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[OpenMPIRBuilder] Split calculation of canonical loop trip count, NFC #127820

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38 changes: 31 additions & 7 deletions llvm/include/llvm/Frontend/OpenMP/OMPIRBuilder.h
Original file line number Diff line number Diff line change
Expand Up @@ -728,13 +728,12 @@ class OpenMPIRBuilder {
LoopBodyGenCallbackTy BodyGenCB, Value *TripCount,
const Twine &Name = "loop");

/// Generator for the control flow structure of an OpenMP canonical loop.
/// Calculate the trip count of a canonical loop.
///
/// Instead of a logical iteration space, this allows specifying user-defined
/// loop counter values using increment, upper- and lower bounds. To
/// disambiguate the terminology when counting downwards, instead of lower
/// bounds we use \p Start for the loop counter value in the first body
/// iteration.
/// This allows specifying user-defined loop counter values using increment,
/// upper- and lower bounds. To disambiguate the terminology when counting
/// downwards, instead of lower bounds we use \p Start for the loop counter
/// value in the first body iteration.
///
/// Consider the following limitations:
///
Expand All @@ -758,7 +757,32 @@ class OpenMPIRBuilder {
///
/// for (int i = 0; i < 42; i -= 1u)
///
//
/// \param Loc The insert and source location description.
/// \param Start Value of the loop counter for the first iterations.
/// \param Stop Loop counter values past this will stop the loop.
/// \param Step Loop counter increment after each iteration; negative
/// means counting down.
/// \param IsSigned Whether Start, Stop and Step are signed integers.
/// \param InclusiveStop Whether \p Stop itself is a valid value for the loop
/// counter.
/// \param Name Base name used to derive instruction names.
///
/// \returns The value holding the calculated trip count.
Value *calculateCanonicalLoopTripCount(const LocationDescription &Loc,
Value *Start, Value *Stop, Value *Step,
bool IsSigned, bool InclusiveStop,
const Twine &Name = "loop");

/// Generator for the control flow structure of an OpenMP canonical loop.
///
/// Instead of a logical iteration space, this allows specifying user-defined
/// loop counter values using increment, upper- and lower bounds. To
/// disambiguate the terminology when counting downwards, instead of lower
/// bounds we use \p Start for the loop counter value in the first body
///
/// It calls \see calculateCanonicalLoopTripCount for trip count calculations,
/// so limitations of that method apply here as well.
///
/// \param Loc The insert and source location description.
/// \param BodyGenCB Callback that will generate the loop body code.
/// \param Start Value of the loop counter for the first iterations.
Expand Down
27 changes: 18 additions & 9 deletions llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -4059,10 +4059,9 @@ OpenMPIRBuilder::createCanonicalLoop(const LocationDescription &Loc,
return CL;
}

Expected<CanonicalLoopInfo *> OpenMPIRBuilder::createCanonicalLoop(
const LocationDescription &Loc, LoopBodyGenCallbackTy BodyGenCB,
Value *Start, Value *Stop, Value *Step, bool IsSigned, bool InclusiveStop,
InsertPointTy ComputeIP, const Twine &Name) {
Value *OpenMPIRBuilder::calculateCanonicalLoopTripCount(
const LocationDescription &Loc, Value *Start, Value *Stop, Value *Step,
bool IsSigned, bool InclusiveStop, const Twine &Name) {

// Consider the following difficulties (assuming 8-bit signed integers):
// * Adding \p Step to the loop counter which passes \p Stop may overflow:
Expand All @@ -4075,9 +4074,7 @@ Expected<CanonicalLoopInfo *> OpenMPIRBuilder::createCanonicalLoop(
assert(IndVarTy == Stop->getType() && "Stop type mismatch");
assert(IndVarTy == Step->getType() && "Step type mismatch");

LocationDescription ComputeLoc =
ComputeIP.isSet() ? LocationDescription(ComputeIP, Loc.DL) : Loc;
updateToLocation(ComputeLoc);
updateToLocation(Loc);

ConstantInt *Zero = ConstantInt::get(IndVarTy, 0);
ConstantInt *One = ConstantInt::get(IndVarTy, 1);
Expand Down Expand Up @@ -4117,8 +4114,20 @@ Expected<CanonicalLoopInfo *> OpenMPIRBuilder::createCanonicalLoop(
Value *OneCmp = Builder.CreateICmp(CmpInst::ICMP_ULE, Span, Incr);
CountIfLooping = Builder.CreateSelect(OneCmp, One, CountIfTwo);
}
Value *TripCount = Builder.CreateSelect(ZeroCmp, Zero, CountIfLooping,
"omp_" + Name + ".tripcount");

return Builder.CreateSelect(ZeroCmp, Zero, CountIfLooping,
"omp_" + Name + ".tripcount");
}

Expected<CanonicalLoopInfo *> OpenMPIRBuilder::createCanonicalLoop(
const LocationDescription &Loc, LoopBodyGenCallbackTy BodyGenCB,
Value *Start, Value *Stop, Value *Step, bool IsSigned, bool InclusiveStop,
InsertPointTy ComputeIP, const Twine &Name) {
LocationDescription ComputeLoc =
ComputeIP.isSet() ? LocationDescription(ComputeIP, Loc.DL) : Loc;

Value *TripCount = calculateCanonicalLoopTripCount(
ComputeLoc, Start, Stop, Step, IsSigned, InclusiveStop, Name);

auto BodyGen = [=](InsertPointTy CodeGenIP, Value *IV) {
Builder.restoreIP(CodeGenIP);
Expand Down
16 changes: 3 additions & 13 deletions llvm/unittests/Frontend/OpenMPIRBuilderTest.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -1441,8 +1441,7 @@ TEST_F(OpenMPIRBuilderTest, CanonicalLoopSimple) {
EXPECT_EQ(&Loop->getAfter()->front(), RetInst);
}

TEST_F(OpenMPIRBuilderTest, CanonicalLoopBounds) {
using InsertPointTy = OpenMPIRBuilder::InsertPointTy;
TEST_F(OpenMPIRBuilderTest, CanonicalLoopTripCount) {
OpenMPIRBuilder OMPBuilder(*M);
OMPBuilder.initialize();
IRBuilder<> Builder(BB);
Expand All @@ -1458,17 +1457,8 @@ TEST_F(OpenMPIRBuilderTest, CanonicalLoopBounds) {
Value *StartVal = ConstantInt::get(LCTy, Start);
Value *StopVal = ConstantInt::get(LCTy, Stop);
Value *StepVal = ConstantInt::get(LCTy, Step);
auto LoopBodyGenCB = [&](InsertPointTy CodeGenIP, llvm::Value *LC) {
return Error::success();
};
ASSERT_EXPECTED_INIT_RETURN(
CanonicalLoopInfo *, Loop,
OMPBuilder.createCanonicalLoop(Loc, LoopBodyGenCB, StartVal, StopVal,
StepVal, IsSigned, InclusiveStop),
-1);
Loop->assertOK();
Builder.restoreIP(Loop->getAfterIP());
Value *TripCount = Loop->getTripCount();
Value *TripCount = OMPBuilder.calculateCanonicalLoopTripCount(
Loc, StartVal, StopVal, StepVal, IsSigned, InclusiveStop);
return cast<ConstantInt>(TripCount)->getValue().getZExtValue();
};

Expand Down
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