[llvm] 24b9775 - [LoopPeel] Remove known trip count restriction when peeling last. (#140792)
via llvm-commits
llvm-commits at lists.llvm.org
Mon May 26 12:08:06 PDT 2025
Author: Florian Hahn
Date: 2025-05-26T20:08:02+01:00
New Revision: 24b97756decb7bf0e26dcf0e30a7a9aaf27f417c
URL: https://github.com/llvm/llvm-project/commit/24b97756decb7bf0e26dcf0e30a7a9aaf27f417c
DIFF: https://github.com/llvm/llvm-project/commit/24b97756decb7bf0e26dcf0e30a7a9aaf27f417c.diff
LOG: [LoopPeel] Remove known trip count restriction when peeling last. (#140792)
Remove the restriction that the loop must be known to execute at least 2
iterations when peeling the last iteration. If we cannot prove at least
2 iterations are executed, a check and branch to skip the peeled loop is
inserted.
PR: https://github.com/llvm/llvm-project/pull/140792
Added:
Modified:
llvm/include/llvm/Transforms/Utils/LoopPeel.h
llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
llvm/lib/Transforms/Utils/LoopPeel.cpp
llvm/test/Transforms/LoopUnroll/peel-last-iteration-expansion-cost.ll
llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-constant-trip-count.ll
llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-variable-trip-count.ll
llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/Transforms/Utils/LoopPeel.h b/llvm/include/llvm/Transforms/Utils/LoopPeel.h
index dd59a9c766e45..49dbc9aa1f2a9 100644
--- a/llvm/include/llvm/Transforms/Utils/LoopPeel.h
+++ b/llvm/include/llvm/Transforms/Utils/LoopPeel.h
@@ -44,7 +44,8 @@ gatherPeelingPreferences(Loop *L, ScalarEvolution &SE,
void computePeelCount(Loop *L, unsigned LoopSize,
TargetTransformInfo::PeelingPreferences &PP,
unsigned TripCount, DominatorTree &DT,
- ScalarEvolution &SE, AssumptionCache *AC = nullptr,
+ ScalarEvolution &SE, const TargetTransformInfo &TTI,
+ AssumptionCache *AC = nullptr,
unsigned Threshold = UINT_MAX);
} // end namespace llvm
diff --git a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
index 0b9fee5727c6f..afa7abfea419e 100644
--- a/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopUnrollPass.cpp
@@ -1014,7 +1014,7 @@ bool llvm::computeUnrollCount(
}
// 5th priority is loop peeling.
- computePeelCount(L, LoopSize, PP, TripCount, DT, SE, AC, UP.Threshold);
+ computePeelCount(L, LoopSize, PP, TripCount, DT, SE, TTI, AC, UP.Threshold);
if (PP.PeelCount) {
UP.Runtime = false;
UP.Count = 1;
diff --git a/llvm/lib/Transforms/Utils/LoopPeel.cpp b/llvm/lib/Transforms/Utils/LoopPeel.cpp
index f348d24ec24fb..e1dc052837f7f 100644
--- a/llvm/lib/Transforms/Utils/LoopPeel.cpp
+++ b/llvm/lib/Transforms/Utils/LoopPeel.cpp
@@ -38,6 +38,7 @@
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/LoopSimplify.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
+#include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
#include "llvm/Transforms/Utils/ValueMapper.h"
#include <algorithm>
#include <cassert>
@@ -330,11 +331,7 @@ static unsigned peelToTurnInvariantLoadsDerefencebale(Loop &L,
bool llvm::canPeelLastIteration(const Loop &L, ScalarEvolution &SE) {
const SCEV *BTC = SE.getBackedgeTakenCount(&L);
- // The loop must execute at least 2 iterations to guarantee that peeled
- // iteration executes.
- // TODO: Add checks during codegen.
