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[IRCE] Recognize loops with unsigned latch conditions

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This patch enables recognition of loops with ult/ugt latch conditions.

Differential Revision: https://reviews.llvm.org/D35302

llvm-svn: 310027
This commit is contained in:
Max Kazantsev 2017-08-04 05:40:20 +00:00
parent 6656c50c3a
commit 1aed4a4dfc
4 changed files with 716 additions and 51 deletions
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159
lib/Transforms/Scalar/InductiveRangeCheckElimination.cpp
View File

@ -459,11 +459,13 @@ struct LoopStructure {
Value *IndVarStart;
Value *LoopExitAt;
bool IndVarIncreasing;
bool IsSignedPredicate;
LoopStructure()
: Tag(""), Header(nullptr), Latch(nullptr), LatchBr(nullptr),
LatchExit(nullptr), LatchBrExitIdx(-1), IndVarNext(nullptr),
IndVarStart(nullptr), LoopExitAt(nullptr), IndVarIncreasing(false) {}
IndVarStart(nullptr), LoopExitAt(nullptr), IndVarIncreasing(false),
IsSignedPredicate(true) {}
template <typename M> LoopStructure map(M Map) const {
LoopStructure Result;
@ -477,6 +479,7 @@ struct LoopStructure {
Result.IndVarStart = Map(IndVarStart);
Result.LoopExitAt = Map(LoopExitAt);
Result.IndVarIncreasing = IndVarIncreasing;
Result.IsSignedPredicate = IsSignedPredicate;
return Result;
}
@ -542,7 +545,7 @@ class LoopConstrainer {
// intersection of `Range' and the iteration space of the original loop.
// Return None if unable to compute the set of subranges.
//
Optional<SubRanges> calculateSubRanges() const;
Optional<SubRanges> calculateSubRanges(bool IsSignedPredicate) const;
// Clone `OriginalLoop' and return the result in CLResult. The IR after
// running `cloneLoop' is well formed except for the PHI nodes in CLResult --
@ -649,22 +652,25 @@ void LoopConstrainer::replacePHIBlock(PHINode *PN, BasicBlock *Block,
PN->setIncomingBlock(i, ReplaceBy);
}
static bool CanBeSMax(ScalarEvolution &SE, const SCEV *S) {
APInt SMax =
APInt::getSignedMaxValue(cast<IntegerType>(S->getType())->getBitWidth());
return SE.getSignedRange(S).contains(SMax) &&
SE.getUnsignedRange(S).contains(SMax);
static bool CanBeMax(ScalarEvolution &SE, const SCEV *S, bool Signed) {
APInt Max = Signed ?
APInt::getSignedMaxValue(cast<IntegerType>(S->getType())->getBitWidth()) :
APInt::getMaxValue(cast<IntegerType>(S->getType())->getBitWidth());
return SE.getSignedRange(S).contains(Max) &&
SE.getUnsignedRange(S).contains(Max);
}
static bool CanBeSMin(ScalarEvolution &SE, const SCEV *S) {
APInt SMin =
APInt::getSignedMinValue(cast<IntegerType>(S->getType())->getBitWidth());
return SE.getSignedRange(S).contains(SMin) &&
SE.getUnsignedRange(S).contains(SMin);
static bool CanBeMin(ScalarEvolution &SE, const SCEV *S, bool Signed) {
APInt Min = Signed ?
