_ENABLE_DUMP from config.h to llvm-config.h so
it'll be picked up by public headers.
Differential Revision: https://reviews.llvm.org/D38406
llvm-svn: 315590
There is data racing to the static variable RecordIndex in index profile reader
when merging in multiple threads. Make it a member variable in
IndexedInstrProfReader to fix this.
Differential Revision: https://reviews.llvm.org/D38431
llvm-svn: 314990
Passing "-dump" to llvm-cov will now print more detailed information
about function hash and counter mismatches. This should make it easier
to debug *.profdata files which contain incorrect records, and to debug
other scenarios where coverage goes missing due to mismatch issues.
llvm-svn: 313853
After clang started emitting deferred regions (r312818), llvm-cov has
had a hard time picking reasonable line execuction counts. There have
been one or two generic improvements in this area (e.g r310012), but
line counts can still report coverage for whitespace instead of code
(llvm.org/PR34612).
To fix the problem:
* Introduce a new region kind so that frontends can explicitly label
gap areas.
This is done by changing the encoding of the columnEnd field of
MappingRegion. This doesn't substantially increase binary size, and
makes it easy to maintain backwards-compatibility.
* Don't set the line count to a count from a gap area, unless the count
comes from a wrapped segment.
* Don't highlight gap areas as uncovered.
Fixes llvm.org/PR34612.
llvm-svn: 313597
A coverage segment contains a starting line and column, an execution
count, and some other metadata. Clients of the coverage library use
segments to prepare line-oriented reports.
Users of the coverage library depend on segments being unique and sorted
in source order. Currently this is not guaranteed (this is why the clang
change which introduced deferred regions was reverted).
This commit documents the "unique and sorted" condition and asserts that
it holds. It also fixes the SegmentBuilder so that it produces correct
output in some edge cases.
Testing: I've added unit tests for some edge cases. I've also checked
that the new SegmentBuilder implementation is fully covered. Apart from
running check-profile and the llvm-cov tests, I've successfully used a
stage1 llvm-cov to prepare a coverage report for an instrumented clang
binary.
Differential Revision: https://reviews.llvm.org/D36813
llvm-svn: 312817
Each source region has a start and end location. Report an error when
the end location does not precede the begin location.
The old lineExecutionCounts.covmapping test actually had a buggy source
region in it. This commit introduces a regenerated copy of the coverage
and moves the old copy to malformedRegions.covmapping, for a test.
Differential Revision: https://reviews.llvm.org/D37387
llvm-svn: 312814
Summary: As we support multiple callsites for the same location, we need to traverse all locations to get the number of callsites.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: sanjoy, llvm-commits
Differential Revision: https://reviews.llvm.org/D36246
llvm-svn: 309907
The CoverageMapping::getInstantiations() API retrieved all function
records corresponding to functions with more than one instantiation (e.g
template functions with multiple specializations). However, there was no
simple way to determine *which* function a given record was an
instantiation of. This was an oversight, since it's useful to aggregate
coverage information over all instantiations of a function.
llvm-cov works around this by building a mapping of source locations to
instantiation sets, but this duplicates logic that libCoverage already
has (see FunctionInstantiationSetCollector).
This change adds a new API, CoverageMapping::getInstantiationGroups(),
which returns a list of InstantiationGroups. A group contains records
for each instantiation of some particular function, and also provides
utilities to get the total execution count within the group, the source
location of the common definition, etc.
This lets removes some hacky logic in llvm-cov by reusing
FunctionInstantiationSetCollector and makes the CoverageMapping API
friendlier for other clients.
llvm-svn: 309904
The coverage tool needs to know which slice to look at when it's handed
a universal binary. Some projects need to look at aggregate coverage
reports for a variety of slices in different binaries: this patch adds
support for these kinds of projects to llvm-cov.
rdar://problem/33579007
llvm-svn: 309747
Reduces llvm-profdata memory usage on a large profile from 7.8GB to 5.1GB.
