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

#include "llvm/CodeGen/GlobalISel/RegisterBankInfo.h"

Collaboration diagram for llvm::RegisterBankInfo::ValueMapping:

Public Member Functions
	ValueMapping ()
	The default constructor creates an invalid (isValid() == false) instance. More...

	ValueMapping (const PartialMapping *BreakDown, unsigned NumBreakDowns)
	Initialize a ValueMapping with the given parameter. More...

const PartialMapping *	begin () const
	Iterators through the PartialMappings. More...

const PartialMapping *	end () const

bool	isValid () const
	Check if this ValueMapping is valid. More...

bool	verify (unsigned MeaningfulBitWidth) const
	Verify that this mapping makes sense for a value of `MeaningfulBitWidth`. More...

void	dump () const
	Print this on dbgs() stream. More...

void	print (raw_ostream &OS) const
	Print this on `OS`;. More...

Public Attributes
const PartialMapping *	BreakDown
	How the value is broken down between the different register banks. More...

unsigned	NumBreakDowns
	Number of partial mapping to break down this value. More...

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 143 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 152 of file RegisterBankInfo.h.

◆ ValueMapping() [2/2]

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

inline

Initialize a ValueMapping with the given parameter.

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

Definition at line 157 of file RegisterBankInfo.h.

Member Function Documentation

◆ begin()

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

inline

Iterators through the PartialMappings.

Definition at line 161 of file RegisterBankInfo.h.

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

◆ dump()

LLVM_DUMP_METHOD void RegisterBankInfo::ValueMapping::dump ( ) const

Print this on dbgs() stream.

Definition at line 531 of file RegisterBankInfo.cpp.

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

◆ end()

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

inline

Definition at line 162 of file RegisterBankInfo.h.

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

◆ isValid()

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

inline

Check if this ValueMapping is valid.

Definition at line 165 of file RegisterBankInfo.h.

References llvm::RegisterBankInfo::PartialMapping::dump(), llvm::RegisterBankInfo::PartialMapping::print(), and llvm::RegisterBankInfo::PartialMapping::verify().

◆ print()

void RegisterBankInfo::ValueMapping::print ( raw_ostream & OS ) const

Print this on OS;.

Definition at line 537 of file RegisterBankInfo.cpp.

◆ verify()

bool RegisterBankInfo::ValueMapping::verify ( unsigned 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 501 of file RegisterBankInfo.cpp.

References assert(), llvm::APInt::getBitsSet(), llvm::RegisterBankInfo::PartialMapping::getHighBitIdx(), llvm::APInt::isAllOnesValue(), llvm::max(), 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 145 of file RegisterBankInfo.h.

Referenced by llvm::ARM::checkValueMapping(), and llvm::RegBankSelect::getAnalysisUsage().

◆ NumBreakDowns

unsigned llvm::RegisterBankInfo::ValueMapping::NumBreakDowns

Number of partial mapping to break down this value.

Definition at line 148 of file RegisterBankInfo.h.

Referenced by llvm::RegisterBankInfo::applyDefaultMapping(), llvm::ARM::checkValueMapping(), llvm::RegBankSelect::getAnalysisUsage(), llvm::RegisterBankInfo::OperandsMapper::getVRegs(), and llvm::RegisterBankInfo::OperandsMapper::OperandsMapper().

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

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

Public Member Functions

Public Attributes

Detailed Description

Constructor & Destructor Documentation

◆ ValueMapping() [1/2]

◆ ValueMapping() [2/2]

Member Function Documentation

◆ begin()

◆ dump()

◆ end()

◆ isValid()

◆ print()

◆ verify()

Member Data Documentation

◆ BreakDown

◆ NumBreakDowns