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//===-- BasicBlockSectionsProfileReader.cpp -------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Implementation of the basic block sections profile reader pass. It parses
// and stores the basic block sections profile file (which is specified via the
// `-basic-block-sections` flag).
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/BasicBlockSectionsProfileReader.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/LineIterator.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include <llvm/ADT/STLExtras.h>
using namespace llvm;
char BasicBlockSectionsProfileReader::ID = 0;
INITIALIZE_PASS(BasicBlockSectionsProfileReader, "bbsections-profile-reader",
"Reads and parses a basic block sections profile.", false,
false)
bool BasicBlockSectionsProfileReader::isFunctionHot(StringRef FuncName) const {
return getBBClusterInfoForFunction(FuncName).first;
}
std::pair<bool, SmallVector<BBClusterInfo>>
BasicBlockSectionsProfileReader::getBBClusterInfoForFunction(
StringRef FuncName) const {
auto R = ProgramBBClusterInfo.find(getAliasName(FuncName));
return R != ProgramBBClusterInfo.end()
? std::pair(true, R->second)
: std::pair(false, SmallVector<BBClusterInfo>{});
}
// Basic Block Sections can be enabled for a subset of machine basic blocks.
// This is done by passing a file containing names of functions for which basic
// block sections are desired. Additionally, machine basic block ids of the
// functions can also be specified for a finer granularity. Moreover, a cluster
// of basic blocks could be assigned to the same section.
// Optionally, a debug-info filename can be specified for each function to allow
// distinguishing internal-linkage functions of the same name.
// A file with basic block sections for all of function main and three blocks
// for function foo (of which 1 and 2 are placed in a cluster) looks like this:
// (Profile for function foo is only loaded when its debug-info filename
// matches 'path/to/foo_file.cc').
// ----------------------------
// list.txt:
// !main
// !foo M=path/to/foo_file.cc
// !!1 2
// !!4
Error BasicBlockSectionsProfileReader::ReadProfile() {
assert(MBuf);
line_iterator LineIt(*MBuf, /*SkipBlanks=*/true, /*CommentMarker=*/'#');
auto invalidProfileError = [&](auto Message) {
return make_error<StringError>(
Twine("Invalid profile " + MBuf->getBufferIdentifier() + " at line " +
Twine(LineIt.line_number()) + ": " + Message),
inconvertibleErrorCode());
};
auto FI = ProgramBBClusterInfo.end();
// Current cluster ID corresponding to this function.
unsigned CurrentCluster = 0;
// Current position in the current cluster.
unsigned CurrentPosition = 0;
// Temporary set to ensure every basic block ID appears once in the clusters
// of a function.
SmallSet<unsigned, 4> FuncBBIDs;
for (; !LineIt.is_at_eof(); ++LineIt) {
StringRef S(*LineIt);
if (S[0] == '@')
continue;
// Check for the leading "!"
if (!S.consume_front("!") || S.empty())
break;
// Check for second "!" which indicates a cluster of basic blocks.
if (S.consume_front("!")) {
// Skip the profile when we the profile iterator (FI) refers to the
// past-the-end element.
if (FI == ProgramBBClusterInfo.end())
continue;
SmallVector<StringRef, 4> BBIDs;
S.split(BBIDs, ' ');
// Reset current cluster position.
CurrentPosition = 0;
for (auto BBIDStr : BBIDs) {
unsigned long long BBID;
if (getAsUnsignedInteger(BBIDStr, 10, BBID))
return invalidProfileError(Twine("Unsigned integer expected: '") +
BBIDStr + "'.");
if (!FuncBBIDs.insert(BBID).second)
return invalidProfileError(Twine("Duplicate basic block id found '") +
BBIDStr + "'.");
if (BBID == 0 && CurrentPosition)
return invalidProfileError("Entry BB (0) does not begin a cluster.");
FI->second.emplace_back(
BBClusterInfo{((unsigned)BBID), CurrentCluster, CurrentPosition++});
}
CurrentCluster++;
} else {
// This is a function name specifier. It may include a debug info filename
// specifier starting with `M=`.
auto [AliasesStr, DIFilenameStr] = S.split(' ');
SmallString<128> DIFilename;
if (DIFilenameStr.startswith("M=")) {
DIFilename =
sys::path::remove_leading_dotslash(DIFilenameStr.substr(2));
if (DIFilename.empty())
return invalidProfileError("Empty module name specifier.");
} else if (!DIFilenameStr.empty()) {
return invalidProfileError("Unknown string found: '" + DIFilenameStr +
"'.");
}
// Function aliases are separated using '/'. We use the first function
// name for the cluster info mapping and delegate all other aliases to
// this one.
SmallVector<StringRef, 4> Aliases;
AliasesStr.split(Aliases, '/');
bool FunctionFound = any_of(Aliases, [&](StringRef Alias) {
auto It = FunctionNameToDIFilename.find(Alias);
// No match if this function name is not found in this module.
if (It == FunctionNameToDIFilename.end())
return false;
// Return a match if debug-info-filename is not specified. Otherwise,
// check for equality.
return DIFilename.empty() || It->second.equals(DIFilename);
});
if (!FunctionFound) {
// Skip the following profile by setting the profile iterator (FI) to
// the past-the-end element.
FI = ProgramBBClusterInfo.end();
continue;
}
for (size_t i = 1; i < Aliases.size(); ++i)
FuncAliasMap.try_emplace(Aliases[i], Aliases.front());
// Prepare for parsing clusters of this function name.
// Start a new cluster map for this function name.
auto R = ProgramBBClusterInfo.try_emplace(Aliases.front());
// Report error when multiple profiles have been specified for the same
// function.
if (!R.second)
return invalidProfileError("Duplicate profile for function '" +
Aliases.front() + "'.");
FI = R.first;
CurrentCluster = 0;
FuncBBIDs.clear();
}
}
return Error::success();
}
bool BasicBlockSectionsProfileReader::doInitialization(Module &M) {
if (!MBuf)
return false;
// Get the function name to debug info filename mapping.
FunctionNameToDIFilename.clear();
for (const Function &F : M) {
SmallString<128> DIFilename;
if (F.isDeclaration())
continue;
DISubprogram *Subprogram = F.getSubprogram();
if (Subprogram) {
llvm::DICompileUnit *CU = Subprogram->getUnit();
if (CU)
DIFilename = sys::path::remove_leading_dotslash(CU->getFilename());
}
[[maybe_unused]] bool inserted =
FunctionNameToDIFilename.try_emplace(F.getName(), DIFilename).second;
assert(inserted);
}
if (auto Err = ReadProfile())
report_fatal_error(std::move(Err));
return false;
}
ImmutablePass *
llvm::createBasicBlockSectionsProfileReaderPass(const MemoryBuffer *Buf) {
return new BasicBlockSectionsProfileReader(Buf);
}
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