- if (isa<SCEVCouldNotCompute>(BTC) ||
- !SE.isKnownPredicate(CmpInst::ICMP_UGT, BTC, SE.getZero(BTC->getType())))
+ if (isa<SCEVCouldNotCompute>(BTC))
return false;
// Check if the exit condition of the loop can be adjusted by the peeling
@@ -364,12 +361,18 @@ bool llvm::canPeelLastIteration(const Loop &L, ScalarEvolution &SE) {
/// is known at the second-to-last.
static bool shouldPeelLastIteration(Loop &L, CmpPredicate Pred,
const SCEVAddRecExpr *LeftAR,
- const SCEV *RightSCEV,
- ScalarEvolution &SE) {
+ const SCEV *RightSCEV, ScalarEvolution &SE,
+ const TargetTransformInfo &TTI) {
if (!canPeelLastIteration(L, SE))
return false;
const SCEV *BTC = SE.getBackedgeTakenCount(&L);
+ SCEVExpander Expander(SE, L.getHeader()->getDataLayout(), "loop-peel");
+ if (!SE.isKnownNonZero(BTC) &&
+ Expander.isHighCostExpansion(BTC, &L, SCEVCheapExpansionBudget, &TTI,
+ L.getLoopPredecessor()->getTerminator()))
+ return false;
+
const SCEV *ValAtLastIter = LeftAR->evaluateAtIteration(BTC, SE);
const SCEV *ValAtSecondToLastIter = LeftAR->evaluateAtIteration(
SE.getMinusSCEV(BTC, SE.getOne(BTC->getType())), SE);
@@ -391,7 +394,8 @@ static bool shouldPeelLastIteration(Loop &L, CmpPredicate Pred,
// ..
// }
static std::pair<unsigned, unsigned>
-countToEliminateCompares(Loop &L, unsigned MaxPeelCount, ScalarEvolution &SE) {
+countToEliminateCompares(Loop &L, unsigned MaxPeelCount, ScalarEvolution &SE,
+ const TargetTransformInfo &TTI) {
assert(L.isLoopSimplifyForm() && "Loop needs to be in loop simplify form");
unsigned DesiredPeelCount = 0;
unsigned DesiredPeelCountLast = 0;
@@ -479,7 +483,7 @@ countToEliminateCompares(Loop &L, unsigned MaxPeelCount, ScalarEvolution &SE) {
const SCEV *Step = LeftAR->getStepRecurrence(SE);
if (!PeelWhilePredicateIsKnown(NewPeelCount, IterVal, RightSCEV, Step,
Pred)) {
- if (shouldPeelLastIteration(L, Pred, LeftAR, RightSCEV, SE))
+ if (shouldPeelLastIteration(L, Pred, LeftAR, RightSCEV, SE, TTI))
DesiredPeelCountLast = 1;
return;
}
@@ -593,8 +597,8 @@ static bool violatesLegacyMultiExitLoopCheck(Loop *L) {
void llvm::computePeelCount(Loop *L, unsigned LoopSize,
TargetTransformInfo::PeelingPreferences &PP,
unsigned TripCount, DominatorTree &DT,
- ScalarEvolution &SE, AssumptionCache *AC,
- unsigned Threshold) {
+ ScalarEvolution &SE, const TargetTransformInfo &TTI,
+ AssumptionCache *AC, unsigned Threshold) {
assert(LoopSize > 0 && "Zero loop size is not allowed!");
// Save the PP.PeelCount value set by the target in
// TTI.getPeelingPreferences or by the flag -unroll-peel-count.
@@ -656,7 +660,7 @@ void llvm::computePeelCount(Loop *L, unsigned LoopSize,
}
const auto &[CountToEliminateCmps, CountToEliminateCmpsLast] =
- countToEliminateCompares(*L, MaxPeelCount, SE);
+ countToEliminateCompares(*L, MaxPeelCount, SE, TTI);
DesiredPeelCount = std::max(DesiredPeelCount, CountToEliminateCmps);
if (DesiredPeelCount == 0)
@@ -822,7 +826,7 @@ static void initBranchWeights(DenseMap<Instruction *, WeightInfo> &WeightInfos,
/// instructions in the last peeled-off iteration.
static void cloneLoopBlocks(
Loop *L, unsigned IterNumber, bool PeelLast, BasicBlock *InsertTop,
- BasicBlock *InsertBot,
+ BasicBlock *InsertBot, BasicBlock *OrigPreHeader,
SmallVectorImpl<std::pair<BasicBlock *, BasicBlock *>> &ExitEdges,
SmallVectorImpl<BasicBlock *> &NewBlocks, LoopBlocksDFS &LoopBlocks,
ValueToValueMapTy &VMap, ValueToValueMapTy &LVMap, DominatorTree *DT,
@@ -914,12 +918,22 @@ static void cloneLoopBlocks(
// loop iteration. Since this copy is no longer part of the loop, we
// resolve this statically:
if (PeelLast) {
- // For the last iteration, we use the value from the latch of the original
- // loop directly.
