llvm-project/mlir/test/lib/Dialect/SCF/TestParallelLoopUnrolling.cpp
fabrizio-indirli dbd9818db3
[mlir][scf] Add parallelLoopUnrollByFactors() (#164958)
- In the SCF Utils, add the `parallelLoopUnrollByFactors()` function to
unroll scf::ParallelOp loops according to the specified unroll factors
- Add a test pass "TestParallelLoopUnrolling" and the related LIT test
- Expose `mlir::parallelLoopUnrollByFactors()`,
`mlir::generateUnrolledLoop()`, and `mlir::scf::computeUbMinusLb()`
functions in the mlir/Dialect/SCF/Utils/Utils.h and /IR/SCF.h headers to
make them available to other passes.
- In `mlir::generateUnrolledLoop()`, add an optional `IRMapping *clonedToSrcOpsMap` 
argument to map the new cloned operations to their
original ones. In the function body, change the default `AnnotateFn`
type to `static const` to silence potential warnings about dangling
references when a function_ref is assigned to a variable with automatic
storage.

Signed-off-by: Fabrizio Indirli <Fabrizio.Indirli@arm.com>
2025-10-27 14:51:51 +00:00

86 lines
2.9 KiB
C++

//=== TestParallelLoopUnrolling.cpp - loop unrolling test pass ===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements a pass to unroll loops by a specified unroll factor.
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/SCF/IR/SCF.h"
#include "mlir/Dialect/SCF/Utils/Utils.h"
#include "mlir/IR/Builders.h"
#include "mlir/Pass/Pass.h"
using namespace mlir;
namespace {
static unsigned getNestingDepth(Operation *op) {
Operation *currOp = op;
unsigned depth = 0;
while ((currOp = currOp->getParentOp())) {
if (isa<scf::ParallelOp>(currOp))
depth++;
}
return depth;
}
struct TestParallelLoopUnrollingPass
: public PassWrapper<TestParallelLoopUnrollingPass, OperationPass<>> {
MLIR_DEFINE_EXPLICIT_INTERNAL_INLINE_TYPE_ID(TestParallelLoopUnrollingPass)
StringRef getArgument() const final { return "test-parallel-loop-unrolling"; }
StringRef getDescription() const final {
return "Tests parallel loop unrolling transformation";
}
TestParallelLoopUnrollingPass() = default;
TestParallelLoopUnrollingPass(const TestParallelLoopUnrollingPass &) {}
void getDependentDialects(DialectRegistry &registry) const override {
registry.insert<arith::ArithDialect>();
}
void runOnOperation() override {
SmallVector<scf::ParallelOp, 4> loops;
getOperation()->walk([&](scf::ParallelOp parLoop) {
if (getNestingDepth(parLoop) == loopDepth)
loops.push_back(parLoop);
});
auto annotateFn = [this](unsigned i, Operation *op, OpBuilder b) {
if (annotateLoop) {
op->setAttr("unrolled_iteration", b.getUI32IntegerAttr(i));
}
};
PatternRewriter rewriter(getOperation()->getContext());
for (auto loop : loops) {
(void)parallelLoopUnrollByFactors(loop, unrollFactors, rewriter,
annotateFn);
}
}
ListOption<uint64_t> unrollFactors{
*this, "unroll-factors",
llvm::cl::desc(
"Unroll factors for each parallel loop dim. If fewer factors than "
"loop dims are provided, they are applied to the inner dims.")};
Option<unsigned> loopDepth{*this, "loop-depth", llvm::cl::desc("Loop depth."),
llvm::cl::init(0)};
Option<bool> annotateLoop{*this, "annotate",
llvm::cl::desc("Annotate unrolled iterations."),
llvm::cl::init(false)};
};
} // namespace
namespace mlir {
namespace test {
void registerTestParallelLoopUnrollingPass() {
PassRegistration<TestParallelLoopUnrollingPass>();
}
} // namespace test
} // namespace mlir