Parameters that control the generic loop unrolling transformation. More...

#include "llvm/Analysis/TargetTransformInfo.h"

Public Attributes
unsigned	Threshold
	The cost threshold for the unrolled loop.

unsigned	MaxPercentThresholdBoost
	If complete unrolling will reduce the cost of the loop, we will boost the Threshold by a certain percent to allow more aggressive complete unrolling.

unsigned	OptSizeThreshold
	The cost threshold for the unrolled loop when optimizing for size (set to UINT_MAX to disable).

unsigned	PartialThreshold
	The cost threshold for the unrolled loop, like Threshold, but used for partial/runtime unrolling (set to UINT_MAX to disable).

unsigned	PartialOptSizeThreshold
	The cost threshold for the unrolled loop when optimizing for size, like OptSizeThreshold, but used for partial/runtime unrolling (set to UINT_MAX to disable).

unsigned	Count
	A forced unrolling factor (the number of concatenated bodies of the original loop in the unrolled loop body).

unsigned	DefaultUnrollRuntimeCount
	Default unroll count for loops with run-time trip count.

unsigned	MaxCount

unsigned	MaxUpperBound
	Set the maximum upper bound of trip count.

unsigned	FullUnrollMaxCount
	Set the maximum unrolling factor for full unrolling.

unsigned	BEInsns

bool	Partial
	Allow partial unrolling (unrolling of loops to expand the size of the loop body, not only to eliminate small constant-trip-count loops).

bool	Runtime
	Allow runtime unrolling (unrolling of loops to expand the size of the loop body even when the number of loop iterations is not known at compile time).

bool	AllowRemainder
	Allow generation of a loop remainder (extra iterations after unroll).

bool	AllowExpensiveTripCount
	Allow emitting expensive instructions (such as divisions) when computing the trip count of a loop for runtime unrolling.

bool	Force
	Apply loop unroll on any kind of loop (mainly to loops that fail runtime unrolling).

bool	UpperBound
	Allow using trip count upper bound to unroll loops.

bool	UnrollRemainder
	Allow unrolling of all the iterations of the runtime loop remainder.

bool	UnrollAndJam
	Allow unroll and jam. Used to enable unroll and jam for the target.

unsigned	UnrollAndJamInnerLoopThreshold
	Threshold for unroll and jam, for inner loop size.

unsigned	MaxIterationsCountToAnalyze
	Don't allow loop unrolling to simulate more than this number of iterations when checking full unroll profitability.

bool	UnrollVectorizedLoop = false
	Don't disable runtime unroll for the loops which were vectorized.

unsigned	SCEVExpansionBudget
	Don't allow runtime unrolling if expanding the trip count takes more than SCEVExpansionBudget.

Detailed Description

Parameters that control the generic loop unrolling transformation.

Definition at line 530 of file TargetTransformInfo.h.

Member Data Documentation

◆ AllowExpensiveTripCount

bool llvm::TargetTransformInfo::UnrollingPreferences::AllowExpensiveTripCount

Allow emitting expensive instructions (such as divisions) when computing the trip count of a loop for runtime unrolling.

Definition at line 596 of file TargetTransformInfo.h.

Referenced by llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), llvm::PPCTTIImpl::getUnrollingPreferences(), llvm::SystemZTTIImpl::getUnrollingPreferences(), and tryToUnrollLoop().

◆ AllowRemainder

bool llvm::TargetTransformInfo::UnrollingPreferences::AllowRemainder

Allow generation of a loop remainder (extra iterations after unroll).

Definition at line 593 of file TargetTransformInfo.h.

Referenced by computeUnrollAndJamCount(), llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), shouldPartialUnroll(), shouldPragmaUnroll(), and tryToUnrollLoop().

◆ BEInsns

unsigned llvm::TargetTransformInfo::UnrollingPreferences::BEInsns

Definition at line 584 of file TargetTransformInfo.h.

Referenced by computeHeuristicUnrollFactor(), llvm::gatherUnrollingPreferences(), getUnrollAndJammedLoopSize(), llvm::UnrollCostEstimator::getUnrolledLoopSize(), llvm::BasicTTIImplBase< T >::getUnrollingPreferences(), llvm::AMDGPUTTIImpl::getUnrollingPreferences(), llvm::WebAssemblyTTIImpl::getUnrollingPreferences(), shouldPartialUnroll(), tryToUnrollAndJamLoop(), and tryToUnrollLoop().

◆ Count

unsigned llvm::TargetTransformInfo::UnrollingPreferences::Count

A forced unrolling factor (the number of concatenated bodies of the original loop in the unrolled loop body).

When set to 0, the unrolling transformation will select an unrolling factor based on the current cost threshold and other factors.

Definition at line 564 of file TargetTransformInfo.h.

Referenced by computeHeuristicUnrollFactor(), computeUnrollAndJamCount(), llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), getUnrollAndJammedLoopSize(), llvm::UnrollCostEstimator::getUnrolledLoopSize(), shouldPartialUnroll(), tryToUnrollAndJamLoop(), and tryToUnrollLoop().

