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[flang][fir]: Add conversion of fir.iterate_while to scf.while. #152439

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Merged
merged 9 commits into from
Aug 14, 2025
Merged

[flang][fir]: Add conversion of fir.iterate_while to scf.while. #152439

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f5277a8
[flang][fir]: Add conversion of `fir.iterate_while` to `scf.while`.
terapines-osc-mlir Aug 7, 2025
d9eaf2b
Refactor: Using `rewriter.inlineBlockBefore` instead of `mlir::IRMapp…
terapines-osc-mlir Aug 8, 2025
f4a5d4f
Fix: Attributes were not copied to scf.while from fir.iterate_while.
terapines-osc-mlir Aug 11, 2025
cbcef2f
Refactor: Using rewriter.replaceOpWithNewOp instead of T::create + er…
terapines-osc-mlir Aug 11, 2025
39983c8
Trivial Changes: Unused variable in iteration got renamed to `_`.
terapines-osc-mlir Aug 11, 2025
edaf29b
Simplify the code
terapines-osc-mlir Aug 11, 2025
0dd8686
Trivial Changes: Unnecessary include (introduced by IDE) got eliminated.
terapines-osc-mlir Aug 11, 2025
66f9e9d
Refactor: Some variable renames, some explicit types instead of auto.
terapines-osc-mlir Aug 12, 2025
e9efb92
Style Changes: Using expanded namespace.
terapines-osc-mlir Aug 13, 2025
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74 changes: 71 additions & 3 deletions flang/lib/Optimizer/Transforms/FIRToSCF.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@ struct DoLoopConversion : public mlir::OpRewritePattern<fir::DoLoopOp> {
mlir::Value high = doLoopOp.getUpperBound();
assert(low && high && "must be a Value");
mlir::Value step = doLoopOp.getStep();
llvm::SmallVector<mlir::Value> iterArgs;
mlir::SmallVector<mlir::Value> iterArgs;
if (hasFinalValue)
iterArgs.push_back(low);
iterArgs.append(doLoopOp.getIterOperands().begin(),
Expand Down Expand Up @@ -88,6 +88,73 @@ struct DoLoopConversion : public mlir::OpRewritePattern<fir::DoLoopOp> {
}
};

struct IterWhileConversion : public mlir::OpRewritePattern<fir::IterWhileOp> {
using OpRewritePattern<fir::IterWhileOp>::OpRewritePattern;

mlir::LogicalResult
matchAndRewrite(fir::IterWhileOp iterWhileOp,
mlir::PatternRewriter &rewriter) const override {

mlir::Location loc = iterWhileOp.getLoc();
mlir::Value lowerBound = iterWhileOp.getLowerBound();
mlir::Value upperBound = iterWhileOp.getUpperBound();
mlir::Value step = iterWhileOp.getStep();

mlir::Value okInit = iterWhileOp.getIterateIn();
mlir::ValueRange iterArgs = iterWhileOp.getInitArgs();

mlir::SmallVector<mlir::Value> initVals;
initVals.push_back(lowerBound);
initVals.push_back(okInit);
initVals.append(iterArgs.begin(), iterArgs.end());

mlir::SmallVector<mlir::Type> loopTypes;
loopTypes.push_back(lowerBound.getType());
loopTypes.push_back(okInit.getType());
for (auto val : iterArgs)
loopTypes.push_back(val.getType());

auto scfWhileOp =
mlir::scf::WhileOp::create(rewriter, loc, loopTypes, initVals);

auto &beforeBlock = *rewriter.createBlock(
&scfWhileOp.getBefore(), scfWhileOp.getBefore().end(), loopTypes,
mlir::SmallVector<mlir::Location>(loopTypes.size(), loc));

mlir::Region::BlockArgListType argsInBefore =
scfWhileOp.getBefore().getArguments();
auto ivInBefore = argsInBefore[0];
auto earlyExitInBefore = argsInBefore[1];

rewriter.setInsertionPointToStart(&beforeBlock);

mlir::Value inductionCmp = mlir::arith::CmpIOp::create(
rewriter, loc, mlir::arith::CmpIPredicate::sle, ivInBefore, upperBound);
mlir::Value cond = mlir::arith::AndIOp::create(rewriter, loc, inductionCmp,
earlyExitInBefore);

mlir::scf::ConditionOp::create(rewriter, loc, cond, argsInBefore);

rewriter.moveBlockBefore(iterWhileOp.getBody(), &scfWhileOp.getAfter(),
scfWhileOp.getAfter().begin());

auto *afterBody = scfWhileOp.getAfterBody();
auto resultOp = mlir::cast<fir::ResultOp>(afterBody->getTerminator());
mlir::SmallVector<mlir::Value> results(resultOp->getOperands());
mlir::Value ivInAfter = scfWhileOp.getAfterArguments()[0];