APInt::getSignedMinValue(cast<IntegerType>(S->getType())->getBitWidth()) :
APInt::getMinValue(cast<IntegerType>(S->getType())->getBitWidth());
return SE.getSignedRange(S).contains(Min) &&
SE.getUnsignedRange(S).contains(Min);
}
Optional<LoopStructure>
LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BPI,
LoopStructure::parseLoopStructure(ScalarEvolution &SE,
BranchProbabilityInfo &BPI,
Loop &L, const char *&FailureReason) {
if (!L.isLoopSimplifyForm()) {
FailureReason = "loop not in LoopSimplify form";
@ -794,6 +800,7 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
const SCEVAddRecExpr *IndVarNext = cast<SCEVAddRecExpr>(LeftSCEV);
bool IsIncreasing = false;
bool IsSignedPredicate = true;
if (!IsInductionVar(IndVarNext, IsIncreasing)) {
FailureReason = "LHS in icmp not induction variable";
return None;
@ -804,7 +811,6 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
const SCEV *IndVarStart = SE.getAddExpr(StartNext, Addend);
ConstantInt *One = ConstantInt::get(IndVarTy, 1);
// TODO: generalize the predicates here to also match their unsigned variants.
if (IsIncreasing) {
bool DecreasedRightValueByOne = false;
// Try to turn eq/ne predicates to those we can work with.
@ -812,38 +818,54 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
// while (++i != len) { while (++i < len) {
// ... ---> ...
// } }
Pred = ICmpInst::ICMP_SLT;
// If both parts are known non-negative, it is profitable to use unsigned
// comparison in increasing loop. This allows us to make the comparison
// check against "RightSCEV + 1" more optimistic.
if (SE.isKnownNonNegative(IndVarStart) &&
SE.isKnownNonNegative(RightSCEV))
Pred = ICmpInst::ICMP_ULT;
else
Pred = ICmpInst::ICMP_SLT;
else if (Pred == ICmpInst::ICMP_EQ && LatchBrExitIdx == 0 &&
!CanBeSMin(SE, RightSCEV)) {
!CanBeMin(SE, RightSCEV, /* IsSignedPredicate */ true)) {
// while (true) { while (true) {
// if (++i == len) ---> if (++i > len - 1)
// break; break;
// ... ...
// } }
// TODO: Insert ICMP_UGT if both are non-negative?
Pred = ICmpInst::ICMP_SGT;
RightSCEV = SE.getMinusSCEV(RightSCEV, SE.getOne(RightSCEV->getType()));
DecreasedRightValueByOne = true;
}
bool LTPred = (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_ULT);
bool GTPred = (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_UGT);
bool FoundExpectedPred =
(Pred == ICmpInst::ICMP_SLT && LatchBrExitIdx == 1) ||
(Pred == ICmpInst::ICMP_SGT && LatchBrExitIdx == 0);
(LTPred && LatchBrExitIdx == 1) || (GTPred && LatchBrExitIdx == 0);
if (!FoundExpectedPred) {
FailureReason = "expected icmp slt semantically, found something else";
return None;
}
IsSignedPredicate =
Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGT;
// The predicate that we need to check that the induction variable lies
// within bounds.
ICmpInst::Predicate BoundPred =
IsSignedPredicate ? CmpInst::ICMP_SLT : CmpInst::ICMP_ULT;
if (LatchBrExitIdx == 0) {
if (CanBeSMax(SE, RightSCEV)) {
if (CanBeMax(SE, RightSCEV, IsSignedPredicate)) {
// TODO: this restriction is easily removable -- we just have to
// remember that the icmp was an slt and not an sle.
FailureReason = "limit may overflow when coercing sle to slt";
FailureReason = "limit may overflow when coercing le to lt";
return None;
}
if (!SE.isLoopEntryGuardedByCond(
&L, CmpInst::ICMP_SLT, IndVarStart,
&L, BoundPred, IndVarStart,
SE.getAddExpr(RightSCEV, SE.getOne(RightSCEV->getType())))) {
FailureReason = "Induction variable start not bounded by upper limit";
return None;
@ -856,8 +878,7 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
RightValue = B.CreateAdd(RightValue, One);
}
} else {
if (!SE.isLoopEntryGuardedByCond(&L, CmpInst::ICMP_SLT, IndVarStart,
RightSCEV)) {
if (!SE.isLoopEntryGuardedByCond(&L, BoundPred, IndVarStart, RightSCEV)) {
FailureReason = "Induction variable start not bounded by upper limit";
return None;
}
@ -871,38 +892,51 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
// while (--i != len) { while (--i > len) {
// ... ---> ...
