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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 https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines constructor functions for instrumentation passes.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_TRANSFORMS_INSTRUMENTATION_H
 #define LLVM_TRANSFORMS_INSTRUMENTATION_H
 
 #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>
 
 namespace llvm {
 
 class Triple;
 class OptimizationRemarkEmitter;
 class Comdat;
 class CallBase;
 class Module;
 
 /// Check if module has flag attached, if not add the flag.
 bool checkIfAlreadyInstrumented(Module &M, StringRef Flag);
 
 /// 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,
                                              Twine 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);
 
 // Place global in a large section for x86-64 ELF binaries to mitigate
 // relocation overflow pressure. This can be be used for metadata globals that
 // aren't directly accessed by code, which has no performance impact.
 void setGlobalVariableLargeSection(const Triple &TargetTriple,
                                    GlobalVariable &GV);
 
 // 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;
 
   // Use sampling to reduce the profile instrumentation runtime overhead.
   bool Sampling = false;
 
   // Name of the profile file to use as output
   std::string InstrProfileOutput;
 
   InstrProfOptions() = default;
 };
 
 // Create the variable for profile sampling.
 void createProfileSamplingVar(Module &M);
 
 // Options for sanitizer coverage instrumentation.
 struct SanitizerCoverageOptions {
   enum Type {
     SCK_None = 0,
     SCK_Function,
     SCK_BB,
     SCK_Edge
   } 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;
   bool GatedCallbacks = 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())
       return;
     if (DISubprogram *SP = F.getSubprogram())
       IRB.SetCurrentDebugLocation(DILocation::get(SP->getContext(), 0, 0, SP));
   }
 
   explicit InstrumentationIRBuilder(Instruction *IP) : IRBuilder<>(IP) {
     ensureDebugInfo(*this, *IP->getFunction());
   }
 
   explicit InstrumentationIRBuilder(BasicBlock *BB, BasicBlock::iterator It)
       : IRBuilder<>(BB, It) {
     ensureDebugInfo(*this, *BB->getParent());
   }
 };
 } // end namespace llvm
 
 #endif // LLVM_TRANSFORMS_INSTRUMENTATION_H

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