Skip to content

Make 'UnrollMaxUpperBound' to be overridable by target. #76029

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Dec 21, 2023
Merged

Make 'UnrollMaxUpperBound' to be overridable by target. #76029

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 4 additions & 0 deletions llvm/include/llvm/Analysis/TargetTransformInfo.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -560,6 +560,10 @@ class TargetTransformInfo {
// (set to UINT_MAX to disable). This does not apply in cases where the
// loop is being fully unrolled.
unsigned MaxCount;
/// 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.
unsigned MaxUpperBound;
/// 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.
Expand Down
9 changes: 6 additions & 3 deletions llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -200,6 +200,7 @@ TargetTransformInfo::UnrollingPreferences llvm::gatherUnrollingPreferences(
UP.Count = 0;
UP.DefaultUnrollRuntimeCount = 8;
UP.MaxCount = std::numeric_limits<unsigned>::max();
UP.MaxUpperBound = UnrollMaxUpperBound;
UP.FullUnrollMaxCount = std::numeric_limits<unsigned>::max();
UP.BEInsns = 2;
UP.Partial = false;
Expand Down Expand Up @@ -237,6 +238,8 @@ TargetTransformInfo::UnrollingPreferences llvm::gatherUnrollingPreferences(
UP.MaxPercentThresholdBoost = UnrollMaxPercentThresholdBoost;
if (UnrollMaxCount.getNumOccurrences() > 0)
UP.MaxCount = UnrollMaxCount;
if (UnrollMaxUpperBound.getNumOccurrences() > 0)
UP.MaxUpperBound = UnrollMaxUpperBound;
if (UnrollFullMaxCount.getNumOccurrences() > 0)
UP.FullUnrollMaxCount = UnrollFullMaxCount;
if (UnrollAllowPartial.getNumOccurrences() > 0)
Expand Down Expand Up @@ -777,7 +780,7 @@ shouldPragmaUnroll(Loop *L, const PragmaInfo &PInfo,
return TripCount;

if (PInfo.PragmaEnableUnroll && !TripCount && MaxTripCount &&
MaxTripCount <= UnrollMaxUpperBound)
MaxTripCount <= UP.MaxUpperBound)
return MaxTripCount;

// if didn't return until here, should continue to other priorties
Expand Down Expand Up @@ -952,7 +955,7 @@ bool llvm::computeUnrollCount(
// cost of exact full unrolling. As such, if we have an exact count and
// found it unprofitable, we'll never chose to bounded unroll.
if (!TripCount && MaxTripCount && (UP.UpperBound || MaxOrZero) &&
MaxTripCount <= UnrollMaxUpperBound) {
MaxTripCount <= UP.MaxUpperBound) {
UP.Count = MaxTripCount;
if (auto UnrollFactor = shouldFullUnroll(L, TTI, DT, SE, EphValues,
MaxTripCount, UCE, UP)) {
Expand Down Expand Up @@ -1026,7 +1029,7 @@ bool llvm::computeUnrollCount(
}

// Don't unroll a small upper bound loop unless user or TTI asked to do so.
if (MaxTripCount && !UP.Force && MaxTripCount < UnrollMaxUpperBound) {
if (MaxTripCount && !UP.Force && MaxTripCount < UP.MaxUpperBound) {
UP.Count = 0;
return false;
}
Expand Down