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Handle inline stacks in gcov-encoded sample profiles.

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This patch adds support for reading sample profiles with inline stacks.
Inline stacks in a profile are generated when the sampled binary has
samples in inlined functions.

For instance, if main() calls foo() and foo() calls bar(), and bar() is
inlined into foo() and foo() inlined into main(), the profile may look
something like:

main total:364084 head:0
  [ ... ]
  2.3: _Z3fool total:243786
    1: 60149
    1.2: 38568
    1.4: 46511
    1.7: _Z3bari total:98558
      1.1: 52672
      1.2: 45886

At line 2, discriminator 3, main() calls foo(). In turn, foo() calls
bar() at line 1, discriminator 7.

In the textual format, this stacking of inline calls is represented
with indentation.

With this change, LLVM can now read sample profile files generated by
the create_gcov tool from https://github.com/google/autofdo.

llvm-svn: 249644
This commit is contained in:
Diego Novillo
2015-10-08 00:39:11 +00:00
parent 468c998031
commit b7fca57493
7 changed files with 139 additions and 53 deletions
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112
llvm/lib/ProfileData/SampleProfReader.cpp
View File

@@ -132,13 +132,14 @@ using namespace llvm;
/// \brief Print the samples collected for a function on stream \p OS.
///
/// \param OS Stream to emit the output to.
void FunctionSamples::print(raw_ostream &OS) {
void FunctionSamples::print(raw_ostream &OS, unsigned Indent) const {
OS << TotalSamples << ", " << TotalHeadSamples << ", " << BodySamples.size()
<< " sampled lines\n";
for (const auto &SI : BodySamples) {
LineLocation Loc = SI.first;
const SampleRecord &Sample = SI.second;
OS << "\tline offset: " << Loc.LineOffset
OS.indent(Indent);
OS << "line offset: " << Loc.LineOffset
<< ", discriminator: " << Loc.Discriminator
<< ", number of samples: " << Sample.getSamples();
if (Sample.hasCalls()) {
@@ -148,7 +149,15 @@ void FunctionSamples::print(raw_ostream &OS) {
}
OS << "\n";
}
OS << "\n";
for (const auto &CS : CallsiteSamples) {
CallsiteLocation Loc = CS.first;
const FunctionSamples &CalleeSamples = CS.second;
OS.indent(Indent);
OS << "line offset: " << Loc.LineOffset
<< ", discriminator: " << Loc.Discriminator
<< ", inlined callee: " << Loc.CalleeName << ": ";
CalleeSamples.print(OS, Indent + 2);
}
}
/// \brief Dump the function profile for \p FName.
@@ -266,7 +275,7 @@ static bool ParseLine(const StringRef &Input, bool &IsCallsite, unsigned &Depth,
std::error_code SampleProfileReaderText::read() {
line_iterator LineIt(*Buffer, /*SkipBlanks=*/true, '#');
SmallVector<FunctionSamples *, 10> InlineStack;
InlineCallStack InlineStack;
for (; !LineIt.is_at_eof(); ++LineIt) {
if ((*LineIt)[(*LineIt).find_first_not_of(' ')] == '#')
@@ -559,31 +568,18 @@ std::error_code SampleProfileReaderGCC::readFunctionProfiles() {
if (!GcovBuffer.readInt(NumFunctions))
return sampleprof_error::truncated;
SourceStack Stack;
InlineCallStack Stack;
for (uint32_t I = 0; I < NumFunctions; ++I)
if (std::error_code EC = readOneFunctionProfile(Stack, true))
if (std::error_code EC = readOneFunctionProfile(Stack, true, 0))
return EC;
return sampleprof_error::success;
}
std::error_code SampleProfileReaderGCC::addSourceCount(StringRef Name,
const SourceStack &Src,
uint64_t Count) {
if (Src.size() == 0 || Src[0].Malformed())
return sampleprof_error::malformed;
FunctionSamples &FProfile = Profiles[Name];
FProfile.addTotalSamples(Count);
// FIXME(dnovillo) - Properly update inline stack for FnName.
FProfile.addBodySamples(Src[0].Line, Src[0].Discriminator, Count);
return sampleprof_error::success;
}
std::error_code
SampleProfileReaderGCC::readOneFunctionProfile(const SourceStack &Stack,
bool Update) {
std::error_code SampleProfileReaderGCC::readOneFunctionProfile(
const InlineCallStack &InlineStack, bool Update, uint32_t Offset) {
uint64_t HeadCount = 0;
if (Stack.size() == 0)
if (InlineStack.size() == 0)
if (!GcovBuffer.readInt64(HeadCount))
return sampleprof_error::truncated;
