LLVM: llvm::DivergenceAnalysis Class Reference

LLVM 8.0.1

Generic divergence analysis for reducible CFGs. More...

#include "llvm/Analysis/DivergenceAnalysis.h"

Public Member Functions
	DivergenceAnalysis (const Function &F, const Loop *RegionLoop, const DominatorTree &DT, const LoopInfo &LI, SyncDependenceAnalysis &SDA, bool IsLCSSAForm)
	This instance will analyze the whole function `F` or the loop `RegionLoop`. More...

const Loop *	getRegionLoop () const
	The loop that defines the analyzed region (if any). More...

const Function &	getFunction () const

bool	inRegion (const BasicBlock &BB) const
	Whether `BB` is part of the region. More...

bool	inRegion (const Instruction &I) const
	Whether `I` is part of the region. More...

void	addUniformOverride (const Value &UniVal)
	Mark `UniVal` as a value that is always uniform. More...

void	markDivergent (const Value &DivVal)
	Mark `DivVal` as a value that is always divergent. More...

void	compute ()
	Propagate divergence to all instructions in the region. More...

bool	hasDetectedDivergence () const
	Whether any value was marked or analyzed to be divergent. More...

bool	isAlwaysUniform (const Value &Val) const
	Whether `Val` will always return a uniform value regardless of its operands. More...

bool	isDivergent (const Value &Val) const
	Whether `Val` is a divergent value. More...

void	print (raw_ostream &OS, const Module *) const

Detailed Description

Generic divergence analysis for reducible CFGs.

This analysis propagates divergence in a data-parallel context from sources of divergence to all users. It requires reducible CFGs. All assignments should be in SSA form.

Definition at line 38 of file DivergenceAnalysis.h.

Constructor & Destructor Documentation

◆ DivergenceAnalysis()

DivergenceAnalysis::DivergenceAnalysis	(	const Function &	F,
		const Loop *	RegionLoop,
		const DominatorTree &	DT,
		const LoopInfo &	LI,
		SyncDependenceAnalysis &	SDA,
		bool	IsLCSSAForm
	)

This instance will analyze the whole function F or the loop RegionLoop.

Parameters

RegionLoop	if non-null the analysis is restricted to `RegionLoop`. Otherwise the whole function is analyzed.
IsLCSSAForm	whether the analysis may assume that the IR in the region in in LCSSA form.

Definition at line 95 of file DivergenceAnalysis.cpp.

Member Function Documentation

◆ addUniformOverride()

void DivergenceAnalysis::addUniformOverride ( const Value & UniVal )

Mark UniVal as a value that is always uniform.

Definition at line 107 of file DivergenceAnalysis.cpp.

References assert(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::dyn_cast(), llvm::PHINode::getIncomingValue(), llvm::LoopInfoBase< BlockT, LoopT >::getLoopFor(), llvm::PHINode::getNumIncomingValues(), llvm::Instruction::getNumSuccessors(), llvm::Instruction::getParent(), llvm::LoopBase< BlockT, LoopT >::getParentLoop(), llvm::PHINode::hasConstantOrUndefValue(), I, llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::insert(), isDivergent(), llvm_unreachable, and llvm::User::operands().

Referenced by getFunction(), and llvm::GPUDivergenceAnalysis::GPUDivergenceAnalysis().

◆ compute()

void DivergenceAnalysis::compute ( )

Propagate divergence to all instructions in the region.

Divergence is seeded by calls to markDivergent.

Definition at line 364 of file DivergenceAnalysis.cpp.

References llvm::dyn_cast(), I, isAlwaysUniform(), isDivergent(), llvm::Instruction::isTerminator(), and markDivergent().

Referenced by getFunction(), and llvm::GPUDivergenceAnalysis::GPUDivergenceAnalysis().

◆ getFunction()

const Function& llvm::DivergenceAnalysis::getFunction ( ) const

inline

Definition at line 53 of file DivergenceAnalysis.h.

References addUniformOverride(), compute(), I, inRegion(), and markDivergent().

Referenced by llvm::GPUDivergenceAnalysis::getFunction(), and llvm::GPUDivergenceAnalysis::print().

