300 lines
13 KiB
C++
300 lines
13 KiB
C++
//===- LowerGpuOpsToNVVMOps.cpp - MLIR GPU to NVVM lowering passes --------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements a pass to generate NVVMIR operations for higher-level
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// GPU operations.
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//
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//===----------------------------------------------------------------------===//
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#include "mlir/Conversion/GPUToNVVM/GPUToNVVMPass.h"
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#include "mlir/Conversion/ArithToLLVM/ArithToLLVM.h"
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#include "mlir/Conversion/ControlFlowToLLVM/ControlFlowToLLVM.h"
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#include "mlir/Conversion/FuncToLLVM/ConvertFuncToLLVM.h"
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#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
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#include "mlir/Conversion/LLVMCommon/LoweringOptions.h"
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#include "mlir/Conversion/LLVMCommon/TypeConverter.h"
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#include "mlir/Conversion/MemRefToLLVM/MemRefToLLVM.h"
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#include "mlir/Dialect/ControlFlow/IR/ControlFlow.h"
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#include "mlir/Dialect/Func/IR/FuncOps.h"
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#include "mlir/Dialect/GPU/IR/GPUDialect.h"
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#include "mlir/Dialect/GPU/Transforms/Passes.h"
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#include "mlir/Dialect/LLVMIR/NVVMDialect.h"
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#include "mlir/Dialect/Math/IR/Math.h"
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#include "mlir/Dialect/MemRef/IR/MemRef.h"
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#include "mlir/Transforms/DialectConversion.h"
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#include "mlir/Transforms/GreedyPatternRewriteDriver.h"
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#include "../GPUCommon/GPUOpsLowering.h"
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#include "../GPUCommon/IndexIntrinsicsOpLowering.h"
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#include "../GPUCommon/OpToFuncCallLowering.h"
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namespace mlir {
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#define GEN_PASS_DEF_CONVERTGPUOPSTONVVMOPS
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#include "mlir/Conversion/Passes.h.inc"
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} // namespace mlir
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using namespace mlir;
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namespace {
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/// Convert gpu dialect shfl mode enum to the equivalent nvvm one.
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static NVVM::ShflKind convertShflKind(gpu::ShuffleMode mode) {
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switch (mode) {
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case gpu::ShuffleMode::XOR:
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return NVVM::ShflKind::bfly;
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case gpu::ShuffleMode::UP:
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return NVVM::ShflKind::up;
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case gpu::ShuffleMode::DOWN:
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return NVVM::ShflKind::down;
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case gpu::ShuffleMode::IDX:
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return NVVM::ShflKind::idx;
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}
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llvm_unreachable("unknown shuffle mode");
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}
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struct GPUShuffleOpLowering : public ConvertOpToLLVMPattern<gpu::ShuffleOp> {
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using ConvertOpToLLVMPattern<gpu::ShuffleOp>::ConvertOpToLLVMPattern;
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/// Lowers a shuffle to the corresponding NVVM op.
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///
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/// Convert the `width` argument into an activeMask (a bitmask which specifies
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/// which threads participate in the shuffle) and a maskAndClamp (specifying
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/// the highest lane which participates in the shuffle).
