torch-mlir/lib/E2E/E2E.cpp

309 lines
13 KiB
C++

//===----------------------------------------------------------------------===//
//
// 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 is the base file for our "end-to-end" npcomp lowering pipeline.
// At the moment, the first "end" is TCF ops and the second "end" is `llvm`
// dialect suitable for jitting.
//
//===----------------------------------------------------------------------===//
#include "npcomp/E2E/E2E.h"
#include "PassDetail.h"
#include "mlir/Conversion/SCFToStandard/SCFToStandard.h"
#include "mlir/Conversion/ShapeToStandard/ShapeToStandard.h"
#include "mlir/Dialect/Linalg/IR/LinalgOps.h"
#include "mlir/Dialect/Linalg/IR/LinalgTypes.h"
#include "mlir/Dialect/Linalg/Passes.h"
#include "mlir/Dialect/Shape/IR/Shape.h"
#include "mlir/Dialect/StandardOps/IR/Ops.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Pass/PassRegistry.h"
#include "mlir/Transforms/DialectConversion.h"
#include "mlir/Transforms/Passes.h"
#include "npcomp/Conversion/TCFToTCP/TCFToTCP.h"
#include "npcomp/Dialect/TCP/IR/TCPDialect.h"
#include "npcomp/Dialect/TCP/IR/TCPOps.h"
using namespace mlir;
using namespace mlir::NPCOMP;
//===----------------------------------------------------------------------===//
// Pass registration
//===----------------------------------------------------------------------===//
namespace {
#define GEN_PASS_REGISTRATION
#include "npcomp/E2E/Passes.h.inc"
} // end namespace
void mlir::NPCOMP::registerE2EPasses() {
::registerPasses();
mlir::PassPipelineRegistration<E2ELoweringPipelineOptions>(
"e2e-lowering-pipeline", "E2E lowering pipeline.",
mlir::NPCOMP::createE2ELoweringPipeline);
}
//===----------------------------------------------------------------------===//
// LowerAllocMemRefOps
//===----------------------------------------------------------------------===//
namespace {
class LowerAllocMemRefOp : public OpRewritePattern<tcp::AllocMemRefOp> {
public:
using OpRewritePattern::OpRewritePattern;
LogicalResult matchAndRewrite(tcp::AllocMemRefOp op,
PatternRewriter &rewriter) const override {
auto memrefType = op.getType().cast<MemRefType>();
auto shape = op.getOperand();
// std.alloc only accepts the dynamic extents as operands, so only
// collect those.
SmallVector<Value, 6> dynamicExtents;
for (int i = 0, e = memrefType.getRank(); i < e; i++) {
if (memrefType.isDynamicDim(i)) {
auto extent =
rewriter.create<shape::GetExtentOp>(op.getLoc(), shape, i);
dynamicExtents.push_back(extent);
}
}
rewriter.replaceOpWithNewOp<AllocOp>(op, memrefType, dynamicExtents);
return success();
}
};
} // namespace
namespace {
class LowerAllocMemRefOps
: public LowerAllocMemRefOpsBase<LowerAllocMemRefOps> {
void getDependentDialects(DialectRegistry &registry) const override {
registry.insert<shape::ShapeDialect>();
}
void runOnOperation() override {
auto func = getOperation();
auto *context = &getContext();
OwningRewritePatternList patterns;
patterns.insert<LowerAllocMemRefOp>(context);
ConversionTarget target(*context);
target.addIllegalOp<tcp::AllocMemRefOp>();
target.addLegalOp<shape::GetExtentOp>();
target.addLegalOp<AllocOp>();
target.addLegalOp<ConstantOp>();
if (failed(applyPartialConversion(func, target, patterns))) {
return signalPassFailure();
}
}
};
} // namespace
std::unique_ptr<OperationPass<FuncOp>>
mlir::NPCOMP::createLowerAllocMemRefOpsPass() {
return std::make_unique<LowerAllocMemRefOps>();
}
//===----------------------------------------------------------------------===//
// RestrictedCanonicalizer
//===----------------------------------------------------------------------===//
namespace {
struct RestrictedCanonicalizer
: public RestrictedCanonicalizerBase<RestrictedCanonicalizer> {
void runOnOperation() override {
auto *context = &getContext();
// Find the dialects from their names.