+ // For the last iteration, we introduce new phis for each header phi in
+ // InsertTop, using the incoming value from the preheader for the original
+ // preheader (when skipping the main loop) and the incoming value from the
+ // latch for the latch (when continuing from the main loop).
+ IRBuilder<> B(InsertTop->getTerminator());
for (BasicBlock::iterator I = Header->begin(); isa<PHINode>(I); ++I) {
PHINode *NewPHI = cast<PHINode>(VMap[&*I]);
- VMap[&*I] = NewPHI->getIncomingValueForBlock(Latch);
+ PHINode *PN = B.CreatePHI(NewPHI->getType(), 2);
NewPHI->eraseFromParent();
+ if (OrigPreHeader)
+ PN->addIncoming(cast<PHINode>(&*I)->getIncomingValueForBlock(PreHeader),
+ OrigPreHeader);
+
+ PN->addIncoming(cast<PHINode>(&*I)->getIncomingValueForBlock(Latch),
+ Latch);
+ VMap[&*I] = PN;
}
} else {
// For the first iteration, we use the value from the preheader directly.
@@ -1053,7 +1067,7 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, bool PeelLast, LoopInfo *LI,
// Set up all the necessary basic blocks.
BasicBlock *InsertTop;
BasicBlock *InsertBot;
- BasicBlock *NewPreHeader;
+ BasicBlock *NewPreHeader = nullptr;
DenseMap<Instruction *, Value *> ExitValues;
if (PeelLast) {
// It is convenient to split the single exit block from the latch the
@@ -1084,11 +1098,34 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, bool PeelLast, LoopInfo *LI,
for (PHINode &P : Exit->phis())
ExitValues[&P] = P.getIncomingValueForBlock(Latch);
+ const SCEV *BTC = SE->getBackedgeTakenCount(L);
+
InsertTop = SplitEdge(Latch, Exit, &DT, LI);
InsertBot = SplitBlock(InsertTop, InsertTop->getTerminator(), &DT, LI);
InsertTop->setName(Exit->getName() + ".peel.begin");
InsertBot->setName(Exit->getName() + ".peel.next");
+ NewPreHeader = nullptr;
+
+ // If the original loop may only execute a single iteration we need to
+ // insert a trip count check and skip the original loop with the last
+ // iteration peeled off if necessary.
+ if (!SE->isKnownNonZero(BTC)) {
+ NewPreHeader = SplitEdge(PreHeader, Header, &DT, LI);
+ SCEVExpander Expander(*SE, Latch->getDataLayout(), "loop-peel");
+
+ BranchInst *PreHeaderBR = cast<BranchInst>(PreHeader->getTerminator());
+ Value *BTCValue =
+ Expander.expandCodeFor(BTC, BTC->getType(), PreHeaderBR);
+ IRBuilder<> B(PreHeaderBR);
+ Value *Cond =
+ B.CreateICmpNE(BTCValue, ConstantInt::get(BTCValue->getType(), 0));
+ B.CreateCondBr(Cond, NewPreHeader, InsertTop);
+ PreHeaderBR->eraseFromParent();
+
+ // PreHeader now dominates InsertTop.
+ DT.changeImmediateDominator(InsertTop, PreHeader);
+ }
} else {
// It is convenient to split the preheader into 3 parts - two blocks to
// anchor the peeled copy of the loop body, and a new preheader for the
@@ -1162,8 +1199,9 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, bool PeelLast, LoopInfo *LI,
for (unsigned Iter = 0; Iter < PeelCount; ++Iter) {
SmallVector<BasicBlock *, 8> NewBlocks;
- cloneLoopBlocks(L, Iter, PeelLast, InsertTop, InsertBot, ExitEdges,
- NewBlocks, LoopBlocks, VMap, LVMap, &DT, LI,
+ cloneLoopBlocks(L, Iter, PeelLast, InsertTop, InsertBot,
+ NewPreHeader ? PreHeader : nullptr, ExitEdges, NewBlocks,
+ LoopBlocks, VMap, LVMap, &DT, LI,
LoopLocalNoAliasDeclScopes, *SE);
// Remap to use values from the current iteration instead of the
@@ -1216,9 +1254,11 @@ bool llvm::peelLoop(Loop *L, unsigned PeelCount, bool PeelLast, LoopInfo *LI,
if (PeelLast) {
// Now adjust users of the original exit values by replacing them with the
- // exit value from the peeled iteration.