◆ getRegionLoop()

const Loop* llvm::DivergenceAnalysis::getRegionLoop ( ) const

inline

The loop that defines the analyzed region (if any).

Definition at line 52 of file DivergenceAnalysis.h.

◆ hasDetectedDivergence()

bool llvm::DivergenceAnalysis::hasDetectedDivergence ( ) const

inline

Whether any value was marked or analyzed to be divergent.

Definition at line 71 of file DivergenceAnalysis.h.

References llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::empty(), isAlwaysUniform(), isDivergent(), and print().

Referenced by llvm::GPUDivergenceAnalysis::hasDivergence().

◆ inRegion() [1/2]

bool DivergenceAnalysis::inRegion ( const BasicBlock & BB ) const

Whether BB is part of the region.

Definition at line 184 of file DivergenceAnalysis.cpp.

References assert(), llvm::LoopBase< BlockT, LoopT >::contains(), llvm::dbgs(), llvm::DominatorTree::dominates(), llvm::dyn_cast(), llvm::LoopBase< BlockT, LoopT >::getHeader(), llvm::LoopInfoBase< BlockT, LoopT >::getLoopFor(), llvm::Value::getName(), llvm::Loop::getName(), llvm::Instruction::getParent(), llvm::BasicBlock::getParent(), llvm::LoopBase< BlockT, LoopT >::getParentLoop(), llvm::detail::DenseSetImpl< ValueT, DenseMap< ValueT, detail::DenseSetEmpty, ValueInfoT, detail::DenseSetPair< ValueT > >, ValueInfoT >::insert(), isAlwaysUniform(), isDivergent(), llvm::SyncDependenceAnalysis::join_blocks(), LLVM_DEBUG, markDivergent(), llvm::User::operands(), llvm::BasicBlock::phis(), llvm::successors(), and llvm::Value::users().

Referenced by getFunction(), and inRegion().

◆ inRegion() [2/2]

bool DivergenceAnalysis::inRegion ( const Instruction & I ) const

Whether I is part of the region.

Definition at line 180 of file DivergenceAnalysis.cpp.

References llvm::Instruction::getParent(), and inRegion().

◆ isAlwaysUniform()

bool DivergenceAnalysis::isAlwaysUniform ( const Value & Val ) const

Whether Val will always return a uniform value regardless of its operands.

Definition at line 408 of file DivergenceAnalysis.cpp.

References llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::end(), and llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::find().

Referenced by compute(), hasDetectedDivergence(), inRegion(), and markDivergent().

◆ isDivergent()

bool DivergenceAnalysis::isDivergent ( const Value & Val ) const

Whether Val is a divergent value.

Definition at line 412 of file DivergenceAnalysis.cpp.

References llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::end(), and llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::find().

Referenced by addUniformOverride(), compute(), llvm::GPUDivergenceAnalysis::getFunction(), hasDetectedDivergence(), inRegion(), llvm::GPUDivergenceAnalysis::isDivergent(), llvm::GPUDivergenceAnalysis::isUniform(), and print().

◆ markDivergent()

void DivergenceAnalysis::markDivergent ( const Value & DivVal )

Mark DivVal as a value that is always divergent.

Definition at line 101 of file DivergenceAnalysis.cpp.

References assert(), llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::insert(), and isAlwaysUniform().

Referenced by compute(), getFunction(), llvm::GPUDivergenceAnalysis::GPUDivergenceAnalysis(), and inRegion().

◆ print()

void DivergenceAnalysis::print	(	raw_ostream &	OS,
		const Module *
	)		const

Definition at line 416 of file DivergenceAnalysis.cpp.

References llvm::detail::DenseSetImpl< ValueT, MapTy, ValueInfoT >::empty(), llvm::instructions(), and isDivergent().

Referenced by hasDetectedDivergence(), llvm::GPUDivergenceAnalysis::isUniform(), and llvm::GPUDivergenceAnalysis::print().

The documentation for this class was generated from the following files:

include/llvm/Analysis/DivergenceAnalysis.h
lib/Analysis/DivergenceAnalysis.cpp