rewriter.setInsertionPointToStart(afterBody);
results[0] = mlir::arith::AddIOp::create(rewriter, loc, ivInAfter, step);

rewriter.setInsertionPointToEnd(afterBody);
rewriter.replaceOpWithNewOp<mlir::scf::YieldOp>(resultOp, results);

scfWhileOp->setAttrs(iterWhileOp->getAttrs());
rewriter.replaceOp(iterWhileOp, scfWhileOp);
return mlir::success();
}
};

void copyBlockAndTransformResult(mlir::PatternRewriter &rewriter,
mlir::Block &srcBlock, mlir::Block &dstBlock) {
mlir::Operation *srcTerminator = srcBlock.getTerminator();
Expand Down Expand Up @@ -132,9 +199,10 @@ struct IfConversion : public mlir::OpRewritePattern<fir::IfOp> {

void FIRToSCFPass::runOnOperation() {
mlir::RewritePatternSet patterns(&getContext());
patterns.add<DoLoopConversion, IfConversion>(patterns.getContext());
patterns.add<DoLoopConversion, IterWhileConversion, IfConversion>(
patterns.getContext());
mlir::ConversionTarget target(getContext());
target.addIllegalOp<fir::DoLoopOp, fir::IfOp>();
target.addIllegalOp<fir::DoLoopOp, fir::IterWhileOp, fir::IfOp>();
target.markUnknownOpDynamicallyLegal([](mlir::Operation *) { return true; });
if (failed(
applyPartialConversion(getOperation(), target, std::move(patterns))))
Expand Down
99 changes: 99 additions & 0 deletions flang/test/Fir/FirToSCF/iter-while.fir
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Original file line number Diff line number Diff line change
@@ -0,0 +1,99 @@
// RUN: fir-opt %s --fir-to-scf | FileCheck %s

// CHECK-LABEL: func.func @test_simple_iterate_while_1() -> (index, i1, i16, i32) {
// CHECK: %[[VAL_0:.*]] = arith.constant 11 : index
// CHECK: %[[VAL_1:.*]] = arith.constant 22 : index
// CHECK: %[[VAL_2:.*]] = arith.constant 2 : index
// CHECK: %[[VAL_3:.*]] = arith.constant true
// CHECK: %[[VAL_4:.*]] = arith.constant 123 : i16
// CHECK: %[[VAL_5:.*]] = arith.constant 456 : i32
// CHECK: %[[VAL_6:.*]]:4 = scf.while (%[[VAL_7:.*]] = %[[VAL_0]], %[[VAL_8:.*]] = %[[VAL_3]], %[[VAL_9:.*]] = %[[VAL_4]], %[[VAL_10:.*]] = %[[VAL_5]]) : (index, i1, i16, i32) -> (index, i1, i16, i32) {
// CHECK: %[[VAL_11:.*]] = arith.cmpi sle, %[[VAL_7]], %[[VAL_1]] : index
// CHECK: %[[VAL_12:.*]] = arith.andi %[[VAL_11]], %[[VAL_8]] : i1
// CHECK: scf.condition(%[[VAL_12]]) %[[VAL_7]], %[[VAL_8]], %[[VAL_9]], %[[VAL_10]] : index, i1, i16, i32
// CHECK: } do {
// CHECK: ^bb0(%[[VAL_13:.*]]: index, %[[VAL_14:.*]]: i1, %[[VAL_15:.*]]: i16, %[[VAL_16:.*]]: i32):
// CHECK: %[[VAL_17:.*]] = arith.addi %[[VAL_13]], %[[VAL_2]] : index
// CHECK: %[[VAL_18:.*]] = arith.constant true
// CHECK: %[[VAL_19:.*]] = arith.constant 22 : i16
// CHECK: %[[VAL_20:.*]] = arith.constant 33 : i32
// CHECK: scf.yield %[[VAL_17]], %[[VAL_18]], %[[VAL_19]], %[[VAL_20]] : index, i1, i16, i32
// CHECK: }
// CHECK: return %[[VAL_21:.*]]#0, %[[VAL_21]]#1, %[[VAL_21]]#2, %[[VAL_21]]#3 : index, i1, i16, i32
// CHECK: }
func.func @test_simple_iterate_while_1() -> (index, i1, i16, i32) {
%lo = arith.constant 11 : index
%up = arith.constant 22 : index
%step = arith.constant 2 : index
%ok = arith.constant 1 : i1
%val1 = arith.constant 123 : i16
%val2 = arith.constant 456 : i32