// } }
// We intentionally don't turn the predicate into UGT even if we know that
// both operands are non-negative, because it will only pessimize our
// check against "RightSCEV - 1".
Pred = ICmpInst::ICMP_SGT;
else if (Pred == ICmpInst::ICMP_EQ && LatchBrExitIdx == 0 &&
!CanBeSMax(SE, RightSCEV)) {
!CanBeMax(SE, RightSCEV, /* IsSignedPredicate */ true)) {
// while (true) { while (true) {
// if (--i == len) ---> if (--i < len + 1)
// break; break;
// ... ...
// } }
// TODO: Insert ICMP_ULT if both are non-negative?
Pred = ICmpInst::ICMP_SLT;
RightSCEV = SE.getAddExpr(RightSCEV, SE.getOne(RightSCEV->getType()));
IncreasedRightValueByOne = true;
}
bool LTPred = (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_ULT);
bool GTPred = (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_UGT);
bool FoundExpectedPred =
(Pred == ICmpInst::ICMP_SGT && LatchBrExitIdx == 1) ||
(Pred == ICmpInst::ICMP_SLT && LatchBrExitIdx == 0);
(GTPred && LatchBrExitIdx == 1) || (LTPred && LatchBrExitIdx == 0);
if (!FoundExpectedPred) {
FailureReason = "expected icmp sgt semantically, found something else";
return None;
}
IsSignedPredicate =
Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SGT;
// The predicate that we need to check that the induction variable lies
// within bounds.
ICmpInst::Predicate BoundPred =
IsSignedPredicate ? CmpInst::ICMP_SGT : CmpInst::ICMP_UGT;
if (LatchBrExitIdx == 0) {
if (CanBeSMin(SE, RightSCEV)) {
if (CanBeMin(SE, RightSCEV, IsSignedPredicate)) {
// TODO: this restriction is easily removable -- we just have to
// remember that the icmp was an sgt and not an sge.
FailureReason = "limit may overflow when coercing sge to sgt";
FailureReason = "limit may overflow when coercing ge to gt";
return None;
}
if (!SE.isLoopEntryGuardedByCond(
&L, CmpInst::ICMP_SGT, IndVarStart,
&L, BoundPred, IndVarStart,
SE.getMinusSCEV(RightSCEV, SE.getOne(RightSCEV->getType())))) {
FailureReason = "Induction variable start not bounded by lower limit";
return None;
@ -915,8 +949,7 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
RightValue = B.CreateSub(RightValue, One);
}
} else {
if (!SE.isLoopEntryGuardedByCond(&L, CmpInst::ICMP_SGT, IndVarStart,
RightSCEV)) {
if (!SE.isLoopEntryGuardedByCond(&L, BoundPred, IndVarStart, RightSCEV)) {
FailureReason = "Induction variable start not bounded by lower limit";
return None;
}
@ -924,7 +957,6 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
"Right value can be increased only for LatchBrExitIdx == 0!");
}
}
BasicBlock *LatchExit = LatchBr->getSuccessor(LatchBrExitIdx);
assert(SE.getLoopDisposition(LatchCount, &L) ==
@ -950,6 +982,7 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
Result.IndVarNext = LeftValue;
Result.IndVarIncreasing = IsIncreasing;
Result.LoopExitAt = RightValue;
Result.IsSignedPredicate = IsSignedPredicate;
FailureReason = nullptr;
@ -957,7 +990,7 @@ LoopStructure::parseLoopStructure(ScalarEvolution &SE, BranchProbabilityInfo &BP
}
Optional<LoopConstrainer::SubRanges>
LoopConstrainer::calculateSubRanges() const {
LoopConstrainer::calculateSubRanges(bool IsSignedPredicate) const {
IntegerType *Ty = cast<IntegerType>(LatchTakenCount->getType());
if (Range.getType() != Ty)
@ -1007,19 +1040,25 @@ LoopConstrainer::calculateSubRanges() const {
GreatestSeen = Start;
}
auto Clamp = [this, Smallest, Greatest](const SCEV *S) {
return SE.getSMaxExpr(Smallest, SE.getSMinExpr(Greatest, S));
auto Clamp = [this, Smallest, Greatest, IsSignedPredicate](const SCEV *S) {
return IsSignedPredicate
? SE.getSMaxExpr(Smallest, SE.getSMinExpr(Greatest, S))
: SE.getUMaxExpr(Smallest, SE.getUMinExpr(Greatest, S));
};
// In some cases we can prove that we don't need a pre or post loop
// In some cases we can prove that we don't need a pre or post loop.