◆ DefaultUnrollRuntimeCount

unsigned llvm::TargetTransformInfo::UnrollingPreferences::DefaultUnrollRuntimeCount

Default unroll count for loops with run-time trip count.

Definition at line 566 of file TargetTransformInfo.h.

Referenced by llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), getAppleRuntimeUnrollPreferences(), llvm::AArch64TTIImpl::getUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), llvm::SystemZTTIImpl::getUnrollingPreferences(), and shouldPartialUnroll().

◆ Force

bool llvm::TargetTransformInfo::UnrollingPreferences::Force

Apply loop unroll on any kind of loop (mainly to loops that fail runtime unrolling).

Definition at line 599 of file TargetTransformInfo.h.

Referenced by computeHeuristicUnrollFactor(), computeUnrollAndJamCount(), llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), llvm::RISCVTTIImpl::getUnrollingPreferences(), llvm::SystemZTTIImpl::getUnrollingPreferences(), and tryToUnrollLoop().

◆ FullUnrollMaxCount

unsigned llvm::TargetTransformInfo::UnrollingPreferences::FullUnrollMaxCount

Set the maximum unrolling factor for full unrolling.

Like MaxCount, but applies even if full unrolling is selected. This allows a target to fall back to Partial unrolling if full unrolling is above FullUnrollMaxCount.

Definition at line 579 of file TargetTransformInfo.h.

Referenced by llvm::gatherUnrollingPreferences(), llvm::SystemZTTIImpl::getUnrollingPreferences(), and shouldFullUnroll().

◆ MaxCount

unsigned llvm::TargetTransformInfo::UnrollingPreferences::MaxCount

Definition at line 571 of file TargetTransformInfo.h.

Referenced by llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), getFalkorUnrollingPreferences(), llvm::AMDGPUTTIImpl::getUnrollingPreferences(), llvm::SystemZTTIImpl::getUnrollingPreferences(), and shouldPartialUnroll().

◆ MaxIterationsCountToAnalyze

unsigned llvm::TargetTransformInfo::UnrollingPreferences::MaxIterationsCountToAnalyze

Don't allow loop unrolling to simulate more than this number of iterations when checking full unroll profitability.

Definition at line 613 of file TargetTransformInfo.h.

Referenced by llvm::gatherUnrollingPreferences(), llvm::AMDGPUTTIImpl::getUnrollingPreferences(), and shouldFullUnroll().

◆ MaxPercentThresholdBoost

unsigned llvm::TargetTransformInfo::UnrollingPreferences::MaxPercentThresholdBoost

If complete unrolling will reduce the cost of the loop, we will boost the Threshold by a certain percent to allow more aggressive complete unrolling.

This value provides the maximum boost percentage that we can apply to Threshold (The value should be no less than 100). BoostedThreshold = Threshold * min(RolledCost / UnrolledCost, MaxPercentThresholdBoost / 100) E.g. if complete unrolling reduces the loop execution time by 50% then we boost the threshold by the factor of 2x. If unrolling is not expected to reduce the running time, then we do not increase the threshold.

Definition at line 549 of file TargetTransformInfo.h.

Referenced by llvm::gatherUnrollingPreferences(), and shouldFullUnroll().

◆ MaxUpperBound

unsigned llvm::TargetTransformInfo::UnrollingPreferences::MaxUpperBound

Set the maximum upper bound of trip count.

Allowing the MaxUpperBound to be overrided by a target gives more flexiblity on certain cases. By default, MaxUpperBound uses UnrollMaxUpperBound which value is 8.

Definition at line 575 of file TargetTransformInfo.h.

Referenced by llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), and shouldPragmaUnroll().

◆ OptSizeThreshold

unsigned llvm::TargetTransformInfo::UnrollingPreferences::OptSizeThreshold

The cost threshold for the unrolled loop when optimizing for size (set to UINT_MAX to disable).

Definition at line 552 of file TargetTransformInfo.h.

Referenced by computeHeuristicUnrollFactor(), llvm::gatherUnrollingPreferences(), llvm::BasicTTIImplBase< T >::getUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), llvm::RISCVTTIImpl::getUnrollingPreferences(), and llvm::WebAssemblyTTIImpl::getUnrollingPreferences().

◆ Partial

bool llvm::TargetTransformInfo::UnrollingPreferences::Partial

Allow partial unrolling (unrolling of loops to expand the size of the loop body, not only to eliminate small constant-trip-count loops).

Definition at line 587 of file TargetTransformInfo.h.

◆ PartialOptSizeThreshold

unsigned llvm::TargetTransformInfo::UnrollingPreferences::PartialOptSizeThreshold

The cost threshold for the unrolled loop when optimizing for size, like OptSizeThreshold, but used for partial/runtime unrolling (set to UINT_MAX to disable).

Definition at line 559 of file TargetTransformInfo.h.

Referenced by computeHeuristicUnrollFactor(), llvm::gatherUnrollingPreferences(), llvm::BasicTTIImplBase< T >::getUnrollingPreferences(), llvm::AArch64TTIImpl::getUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), llvm::RISCVTTIImpl::getUnrollingPreferences(), and llvm::WebAssemblyTTIImpl::getUnrollingPreferences().

