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//===- Transforms/Instrumentation.h - Instrumentation passes ----*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file defines constructor functions for instrumentation passes.
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include <cassert>
#include <cstdint>
#include <limits>
#include <string>
#include <vector>
namespace llvm {
class Triple;
class OptimizationRemarkEmitter;
class Comdat;
class CallBase;
/// Instrumentation passes often insert conditional checks into entry blocks.
/// Call this function before splitting the entry block to move instructions
/// that must remain in the entry block up before the split point. Static
/// allocas and llvm.localescape calls, for example, must remain in the entry
/// block.
BasicBlock::iterator PrepareToSplitEntryBlock(BasicBlock &BB,
BasicBlock::iterator IP);
// Create a constant for Str so that we can pass it to the run-time lib.
GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
bool AllowMerging,
const char *NamePrefix = "");
// Returns F.getComdat() if it exists.
// Otherwise creates a new comdat, sets F's comdat, and returns it.
// Returns nullptr on failure.
Comdat *getOrCreateFunctionComdat(Function &F, Triple &T);
// Insert GCOV profiling instrumentation
struct GCOVOptions {
static GCOVOptions getDefault();
// Specify whether to emit .gcno files.
bool EmitNotes;
// Specify whether to modify the program to emit .gcda files when run.
bool EmitData;
// A four-byte version string. The meaning of a version string is described in
// gcc's gcov-io.h
char Version[4];
// Add the 'noredzone' attribute to added runtime library calls.
bool NoRedZone;
// Use atomic profile counter increments.
bool Atomic = false;
// Regexes separated by a semi-colon to filter the files to instrument.
std::string Filter;
// Regexes separated by a semi-colon to filter the files to not instrument.
std::string Exclude;
// The pgo-specific indirect call promotion function declared below is used by
// the pgo-driven indirect call promotion and sample profile passes. It's a
// wrapper around llvm::promoteCall, et al. that additionally computes !prof
// metadata. We place it in a pgo namespace so it's not confused with the
// generic utilities.
namespace pgo {
// Helper function that transforms CB (either an indirect-call instruction, or
// an invoke instruction , to a conditional call to F. This is like:
// if (Inst.CalledValue == F)
// F(...);
// else
// Inst(...);
// end
// TotalCount is the profile count value that the instruction executes.
// Count is the profile count value that F is the target function.
// These two values are used to update the branch weight.
// If \p AttachProfToDirectCall is true, a prof metadata is attached to the
// new direct call to contain \p Count.
// Returns the promoted direct call instruction.
CallBase &promoteIndirectCall(CallBase &CB, Function *F, uint64_t Count,
uint64_t TotalCount, bool AttachProfToDirectCall,
OptimizationRemarkEmitter *ORE);
} // namespace pgo
/// Options for the frontend instrumentation based profiling pass.
struct InstrProfOptions {
// Add the 'noredzone' attribute to added runtime library calls.
bool NoRedZone = false;
// Do counter register promotion
bool DoCounterPromotion = false;
// Use atomic profile counter increments.
bool Atomic = false;
// Use BFI to guide register promotion
bool UseBFIInPromotion = false;
// Name of the profile file to use as output
std::string InstrProfileOutput;
InstrProfOptions() = default;
// Options for sanitizer coverage instrumentation.
struct SanitizerCoverageOptions {
enum Type {
SCK_None = 0,
} CoverageType = SCK_None;
bool IndirectCalls = false;
bool TraceBB = false;
bool TraceCmp = false;
bool TraceDiv = false;
bool TraceGep = false;
bool Use8bitCounters = false;
bool TracePC = false;
bool TracePCGuard = false;
bool Inline8bitCounters = false;
bool InlineBoolFlag = false;
bool PCTable = false;
bool NoPrune = false;
bool StackDepth = false;
bool TraceLoads = false;
bool TraceStores = false;
bool CollectControlFlow = false;
SanitizerCoverageOptions() = default;
/// Calculate what to divide by to scale counts.
/// Given the maximum count, calculate a divisor that will scale all the
/// weights to strictly less than std::numeric_limits<uint32_t>::max().
static inline uint64_t calculateCountScale(uint64_t MaxCount) {
return MaxCount < std::numeric_limits<uint32_t>::max()
? 1
: MaxCount / std::numeric_limits<uint32_t>::max() + 1;
/// Scale an individual branch count.
/// Scale a 64-bit weight down to 32-bits using \c Scale.
static inline uint32_t scaleBranchCount(uint64_t Count, uint64_t Scale) {
uint64_t Scaled = Count / Scale;
assert(Scaled <= std::numeric_limits<uint32_t>::max() && "overflow 32-bits");
return Scaled;
// Use to ensure the inserted instrumentation has a DebugLocation; if none is
// attached to the source instruction, try to use a DILocation with offset 0
// scoped to surrounding function (if it has a DebugLocation).
// Some non-call instructions may be missing debug info, but when inserting
// instrumentation calls, some builds (e.g. LTO) want calls to have debug info
// if the enclosing function does.
struct InstrumentationIRBuilder : IRBuilder<> {
static void ensureDebugInfo(IRBuilder<> &IRB, const Function &F) {
if (IRB.getCurrentDebugLocation())
if (DISubprogram *SP = F.getSubprogram())
IRB.SetCurrentDebugLocation(DILocation::get(SP->getContext(), 0, 0, SP));
explicit InstrumentationIRBuilder(Instruction *IP) : IRBuilder<>(IP) {
ensureDebugInfo(*this, *IP->getFunction());
} // end namespace llvm