DenseSet<StringRef> neededDialects;
for (const std::string &dialectName : includedDialects)
neededDialects.insert(dialectName);
DenseSet<Dialect *> dialectsToCanonicalize;
for (Dialect *dialect : context->getLoadedDialects()) {
if (neededDialects.count(dialect->getNamespace())) {
dialectsToCanonicalize.insert(dialect);
// Erase the dialect so that we can report an error below for any
// dialect names that are not loaded.
neededDialects.erase(dialect->getNamespace());
}
}
// Report a helpful error if a dialect is not found.
auto missingDialects = llvm::to_vector<6>(neededDialects);
if (!missingDialects.empty()) {
llvm::sort(missingDialects);
std::string buf;
llvm::raw_string_ostream os(buf);
llvm::interleaveComma(missingDialects, os);
llvm::report_fatal_error("restricted-canonicalize: unknown dialects: " +
os.str());
}
// Collect all canonicalization patterns from ops in the included dialects.
OwningRewritePatternList patterns;
for (AbstractOperation *op : context->getRegisteredOperations())
if (dialectsToCanonicalize.count(&op->dialect))
op->getCanonicalizationPatterns(patterns, context);
Operation *op = getOperation();
applyPatternsAndFoldGreedily(op->getRegions(), patterns);
}
};
} // end anonymous namespace
std::unique_ptr<Pass> mlir::NPCOMP::createRestrictedCanonicalizerPass() {
return std::make_unique<RestrictedCanonicalizer>();
}
//===----------------------------------------------------------------------===//
// createE2ELoweringPipeline
//===----------------------------------------------------------------------===//
void mlir::NPCOMP::createE2ELoweringPipeline(
OpPassManager &pm, const E2ELoweringPipelineOptions &options) {
// This "end to end" lowering pipline loewrings from approximately the "numpy"
// level of abstraction (which is a dialect we call "TCF", or "Tensor Compute
// Frontend") all the way down to LLVM IR.
// Convert from TCF to TCP.
//
// TCF has implicit broadcasting, and issues errors "inside the ops" in the
// case of invalid broadcasts.
//
// TCP does not. So we need to reify the broadcasting and error checking.
pm.addPass(createConvertTCFToTCPPass());
// For operations with a shape transfer function, explicitly bypass their
// shape computations with tcp.shaped_results ops.
//
// Right now, our lowering flow depends heavily on descriptors, so technically
// we don't need to bypass shapes -- we can just splat out the shape
// calculations when lowering the ops themselves. However, this design keeps
// the door open to various future directions, and is an interesting example
// in its own right.
//
// For example, if we want to lower to command-buffer style API's like Vulkan,
// then we need (for correctness) to bypass the shapes (actually,
// something more sophisticated than just that) if we want to do command
// buffer formation while we are still on tensors (e.g. to record workgroup
// sizes). We might not care about pursuing that direction here though. So
// consider this pass as purely advisory now.
//
// One case where we might still be interested in this is dealing with
// linalg.generic ops and other types of "fusions" that have shape transfer
// functions that are not easily reconstructible and thus we have to capture
// the shape transfer functions earlier in the pipeline.
pm.addPass(createBypassShapesPass());
// Lower shape constraints before we enter tensor->memref conversion.
// That is, we expand shape.cstr_* ops to eager error handling code.
pm.addPass(createConvertShapeConstraintsPass());
// Run shape canonicalizations. In particular, this erases shape.assuming,
// now that we have converted shape constraints.