ICmpInst::Predicate PredLE =
IsSignedPredicate ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
ICmpInst::Predicate PredLT =
IsSignedPredicate ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
bool ProvablyNoPreloop =
SE.isKnownPredicate(ICmpInst::ICMP_SLE, Range.getBegin(), Smallest);
SE.isKnownPredicate(PredLE, Range.getBegin(), Smallest);
if (!ProvablyNoPreloop)
Result.LowLimit = Clamp(Range.getBegin());
bool ProvablyNoPostLoop =
SE.isKnownPredicate(ICmpInst::ICMP_SLT, GreatestSeen, Range.getEnd());
SE.isKnownPredicate(PredLT, GreatestSeen, Range.getEnd());
if (!ProvablyNoPostLoop)
Result.HighLimit = Clamp(Range.getEnd());
@ -1166,22 +1205,35 @@ LoopConstrainer::RewrittenRangeInfo LoopConstrainer::changeIterationSpaceEnd(
BranchInst *PreheaderJump = cast<BranchInst>(Preheader->getTerminator());
bool Increasing = LS.IndVarIncreasing;
bool IsSignedPredicate = LS.IsSignedPredicate;
IRBuilder<> B(PreheaderJump);
// EnterLoopCond - is it okay to start executing this `LS'?
Value *EnterLoopCond = Increasing
? B.CreateICmpSLT(LS.IndVarStart, ExitSubloopAt)
: B.CreateICmpSGT(LS.IndVarStart, ExitSubloopAt);
Value *EnterLoopCond = nullptr;
if (Increasing)
EnterLoopCond = IsSignedPredicate
? B.CreateICmpSLT(LS.IndVarStart, ExitSubloopAt)
: B.CreateICmpULT(LS.IndVarStart, ExitSubloopAt);
else
EnterLoopCond = IsSignedPredicate
? B.CreateICmpSGT(LS.IndVarStart, ExitSubloopAt)
: B.CreateICmpUGT(LS.IndVarStart, ExitSubloopAt);
B.CreateCondBr(EnterLoopCond, LS.Header, RRI.PseudoExit);
PreheaderJump->eraseFromParent();
LS.LatchBr->setSuccessor(LS.LatchBrExitIdx, RRI.ExitSelector);
B.SetInsertPoint(LS.LatchBr);
Value *TakeBackedgeLoopCond =
Increasing ? B.CreateICmpSLT(LS.IndVarNext, ExitSubloopAt)
: B.CreateICmpSGT(LS.IndVarNext, ExitSubloopAt);
Value *TakeBackedgeLoopCond = nullptr;
if (Increasing)
TakeBackedgeLoopCond = IsSignedPredicate
? B.CreateICmpSLT(LS.IndVarNext, ExitSubloopAt)
: B.CreateICmpULT(LS.IndVarNext, ExitSubloopAt);
else
TakeBackedgeLoopCond = IsSignedPredicate
? B.CreateICmpSGT(LS.IndVarNext, ExitSubloopAt)
: B.CreateICmpUGT(LS.IndVarNext, ExitSubloopAt);
Value *CondForBranch = LS.LatchBrExitIdx == 1
? TakeBackedgeLoopCond
: B.CreateNot(TakeBackedgeLoopCond);
@ -1193,9 +1245,15 @@ LoopConstrainer::RewrittenRangeInfo LoopConstrainer::changeIterationSpaceEnd(
// IterationsLeft - are there any more iterations left, given the original
// upper bound on the induction variable? If not, we branch to the "real"
// exit.
