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This adds a new scalar pass that reads a file with samples generated by 'perf' during runtime. The samples read from the profile are incorporated and emmited as IR metadata reflecting that profile. The profile file is assumed to have been generated by an external profile source. The profile information is converted into IR metadata, which is later used by the analysis routines to estimate block frequencies, edge weights and other related data. External profile information files have no fixed format, each profiler is free to define its own. This includes both the on-disk representation of the profile and the kind of profile information stored in the file. A common kind of profile is based on sampling (e.g., perf), which essentially counts how many times each line of the program has been executed during the run. The SampleProfileLoader pass is organized as a scalar transformation. On startup, it reads the file given in -sample-profile-file to determine what kind of profile it contains. This file is assumed to contain profile information for the whole application. The profile data in the file is read and incorporated into the internal state of the corresponding profiler. To facilitate testing, I've organized the profilers to support two file formats: text and native. The native format is whatever on-disk representation the profiler wants to support, I think this will mostly be bitcode files, but it could be anything the profiler wants to support. To do this, every profiler must implement the SampleProfile::loadNative() function. The text format is mostly meant for debugging. Records are separated by newlines, but each profiler is free to interpret records as it sees fit. Profilers must implement the SampleProfile::loadText() function. Finally, the pass will call SampleProfile::emitAnnotations() for each function in the current translation unit. This function needs to translate the loaded profile into IR metadata, which the analyzer will later be able to use. This patch implements the first steps towards the above design. I've implemented a sample-based flat profiler. The format of the profile is fairly simplistic. Each sampled function contains a list of relative line locations (from the start of the function) together with a count representing how many samples were collected at that line during execution. I generate this profile using perf and a separate converter tool. Currently, I have only implemented a text format for these profiles. I am interested in initial feedback to the whole approach before I send the other parts of the implementation for review. This patch implements: - The SampleProfileLoader pass. - The base ExternalProfile class with the core interface. - A SampleProfile sub-class using the above interface. The profiler generates branch weight metadata on every branch instructions that matches the profiles. - A text loader class to assist the implementation of SampleProfile::loadText(). - Basic unit tests for the pass. Additionally, the patch uses profile information to compute branch weights based on instruction samples. This patch converts instruction samples into branch weights. It does a fairly simplistic conversion: Given a multi-way branch instruction, it calculates the weight of each branch based on the maximum sample count gathered from each target basic block. Note that this assignment of branch weights is somewhat lossy and can be misleading. If a basic block has more than one incoming branch, all the incoming branches will get the same weight. In reality, it may be that only one of them is the most heavily taken branch. I will adjust this assignment in subsequent patches. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194566 91177308-0d34-0410-b5e6-96231b3b80d8
195 lines
5.9 KiB
C++
195 lines
5.9 KiB
C++
//===-- Scalar.cpp --------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements common infrastructure for libLLVMScalarOpts.a, which
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// implements several scalar transformations over the LLVM intermediate
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// representation, including the C bindings for that library.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm-c/Initialization.h"
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#include "llvm-c/Transforms/Scalar.h"
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#include "llvm/Analysis/Passes.h"
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#include "llvm/Analysis/Verifier.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/InitializePasses.h"
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#include "llvm/PassManager.h"
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using namespace llvm;
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/// initializeScalarOptsPasses - Initialize all passes linked into the
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/// ScalarOpts library.
