llvm-project/mlir/lib/Conversion/VectorToLLVM/ConvertVectorToLLVMPass.cpp
Yang Bai 4eb1a07d7d
[mlir][vector] Support multi-dimensional vectors in VectorFromElementsLowering (#151175)
This patch introduces a new unrolling-based approach for lowering
multi-dimensional `vector.from_elements` operations.

**Implementation Details:**
1. **New Transform Pattern**: Added `UnrollFromElements` that unrolls a
N-D(N>=2) from_elements op to a (N-1)-D from_elements op align the
outermost dimension.
2. **Utility Functions**: Added `unrollVectorOp` to reuse the unroll
algo of vector.gather for vector.from_elements.
3. **Integration**: Added the unrolling pattern to the
convert-vector-to-llvm pass as a temporal transformation.
4. Use direct LLVM dialect operations instead of intermediate
vector.insert operations for efficiency in `VectorFromElementsLowering`.

**Example:**
```mlir
// unroll
%v = vector.from_elements  %e0, %e1, %e2, %e3 : vector<2x2xf32>
=>
%poison_2d = ub.poison : vector<2x2xf32>
%vec_1d_0 = vector.from_elements %e0, %e1 : vector<2xf32>
%vec_2d_0 = vector.insert %vec_1d_0, %poison_2d [0] : vector<2xf32> into vector<2x2xf32>
%vec_1d_1 = vector.from_elements %e2, %e3 : vector<2xf32>
%result = vector.insert %vec_1d_1, %vec_2d_0 [1] : vector<2xf32> into vector<2x2xf32>

// convert-vector-to-llvm
%v = vector.from_elements %e0, %e1, %e2, %e3 : vector<2x2xf32>
=>
%poison_2d = ub.poison : vector<2x2xf32>
%poison_2d_cast = builtin.unrealized_conversion_cast %poison_2d : vector<2x2xf32> to !llvm.array<2 x vector<2xf32>>
%poison_1d_0 = llvm.mlir.poison : vector<2xf32>
%c0_0 = llvm.mlir.constant(0 : i64) : i64
%vec_1d_0_0 = llvm.insertelement %e0, %poison_1d_0[%c0_0 : i64] : vector<2xf32>
%c1_0 = llvm.mlir.constant(1 : i64) : i64
%vec_1d_0_1 = llvm.insertelement %e1, %vec_1d_0_0[%c1_0 : i64] : vector<2xf32>
%vec_2d_0 = llvm.insertvalue %vec_1d_0_1, %poison_2d_cast[0] : !llvm.array<2 x vector<2xf32>>
%poison_1d_1 = llvm.mlir.poison : vector<2xf32>
%c0_1 = llvm.mlir.constant(0 : i64) : i64
%vec_1d_1_0 = llvm.insertelement %e2, %poison_1d_1[%c0_1 : i64] : vector<2xf32>
%c1_1 = llvm.mlir.constant(1 : i64) : i64
%vec_1d_1_1 = llvm.insertelement %e3, %vec_1d_1_0[%c1_1 : i64] : vector<2xf32>
%vec_2d_1 = llvm.insertvalue %vec_1d_1_1, %vec_2d_0[1] : !llvm.array<2 x vector<2xf32>>
%result = builtin.unrealized_conversion_cast %vec_2d_1 : !llvm.array<2 x vector<2xf32>> to vector<2x2xf32>
```

---------

Co-authored-by: Nicolas Vasilache <Nico.Vasilache@amd.com>
Co-authored-by: Yang Bai <yangb@nvidia.com>
Co-authored-by: James Newling <james.newling@gmail.com>
Co-authored-by: Diego Caballero <dieg0ca6aller0@gmail.com>
2025-08-18 10:09:12 -07:00