Value *IterationsLeft = Increasing
? B.CreateICmpSLT(LS.IndVarNext, LS.LoopExitAt)
: B.CreateICmpSGT(LS.IndVarNext, LS.LoopExitAt);
Value *IterationsLeft = nullptr;
if (Increasing)
IterationsLeft = IsSignedPredicate
? B.CreateICmpSLT(LS.IndVarNext, LS.LoopExitAt)
: B.CreateICmpULT(LS.IndVarNext, LS.LoopExitAt);
else
IterationsLeft = IsSignedPredicate
? B.CreateICmpSGT(LS.IndVarNext, LS.LoopExitAt)
: B.CreateICmpUGT(LS.IndVarNext, LS.LoopExitAt);
B.CreateCondBr(IterationsLeft, RRI.PseudoExit, LS.LatchExit);
BranchInst *BranchToContinuation =
@ -1312,7 +1370,8 @@ bool LoopConstrainer::run() {
OriginalPreheader = Preheader;
MainLoopPreheader = Preheader;
Optional<SubRanges> MaybeSR = calculateSubRanges();
bool IsSignedPredicate = MainLoopStructure.IsSignedPredicate;
Optional<SubRanges> MaybeSR = calculateSubRanges(IsSignedPredicate);
if (!MaybeSR.hasValue()) {
DEBUG(dbgs() << "irce: could not compute subranges\n");
return false;
@ -1346,7 +1405,7 @@ bool LoopConstrainer::run() {
if (Increasing)
ExitPreLoopAtSCEV = *SR.LowLimit;
else {
if (CanBeSMin(SE, *SR.HighLimit)) {
if (CanBeMin(SE, *SR.HighLimit, IsSignedPredicate)) {
DEBUG(dbgs() << "irce: could not prove no-overflow when computing "
<< "preloop exit limit. HighLimit = " << *(*SR.HighLimit)
<< "\n");
@ -1365,7 +1424,7 @@ bool LoopConstrainer::run() {
if (Increasing)
ExitMainLoopAtSCEV = *SR.HighLimit;
else {
if (CanBeSMin(SE, *SR.LowLimit)) {
if (CanBeMin(SE, *SR.LowLimit, IsSignedPredicate)) {
DEBUG(dbgs() << "irce: could not prove no-overflow when computing "
<< "mainloop exit limit. LowLimit = " << *(*SR.LowLimit)
<< "\n");

37
test/Transforms/IRCE/eq_ne.ll
View File

@ -1,6 +1,7 @@
; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s
; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_01u: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK-NOT: irce: in function test_02: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_03: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK-NOT: irce: in function test_04: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
@ -9,7 +10,8 @@
; CHECK: irce: in function test_07: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK-NOT: irce: in function test_08: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; Show that IRCE can turn 'ne' condition to 'slt' in increasing IV.
; Show that IRCE can turn 'ne' condition to 'slt' in increasing IV when the IV
; can be negative at some point.
define void @test_01(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_01
@ -18,6 +20,39 @@ define void @test_01(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp slt i32 [[PSEUDO_PHI]], 100
; CHECK-NEXT: br i1 [[COND]]
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ -3, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, 1
%abc = icmp slt i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ne i32 %idx.next, 100
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Show that IRCE can turn 'ne' condition to 'ult' in increasing IV when IV is
; non-negative.