The ProfData API now supports reporting all the errors/warnings rather
than only the first, though llvm-profdata ignores everything after the
first for now to preserve existing behavior. (if there's a desire for
other behavior, happy to implement that - but might be as well left for
a separate patch)
Reviewers: davidxl
Differential Revision: https://reviews.llvm.org/D35149
llvm-svn: 307516
The InstrProfWriter already stores the name and hash of the record in
the nested maps it uses for lookup while merging - this data is
duplicated in the value within the maps.
Refactor the InstrProfRecord to use a nested struct for the counters
themselves so that InstrProfWriter can use this nested struct alone
without the name or hash duplicated there.
This work is incomplete, but enough to demonstrate the value (around a
50% decrease in memory usage for a large test case (10GB -> 5GB)).
Though most of that decrease is probably from removing the
SoftInstrProfError as well, but I haven't implemented a replacement for
it yet. (it needs to go with the counters, because the operations on the
counters - merging, etc, are where the failures are - unlike the
name/hash which are totally unused by those counter-related operations
and thus easy to split out)
Ongoing discussion about removing SoftInstrProfError as a field of the
InstrProfRecord is happening on the thread that added it - including
the possibility of moving back towards an earlier version of that
proposed patch that passed SoftInstrProfError through the various APIs,
rather than as a member of InstrProfRecord.
Reviewers: davidxl
Differential Revision: https://reviews.llvm.org/D34838
llvm-svn: 307298
These overloads are essentially dead, and pose a maintenance cost
without adding any benefit. This is coming up now because I'd like to
experiment with changing the way we store coverage mapping data, and
would rather not have to fix up the old overloads while doing so.
Testing: check-{llvm,profile}, build clang.
llvm-svn: 306776
Examining a large profile example, it seems relatively few records have
non-empty IndirectCall and MemOP data, so indirecting these through a
unique_ptr (non-null only when they are non-empty) Reduces memory usage
on this particular example from 14GB to 10GB according to valgrind's
massif.
I suspect it'd still be worth moving InstrProfWriter to its own data
structure that had Counts and the indirected IndirectCall+MemOP, and did
not include the Name, Hash, or Error fields. This would reduce the size
of this dominant data structure by half of this new, lower amount.
(Name(2), Hash(1), Error(1) ~= Counts(vector, 3), ValueProfData
(unique_ptr, 1))
-> From code review feedback, might actually refactor InstrProfRecord
itself to have a sub-struct with all the counts, and use that from
InstrProfWriter, rather than InstrProfWriter owning its own data
structure for this.
Reviewers: davidxl
Differential Revision: https://reviews.llvm.org/D34694
llvm-svn: 306631
With PR33517, it became apparent that symbol table creation can fail
when presented with malformed inputs. This patch makes that sort of
error detectable, so llvm-cov etc. can fail more gracefully.
Specifically, we now check that function records loaded from corrupted coverage
mapping data are rejected, e.g when the recorded function name is garbage.
Testing: check-{llvm,clang,profile}, some unit test updates.
llvm-svn: 305767
With PR33517, it became apparent that symbol table creation can fail
when presented with malformed inputs. This patch makes that sort of
error detectable, so llvm-cov etc. can fail more gracefully.
Specifically, we now check that function names within the symbol table
aren't empty.
Testing: check-{llvm,clang,profile}, some unit test updates.
llvm-svn: 305765
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.
I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.
This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.
Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).
llvm-svn: 304787
Summary: This patch changes the function profile output order to be deterministic. In order to make it easier to understand, hottest functions (with most total samples) is ordered first.
Reviewers: dnovillo, davidxl
Reviewed By: dnovillo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33111
llvm-svn: 302851
This is a version of D32090 that unifies all of the
`getInstrProf*SectionName` helper functions. (Note: the build failures
which D32090 would have addressed were fixed with r300352.)
We should unify these helper functions because they are hard to use in
their current form. E.g we recently introduced more helpers to fix
section naming for COFF files. This scheme doesn't totally succeed at
hiding low-level details about section naming, so we should switch to an
API that is easier to maintain.
This is not an NFC commit because it fixes llvm-cov's testing support
for COFF files (this falls out of the API change naturally). This is an
area where we lack tests -- I will see about adding one as a follow up.