151 lines
6.1 KiB
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//===- VectorToLLVM.cpp - Conversion from Vector to the LLVM dialect ------===//
//
// 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/Conversion/VectorToLLVM/ConvertVectorToLLVMPass.h"
#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
#include "mlir/Conversion/LLVMCommon/TypeConverter.h"
#include "mlir/Dialect/AMX/AMXDialect.h"
#include "mlir/Dialect/AMX/Transforms.h"
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/ArmNeon/ArmNeonDialect.h"
#include "mlir/Dialect/ArmNeon/Transforms.h"
#include "mlir/Dialect/ArmSVE/IR/ArmSVEDialect.h"
#include "mlir/Dialect/ArmSVE/Transforms/Transforms.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/MemRef/IR/MemRef.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "mlir/Dialect/Vector/Transforms/LoweringPatterns.h"
#include "mlir/Dialect/Vector/Transforms/VectorRewritePatterns.h"
#include "mlir/Dialect/X86Vector/Transforms.h"
#include "mlir/Dialect/X86Vector/X86VectorDialect.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
namespace mlir {
#define GEN_PASS_DEF_CONVERTVECTORTOLLVMPASS
#include "mlir/Conversion/Passes.h.inc"
} // namespace mlir
using namespace mlir;
using namespace mlir::vector;
namespace {
struct ConvertVectorToLLVMPass
: public impl::ConvertVectorToLLVMPassBase<ConvertVectorToLLVMPass> {
using Base::Base;
// Override explicitly to allow conditional dialect dependence.
void getDependentDialects(DialectRegistry &registry) const override {
registry.insert<LLVM::LLVMDialect>();
registry.insert<arith::ArithDialect>();
registry.insert<memref::MemRefDialect>();
registry.insert<tensor::TensorDialect>();
if (armNeon)
registry.insert<arm_neon::ArmNeonDialect>();
if (armSVE)
registry.insert<arm_sve::ArmSVEDialect>();
if (amx)
registry.insert<amx::AMXDialect>();
if (x86Vector)
registry.insert<x86vector::X86VectorDialect>();
}
void runOnOperation() override;
};
} // namespace
void ConvertVectorToLLVMPass::runOnOperation() {
// Perform progressive lowering of operations on slices and all contraction
// operations. Also materializes masks, lowers vector.step, rank-reduces FMA,
// applies folding and DCE.
{
RewritePatternSet patterns(&getContext());
populateVectorToVectorCanonicalizationPatterns(patterns);
populateVectorBitCastLoweringPatterns(patterns);
populateVectorBroadcastLoweringPatterns(patterns);
populateVectorContractLoweringPatterns(patterns, vectorContractLowering);
if (vectorContractLowering == vector::VectorContractLowering::Matmul) {
// This pattern creates a dependency on the LLVM dialect, hence we don't
// include it in `populateVectorContractLoweringPatterns` that is part of
// the Vector dialect (and should not depend on LLVM).
populateVectorContractToMatrixMultiply(patterns);
}
populateVectorMaskOpLoweringPatterns(patterns);
populateVectorShapeCastLoweringPatterns(patterns);
populateVectorInterleaveLoweringPatterns(patterns);
populateVectorTransposeLoweringPatterns(patterns, vectorTransposeLowering);
if (vectorTransposeLowering == vector::VectorTransposeLowering::Flat) {
// This pattern creates a dependency on the LLVM dialect, hence we don't
// include it in `populateVectorTransposeLoweringPatterns` that is part of
// the Vector dialect (and should not depend on LLVM).
populateVectorTransposeToFlatTranspose(patterns);
}
// Vector transfer ops with rank > 1 should be lowered with VectorToSCF.
populateVectorTransferLoweringPatterns(patterns, /*maxTransferRank=*/1);
populateVectorMaskMaterializationPatterns(patterns,
force32BitVectorIndices);
populateVectorInsertExtractStridedSliceTransforms(patterns);
populateVectorStepLoweringPatterns(patterns);
populateVectorRankReducingFMAPattern(patterns);
populateVectorGatherLoweringPatterns(patterns);
populateVectorFromElementsLoweringPatterns(patterns);
if (armI8MM) {
if (armNeon)
arm_neon::populateLowerContractionToNeonI8MMPatterns(patterns);
if (armSVE)
populateLowerContractionToSVEI8MMPatterns(patterns);
}
if (armBF16) {
if (armNeon)
arm_neon::populateLowerContractionToNeonBFMMLAPatterns(patterns);
if (armSVE)
populateLowerContractionToSVEBFMMLAPatterns(patterns);
}
(void)applyPatternsGreedily(getOperation(), std::move(patterns));
}
// Convert to the LLVM IR dialect.
LowerToLLVMOptions options(&getContext());
LLVMTypeConverter converter(&getContext(), options);
RewritePatternSet patterns(&getContext());
populateVectorTransferLoweringPatterns(patterns);
populateVectorToLLVMConversionPatterns(
converter, patterns, reassociateFPReductions, force32BitVectorIndices,
useVectorAlignment);
// Architecture specific augmentations.
LLVMConversionTarget target(getContext());
target.addLegalDialect<arith::ArithDialect>();
target.addLegalDialect<memref::MemRefDialect>();
target.addLegalOp<UnrealizedConversionCastOp>();
if (armNeon) {
// TODO: we may or may not want to include in-dialect lowering to
// LLVM-compatible operations here. So far, all operations in the dialect
// can be translated to LLVM IR so there is no conversion necessary.
target.addLegalDialect<arm_neon::ArmNeonDialect>();
}
if (armSVE) {
configureArmSVELegalizeForExportTarget(target);
populateArmSVELegalizeForLLVMExportPatterns(converter, patterns);
}
if (amx) {
configureAMXLegalizeForExportTarget(target);
populateAMXLegalizeForLLVMExportPatterns(converter, patterns);
}
if (x86Vector) {
configureX86VectorLegalizeForExportTarget(target);
populateX86VectorLegalizeForLLVMExportPatterns(converter, patterns);
}
if (failed(
applyPartialConversion(getOperation(), target, std::move(patterns))))
signalPassFailure();
}