- for (const auto &[P, E] : ExitValues)
+ // exit value from the peeled iteration and remove them.
+ for (const auto &[P, E] : ExitValues) {
P->replaceAllUsesWith(isa<Constant>(E) ? E : &*VMap.lookup(E));
+ P->eraseFromParent();
+ }
formLCSSA(*L, DT, LI, SE);
} else {
// Now adjust the phi nodes in the loop header to get their initial values
diff --git a/llvm/test/Transforms/LoopUnroll/peel-last-iteration-expansion-cost.ll b/llvm/test/Transforms/LoopUnroll/peel-last-iteration-expansion-cost.ll
index 342c70170fef3..f3910f9bfc399 100644
--- a/llvm/test/Transforms/LoopUnroll/peel-last-iteration-expansion-cost.ll
+++ b/llvm/test/Transforms/LoopUnroll/peel-last-iteration-expansion-cost.ll
@@ -25,17 +25,41 @@ define i32 @test_expansion_cost_2(i32 %start, i32 %end) {
; BUDGET3-SAME: i32 [[START:%.*]], i32 [[END:%.*]]) {
; BUDGET3-NEXT: [[ENTRY:.*]]:
; BUDGET3-NEXT: [[SUB:%.*]] = add i32 [[END]], -1
+; BUDGET3-NEXT: [[TMP0:%.*]] = sub i32 [[SUB]], [[START]]
+; BUDGET3-NEXT: [[TMP1:%.*]] = icmp ne i32 [[TMP0]], 0
+; BUDGET3-NEXT: br i1 [[TMP1]], label %[[ENTRY_SPLIT:.*]], label %[[EXIT_PEEL_BEGIN:.*]]
+; BUDGET3: [[ENTRY_SPLIT]]:
; BUDGET3-NEXT: br label %[[LOOP_HEADER:.*]]
; BUDGET3: [[LOOP_HEADER]]:
-; BUDGET3-NEXT: [[TMP3:%.*]] = phi i32 [ [[START]], %[[ENTRY]] ], [ [[IV_NEXT_PEEL:%.*]], %[[LOOP_LATCH:.*]] ]
-; BUDGET3-NEXT: [[C_PEEL:%.*]] = icmp eq i32 [[TMP3]], [[SUB]]
-; BUDGET3-NEXT: br i1 [[C_PEEL]], label %[[THEN:.*]], label %[[LOOP_LATCH]]
+; BUDGET3-NEXT: [[IV:%.*]] = phi i32 [ [[START]], %[[ENTRY_SPLIT]] ], [ [[IV_NEXT:%.*]], %[[LOOP_LATCH:.*]] ]
+; BUDGET3-NEXT: [[C:%.*]] = icmp eq i32 [[IV]], [[SUB]]
+; BUDGET3-NEXT: br i1 [[C]], label %[[THEN:.*]], label %[[LOOP_LATCH]]
; BUDGET3: [[THEN]]:
; BUDGET3-NEXT: br label %[[LOOP_LATCH]]
; BUDGET3: [[LOOP_LATCH]]:
-; BUDGET3-NEXT: [[IV_NEXT_PEEL]] = add nsw i32 [[TMP3]], 1
+; BUDGET3-NEXT: [[IV_NEXT]] = add nsw i32 [[IV]], 1
+; BUDGET3-NEXT: [[TMP2:%.*]] = sub i32 [[END]], 1
+; BUDGET3-NEXT: [[EC:%.*]] = icmp eq i32 [[IV_NEXT]], [[TMP2]]
+; BUDGET3-NEXT: br i1 [[EC]], label %[[EXIT_PEEL_BEGIN_LOOPEXIT:.*]], label %[[LOOP_HEADER]], !llvm.loop [[LOOP0:![0-9]+]]
+; BUDGET3: [[EXIT_PEEL_BEGIN_LOOPEXIT]]:
+; BUDGET3-NEXT: [[DOTPH:%.*]] = phi i32 [ [[IV_NEXT]], %[[LOOP_LATCH]] ]
+; BUDGET3-NEXT: br label %[[EXIT_PEEL_BEGIN]]
+; BUDGET3: [[EXIT_PEEL_BEGIN]]:
+; BUDGET3-NEXT: [[TMP3:%.*]] = phi i32 [ [[START]], %[[ENTRY]] ], [ [[DOTPH]], %[[EXIT_PEEL_BEGIN_LOOPEXIT]] ]
+; BUDGET3-NEXT: br label %[[LOOP_HEADER_PEEL:.*]]
+; BUDGET3: [[LOOP_HEADER_PEEL]]:
+; BUDGET3-NEXT: [[C_PEEL:%.*]] = icmp eq i32 [[TMP3]], [[SUB]]
+; BUDGET3-NEXT: br i1 [[C_PEEL]], label %[[THEN_PEEL:.*]], label %[[LOOP_LATCH_PEEL:.*]]
+; BUDGET3: [[THEN_PEEL]]:
+; BUDGET3-NEXT: br label %[[LOOP_LATCH_PEEL]]