define void @test_01u(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_01u
; CHECK: main.exit.selector:
; CHECK-NEXT: [[PSEUDO_PHI:%[^ ]+]] = phi i32 [ %idx.next, %in.bounds ]
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 [[PSEUDO_PHI]], 100
; CHECK-NEXT: br i1 [[COND]]
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop

263
test/Transforms/IRCE/unsigned_comparisons_ugt.ll Normal file
View File

@ -0,0 +1,263 @@
; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s
; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_02: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_03: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_04: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK-NOT: irce: in function test_05: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_06: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; UGT condition for increasing loop.
define void @test_01(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_01(
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 100
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; UGT condition for decreasing loop.
define void @test_02(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_02(
; CHECK: entry:
; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND1:%[^ ]+]] = icmp ugt i32 %len, 1
; CHECK-NEXT: %umax = select i1 [[COND1]], i32 %len, i32 1
; CHECK-NEXT: %exit.preloop.at = add i32 %umax, -1
; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp ugt i32 100, %exit.preloop.at
; CHECK-NEXT: br i1 [[COND2]], label %loop.preloop.preheader, label %preloop.pseudo.exit
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ 100, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 100, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 0
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Check SINT_MAX + 1, test is similar to test_01.
define void @test_03(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_03(
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 2147483648
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; Check SINT_MAX + 1, test is similar to test_02.
define void @test_04(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_04(
; CHECK: entry:
; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND1:%[^ ]+]] = icmp ugt i32 %len, 1
; CHECK-NEXT: %umax = select i1 [[COND1]], i32 %len, i32 1
; CHECK-NEXT: %exit.preloop.at = add i32 %umax, -1
; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp ugt i32 -2147483648, %exit.preloop.at
; CHECK-NEXT: br i1 [[COND2]], label %loop.preloop.preheader, label %preloop.pseudo.exit
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ -2147483648, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 2147483648, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 0
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Increasing loop, UINT_MAX. Negative test: we cannot add 1 to UINT_MAX.
define void @test_05(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_05(
; CHECK-NOT: loop.preloop:
; CHECK-NOT: loop.postloop:
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 4294967295
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; Decreasing loop, UINT_MAX. Positive test.
define void @test_06(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_06(
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add nuw i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ -1, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add nuw i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 4294967295, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nuw i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ugt i32 %idx.next, 0
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
!0 = !{i32 0, i32 50}

308
test/Transforms/IRCE/unsigned_comparisons_ult.ll Normal file
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@ -0,0 +1,308 @@
; RUN: opt -verify-loop-info -irce-print-changed-loops -irce -S < %s 2>&1 | FileCheck %s
; CHECK: irce: in function test_01: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_02: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_03: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_04: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_05: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK: irce: in function test_06: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; CHECK-NOT: irce: in function test_07: constrained Loop at depth 1 containing: %loop<header><exiting>,%in.bounds<latch><exiting>
; ULT condition for increasing loop.
define void @test_01(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_01
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ult i32 %idx.next, 100
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; ULT condition for decreasing loops.
define void @test_02(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_02(
; CHECK: entry:
; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND1:%[^ ]+]] = icmp ugt i32 %len, 1
; CHECK-NEXT: %umax = select i1 [[COND1]], i32 %len, i32 1
; CHECK-NEXT: %exit.preloop.at = add i32 %umax, -1
; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp ugt i32 100, %exit.preloop.at
; CHECK-NEXT: br i1 [[COND2]], label %loop.preloop.preheader, label %preloop.pseudo.exit
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ 100, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 100, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ult i32 %idx.next, 1
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; Check SINT_MAX.
define void @test_03(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_03
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ult i32 %idx.next, 2147483647
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Check SINT_MAX + 1, test is similar to test_01.
define void @test_04(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_04
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ult i32 %idx.next, 2147483648
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Check SINT_MAX + 1, test is similar to test_02.