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///
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/// %one = llvm.constant(1 : i32) : i32
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/// %minus_one = llvm.constant(-1 : i32) : i32
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/// %thirty_two = llvm.constant(32 : i32) : i32
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/// %num_lanes = llvm.sub %thirty_two, %width : i32
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/// %active_mask = llvm.lshr %minus_one, %num_lanes : i32
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/// %mask_and_clamp = llvm.sub %width, %one : i32
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/// %shfl = nvvm.shfl.sync.bfly %active_mask, %value, %offset,
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/// %mask_and_clamp : !llvm<"{ float, i1 }">
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/// %shfl_value = llvm.extractvalue %shfl[0] :
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/// !llvm<"{ float, i1 }">
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/// %shfl_pred = llvm.extractvalue %shfl[1] :
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/// !llvm<"{ float, i1 }">
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LogicalResult
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matchAndRewrite(gpu::ShuffleOp op, OpAdaptor adaptor,
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ConversionPatternRewriter &rewriter) const override {
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Location loc = op->getLoc();
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auto valueTy = adaptor.getValue().getType();
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auto int32Type = IntegerType::get(rewriter.getContext(), 32);
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auto predTy = IntegerType::get(rewriter.getContext(), 1);
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auto resultTy = LLVM::LLVMStructType::getLiteral(rewriter.getContext(),
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{valueTy, predTy});
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Value one = rewriter.create<LLVM::ConstantOp>(loc, int32Type, 1);
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Value minusOne = rewriter.create<LLVM::ConstantOp>(loc, int32Type, -1);
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Value thirtyTwo = rewriter.create<LLVM::ConstantOp>(loc, int32Type, 32);
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Value numLeadInactiveLane = rewriter.create<LLVM::SubOp>(
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loc, int32Type, thirtyTwo, adaptor.getWidth());
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// Bit mask of active lanes: `(-1) >> (32 - activeWidth)`.
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Value activeMask = rewriter.create<LLVM::LShrOp>(loc, int32Type, minusOne,
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numLeadInactiveLane);
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Value maskAndClamp;
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if (op.getMode() == gpu::ShuffleMode::UP) {
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// Clamp lane: `32 - activeWidth`
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maskAndClamp = numLeadInactiveLane;
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} else {
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// Clamp lane: `activeWidth - 1`
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maskAndClamp =
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rewriter.create<LLVM::SubOp>(loc, int32Type, adaptor.getWidth(), one);
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}
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auto returnValueAndIsValidAttr = rewriter.getUnitAttr();
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Value shfl = rewriter.create<NVVM::ShflOp>(
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loc, resultTy, activeMask, adaptor.getValue(), adaptor.getOffset(),
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maskAndClamp, convertShflKind(op.getMode()), returnValueAndIsValidAttr);
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Value shflValue = rewriter.create<LLVM::ExtractValueOp>(loc, shfl, 0);
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Value isActiveSrcLane = rewriter.create<LLVM::ExtractValueOp>(loc, shfl, 1);
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rewriter.replaceOp(op, {shflValue, isActiveSrcLane});
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return success();
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}
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};
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struct GPULaneIdOpToNVVM : ConvertOpToLLVMPattern<gpu::LaneIdOp> {
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using ConvertOpToLLVMPattern<gpu::LaneIdOp>::ConvertOpToLLVMPattern;
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LogicalResult
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matchAndRewrite(gpu::LaneIdOp op, gpu::LaneIdOp::Adaptor adaptor,
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ConversionPatternRewriter &rewriter) const override {
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auto loc = op->getLoc();
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MLIRContext *context = rewriter.getContext();
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Value newOp = rewriter.create<NVVM::LaneIdOp>(loc, rewriter.getI32Type());
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// Truncate or extend the result depending on the index bitwidth specified
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// by the LLVMTypeConverter options.
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const unsigned indexBitwidth = getTypeConverter()->getIndexTypeBitwidth();
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if (indexBitwidth > 32) {
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newOp = rewriter.create<LLVM::SExtOp>(
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loc, IntegerType::get(context, indexBitwidth), newOp);
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} else if (indexBitwidth < 32) {
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newOp = rewriter.create<LLVM::TruncOp>(
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loc, IntegerType::get(context, indexBitwidth), newOp);
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}
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rewriter.replaceOp(op, {newOp});
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return success();
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}
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};
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/// Import the GPU Ops to NVVM Patterns.
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#include "GPUToNVVM.cpp.inc"
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/// A pass that replaces all occurrences of GPU device operations with their
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/// corresponding NVVM equivalent.
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///
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/// This pass only handles device code and is not meant to be run on GPU host
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/// code.