+; BUDGET3: [[LOOP_LATCH_PEEL]]:
+; BUDGET3-NEXT: [[IV_NEXT_PEEL:%.*]] = add nsw i32 [[TMP3]], 1
; BUDGET3-NEXT: [[EC_PEEL:%.*]] = icmp eq i32 [[IV_NEXT_PEEL]], [[END]]
-; BUDGET3-NEXT: br i1 [[EC_PEEL]], label %[[EXIT:.*]], label %[[LOOP_HEADER]]
+; BUDGET3-NEXT: br i1 [[EC_PEEL]], label %[[EXIT_PEEL_NEXT:.*]], label %[[EXIT_PEEL_NEXT]]
+; BUDGET3: [[EXIT_PEEL_NEXT]]:
+; BUDGET3-NEXT: br label %[[LOOP_HEADER_PEEL_NEXT:.*]]
+; BUDGET3: [[LOOP_HEADER_PEEL_NEXT]]:
+; BUDGET3-NEXT: br label %[[EXIT:.*]]
; BUDGET3: [[EXIT]]:
; BUDGET3-NEXT: ret i32 0
;
@@ -59,3 +83,7 @@ loop.latch:
exit:
ret i32 0
}
+;.
+; BUDGET3: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]]}
+; BUDGET3: [[META1]] = !{!"llvm.loop.peeled.count", i32 1}
+;.
diff --git a/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-constant-trip-count.ll b/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-constant-trip-count.ll
index f1290069bda0c..5c9b2fa6a9d60 100644
--- a/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-constant-trip-count.ll
+++ b/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-constant-trip-count.ll
@@ -13,7 +13,6 @@ define i64 @peel_single_block_loop_iv_step_1() {
; CHECK-NEXT: br i1 [[EC1]], label %[[LOOP]], label %[[EXIT_PEEL_BEGIN:.*]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: [[EXIT_PEEL_BEGIN]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT1]], %[[LOOP]] ]
-; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i64 [ [[IV1]], %[[LOOP]] ]
; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
; CHECK: [[LOOP_PEEL]]:
; CHECK-NEXT: [[CMP18_NOT:%.*]] = icmp eq i64 [[IV]], 63
@@ -92,7 +91,6 @@ define i64 @peel_single_block_loop_iv_step_1_eq_pred() {
; CHECK-NEXT: br i1 [[CMP_PEEL]], label %[[EXIT_PEEL_BEGIN:.*]], label %[[LOOP]], !llvm.loop [[LOOP2:![0-9]+]]
; CHECK: [[EXIT_PEEL_BEGIN]]:
; CHECK-NEXT: [[IV_NEXT_LCSSA:%.*]] = phi i64 [ [[IV_LCSSA]], %[[LOOP]] ]
-; CHECK-NEXT: [[IV_LCSSA1:%.*]] = phi i64 [ [[IV]], %[[LOOP]] ]
; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
; CHECK: [[LOOP_PEEL]]:
; CHECK-NEXT: [[CMP_PEEL1:%.*]] = icmp eq i64 [[IV_NEXT_LCSSA]], 63
@@ -171,7 +169,6 @@ define i64 @peel_single_block_loop_iv_step_1_nested_loop() {
; CHECK-NEXT: br i1 [[EC]], label %[[LOOP]], label %[[OUTER_LATCH_PEEL_BEGIN:.*]], !llvm.loop [[LOOP3:![0-9]+]]
; CHECK: [[OUTER_LATCH_PEEL_BEGIN]]:
; CHECK-NEXT: [[IV_NEXT_LCSSA:%.*]] = phi i64 [ [[IV_NEXT]], %[[LOOP]] ]
-; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i64 [ [[IV]], %[[LOOP]] ]
; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
; CHECK: [[LOOP_PEEL]]:
; CHECK-NEXT: [[CMP_PEEL:%.*]] = icmp eq i64 [[IV_NEXT_LCSSA]], 63
@@ -237,7 +234,6 @@ define i64 @peel_multi_block_loop_iv_step_1() {
; CHECK-NEXT: br i1 [[EC]], label %[[LOOP]], label %[[EXIT_PEEL_BEGIN:.*]], !llvm.loop [[LOOP4:![0-9]+]]