define void @test_05(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_05(
; CHECK: entry:
; CHECK-NEXT: %len = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND1:%[^ ]+]] = icmp ugt i32 %len, 1
; CHECK-NEXT: %umax = select i1 [[COND1]], i32 %len, i32 1
; CHECK-NEXT: %exit.preloop.at = add i32 %umax, -1
; CHECK-NEXT: [[COND2:%[^ ]+]] = icmp ugt i32 -2147483648, %exit.preloop.at
; CHECK-NEXT: br i1 [[COND2]], label %loop.preloop.preheader, label %preloop.pseudo.exit
; CHECK: mainloop:
; CHECK-NEXT: br label %loop
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.preloop.copy, %mainloop ], [ %idx.next, %in.bounds ]
; CHECK-NEXT: %idx.next = add i32 %idx, -1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %len
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.postloop:
; CHECK: loop.preloop:
; CHECK-NEXT: %idx.preloop = phi i32 [ %idx.next.preloop, %in.bounds.preloop ], [ -2147483648, %loop.preloop.preheader ]
; CHECK-NEXT: %idx.next.preloop = add i32 %idx.preloop, -1
; CHECK-NEXT: %abc.preloop = icmp ult i32 %idx.preloop, %len
; CHECK-NEXT: br i1 %abc.preloop, label %in.bounds.preloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 2147483648, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ult i32 %idx.next, 1
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
; Increasing loop, UINT_MAX. Positive test.
define void @test_06(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_06
; CHECK: entry:
; CHECK-NEXT: %exit.mainloop.at = load i32, i32* %a_len_ptr, !range !0
; CHECK-NEXT: [[COND:%[^ ]+]] = icmp ult i32 0, %exit.mainloop.at
; CHECK-NEXT: br i1 [[COND]], label %loop.preheader, label %main.pseudo.exit
; CHECK: loop:
; CHECK-NEXT: %idx = phi i32 [ %idx.next, %in.bounds ], [ 0, %loop.preheader ]
; CHECK-NEXT: %idx.next = add nuw nsw i32 %idx, 1
; CHECK-NEXT: %abc = icmp ult i32 %idx, %exit.mainloop.at
; CHECK-NEXT: br i1 true, label %in.bounds, label %out.of.bounds.loopexit1
; CHECK-NOT: loop.preloop:
; CHECK: loop.postloop:
; CHECK-NEXT: %idx.postloop = phi i32 [ %idx.copy, %postloop ], [ %idx.next.postloop, %in.bounds.postloop ]
; CHECK-NEXT: %idx.next.postloop = add nuw nsw i32 %idx.postloop, 1
; CHECK-NEXT: %abc.postloop = icmp ult i32 %idx.postloop, %exit.mainloop.at
; CHECK-NEXT: br i1 %abc.postloop, label %in.bounds.postloop, label %out.of.bounds.loopexit
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 0, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nsw nuw i32 %idx, 1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ult i32 %idx.next, 4294967295
br i1 %next, label %loop, label %exit
out.of.bounds:
ret void
exit:
ret void
}
; Decreasing loop, UINT_MAX. Negative test: we cannot substract -1 from 0.
define void @test_07(i32* %arr, i32* %a_len_ptr) #0 {
; CHECK: test_07(
; CHECK-NOT: loop.preloop:
; CHECK-NOT: loop.postloop:
entry:
%len = load i32, i32* %a_len_ptr, !range !0
br label %loop
loop:
%idx = phi i32 [ 4294967295, %entry ], [ %idx.next, %in.bounds ]
%idx.next = add nuw i32 %idx, -1
%abc = icmp ult i32 %idx, %len
br i1 %abc, label %in.bounds, label %out.of.bounds
in.bounds:
%addr = getelementptr i32, i32* %arr, i32 %idx
store i32 0, i32* %addr
%next = icmp ult i32 %idx.next, 0
br i1 %next, label %exit, label %loop
out.of.bounds:
ret void
exit:
ret void
}
!0 = !{i32 0, i32 50}