llvm::RegisterBankInfo::ValueMapping Struct Reference

Helper struct that represents how a value is mapped through different register banks. More...

#include "llvm/CodeGen/RegisterBankInfo.h"

Public Member Functions
	ValueMapping ()
	The default constructor creates an invalid (isValid() == false) instance.
constexpr	ValueMapping (const PartialMapping *BreakDown, unsigned NumBreakDowns)
	Initialize a ValueMapping with the given parameter.
const PartialMapping *	begin () const
	Iterators through the PartialMappings.
const PartialMapping *	end () const
bool	partsAllUniform () const
bool	isValid () const
	Check if this ValueMapping is valid.
bool	verify (const RegisterBankInfo &RBI, TypeSize MeaningfulBitWidth) const
	Verify that this mapping makes sense for a value of MeaningfulBitWidth.
void	dump () const
	Print this on dbgs() stream.
void	print (raw_ostream &OS) const
	Print this on OS;.

Public Attributes
const PartialMapping *	BreakDown
	How the value is broken down between the different register banks.
unsigned	NumBreakDowns
	Number of partial mapping to break down this value.

Detailed Description

Helper struct that represents how a value is mapped through different register banks.

Note

: So far we do not have any users of the complex mappings (mappings with more than one partial mapping), but when we do, we would have needed to duplicate partial mappings. The alternative could be to use an array of pointers of partial mapping (i.e., PartialMapping **BreakDown) and duplicate the pointers instead.

E.g., Let say we have a 32-bit add and a <2 x 32-bit> vadd. We can expand the <2 x 32-bit> add into 2 x 32-bit add.

Currently the TableGen-like file would look like:

PartialMapping[] = {
/*32-bit add*/      {0, 32, GPR}, // Scalar entry repeated for first
                                  // vec elt.
/*2x32-bit add*/    {0, 32, GPR}, {32, 32, GPR},
/*<2x32-bit> vadd*/ {0, 64, VPR}
}; // PartialMapping duplicated.
 
ValueMapping[] {
  /*plain 32-bit add*/       {&PartialMapping[0], 1},
  /*expanded vadd on 2xadd*/ {&PartialMapping[1], 2},
  /*plain <2x32-bit> vadd*/  {&PartialMapping[3], 1}
};

With the array of pointer, we would have:

PartialMapping[] = {
/*32-bit add lower */ { 0, 32, GPR},
/*32-bit add upper */ {32, 32, GPR},
/*<2x32-bit> vadd */  { 0, 64, VPR}
}; // No more duplication.
 
BreakDowns[] = {
/*AddBreakDown*/   &PartialMapping[0],
/*2xAddBreakDown*/ &PartialMapping[0], &PartialMapping[1],
/*VAddBreakDown*/  &PartialMapping[2]
}; // Addresses of PartialMapping duplicated (smaller).
 
ValueMapping[] {
  /*plain 32-bit add*/       {&BreakDowns[0], 1},
  /*expanded vadd on 2xadd*/ {&BreakDowns[1], 2},
  /*plain <2x32-bit> vadd*/  {&BreakDowns[3], 1}
};

Given that a PartialMapping is actually small, the code size impact is actually a degradation. Moreover the compile time will be hit by the additional indirection. If PartialMapping gets bigger we may reconsider.

Definition at line 146 of file RegisterBankInfo.h.

Constructor & Destructor Documentation

ValueMapping() [1/2]

llvm::RegisterBankInfo::ValueMapping::ValueMapping ( )

inline

The default constructor creates an invalid (isValid() == false) instance.

Definition at line 155 of file RegisterBankInfo.h.

ValueMapping() [2/2]

constexpr llvm::RegisterBankInfo::ValueMapping::ValueMapping ( const PartialMapping *  BreakDown, unsigned  NumBreakDowns  )

inlineconstexpr

Initialize a ValueMapping with the given parameter.

BreakDown needs to have a life time at least as long as this instance.

Definition at line 160 of file RegisterBankInfo.h.

Member Function Documentation

begin()

const PartialMapping * llvm::RegisterBankInfo::ValueMapping::begin ( ) const

inline

Iterators through the PartialMappings.

