This can be used to preserve profiling information across codebase
changes that have widespread impact on mangled names, but across which
most profiling data should still be usable. For example, when switching
from libstdc++ to libc++, or from the old libstdc++ ABI to the new ABI,
or even from a 32-bit to a 64-bit build.
The user can provide a remapping file specifying parts of mangled names
that should be treated as equivalent (eg, std::__1 should be treated as
equivalent to std::__cxx11), and profile data will be treated as
applying to a particular function if its name is equivalent to the name
of a function in the profile data under the provided equivalences. See
the documentation change for a description of how this is configured.
Remapping is supported for both sample-based profiling and instruction
profiling. We do not support remapping indirect branch target
information, but all other profile data should be remapped
appropriately.
Support is only added for the new pass manager. If someone wants to also
add support for this for the old pass manager, doing so should be
straightforward.
This is the LLVM side of Clang r344199.
Reviewers: davidxl, tejohnson, dlj, erik.pilkington
Subscribers: mehdi_amini, steven_wu, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51249
llvm-svn: 344200
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
getOrCompHotCountThreshold/getOrCompColdCountThreshold introduced in
https://reviews.llvm.org/D45377 contain a bad mistake and will only return 1 or 0
instead of the true hot/cold cutoff value. The patch fixes the mistake. But the
mistake seems not causing big performance difference according to internal server
benchmarks testing.
Differential Revision: https://reviews.llvm.org/D50370
llvm-svn: 339162
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
We found current sampleFDO had a performance issue when triaging a regression.
For a callsite with inline instance in the profile, even if hot callsite inliner
cannot inline it, it may still execute enough times and should not be treated as
cold in regular inliner later. However, currently if such callsite is not inlined
by hot callsite inliner, and the BB where the callsite locates doesn't get
samples from other instructions inside of it, the callsite will have no profile
metadata annotated. In regular inliner cost analysis, if the callsite has no
profile annotated and its caller has profile information, it will be treated as
cold.
The fix changes the isCallsiteHot check and chooses to compare
CallsiteTotalSamples with hot cutoff value computed by ProfileSummaryInfo.
Differential Revision: https://reviews.llvm.org/D45377
llvm-svn: 332058
Summary: In the compile phase of SamplePGO+ThinLTO, ICP is not invoked. Instead, indirect call targets will be included as function metadata for ThinIndex to buidl the call graph. This should not only include functions defined in other modules, but also functions defined in the same module, otherwise ThinIndex may find the callee dead and eliminate it, while ICP in backend will revive the symbol, which leads to undefined symbol.
Reviewers: tejohnson
Reviewed By: tejohnson
Subscribers: sanjoy, llvm-commits, mehdi_amini
Differential Revision: https://reviews.llvm.org/D39480
llvm-svn: 317118
Summary: stripPointerCast is not reliably returning the value that's being type-casted. Instead it may look further at function attributes to further propagate the value. Instead of relying on stripPOintercast, the more reliable solution is to directly use the pointer to the promoted direct call.
Reviewers: tejohnson, davidxl
Reviewed By: tejohnson
Subscribers: llvm-commits, sanjoy
Differential Revision: https://reviews.llvm.org/D38603
llvm-svn: 315077
Summary: In SamplePGO, when an indirect call is promoted in the profiled binary, before profile annotation, it will be promoted and inlined. For the original indirect call, the current implementation will not mark VP profile on it. This is an issue when profile becomes stale. This patch annotates VP prof on indirect calls during annotation.
Reviewers: tejohnson
Reviewed By: tejohnson
Subscribers: sanjoy, llvm-commits
Differential Revision: https://reviews.llvm.org/D38477
llvm-svn: 315016
Summary: In SamplePGO ThinLTO compile phase, we will not invoke ICP as it may introduce confusion to the 2nd annotation. This patch extracted that logic and makes it clearer before profile annotation. In the mean time, we need to make function importing process both inlined callsites as well as not promoted indirect callsites.
Reviewers: tejohnson
Reviewed By: tejohnson
Subscribers: sanjoy, mehdi_amini, llvm-commits, inglorion
Differential Revision: https://reviews.llvm.org/D38094
llvm-svn: 314619
Summary: In the ThinLTO compilation, if a function is inlined in the profiling binary, we need to inline it before annotation. If the callee is not available in the primary module, a first step is needed to import that callee function. For the current implementation, if the call is an indirect call, which has been promoted to >1 targets and inlined, SamplePGO will only import one target with the largest sample count. This patch fixed the bug to import all targets instead.
Reviewers: tejohnson, davidxl
Reviewed By: tejohnson
Subscribers: sanjoy, llvm-commits, mehdi_amini
Differential Revision: https://reviews.llvm.org/D36637
llvm-svn: 313678
Summary: Fix the bug when promoted call return type mismatches with the promoted function, we should not try to inline it. Otherwise it may lead to compiler crash.
