BasicBlockSectionsProfileReader.cpp

//===-- 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/DenseSet.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/IR/DebugInfoMetadata.h"
#include "llvm/Pass.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/LineIterator.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include <llvm/ADT/STLExtras.h>

usingnamespacellvm;

char BasicBlockSectionsProfileReaderWrapperPass::ID = …;
INITIALIZE_PASS(…)

Expected<UniqueBBID>
BasicBlockSectionsProfileReader::parseUniqueBBID(StringRef S) const { … }

bool BasicBlockSectionsProfileReader::isFunctionHot(StringRef FuncName) const { … }

std::pair<bool, SmallVector<BBClusterInfo>>
BasicBlockSectionsProfileReader::getClusterInfoForFunction(
    StringRef FuncName) const { … }

SmallVector<SmallVector<unsigned>>
BasicBlockSectionsProfileReader::getClonePathsForFunction(
    StringRef FuncName) const { … }

// Reads the version 1 basic block sections profile. Profile for each function
// is encoded as follows:
//   m <module_name>
//   f <function_name_1> <function_name_2> ...
//   c <bb_id_1> <bb_id_2> <bb_id_3>
//   c <bb_id_4> <bb_id_5>
//   ...
// Module name specifier (starting with 'm') is optional and allows
// distinguishing profile for internal-linkage functions with the same name. If
// not specified, it will apply to any function with the same name. Function
// name specifier (starting with 'f') can specify multiple function name
// aliases. Basic block clusters are specified by 'c' and specify the cluster of
// basic blocks, and the internal order in which they must be placed in the same
// section.
// This profile can also specify cloning paths which instruct the compiler to
// clone basic blocks along a path. The cloned blocks are then specified in the
// cluster information.
// The following profile lists two cloning paths (starting with 'p') for
// function bar and places the total 9 blocks within two clusters. The first two
// blocks of a cloning path specify the edge along which the path is cloned. For
// instance, path 1 (1 -> 3 -> 4) instructs that 3 and 4 must be cloned along
// the edge 1->3. Within the given clusters, each cloned block is identified by
// "<original block id>.<clone id>". For instance, 3.1 represents the first
// clone of block 3. Original blocks are specified just with their block ids. A
// block cloned multiple times appears with distinct clone ids. The CFG for bar
// is shown below before and after cloning with its final clusters labeled.
//
// f main
// f bar
// p 1 3 4           # cloning path 1
// p 4 2             # cloning path 2
// c 1 3.1 4.1 6     # basic block cluster 1
// c 0 2 3 4 2.1 5   # basic block cluster 2
// ****************************************************************************
// function bar before and after cloning with basic block clusters shown.
// ****************************************************************************
//                                ....      ..............
//      0 -------+                : 0 :---->: 1 ---> 3.1 :
//      |        |                : | :     :........ |  :
//      v        v                : v :             : v  :
// +--> 2 --> 5  1   ~~~~~~>  +---: 2 :             : 4.1: clsuter 1
// |    |        |            |   : | :             : |  :
// |    v        |            |   : v .......       : v  :
// |    3 <------+            |   : 3 <--+  :       : 6  :
// |    |                     |   : |    |  :       :....:
// |    v                     |   : v    |  :
// +--- 4 ---> 6              |   : 4    |  :
//                            |   : |    |  :
//                            |   : v    |  :
//                            |   :2.1---+  : cluster 2
//                            |   : | ......:
//                            |   : v :
//                            +-->: 5 :
//                                ....
// ****************************************************************************
Error BasicBlockSectionsProfileReader::ReadV1Profile() { … }

Error BasicBlockSectionsProfileReader::ReadV0Profile() { … }

// 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() { … }

bool BasicBlockSectionsProfileReaderWrapperPass::doInitialization(Module &M) { … }

AnalysisKey BasicBlockSectionsProfileReaderAnalysis::Key;

BasicBlockSectionsProfileReader
BasicBlockSectionsProfileReaderAnalysis::run(Function &F,
                                             FunctionAnalysisManager &AM) { … }

bool BasicBlockSectionsProfileReaderWrapperPass::isFunctionHot(
    StringRef FuncName) const { … }

std::pair<bool, SmallVector<BBClusterInfo>>
BasicBlockSectionsProfileReaderWrapperPass::getClusterInfoForFunction(
    StringRef FuncName) const { … }

SmallVector<SmallVector<unsigned>>
BasicBlockSectionsProfileReaderWrapperPass::getClonePathsForFunction(
    StringRef FuncName) const { … }

BasicBlockSectionsProfileReader &
BasicBlockSectionsProfileReaderWrapperPass::getBBSPR() { … }

ImmutablePass *llvm::createBasicBlockSectionsProfileReaderWrapperPass(
    const MemoryBuffer *Buf) { … }
llvm/llvm/lib/CodeGen/BasicBlockSectionsProfileReader.cpp