Definition at line 165 of file RegisterBankInfo.h.

References BreakDown.

Referenced by llvm::RegisterBankInfo::OperandsMapper::createVRegs().

dump()

LLVM_DUMP_METHOD void RegisterBankInfo::ValueMapping::dump

(

)

const

Print this on dbgs() stream.

Definition at line 587 of file RegisterBankInfo.cpp.

References llvm::dbgs(), and llvm::print().

end()

const PartialMapping * llvm::RegisterBankInfo::ValueMapping::end ( ) const

inline

Definition at line 166 of file RegisterBankInfo.h.

References BreakDown, and NumBreakDowns.

Referenced by llvm::RegisterBankInfo::OperandsMapper::createVRegs().

isValid()

bool llvm::RegisterBankInfo::ValueMapping::isValid ( ) const

inline

Check if this ValueMapping is valid.

Definition at line 173 of file RegisterBankInfo.h.

References BreakDown, and NumBreakDowns.

partsAllUniform()

bool RegisterBankInfo::ValueMapping::partsAllUniform

(

)

const

Returns

true if all partial mappings are the same size and register bank.

Definition at line 542 of file RegisterBankInfo.cpp.

References llvm::First.

Referenced by llvm::RegBankSelect::repairReg().

print()

void RegisterBankInfo::ValueMapping::print

(

raw_ostream &

OS

)

const

Print this on OS;.

Definition at line 593 of file RegisterBankInfo.cpp.

References OS.

Referenced by llvm::operator<<().

verify()

bool RegisterBankInfo::ValueMapping::verify	(	const RegisterBankInfo &	RBI,
		TypeSize	MeaningfulBitWidth
	)		const

Verify that this mapping makes sense for a value of MeaningfulBitWidth.

Note

This method does not check anything when assertions are disabled.

Returns

True is the check was successful.

Definition at line 555 of file RegisterBankInfo.cpp.

References assert(), llvm::APInt::getBitsSet(), llvm::RegisterBankInfo::PartialMapping::getHighBitIdx(), llvm::APInt::isAllOnes(), llvm::details::FixedOrScalableQuantity< LeafTy, ValueTy >::isScalable(), llvm::RegisterBankInfo::PartialMapping::StartIdx, and llvm::RegisterBankInfo::PartialMapping::verify().

Referenced by llvm::RegisterBankInfo::InstructionMapping::verify().

Member Data Documentation

BreakDown

const PartialMapping* llvm::RegisterBankInfo::ValueMapping::BreakDown

How the value is broken down between the different register banks.

Definition at line 148 of file RegisterBankInfo.h.

Referenced by llvm::RegBankSelect::applyMapping(), llvm::AMDGPURegisterBankInfo::applyMappingBFE(), llvm::AMDGPURegisterBankInfo::applyMappingImpl(), llvm::AMDGPURegisterBankInfo::applyMappingLoad(), llvm::AMDGPURegisterBankInfo::applyMappingSBufferLoad(), llvm::RegBankSelect::assignmentMatch(), begin(), llvm::ARM::checkValueMapping(), end(), llvm::AMDGPURegisterBankInfo::getBreakDownCost(), llvm::RegBankSelect::getRepairCost(), isValid(), and llvm::RegBankSelect::repairReg().

NumBreakDowns

unsigned llvm::RegisterBankInfo::ValueMapping::NumBreakDowns

Number of partial mapping to break down this value.

Definition at line 151 of file RegisterBankInfo.h.

Referenced by llvm::RegisterBankInfo::applyDefaultMapping(), llvm::RegBankSelect::applyMapping(), llvm::RegBankSelect::assignmentMatch(), llvm::ARM::checkValueMapping(), end(), llvm::AMDGPURegisterBankInfo::getBreakDownCost(), llvm::RegBankSelect::getRepairCost(), llvm::RegisterBankInfo::OperandsMapper::getVRegs(), isValid(), llvm::RegBankSelect::repairReg(), and llvm::RegBankSelect::tryAvoidingSplit().

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

• include/llvm/CodeGen/RegisterBankInfo.h
• lib/CodeGen/RegisterBankInfo.cpp