Reviewers: davidxl, tejohnson, eraman
Reviewed By: tejohnson
Subscribers: llvm-commits, sanjoy
Differential Revision: https://reviews.llvm.org/D38018
llvm-svn: 313658
Summary: SampleProfileLoader inlines hot functions if it is inlined in the profiled binary. However, the inline needs to be guarded by legality check, otherwise it could lead to correctness issues.
Reviewers: eraman, davidxl
Reviewed By: eraman
Subscribers: vitalybuka, sanjoy, llvm-commits
Differential Revision: https://reviews.llvm.org/D37779
llvm-svn: 313277
Summary: SampleProfileLoader inlines hot functions if it is inlined in the profiled binary. However, the inline needs to be guarded by legality check, otherwise it could lead to correctness issues.
Reviewers: eraman, davidxl
Reviewed By: eraman
Subscribers: sanjoy, llvm-commits
Differential Revision: https://reviews.llvm.org/D37779
llvm-svn: 313195
Summary: r305009 disables recursive inlining for indirect calls in sample loader pass. The same logic applies to direct recursive calls.
Reviewers: iteratee, davidxl
Reviewed By: iteratee
Subscribers: sanjoy, llvm-commits, eraman
Differential Revision: https://reviews.llvm.org/D34456
llvm-svn: 305934
Summary: Early-inlining of recursive call makes the code size bloat exponentially. We should not disable it.
Reviewers: davidxl, dnovillo, iteratee
Reviewed By: iteratee
Subscribers: iteratee, llvm-commits, sanjoy
Differential Revision: https://reviews.llvm.org/D34017
llvm-svn: 305009
Summary: If there is suffix added in the function name (e.g. module hash added by thinLTO), we will not be able to find a match in profile as the suffix does not exist in profile. This patch build a map from function name to Function *. The map includes the entry for the stripped function name so that inlineHotFunctions can find the corresponding function to promote/inline.
Reviewers: davidxl, dnovillo, tejohnson
Reviewed By: davidxl
Subscribers: mehdi_amini, llvm-commits
Differential Revision: https://reviews.llvm.org/D31952
llvm-svn: 300507
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
Summary: For SamplePGO, the profile may contain cross-module inline stacks. As we need to make sure the profile annotation happens when all the hot inline stacks are expanded, we need to pass this info to the module importer so that it can import proper functions if necessary. This patch implemented this feature by emitting cross-module targets as part of function entry metadata. In the module-summary phase, the metadata is used to build call edges that points to functions need to be imported.
Reviewers: mehdi_amini, tejohnson
Reviewed By: tejohnson
Subscribers: davidxl, llvm-commits
Differential Revision: https://reviews.llvm.org/D30053
llvm-svn: 296498
Summary: The CallTargetProfile should be added to FProfile to be consistent with other profile readers.
Reviewers: dnovillo, davidxl
Reviewed By: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D30233
llvm-svn: 295852
Summary: Checking CS.getCalledFunction() == nullptr does not necessary indicate indirect call. We also need to check if CS.getCalledValue() is not a constant.
Reviewers: davidxl
Reviewed By: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29570
llvm-svn: 294260
Summary: In iterative sample pgo where profile is collected from PGOed binary, we may see indirect call targets promoted and inlined in the profile. Before profile annotation, we need to make this happen in order to annotate correctly on IR. This patch explicitly promotes these indirect calls and inlines them before profile annotation.
Reviewers: xur, davidxl
Reviewed By: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29040
llvm-svn: 293657
Summary: In iterative sample pgo where profile is collected from PGOed binary, we may see indirect call targets promoted and inlined in the profile. Before profile annotation, we need to make this happen in order to annotate correctly on IR. This patch explicitly promotes these indirect calls and inlines them before profile annotation.
Reviewers: xur, davidxl
Reviewed By: davidxl
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D29040
llvm-svn: 292979
Summary: Callsites in the same basic block should share the same hotness. This patch checks for the hottest callsite in the same basic block, and use the hotness for all callsites in that basic block for early inline decisions. It also fixes the test to add "-S" so theat the "CHECK-NOT" is actually checking the content.
Reviewers: dnovillo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D24734
llvm-svn: 281927
Summary: The call target count profile is directly derived from LBR branch->target data. This is more reliable than instruction frequency profiles that could be moved across basic block boundaries. This patches uses call target count profile to annotate call instructions.
Reviewers: davidxl, dnovillo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D24410
llvm-svn: 281911
Summary: Previously we reline on inst-combine to remove inlinable invoke instructions. This causes trouble because a few extra optimizations are schedule early that could introduce too much CFG change (e.g. simplifycfg removes too much control flow). This patch handles invoke instruction in-place during sample profile annotation, so that we do not rely on instcombine to remove those invoke instructions.
Reviewers: davidxl, dnovillo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D24409
llvm-svn: 281870
Summary: The refined propagation algorithm is more accurate and robust.
