clang  6.0.0svn
CodeGenPGO.cpp File Reference
#include "CodeGenPGO.h"
#include "CodeGenFunction.h"
#include "CoverageMappingGen.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/StmtVisitor.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MD5.h"
Include dependency graph for CodeGenPGO.cpp:

Go to the source code of this file.


static llvm::cl::opt< boolEnableValueProfiling ("enable-value-profiling", llvm::cl::ZeroOrMore, llvm::cl::desc("Enable value profiling"), llvm::cl::init(false))
static uint64_t calculateWeightScale (uint64_t MaxWeight)
 Calculate what to divide by to scale weights. More...
static uint32_t scaleBranchWeight (uint64_t Weight, uint64_t Scale)
 Scale an individual branch weight (and add 1). More...

Function Documentation

◆ calculateWeightScale()

static uint64_t calculateWeightScale ( uint64_t  MaxWeight)

Calculate what to divide by to scale weights.

Given the maximum weight, calculate a divisor that will scale all the weights to strictly less than UINT32_MAX.

Definition at line 844 of file CodeGenPGO.cpp.

Referenced by scaleBranchWeight().

◆ EnableValueProfiling()

static llvm::cl::opt<bool> EnableValueProfiling ( "enable-value-profiling"  ,
llvm::cl::ZeroOrMore  ,
llvm::cl::desc("Enable value profiling")  ,

◆ scaleBranchWeight()

static uint32_t scaleBranchWeight ( uint64_t  Weight,
uint64_t  Scale 

Scale an individual branch weight (and add 1).

Scale a 64-bit weight down to 32-bits using Scale.

According to Laplace's Rule of Succession, it is better to compute the weight based on the count plus 1, so universally add 1 to the value.

Scale was calculated by calculateWeightScale() with a weight no greater than Weight.

Definition at line 857 of file CodeGenPGO.cpp.

References calculateWeightScale(), clang::CodeGen::CodeGenPGO::getStmtCount(), clang::CodeGen::CodeGenPGO::haveRegionCounts(), and max().