; CHECK: [[EXIT_PEEL_BEGIN]]:
; CHECK-NEXT: [[IV_NEXT_LCSSA:%.*]] = phi i64 [ [[IV_NEXT]], %[[LATCH]] ]
-; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i64 [ [[IV]], %[[LATCH]] ]
; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
; CHECK: [[LOOP_PEEL]]:
; CHECK-NEXT: [[CMP_PEEL:%.*]] = icmp eq i64 [[IV_NEXT_LCSSA]], 63
@@ -365,7 +361,6 @@ define i64 @peel_single_block_loop_iv_step_1_btc_1() {
; CHECK-NEXT: br i1 false, label %[[LOOP]], label %[[EXIT_PEEL_BEGIN:.*]], !llvm.loop [[LOOP5:![0-9]+]]
; CHECK: [[EXIT_PEEL_BEGIN]]:
; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT1]], %[[LOOP]] ]
-; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i64 [ [[IV1]], %[[LOOP]] ]
; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
; CHECK: [[LOOP_PEEL]]:
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[IV]], 1
@@ -483,9 +478,8 @@ define i32 @peel_loop_with_branch_and_phi_uses(ptr %x, i1 %c) {
; CHECK-NEXT: [[EC1:%.*]] = icmp ne i32 [[IV_NEXT1]], 99
; CHECK-NEXT: br i1 [[EC1]], label %[[LOOP_HEADER]], label %[[LOOPEXIT_PEEL_BEGIN:.*]], !llvm.loop [[LOOP6:![0-9]+]]
; CHECK: [[LOOPEXIT_PEEL_BEGIN]]:
-; CHECK-NEXT: [[RED:%.*]] = phi i32 [ [[ADD1]], %[[LOOP_LATCH]] ]
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ [[IV_NEXT1]], %[[LOOP_LATCH]] ]
-; CHECK-NEXT: [[ADD_LCSSA:%.*]] = phi i32 [ [[ADD1]], %[[LOOP_LATCH]] ]
+; CHECK-NEXT: [[RED:%.*]] = phi i32 [ [[ADD1]], %[[LOOP_LATCH]] ]
; CHECK-NEXT: br label %[[LOOP_HEADER_PEEL:.*]]
; CHECK: [[LOOP_HEADER_PEEL]]:
; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[IV]], 99
diff --git a/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-variable-trip-count.ll b/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-variable-trip-count.ll
index 75f3674732f35..a8712e04d43c1 100644
--- a/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-variable-trip-count.ll
+++ b/llvm/test/Transforms/LoopUnroll/peel-last-iteration-with-variable-trip-count.ll
@@ -9,18 +9,36 @@ define i32 @peel_last_with_trip_count_check_lcssa_phi(i32 %n) {
; CHECK-SAME: i32 [[N:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: [[SUB:%.*]] = add i32 [[N]], -1
+; CHECK-NEXT: [[TMP0:%.*]] = icmp ne i32 [[SUB]], 0
+; CHECK-NEXT: br i1 [[TMP0]], label %[[ENTRY_SPLIT:.*]], label %[[EXIT_PEEL_BEGIN:.*]]
+; CHECK: [[ENTRY_SPLIT]]:
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
-; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: [[IV1:%.*]] = phi i32 [ 0, %[[ENTRY_SPLIT]] ], [ [[IV_NEXT1:%.*]], %[[LOOP]] ]
+; CHECK-NEXT: call void @foo(i32 2)
+; CHECK-NEXT: [[IV_NEXT1]] = add nuw i32 [[IV1]], 1
+; CHECK-NEXT: [[TMP1:%.*]] = sub i32 [[N]], 1
+; CHECK-NEXT: [[EC1:%.*]] = icmp ne i32 [[IV_NEXT1]], [[TMP1]]