%res:4 = fir.iterate_while (%i = %lo to %up step %step) and (%c = %ok) iter_args(%v1 = %val1, %v2 = %val2) -> (index, i1, i16, i32) {
%new_c = arith.constant 1 : i1
%new_v1 = arith.constant 22 : i16
%new_v2 = arith.constant 33 : i32
fir.result %i, %new_c, %new_v1, %new_v2 : index, i1, i16, i32
}

return %res#0, %res#1, %res#2, %res#3 : index, i1, i16, i32
}

// CHECK-LABEL: func.func @test_simple_iterate_while_2(
// CHECK-SAME: %[[ARG0:.*]]: index, %[[ARG1:.*]]: index, %[[ARG2:.*]]: i1, %[[ARG3:.*]]: i32) -> (index, i1, i32) {
// CHECK: %[[VAL_0:.*]] = arith.constant 1 : index
// CHECK: %[[VAL_1:.*]]:3 = scf.while (%[[VAL_2:.*]] = %[[ARG0]], %[[VAL_3:.*]] = %[[ARG2]], %[[VAL_4:.*]] = %[[ARG3]]) : (index, i1, i32) -> (index, i1, i32) {
// CHECK: %[[VAL_5:.*]] = arith.cmpi sle, %[[VAL_2]], %[[ARG1]] : index
// CHECK: %[[VAL_6:.*]] = arith.andi %[[VAL_5]], %[[VAL_3]] : i1
// CHECK: scf.condition(%[[VAL_6]]) %[[VAL_2]], %[[VAL_3]], %[[VAL_4]] : index, i1, i32
// CHECK: } do {
// CHECK: ^bb0(%[[VAL_7:.*]]: index, %[[VAL_8:.*]]: i1, %[[VAL_9:.*]]: i32):
// CHECK: %[[VAL_10:.*]] = arith.addi %[[VAL_7]], %[[VAL_0]] : index
// CHECK: %[[VAL_11:.*]] = arith.constant 123 : i32
// CHECK: %[[VAL_12:.*]] = arith.constant true
// CHECK: scf.yield %[[VAL_10]], %[[VAL_12]], %[[VAL_11]] : index, i1, i32
// CHECK: }
// CHECK: return %[[VAL_13:.*]]#0, %[[VAL_13]]#1, %[[VAL_13]]#2 : index, i1, i32
// CHECK: }
func.func @test_simple_iterate_while_2(%start: index, %stop: index, %cond: i1, %val: i32) -> (index, i1, i32) {
%step = arith.constant 1 : index

%res:3 = fir.iterate_while (%i = %start to %stop step %step) and (%ok = %cond) iter_args(%x = %val) -> (index, i1, i32) {
%new_x = arith.constant 123 : i32
%new_ok = arith.constant 1 : i1
fir.result %i, %new_ok, %new_x : index, i1, i32
}

return %res#0, %res#1, %res#2 : index, i1, i32
}

// CHECK-LABEL: func.func @test_zero_iterations() -> (index, i1, i8) {
// CHECK: %[[VAL_0:.*]] = arith.constant 10 : index
// CHECK: %[[VAL_1:.*]] = arith.constant 5 : index
// CHECK: %[[VAL_2:.*]] = arith.constant 1 : index
// CHECK: %[[VAL_3:.*]] = arith.constant true
// CHECK: %[[VAL_4:.*]] = arith.constant 42 : i8
// CHECK: %[[VAL_5:.*]]:3 = scf.while (%[[VAL_6:.*]] = %[[VAL_0]], %[[VAL_7:.*]] = %[[VAL_3]], %[[VAL_8:.*]] = %[[VAL_4]]) : (index, i1, i8) -> (index, i1, i8) {
// CHECK: %[[VAL_9:.*]] = arith.cmpi sle, %[[VAL_6]], %[[VAL_1]] : index
// CHECK: %[[VAL_10:.*]] = arith.andi %[[VAL_9]], %[[VAL_7]] : i1
// CHECK: scf.condition(%[[VAL_10]]) %[[VAL_6]], %[[VAL_7]], %[[VAL_8]] : index, i1, i8
// CHECK: } do {
// CHECK: ^bb0(%[[VAL_11:.*]]: index, %[[VAL_12:.*]]: i1, %[[VAL_13:.*]]: i8):
// CHECK: %[[VAL_14:.*]] = arith.addi %[[VAL_11]], %[[VAL_2]] : index
// CHECK: scf.yield %[[VAL_14]], %[[VAL_12]], %[[VAL_13]] : index, i1, i8
// CHECK: }
// CHECK: return %[[VAL_15:.*]]#0, %[[VAL_15]]#1, %[[VAL_15]]#2 : index, i1, i8
// CHECK: }
func.func @test_zero_iterations() -> (index, i1, i8) {
%lo = arith.constant 10 : index
%up = arith.constant 5 : index
%step = arith.constant 1 : index
%ok = arith.constant 1 : i1
%x = arith.constant 42 : i8

%res:3 = fir.iterate_while (%i = %lo to %up step %step) and (%c = %ok) iter_args(%xv = %x) -> (index, i1, i8) {
fir.result %i, %c, %xv : index, i1, i8
}

return %res#0, %res#1, %res#2 : index, i1, i8
}