Testing: check-clang, check-profile, check-llvm.
Differential Revision: https://reviews.llvm.org/D32097
llvm-svn: 300381
Summary: For iterative SamplePGO, an indirect call can be speculatively promoted to multiple direct calls and get inlined. All these promoted direct calls will share the same callsite location (offset+discriminator). With the current implementation, we cannot distinguish between different promotion candidates and its inlined instance. This patch adds callee_name to the key of the callsite sample map. And added helper functions to get all inlined callee samples for a given callsite location. This helps the profile annotator promote correct targets and inline it before annotation, and ensures all indirect call targets to be annotated correctly.
Reviewers: davidxl, dnovillo
Reviewed By: davidxl
Subscribers: andreadb, llvm-commits
Differential Revision: https://reviews.llvm.org/D31950
llvm-svn: 300240
This patch optimizes two memory intrinsic operations: memset and memcpy based
on the profiled size of the operation. The high level transformation is like:
mem_op(..., size)
==>
switch (size) {
case s1:
mem_op(..., s1);
goto merge_bb;
case s2:
mem_op(..., s2);
goto merge_bb;
...
default:
mem_op(..., size);
goto merge_bb;
}
merge_bb:
Differential Revision: http://reviews.llvm.org/D28966
llvm-svn: 299446
Summary:
In SamplePGO, if the profile is collected from non-LTO binary, and used to drive ThinLTO, the indirect call promotion may fail because ThinLTO adjusts local function names to avoid conflicts. There are two places of where the mismatch can happen:
1. thin-link prepends SourceFileName to front of FuncName to build the GUID (GlobalValue::getGlobalIdentifier). Unlike instrumentation FDO, SamplePGO does not use the PGOFuncName scheme and therefore the indirect call target profile data contains a hash of the OriginalName.
2. backend compiler promotes some local functions to global and appends .llvm.{$ModuleHash} to the end of the FuncName to derive PromotedFunctionName
This patch tries at the best effort to find the GUID from the original local function name (in profile), and use that in ICP promotion, and in SamplePGO matching that happens in the backend after importing/inlining:
1. in thin-link, it builds the map from OriginalName to GUID so that when thin-link reads in indirect call target profile (represented by OriginalName), it knows which GUID to import.
2. in backend compiler, if sample profile reader cannot find a profile match for PromotedFunctionName, it will try to find if there is a match for OriginalFunctionName.
3. in backend compiler, we build symbol table entry for OriginalFunctionName and pointer to the same symbol of PromotedFunctionName, so that ICP can find the correct target to promote.
Reviewers: mehdi_amini, tejohnson
Reviewed By: tejohnson
Subscribers: llvm-commits, Prazek
Differential Revision: https://reviews.llvm.org/D30754
llvm-svn: 297757
Summary:
Reset the ValueData for each function to avoid using the ones in
the previous function.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: llvm-commits, xur
Differential Revision: https://reviews.llvm.org/D30479
llvm-svn: 296916
Summary: Should use the Valuekind read from the profile.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: llvm-commits, xur
Differential Revision: https://reviews.llvm.org/D30420
llvm-svn: 296391
Current internal option -static-func-full-module-prefix keeps all the
directory path the profile counter names for static functions. The default
of this option is false. This strips the directory names from the source
filename which is problematic:
(1) it creates linker errors for profile-generation compilation, exposed in
our internal benchmarks. We are seeing messages like
"warning: relocation refers to discarded section".
This is due to the name conflicts after the stripping.
(2) the stripping only applies to getPGOFuncName.
Current Thin-LTO module importing for the indirect-calls assumes
the source directory name not being stripped. Current default value
for this option can potentially prevent some inter-module
indirect-call-promotions.
This patch turns the default value for -static-func-full-module-prefix to true.
The second part of the patch is to have an alternative implementation under
the internal option -static-func-strip-dirname-prefix=<value>
This options specifies level of directories to be stripped from the source
filename. Using a large value as the parameter has the same effect as
-static-func-full-module-prefix.
Differential Revision: http://reviews.llvm.org/D29512
llvm-svn: 296206
Wei Mi