+; CHECK-NEXT: br i1 [[EC1]], label %[[LOOP]], label %[[EXIT_PEEL_BEGIN_LOOPEXIT:.*]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK: [[EXIT_PEEL_BEGIN_LOOPEXIT]]:
+; CHECK-NEXT: [[DOTPH:%.*]] = phi i32 [ [[IV_NEXT1]], %[[LOOP]] ]
+; CHECK-NEXT: br label %[[EXIT_PEEL_BEGIN]]
+; CHECK: [[EXIT_PEEL_BEGIN]]:
+; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[ENTRY]] ], [ [[DOTPH]], %[[EXIT_PEEL_BEGIN_LOOPEXIT]] ]
+; CHECK-NEXT: br label %[[LOOP_PEEL:.*]]
+; CHECK: [[LOOP_PEEL]]:
; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[IV]], [[SUB]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C]], i32 1, i32 2
; CHECK-NEXT: call void @foo(i32 [[SEL]])
-; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
+; CHECK-NEXT: [[IV_NEXT:%.*]] = add i32 [[IV]], 1
; CHECK-NEXT: [[EC:%.*]] = icmp ne i32 [[IV_NEXT]], [[N]]
-; CHECK-NEXT: br i1 [[EC]], label %[[LOOP]], label %[[EXIT:.*]]
+; CHECK-NEXT: br i1 [[EC]], label %[[EXIT_PEEL_NEXT:.*]], label %[[EXIT_PEEL_NEXT]]
+; CHECK: [[EXIT_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[LOOP_PEEL_NEXT:.*]]
+; CHECK: [[LOOP_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[EXIT:.*]]
; CHECK: [[EXIT]]:
-; CHECK-NEXT: [[SEL_LCSSA:%.*]] = phi i32 [ [[SEL]], %[[LOOP]] ]
-; CHECK-NEXT: ret i32 [[SEL_LCSSA]]
+; CHECK-NEXT: ret i32 [[SEL]]
;
entry:
%sub = add i32 %n, -1
@@ -160,21 +178,44 @@ define void @peel_last_with_trip_count_check_nested_loop(i32 %n) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[SUB:%.*]] = add i32 [[N]], -1
; CHECK-NEXT: br label %[[OUTER_HEADER:.*]]
-; CHECK: [[OUTER_HEADER_LOOPEXIT:.*]]:
+; CHECK: [[OUTER_HEADER_LOOPEXIT_PEEL_BEGIN_LOOPEXIT:.*]]:
+; CHECK-NEXT: [[DOTPH:%.*]] = phi i32 [ [[IV_NEXT1:%.*]], %[[INNER_LATCH:.*]] ]
+; CHECK-NEXT: br label %[[OUTER_HEADER_LOOPEXIT_PEEL_BEGIN:.*]]
+; CHECK: [[OUTER_HEADER_LOOPEXIT_PEEL_BEGIN]]:
+; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[OUTER_HEADER]] ], [ [[DOTPH]], %[[OUTER_HEADER_LOOPEXIT_PEEL_BEGIN_LOOPEXIT]] ]
+; CHECK-NEXT: br label %[[INNER_HEADER_PEEL:.*]]
+; CHECK: [[INNER_HEADER_PEEL]]:
+; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[IV]], [[SUB]]
+; CHECK-NEXT: br i1 [[C]], label %[[INNER_LATCH_PEEL:.*]], label %[[THEN_PEEL:.*]]
+; CHECK: [[THEN_PEEL]]:
+; CHECK-NEXT: call void @foo(i32 1)
+; CHECK-NEXT: br label %[[INNER_LATCH_PEEL]]
+; CHECK: [[INNER_LATCH_PEEL]]:
+; CHECK-NEXT: [[IV_NEXT:%.*]] = add i32 [[IV]], 1
+; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i32 [[IV_NEXT]], [[N]]
+; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label %[[OUTER_HEADER_LOOPEXIT_PEEL_NEXT:.*]], label %[[OUTER_HEADER_LOOPEXIT_PEEL_NEXT]]
+; CHECK: [[OUTER_HEADER_LOOPEXIT_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[INNER_HEADER_PEEL_NEXT:.*]]
+; CHECK: [[INNER_HEADER_PEEL_NEXT]]:
+; CHECK-NEXT: br label %[[OUTER_HEADER_LOOPEXIT:.*]]
+; CHECK: [[OUTER_HEADER_LOOPEXIT]]:
; CHECK-NEXT: br label %[[OUTER_HEADER]]
; CHECK: [[OUTER_HEADER]]:
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ne i32 [[SUB]], 0
+; CHECK-NEXT: br i1 [[TMP1]], label %[[OUTER_HEADER_SPLIT:.*]], label %[[OUTER_HEADER_LOOPEXIT_PEEL_BEGIN]]
+; CHECK: [[OUTER_HEADER_SPLIT]]:
; CHECK-NEXT: br label %[[INNER_HEADER:.*]]
; CHECK: [[INNER_HEADER]]:
-; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, %[[OUTER_HEADER]] ], [ [[IV_NEXT:%.*]], %[[INNER_LATCH:.*]] ]
-; CHECK-NEXT: [[C:%.*]] = icmp eq i32 [[IV]], [[SUB]]
-; CHECK-NEXT: br i1 [[C]], label %[[INNER_LATCH]], label %[[THEN:.*]]
+; CHECK-NEXT: [[IV1:%.*]] = phi i32 [ 0, %[[OUTER_HEADER_SPLIT]] ], [ [[IV_NEXT1]], %[[INNER_LATCH]] ]
+; CHECK-NEXT: br i1 false, label %[[INNER_LATCH]], label %[[THEN:.*]]
; CHECK: [[THEN]]:
; CHECK-NEXT: call void @foo(i32 1)
; CHECK-NEXT: br label %[[INNER_LATCH]]
; CHECK: [[INNER_LATCH]]:
-; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
-; CHECK-NEXT: [[EXITCOND_NOT:%.*]] = icmp eq i32 [[IV_NEXT]], [[N]]
-; CHECK-NEXT: br i1 [[EXITCOND_NOT]], label %[[OUTER_HEADER_LOOPEXIT]], label %[[INNER_HEADER]]
+; CHECK-NEXT: [[IV_NEXT1]] = add nuw i32 [[IV1]], 1
+; CHECK-NEXT: [[TMP2:%.*]] = sub i32 [[N]], 1
+; CHECK-NEXT: [[EXITCOND_NOT1:%.*]] = icmp eq i32 [[IV_NEXT1]], [[TMP2]]
+; CHECK-NEXT: br i1 [[EXITCOND_NOT1]], label %[[OUTER_HEADER_LOOPEXIT_PEEL_BEGIN_LOOPEXIT]], label %[[INNER_HEADER]], !llvm.loop [[LOOP2:![0-9]+]]
;
entry:
%sub = add i32 %n, -1
@@ -197,3 +238,8 @@ inner.latch:
%exitcond.not = icmp eq i32 %iv.next, %n
br i1 %exitcond.not, label %outer.header, label %inner.header
}
+;.
+; CHECK: [[LOOP0]] = distinct !{[[LOOP0]], [[META1:![0-9]+]]}
+; CHECK: [[META1]] = !{!"llvm.loop.peeled.count", i32 1}
+; CHECK: [[LOOP2]] = distinct !{[[LOOP2]], [[META1]]}
+;.
diff --git a/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll b/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
index f57fb2d9b7057..7d38c18d10667 100644
--- a/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
+++ b/llvm/test/Transforms/LoopUnroll/unroll-and-peel-last-iteration.ll
@@ -20,7 +20,6 @@ define i32 @peel_last_iter_of_outer_lcssa_phi_with_constant_after_unrolling_inne
; CHECK-NEXT: br i1 [[EC]], label %[[EXIT_PEEL_BEGIN:.*]], label %[[OUTER_HEADER]], !llvm.loop [[LOOP0:![0-9]+]]
; CHECK: [[EXIT_PEEL_BEGIN]]:
; CHECK-NEXT: [[IV_NEXT_LCSSA:%.*]] = phi i16 [ [[IV_NEXT]], %[[INNER_LATCH]] ]
-; CHECK-NEXT: [[DOTLCSSA_LCSSA:%.*]] = phi i32 [ 1, %[[INNER_LATCH]] ]
; CHECK-NEXT: br label %[[OUTER_HEADER_PEEL:.*]]
; CHECK: [[OUTER_HEADER_PEEL]]:
; CHECK-NEXT: [[TMP0:%.*]] = icmp eq i16 [[IV_NEXT_LCSSA]], 999
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