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void llvm::initializeScalarOpts(PassRegistry &Registry) {
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initializeADCEPass(Registry);
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initializeSampleProfileLoaderPass(Registry);
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initializeCodeGenPreparePass(Registry);
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initializeConstantPropagationPass(Registry);
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initializeCorrelatedValuePropagationPass(Registry);
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initializeDCEPass(Registry);
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initializeDeadInstEliminationPass(Registry);
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initializeDSEPass(Registry);
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initializeGVNPass(Registry);
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initializeEarlyCSEPass(Registry);
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initializeIndVarSimplifyPass(Registry);
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initializeJumpThreadingPass(Registry);
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initializeLICMPass(Registry);
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initializeLoopDeletionPass(Registry);
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initializeLoopInstSimplifyPass(Registry);
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initializeLoopRotatePass(Registry);
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initializeLoopStrengthReducePass(Registry);
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initializeLoopUnrollPass(Registry);
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initializeLoopUnswitchPass(Registry);
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initializeLoopIdiomRecognizePass(Registry);
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initializeLowerAtomicPass(Registry);
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initializeLowerExpectIntrinsicPass(Registry);
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initializeMemCpyOptPass(Registry);
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initializePartiallyInlineLibCallsPass(Registry);
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initializeReassociatePass(Registry);
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initializeRegToMemPass(Registry);
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initializeSCCPPass(Registry);
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initializeIPSCCPPass(Registry);
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initializeSROAPass(Registry);
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initializeSROA_DTPass(Registry);
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initializeSROA_SSAUpPass(Registry);
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initializeCFGSimplifyPassPass(Registry);
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initializeStructurizeCFGPass(Registry);
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initializeSinkingPass(Registry);
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initializeTailCallElimPass(Registry);
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}
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void LLVMInitializeScalarOpts(LLVMPassRegistryRef R) {
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initializeScalarOpts(*unwrap(R));
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}
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void LLVMAddAggressiveDCEPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createAggressiveDCEPass());
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}
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void LLVMAddCFGSimplificationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createCFGSimplificationPass());
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}
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void LLVMAddDeadStoreEliminationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createDeadStoreEliminationPass());
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}
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void LLVMAddGVNPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createGVNPass());
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}
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void LLVMAddIndVarSimplifyPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createIndVarSimplifyPass());
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}
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void LLVMAddInstructionCombiningPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createInstructionCombiningPass());
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}
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void LLVMAddJumpThreadingPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createJumpThreadingPass());
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}
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void LLVMAddLICMPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLICMPass());
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}
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void LLVMAddLoopDeletionPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopDeletionPass());
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}
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void LLVMAddLoopIdiomPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopIdiomPass());
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}
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void LLVMAddLoopRotatePass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopRotatePass());
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}
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void LLVMAddLoopUnrollPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopUnrollPass());
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}
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void LLVMAddLoopUnswitchPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLoopUnswitchPass());
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}
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void LLVMAddMemCpyOptPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createMemCpyOptPass());
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}
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void LLVMAddPartiallyInlineLibCallsPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createPartiallyInlineLibCallsPass());
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}
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void LLVMAddPromoteMemoryToRegisterPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createPromoteMemoryToRegisterPass());
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}
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void LLVMAddReassociatePass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createReassociatePass());
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}
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void LLVMAddSCCPPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createSCCPPass());
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}
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void LLVMAddScalarReplAggregatesPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createScalarReplAggregatesPass());
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}
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void LLVMAddScalarReplAggregatesPassSSA(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createScalarReplAggregatesPass(-1, false));
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}
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void LLVMAddScalarReplAggregatesPassWithThreshold(LLVMPassManagerRef PM,
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int Threshold) {
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unwrap(PM)->add(createScalarReplAggregatesPass(Threshold));
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}
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void LLVMAddSimplifyLibCallsPass(LLVMPassManagerRef PM) {
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// NOTE: The simplify-libcalls pass has been removed.
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}
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void LLVMAddTailCallEliminationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createTailCallEliminationPass());
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}
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void LLVMAddConstantPropagationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createConstantPropagationPass());
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}
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void LLVMAddDemoteMemoryToRegisterPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createDemoteRegisterToMemoryPass());
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}
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void LLVMAddVerifierPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createVerifierPass());
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}
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void LLVMAddCorrelatedValuePropagationPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createCorrelatedValuePropagationPass());
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}
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void LLVMAddEarlyCSEPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createEarlyCSEPass());
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}
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void LLVMAddTypeBasedAliasAnalysisPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createTypeBasedAliasAnalysisPass());
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}
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void LLVMAddBasicAliasAnalysisPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createBasicAliasAnalysisPass());
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}
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void LLVMAddLowerExpectIntrinsicPass(LLVMPassManagerRef PM) {
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unwrap(PM)->add(createLowerExpectIntrinsicPass());
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}
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