bolt/deps/llvm-18.1.8/mlir/lib/Dialect/SCF/Transforms/ParallelLoopCollapsing.cpp

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2025-02-14 19:21:04 +01:00
//===- ParallelLoopCollapsing.cpp - Pass collapsing parallel loop indices -===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/SCF/Transforms/Passes.h"
#include "mlir/Dialect/SCF/IR/SCF.h"
#include "mlir/Dialect/SCF/Utils/Utils.h"
#include "mlir/Transforms/RegionUtils.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
namespace mlir {
#define GEN_PASS_DEF_TESTSCFPARALLELLOOPCOLLAPSING
#include "mlir/Dialect/SCF/Transforms/Passes.h.inc"
} // namespace mlir
#define DEBUG_TYPE "parallel-loop-collapsing"
using namespace mlir;
namespace {
struct TestSCFParallelLoopCollapsing
: public impl::TestSCFParallelLoopCollapsingBase<
TestSCFParallelLoopCollapsing> {
void runOnOperation() override {
Operation *module = getOperation();
// The common case for GPU dialect will be simplifying the ParallelOp to 3
// arguments, so we do that here to simplify things.
llvm::SmallVector<std::vector<unsigned>, 3> combinedLoops;
// Gather the input args into the format required by
// `collapseParallelLoops`.
if (!clCollapsedIndices0.empty())
combinedLoops.push_back(clCollapsedIndices0);
if (!clCollapsedIndices1.empty()) {
if (clCollapsedIndices0.empty()) {
llvm::errs()
<< "collapsed-indices-1 specified but not collapsed-indices-0";
signalPassFailure();
return;
}
combinedLoops.push_back(clCollapsedIndices1);
}
if (!clCollapsedIndices2.empty()) {
if (clCollapsedIndices1.empty()) {
llvm::errs()
<< "collapsed-indices-2 specified but not collapsed-indices-1";
signalPassFailure();
return;
}
combinedLoops.push_back(clCollapsedIndices2);
}
if (combinedLoops.empty()) {
llvm::errs() << "No collapsed-indices were specified. This pass is only "
"for testing and does not automatically collapse all "
"parallel loops or similar.";
signalPassFailure();
return;
}
// Confirm that the specified loops are [0,N) by testing that N values exist
// with the maximum value being N-1.
llvm::SmallSet<unsigned, 8> flattenedCombinedLoops;
unsigned maxCollapsedIndex = 0;
for (auto &loops : combinedLoops) {
for (auto &loop : loops) {
flattenedCombinedLoops.insert(loop);
maxCollapsedIndex = std::max(maxCollapsedIndex, loop);
}
}
if (maxCollapsedIndex != flattenedCombinedLoops.size() - 1 ||
!flattenedCombinedLoops.contains(maxCollapsedIndex)) {
llvm::errs()
<< "collapsed-indices arguments must include all values [0,N).";
signalPassFailure();
return;
}
// Only apply the transformation on parallel loops where the specified
// transformation is valid, but do NOT early abort in the case of invalid
// loops.
module->walk([&](scf::ParallelOp op) {
if (flattenedCombinedLoops.size() != op.getNumLoops()) {
op.emitOpError("has ")
<< op.getNumLoops()
<< " iter args while this limited functionality testing pass was "
"configured only for loops with exactly "
<< flattenedCombinedLoops.size() << " iter args.";
return;
}
collapseParallelLoops(op, combinedLoops);
});
}
};
} // namespace
std::unique_ptr<Pass> mlir::createTestSCFParallelLoopCollapsingPass() {
return std::make_unique<TestSCFParallelLoopCollapsing>();
}