Skip to content

[UnrollAndJam] Do not preserve loop nests if a loop was fully unrolled. #133510

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
Mar 29, 2025
+46 −5
Merged

[UnrollAndJam] Do not preserve loop nests if a loop was fully unrolled. #133510

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
15 changes: 10 additions & 5 deletions llvm/lib/Transforms/Scalar/LoopUnrollAndJamPass.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -425,7 +425,7 @@ static bool tryToUnrollAndJamLoop(LoopNest &LN, DominatorTree &DT, LoopInfo &LI,
const TargetTransformInfo &TTI,
AssumptionCache &AC, DependenceInfo &DI,
OptimizationRemarkEmitter &ORE, int OptLevel,
LPMUpdater &U) {
LPMUpdater &U, bool &AnyLoopRemoved) {
bool DidSomething = false;
ArrayRef<Loop *> Loops = LN.getLoops();
Loop *OutmostLoop = &LN.getOutermostLoop();
Expand All @@ -441,8 +441,11 @@ static bool tryToUnrollAndJamLoop(LoopNest &LN, DominatorTree &DT, LoopInfo &LI,
tryToUnrollAndJamLoop(L, DT, &LI, SE, TTI, AC, DI, ORE, OptLevel);
if (Result != LoopUnrollResult::Unmodified)
DidSomething = true;
if (L == OutmostLoop && Result == LoopUnrollResult::FullyUnrolled)
U.markLoopAsDeleted(*L, LoopName);
if (Result == LoopUnrollResult::FullyUnrolled) {
if (L == OutmostLoop)
U.markLoopAsDeleted(*L, LoopName);
AnyLoopRemoved = true;
}
}

return DidSomething;
Expand All @@ -457,11 +460,13 @@ PreservedAnalyses LoopUnrollAndJamPass::run(LoopNest &LN,
DependenceInfo DI(&F, &AR.AA, &AR.SE, &AR.LI);
OptimizationRemarkEmitter ORE(&F);

bool AnyLoopRemoved = false;
if (!tryToUnrollAndJamLoop(LN, AR.DT, AR.LI, AR.SE, AR.TTI, AR.AC, DI, ORE,
OptLevel, U))
OptLevel, U, AnyLoopRemoved))
return PreservedAnalyses::all();

auto PA = getLoopPassPreservedAnalyses();
PA.preserve<LoopNestAnalysis>();
if (!AnyLoopRemoved)
PA.preserve<LoopNestAnalysis>();
return PA;
}
36 changes: 36 additions & 0 deletions llvm/test/Transforms/LoopUnrollAndJam/delete_middle_loop.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt -passes="loop(invalidate<all>,loop-unroll-and-jam,loop-unroll-and-jam)" -allow-unroll-and-jam -unroll-and-jam-count=4 < %s -S | FileCheck %s

; This test completely unrolls the middle loop out of a 3-deep loop nest.

define i16 @test_it() {
; CHECK-LABEL: define i16 @test_it() {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br label %[[FOR_COND:.*]]
; CHECK: [[FOR_COND_LOOPEXIT:.*]]:
; CHECK-NEXT: br label %[[FOR_COND]]
; CHECK: [[FOR_COND]]:
; CHECK-NEXT: br label %[[DO_BODY2:.*]]
; CHECK: [[DO_BODY2]]:
; CHECK-NEXT: br label %[[WHILE_COND3:.*]]
; CHECK: [[WHILE_COND3]]:
; CHECK-NEXT: br i1 true, label %[[DO_COND:.*]], label %[[WHILE_COND3]]
; CHECK: [[DO_COND]]:
; CHECK-NEXT: br label %[[FOR_COND_LOOPEXIT]]
;
entry:
br label %for.cond

for.cond: ; preds = %do.cond, %entry
br label %do.body2

do.body2: ; preds = %do.cond, %for.cond
br label %while.cond3

while.cond3: ; preds = %while.cond3, %do.body2
br i1 true, label %do.cond, label %while.cond3

do.cond: ; preds = %while.cond3
br i1 true, label %for.cond, label %do.body2
}