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struct LowerGpuOpsToNVVMOpsPass
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: public impl::ConvertGpuOpsToNVVMOpsBase<LowerGpuOpsToNVVMOpsPass> {
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LowerGpuOpsToNVVMOpsPass() = default;
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LowerGpuOpsToNVVMOpsPass(unsigned indexBitwidth) {
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this->indexBitwidth = indexBitwidth;
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}
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void runOnOperation() override {
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gpu::GPUModuleOp m = getOperation();
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// Request C wrapper emission.
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for (auto func : m.getOps<func::FuncOp>()) {
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func->setAttr(LLVM::LLVMDialect::getEmitCWrapperAttrName(),
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UnitAttr::get(&getContext()));
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}
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// Customize the bitwidth used for the device side index computations.
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LowerToLLVMOptions options(
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m.getContext(),
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DataLayout(cast<DataLayoutOpInterface>(m.getOperation())));
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if (indexBitwidth != kDeriveIndexBitwidthFromDataLayout)
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options.overrideIndexBitwidth(indexBitwidth);
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// MemRef conversion for GPU to NVVM lowering. The GPU dialect uses memory
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// space 5 for private memory attributions, but NVVM represents private
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// memory allocations as local `alloca`s in the default address space. This
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// converter drops the private memory space to support the use case above.
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LLVMTypeConverter converter(m.getContext(), options);
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converter.addConversion([&](MemRefType type) -> Optional<Type> {
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if (type.getMemorySpaceAsInt() !=
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gpu::GPUDialect::getPrivateAddressSpace())
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return std::nullopt;
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return converter.convertType(MemRefType::Builder(type).setMemorySpace(
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IntegerAttr::get(IntegerType::get(m.getContext(), 64), 0)));
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});
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// Lowering for MMAMatrixType.
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converter.addConversion([&](gpu::MMAMatrixType type) -> Type {
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return convertMMAToLLVMType(type);
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});
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RewritePatternSet patterns(m.getContext());
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RewritePatternSet llvmPatterns(m.getContext());
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// Apply in-dialect lowering first. In-dialect lowering will replace ops
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// which need to be lowered further, which is not supported by a single
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// conversion pass.
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populateGpuRewritePatterns(patterns);
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(void)applyPatternsAndFoldGreedily(m, std::move(patterns));
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arith::populateArithToLLVMConversionPatterns(converter, llvmPatterns);
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cf::populateControlFlowToLLVMConversionPatterns(converter, llvmPatterns);
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populateFuncToLLVMConversionPatterns(converter, llvmPatterns);
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populateMemRefToLLVMConversionPatterns(converter, llvmPatterns);
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populateGpuToNVVMConversionPatterns(converter, llvmPatterns);
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populateGpuWMMAToNVVMConversionPatterns(converter, llvmPatterns);
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LLVMConversionTarget target(getContext());
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configureGpuToNVVMConversionLegality(target);
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if (failed(applyPartialConversion(m, target, std::move(llvmPatterns))))
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signalPassFailure();
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}
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};
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} // namespace
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void mlir::configureGpuToNVVMConversionLegality(ConversionTarget &target) {
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target.addIllegalOp<func::FuncOp>();
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target.addLegalDialect<::mlir::LLVM::LLVMDialect>();
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target.addLegalDialect<::mlir::NVVM::NVVMDialect>();
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target.addIllegalDialect<gpu::GPUDialect>();
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target.addIllegalOp<LLVM::CosOp, LLVM::ExpOp, LLVM::Exp2Op, LLVM::FAbsOp,
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LLVM::FCeilOp, LLVM::FFloorOp, LLVM::LogOp, LLVM::Log10Op,
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LLVM::Log2Op, LLVM::PowOp, LLVM::SinOp, LLVM::SqrtOp>();
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// TODO: Remove once we support replacing non-root ops.