Reviewers: davidxl, dnovillo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D23224
llvm-svn: 278522
Summary: Set ProfileSummary in SampleProfilerLoader.
Reviewers: davidxl, eraman
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D21702
llvm-svn: 273745
Summary: Inliner needs ACT when calling InlineFunction. Instead of nullptr, we need to pass it in from SampleProfileLoader
Reviewers: davidxl
Subscribers: eraman, vsk, danielcdh, llvm-commits
Differential Revision: http://reviews.llvm.org/D21205
llvm-svn: 273199
Summary:
Instead of using maximum IR weight as the basic block weight, this patch uses the voting algorithm to find the most likely weight for the basic block. This can effectively avoid the cases when some IRs are annotated incorrectly due to code motion of the profiled binary.
This patch also updates propagate.ll unittest to include discriminator in the input file so that it is testing something meaningful.
Reviewers: davidxl, dnovillo
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D19301
llvm-svn: 267519
Summary: SampleProfile pass needs to be performed after InstructionCombiningPass, which helps eliminate un-inlinable function calls.
Reviewers: davidxl, dnovillo
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D17742
llvm-svn: 262419
This adds two thresholds to the sample profiler to affect inlining
decisions: the concept of global hotness and coldness.
Functions that have accumulated more than a certain fraction of samples at
runtime, are annotated with the InlineHint attribute. Conversely,
functions that accumulate less than a certain fraction of samples, are
annotated with the Cold attribute.
This is very similar to the hints emitted by Clang when using
instrumentation profiles.
Notice that this is a very blunt instrument. A function may have
globally collected a significant fraction of samples, but that does not
necessarily mean that every callsite for that function is hot.
Ideally, we would annotate each callsite with the samples collected at
that callsite. This way, the inliner can incorporate all these weights
into its cost model.
Once the inliner offers this functionality, we can change the hints
emitted here to a more precise per-callsite annotation. For now, this is
providing some measure of speedups with our internal benchmarks. I've
observed speedups of up to 23% (though the geo mean is about 3%). I expect
these numbers to improve as the inliner gets better annotations.
llvm-svn: 254212
If a function was originally inlined but not actually hot at runtime,
its samples will not be counted inside the parent function. This throws
off the coverage calculation because it expects to find more used
records than it should.
Fixed by ignoring functions that will not be inlined into the parent.
Currently, this is inlined functions with 0 samples. In subsequent
patches, I'll change this to mean "cold" functions.
llvm-svn: 253716
The initial coverage checking code for sample records failed to count
records inside inlined profiles. This change fixes the oversight.
llvm-svn: 251752
This adds the flag -mllvm -sample-profile-check-coverage=N to the
SampleProfile pass. N is the percent of input sample records that the
user expects to apply. If the pass does not use N% (or more) of the
sample records in the input, it emits a warning.
This is useful to detect some forms of stale profiles. If the code has
drifted enough from the original profile, there will be records that do
not match the IR anymore.
This will not detect cases where a sample profile record for line L is
referring to some other instructions that also used to be at line L.
llvm-svn: 251568
When emitting a remark for a conditional branch annotation, the remark
uses the line location information of the conditional branch in the
message. In some cases, that information is unavailable and the
optimization would segfaul. I'm still not sure whether this is a bug or
WAI, but the optimizer should not die because of this.
llvm-svn: 251420
This adds a couple of optimization remarks to the SamplePGO
transformation. When it decides to inline a hot function (to mimic the
inline stack and repeat useful inline decisions in the original build).
It will also report branch destinations. For instance, given the code
fragment:
6 if (i < 1000)
7 sum -= i;
8 else
9 sum += -i * rand();
If the 'else' branch is taken most of the time, building this code with
-Rpass=sample-profile will produce:
a.cc:9:14: remark: most popular destination for conditional branches at small.cc:6:9 [-Rpass=sample-profile]
sum += -i * rand();
^
llvm-svn: 251330
In some cases (as illustrated in the unittest), lineno can be less than the heade_lineno because the function body are included from some other files. In this case, offset will be negative. This patch makes clang still able to match the profile to IR in this situation.
http://reviews.llvm.org/D13914
llvm-svn: 250873
The number of samples collected at the head of a function only make
sense for top-level functions (i.e., those actually called as opposed to
being inlined inside another).
Head samples essentially count the time spent inside the function's
prologue. This clearly doesn't make sense for inlined functions, so we
were always emitting 0 in those.
llvm-svn: 250539
Binary encoded profiles used to encode all function names inline at
every reference. This is clearly suboptimal in terms of space. This
patch fixes this by adding a name table to the header of the file.
llvm-svn: 250241
With this patch we can now read and write inline stacks in sample
profiles to the binary encoded profiles.
In a subsequent patch, I will add a string table to the binary encoding.
Right now function names are emitted as strings every time we find them.
This is too bloated and will produce large files in applications with
lots of inlining.
llvm-svn: 249861
Richard Smith