// TODO: This is kind of ugly. Either we use pass options or a constructor
// that takes C++ data structures. The former makes the pass usable on the
// command line (including reproducers), the latter makes the pass more
// convenient.
std::unique_ptr<Pass> shapeCanonicalizer =
createRestrictedCanonicalizerPass();
if (failed(shapeCanonicalizer->initializeOptions("included-dialects=shape")))
llvm::report_fatal_error("couldn't initialize restricted-canonicalize");
pm.addPass(std::move(shapeCanonicalizer));
// --------------------------------------------------------------------------
// Lower the `tensor` type to `memref`.
// --------------------------------------------------------------------------
// We make a conscious effort here to do this as a sequence of separate passes
// rather than a single mega dialect conversion pass.
//
// This means that intermediate steps have source/target materializations
// (tcp.memref_to_tensor / tcp.tensor_to_memref) in the IR.
// Lower ops enclosed in tcp.shaped_results regions.
// For now, this is covering the "tensor compute" ops like tcp.add /
// tcp.broadcast_to (the former being handled via a special subset of
// linalg.generic) -- we only handle those two, so having an isolated pass
// that hardcodes all of them is fine -- eventually we might want something
// more pluggable. The exact interface for this pluggability depends on
// what design we want to settle on for bypassing shape computations.
pm.addPass(createLowerShapedResultsToMemrefPass());
// Lower tensor-valued constants to tcp.global.
pm.addPass(createLowerConstantTensorsToMemrefPass());
// tcp::AllocMemRefOp takes a shape (i.e. extent tensor) as an argument. We
// need to resolve this to std.alloc which takes individual extents.
pm.addPass(createLowerAllocMemRefOpsPass());
// Lower shape ops to std.
// TODO: This should in principle be moved before tensor->memref conversion.
// But some of the tensor->memref lowerings above use shape.get_extent. For
// example, when lowering a broadcast, we need to get an extent from its shape
// operand to allocate the output.
pm.addPass(createConvertShapeToStandardPass());
// Lower std ops to memref.
// This includes ops like extract_element.
pm.addPass(createLowerStdToMemrefPass());
// Lower control flow and other "structural" ops.
//
// These ops are generally not sensitive to the types that they operate on
// (e.g. the types of block operands, function arguments, etc.). But they all
// need to be converted consistently. So it makes sense to do this as the
// final step of conversion, which also finalizes the elimination of all
// stray source/target materializations introduced by the incremental
// tensor->memref lowering.
//
// This completes conversion to memref. There are no `tensor`'s after
// this point.
pm.addPass(createLowerStructuralToMemrefPass());
// TODO: Do buffer assignment. We should be able to just drop in the upstream
// pass?
// At this point, we have lots of loose stuff floating around from lowering,
// so it's a good time to do some general cleanups.
if (options.optimize) {
pm.addPass(createCanonicalizerPass());
pm.addPass(createCSEPass());
}
// --------------------------------------------------------------------------
// Preparation for converting to an LLVM module.
// --------------------------------------------------------------------------
// Now, we begin the process of lowering to LLVM's level of abstraction
// (after which LLVM will take over lowering to machine code).
// Lower linalg ops to loops.
// TODO: Do some linalg optimizations like tiling here.
pm.addPass(createConvertLinalgToLoopsPass());
// Run a some cleanups.
if (options.optimize) {
pm.addPass(createCanonicalizerPass());
pm.addPass(createCSEPass());
}
// --------------------------------------------------------------------------
// Final conversion to an LLVM module.
// --------------------------------------------------------------------------
// Convert scf to std control flow in preparation for going to LLVM.
pm.addPass(createLowerToCFGPass());
// Convert functions signatures and other constructs that interface with the
// runtime to the `npcomprt` dialect.
pm.addPass(createLowerToNpcomprtABIPass());
// Finally, convert to LLVM dialect using our custom LowerToLLVM pass
// which reuses the upstream patterns and gives us a place to add our own
// patterns for our own custom ops like the npcomprt ops.
pm.addPass(createLowerToLLVMPass());
// Although LLVM will clean everything up eventually, for the sake of IR
// clarity while still in MLIR, run some cleanups.
if (options.optimize) {
pm.addPass(createCanonicalizerPass());
pm.addPass(createCSEPass());
}
}