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target.addLegalOp<gpu::YieldOp, gpu::GPUModuleOp, gpu::ModuleEndOp>();
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}
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template <typename OpTy>
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static void populateOpPatterns(LLVMTypeConverter &converter,
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RewritePatternSet &patterns, StringRef f32Func,
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StringRef f64Func) {
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patterns.add<ScalarizeVectorOpLowering<OpTy>>(converter);
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patterns.add<OpToFuncCallLowering<OpTy>>(converter, f32Func, f64Func);
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}
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void mlir::populateGpuToNVVMConversionPatterns(LLVMTypeConverter &converter,
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RewritePatternSet &patterns) {
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populateWithGenerated(patterns);
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patterns
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.add<GPUIndexIntrinsicOpLowering<gpu::ThreadIdOp, NVVM::ThreadIdXOp,
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NVVM::ThreadIdYOp, NVVM::ThreadIdZOp>,
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GPUIndexIntrinsicOpLowering<gpu::BlockDimOp, NVVM::BlockDimXOp,
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NVVM::BlockDimYOp, NVVM::BlockDimZOp>,
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GPUIndexIntrinsicOpLowering<gpu::BlockIdOp, NVVM::BlockIdXOp,
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NVVM::BlockIdYOp, NVVM::BlockIdZOp>,
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GPUIndexIntrinsicOpLowering<gpu::GridDimOp, NVVM::GridDimXOp,
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NVVM::GridDimYOp, NVVM::GridDimZOp>,
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GPULaneIdOpToNVVM, GPUShuffleOpLowering, GPUReturnOpLowering>(
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converter);
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// Explicitly drop memory space when lowering private memory
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// attributions since NVVM models it as `alloca`s in the default
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// memory space and does not support `alloca`s with addrspace(5).
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patterns.add<GPUFuncOpLowering>(
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converter, /*allocaAddrSpace=*/0,
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StringAttr::get(&converter.getContext(),
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NVVM::NVVMDialect::getKernelFuncAttrName()));
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populateOpPatterns<math::AbsFOp>(converter, patterns, "__nv_fabsf",
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"__nv_fabs");
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populateOpPatterns<math::AtanOp>(converter, patterns, "__nv_atanf",
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"__nv_atan");
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populateOpPatterns<math::Atan2Op>(converter, patterns, "__nv_atan2f",
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"__nv_atan2");
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populateOpPatterns<math::CeilOp>(converter, patterns, "__nv_ceilf",
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"__nv_ceil");
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populateOpPatterns<math::CosOp>(converter, patterns, "__nv_cosf", "__nv_cos");
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populateOpPatterns<math::ExpOp>(converter, patterns, "__nv_expf", "__nv_exp");
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populateOpPatterns<math::Exp2Op>(converter, patterns, "__nv_exp2f",
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"__nv_exp2");
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populateOpPatterns<math::ExpM1Op>(converter, patterns, "__nv_expm1f",
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"__nv_expm1");
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populateOpPatterns<math::FloorOp>(converter, patterns, "__nv_floorf",
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"__nv_floor");
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populateOpPatterns<math::LogOp>(converter, patterns, "__nv_logf", "__nv_log");
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populateOpPatterns<math::Log1pOp>(converter, patterns, "__nv_log1pf",
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"__nv_log1p");
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populateOpPatterns<math::Log10Op>(converter, patterns, "__nv_log10f",
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"__nv_log10");
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populateOpPatterns<math::Log2Op>(converter, patterns, "__nv_log2f",
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"__nv_log2");
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populateOpPatterns<math::PowFOp>(converter, patterns, "__nv_powf",
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"__nv_pow");
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populateOpPatterns<math::RsqrtOp>(converter, patterns, "__nv_rsqrtf",
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"__nv_rsqrt");
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populateOpPatterns<math::SinOp>(converter, patterns, "__nv_sinf", "__nv_sin");
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populateOpPatterns<math::SqrtOp>(converter, patterns, "__nv_sqrtf",
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"__nv_sqrt");
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populateOpPatterns<math::TanhOp>(converter, patterns, "__nv_tanhf",
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"__nv_tanh");
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}
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std::unique_ptr<OperationPass<gpu::GPUModuleOp>>
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mlir::createLowerGpuOpsToNVVMOpsPass(unsigned indexBitwidth) {
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return std::make_unique<LowerGpuOpsToNVVMOpsPass>(indexBitwidth);
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}
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