◆ PartialThreshold

unsigned llvm::TargetTransformInfo::UnrollingPreferences::PartialThreshold

The cost threshold for the unrolled loop, like Threshold, but used for partial/runtime unrolling (set to UINT_MAX to disable).

Definition at line 555 of file TargetTransformInfo.h.

Referenced by computeHeuristicUnrollFactor(), llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), llvm::BasicTTIImplBase< T >::getUnrollingPreferences(), llvm::AArch64TTIImpl::getUnrollingPreferences(), llvm::AMDGPUTTIImpl::getUnrollingPreferences(), llvm::NVPTXTTIImpl::getUnrollingPreferences(), llvm::SystemZTTIImpl::getUnrollingPreferences(), llvm::WebAssemblyTTIImpl::getUnrollingPreferences(), shouldPartialUnroll(), and tryToUnrollLoop().

◆ Runtime

bool llvm::TargetTransformInfo::UnrollingPreferences::Runtime

Allow runtime unrolling (unrolling of loops to expand the size of the loop body even when the number of loop iterations is not known at compile time).

Definition at line 591 of file TargetTransformInfo.h.

◆ SCEVExpansionBudget

unsigned llvm::TargetTransformInfo::UnrollingPreferences::SCEVExpansionBudget

Don't allow runtime unrolling if expanding the trip count takes more than SCEVExpansionBudget.

Definition at line 618 of file TargetTransformInfo.h.

Referenced by llvm::gatherUnrollingPreferences(), getAppleRuntimeUnrollPreferences(), and tryToUnrollLoop().

◆ Threshold

unsigned llvm::TargetTransformInfo::UnrollingPreferences::Threshold

The cost threshold for the unrolled loop.

Should be relative to the getInstructionCost values returned by this API, and the expectation is that the unrolled loop's instructions when run through that interface should not exceed this cost. However, this is only an estimate. Also, specific loops may be unrolled even with a cost above this threshold if deemed profitable. Set this to UINT_MAX to disable the loop body cost restriction.

Definition at line 538 of file TargetTransformInfo.h.

Referenced by computeHeuristicUnrollFactor(), computeUnrollAndJamCount(), llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), llvm::AMDGPUTTIImpl::getUnrollingPreferences(), llvm::NVPTXTTIImpl::getUnrollingPreferences(), shouldFullUnroll(), shouldPragmaUnroll(), and tryToUnrollLoop().

◆ UnrollAndJam

bool llvm::TargetTransformInfo::UnrollingPreferences::UnrollAndJam

Allow unroll and jam. Used to enable unroll and jam for the target.

Definition at line 605 of file TargetTransformInfo.h.

Referenced by llvm::gatherUnrollingPreferences(), llvm::AArch64TTIImpl::getUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), llvm::RISCVTTIImpl::getUnrollingPreferences(), and tryToUnrollAndJamLoop().

◆ UnrollAndJamInnerLoopThreshold

unsigned llvm::TargetTransformInfo::UnrollingPreferences::UnrollAndJamInnerLoopThreshold

Threshold for unroll and jam, for inner loop size.

The 'Threshold' value above is used during unroll and jam for the outer loop size. This value is used in the same manner to limit the size of the inner loop.

Definition at line 610 of file TargetTransformInfo.h.

Referenced by computeUnrollAndJamCount(), llvm::gatherUnrollingPreferences(), llvm::AArch64TTIImpl::getUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), and tryToUnrollAndJamLoop().

◆ UnrollRemainder

bool llvm::TargetTransformInfo::UnrollingPreferences::UnrollRemainder

Allow unrolling of all the iterations of the runtime loop remainder.

Definition at line 603 of file TargetTransformInfo.h.

Referenced by llvm::gatherUnrollingPreferences(), llvm::AArch64TTIImpl::getUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), llvm::RISCVTTIImpl::getUnrollingPreferences(), tryToUnrollAndJamLoop(), and tryToUnrollLoop().

◆ UnrollVectorizedLoop

bool llvm::TargetTransformInfo::UnrollingPreferences::UnrollVectorizedLoop = false

Don't disable runtime unroll for the loops which were vectorized.

Definition at line 615 of file TargetTransformInfo.h.

Referenced by llvm::LoopVectorizationPlanner::executePlan(), and llvm::AMDGPUTTIImpl::getUnrollingPreferences().

◆ UpperBound

bool llvm::TargetTransformInfo::UnrollingPreferences::UpperBound

Allow using trip count upper bound to unroll loops.

Definition at line 601 of file TargetTransformInfo.h.

Referenced by llvm::computeUnrollCount(), llvm::gatherUnrollingPreferences(), llvm::BasicTTIImplBase< T >::getUnrollingPreferences(), llvm::AArch64TTIImpl::getUnrollingPreferences(), llvm::ARMTTIImpl::getUnrollingPreferences(), llvm::RISCVTTIImpl::getUnrollingPreferences(), and llvm::WebAssemblyTTIImpl::getUnrollingPreferences().

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

include/llvm/Analysis/TargetTransformInfo.h

Public Attributes