@@ -597,15 +593,31 @@ SampleProfileReaderGCC::readOneFunctionProfile(const SourceStack &Stack,
if (!GcovBuffer.readInt(NumPosCounts))
return sampleprof_error::truncated;
uint32_t NumCallSites;
if (!GcovBuffer.readInt(NumCallSites))
uint32_t NumCallsites;
if (!GcovBuffer.readInt(NumCallsites))
return sampleprof_error::truncated;
if (Stack.size() == 0) {
FunctionSamples &FProfile = Profiles[Name];
FProfile.addHeadSamples(HeadCount);
if (FProfile.getTotalSamples() > 0)
FunctionSamples *FProfile = nullptr;
if (InlineStack.size() == 0) {
// If this is a top function that we have already processed, do not
// update its profile again. This happens in the presence of
// function aliases. Since these aliases share the same function
// body, there will be identical replicated profiles for the
// original function. In this case, we simply not bother updating
// the profile of the original function.
FProfile = &Profiles[Name];
FProfile->addHeadSamples(HeadCount);
if (FProfile->getTotalSamples() > 0)
Update = false;
} else {
// Otherwise, we are reading an inlined instance. The top of the
// inline stack contains the profile of the caller. Insert this
// callee in the caller's CallsiteMap.
FunctionSamples *CallerProfile = InlineStack.front();
uint32_t LineOffset = Offset >> 16;
uint32_t Discriminator = Offset & 0xffff;
FProfile = &CallerProfile->functionSamplesAt(
CallsiteLocation(LineOffset, Discriminator, Name));
}
for (uint32_t I = 0; I < NumPosCounts; ++I) {
@@ -621,13 +633,28 @@ SampleProfileReaderGCC::readOneFunctionProfile(const SourceStack &Stack,
if (!GcovBuffer.readInt64(Count))
return sampleprof_error::truncated;
SourceInfo Info(Name, "", "", 0, Offset >> 16, Offset & 0xffff);
SourceStack NewStack;
NewStack.push_back(Info);
NewStack.insert(NewStack.end(), Stack.begin(), Stack.end());
if (Update)
addSourceCount(NewStack[NewStack.size() - 1].FuncName, NewStack, Count);
// The line location is encoded in the offset as:
// high 16 bits: line offset to the start of the function.
// low 16 bits: discriminator.
uint32_t LineOffset = Offset >> 16;
uint32_t Discriminator = Offset & 0xffff;
InlineCallStack NewStack;
NewStack.push_back(FProfile);
NewStack.insert(NewStack.end(), InlineStack.begin(), InlineStack.end());
if (Update) {
// Walk up the inline stack, adding the samples on this line to
// the total sample count of the callers in the chain.
for (auto CallerProfile : NewStack)
CallerProfile->addTotalSamples(Count);
// Update the body samples for the current profile.
FProfile->addBodySamples(LineOffset, Discriminator, Count);
}
// Process the list of functions called at an indirect call site.
// These are all the targets that a function pointer (or virtual
// function) resolved at runtime.
for (uint32_t J = 0; J < NumTargets; J++) {
uint32_t HistVal;
if (!GcovBuffer.readInt(HistVal))
@@ -647,24 +674,25 @@ SampleProfileReaderGCC::readOneFunctionProfile(const SourceStack &Stack,
if (Update) {
FunctionSamples &TargetProfile = Profiles[TargetName];
TargetProfile.addBodySamples(NewStack[0].Line,
NewStack[0].Discriminator, TargetCount);
TargetProfile.addCalledTargetSamples(LineOffset, Discriminator,
TargetName, TargetCount);
}
}
}
for (uint32_t I = 0; I < NumCallSites; I++) {
// Process all the inlined callers into the current function. These
// are all the callsites that were inlined into this function.
for (uint32_t I = 0; I < NumCallsites; I++) {
// The offset is encoded as:
// high 16 bits: line offset to the start of the function.
// low 16 bits: discriminator.
uint32_t Offset;
if (!GcovBuffer.readInt(Offset))
return sampleprof_error::truncated;
SourceInfo Info(Name, "", "", 0, Offset >> 16, Offset & 0xffff);
SourceStack NewStack;
NewStack.push_back(Info);
NewStack.insert(NewStack.end(), Stack.begin(), Stack.end());
if (std::error_code EC = readOneFunctionProfile(NewStack, Update))
InlineCallStack NewStack;
NewStack.push_back(FProfile);
NewStack.insert(NewStack.end(), InlineStack.begin(), InlineStack.end());
if (std::error_code EC = readOneFunctionProfile(NewStack, Update, Offset))
return EC;
}