LowerExpectIntrinsic.cpp File Reference

#include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/ProfDataUtils.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Transforms/Utils/MisExpect.h"
#include <cmath>

Go to the source code of this file.

Macros
#define	DEBUG_TYPE   "lower-expect-intrinsic"

Functions
	STATISTIC (ExpectIntrinsicsHandled, "Number of 'expect' intrinsic instructions handled")
static std::tuple< uint32_t, uint32_t >	getBranchWeight (Intrinsic::ID IntrinsicID, CallInst *CI, int BranchCount)
static bool	handleSwitchExpect (SwitchInst &SI)
static void	handlePhiDef (CallInst *Expect)
	Handler for PHINodes that define the value argument to an @llvm.expect call.
template<class BrSelInst >
static bool	handleBrSelExpect (BrSelInst &BSI)
static bool	handleBranchExpect (BranchInst &BI)
static bool	lowerExpectIntrinsic (Function &F)

Variables
static cl::opt< uint32_t >	LikelyBranchWeight ("likely-branch-weight", cl::Hidden, cl::init(2000), cl::desc("Weight of the branch likely to be taken (default = 2000)"))
static cl::opt< uint32_t >	UnlikelyBranchWeight ("unlikely-branch-weight", cl::Hidden, cl::init(1), cl::desc("Weight of the branch unlikely to be taken (default = 1)"))

Macro Definition Documentation

DEBUG_TYPE

#define DEBUG_TYPE   "lower-expect-intrinsic"

Definition at line 31 of file LowerExpectIntrinsic.cpp.

Function Documentation

getBranchWeight()

static std::tuple< uint32_t, uint32_t > getBranchWeight ( Intrinsic::ID  IntrinsicID, CallInst *  CI, int  BranchCount  )

static

Definition at line 56 of file LowerExpectIntrinsic.cpp.

References assert(), llvm::CallBase::getArgOperand(), llvm::User::getNumOperands(), LikelyBranchWeight, and UnlikelyBranchWeight.

Referenced by handleBrSelExpect(), handlePhiDef(), and handleSwitchExpect().

handleBranchExpect()

static bool handleBranchExpect ( BranchInst &  BI )

static

Definition at line 357 of file LowerExpectIntrinsic.cpp.

References llvm::BranchInst::isUnconditional().

Referenced by lowerExpectIntrinsic().

handleBrSelExpect()

template<class BrSelInst >

static bool handleBrSelExpect ( BrSelInst &  BSI )

static

Definition at line 276 of file LowerExpectIntrinsic.cpp.

References llvm::misexpect::checkFrontendInstrumentation(), llvm::MDBuilder::createBranchWeights(), llvm::CallBase::getArgOperand(), llvm::ConstantInt::getBitWidth(), getBranchWeight(), llvm::CallBase::getCalledFunction(), llvm::Value::getContext(), llvm::Function::getIntrinsicID(), llvm::User::getOperand(), llvm::CmpInst::getPredicate(), llvm::ConstantInt::getZExtValue(), llvm::CmpInst::ICMP_EQ, llvm::CmpInst::ICMP_NE, and llvm::User::setOperand().

Referenced by lowerExpectIntrinsic().

handlePhiDef()

static void handlePhiDef ( CallInst *  Expect )

static

Handler for PHINodes that define the value argument to an @llvm.expect call.

If the operand of the phi has a constant value and it 'contradicts' with the expected value of phi def, then the corresponding incoming edge of the phi is unlikely to be taken. Using that information, the branch probability info for the originating branch can be inferred.

Definition at line 116 of file LowerExpectIntrinsic.cpp.

References llvm::MDBuilder::createBranchWeights(), llvm::CallBase::getArgOperand(), getBranchWeight(), llvm::CallBase::getCalledFunction(), llvm::Function::getIntrinsicID(), llvm::BinaryOperator::getOpcode(), llvm::User::getOperand(), llvm::ilist_detail::node_parent_access< NodeTy, ParentTy >::getParent(), llvm::BasicBlock::getSinglePredecessor(), llvm::BranchInst::getSuccessor(), llvm::BasicBlock::getTerminator(), llvm::ConstantInt::getValue(), llvm::BranchInst::isConditional(), llvm::BranchInst::isUnconditional(), llvm_unreachable, llvm::SmallVectorTemplateBase< T, bool >::push_back(), llvm::reverse(), llvm::Instruction::setMetadata(), and std::swap().

Referenced by lowerExpectIntrinsic().

handleSwitchExpect()

static bool handleSwitchExpect ( SwitchInst &  SI )

static

Definition at line 76 of file LowerExpectIntrinsic.cpp.

References llvm::misexpect::checkExpectAnnotations(), llvm::CallBase::getArgOperand(), getBranchWeight(), llvm::CallBase::getCalledFunction(), llvm::SwitchInst::CaseHandleImpl< SwitchInstT, ConstantIntT, BasicBlockT >::getCaseIndex(), llvm::Function::getIntrinsicID(), and llvm::setBranchWeights().

Referenced by lowerExpectIntrinsic().

lowerExpectIntrinsic()

static bool lowerExpectIntrinsic ( Function &  F )

static

Definition at line 364 of file LowerExpectIntrinsic.cpp.

References llvm::Instruction::eraseFromParent(), F, llvm::CallBase::getArgOperand(), llvm::CallBase::getCalledFunction(), llvm::Function::getIntrinsicID(), handleBranchExpect(), handleBrSelExpect(), handlePhiDef(), handleSwitchExpect(), llvm::make_early_inc_range(), llvm::Value::replaceAllUsesWith(), and llvm::reverse().

Referenced by llvm::LowerExpectIntrinsicPass::run().

STATISTIC()

STATISTIC	(	ExpectIntrinsicsHandled	,
		"Number of 'expect' intrinsic instructions handled"
	)

Variable Documentation

LikelyBranchWeight

cl::opt< uint32_t > LikelyBranchWeight("likely-branch-weight", cl::Hidden, cl::init(2000), cl::desc("Weight of the branch likely to be taken (default = 2000)")) ( "likely-branch-weight"  , cl::Hidden  , cl::init(2000)  , cl::desc("Weight of the branch likely to be taken (default = 2000)")    )

static

Referenced by getBranchWeight(), and llvm::misexpect::verifyMisExpect().

UnlikelyBranchWeight

cl::opt< uint32_t > UnlikelyBranchWeight("unlikely-branch-weight", cl::Hidden, cl::init(1), cl::desc("Weight of the branch unlikely to be taken (default = 1)")) ( "unlikely-branch-weight"  , cl::Hidden  , cl::init(1)  , cl::desc("Weight of the branch unlikely to be taken (default = 1)")    )

static

Referenced by getBranchWeight(), and llvm::misexpect::verifyMisExpect().