forked from OSchip/llvm-project
124 lines
4.2 KiB
C++
124 lines
4.2 KiB
C++
//===- OpToFuncCallLowering.h - GPU ops lowering to custom calls *- C++ -*-===//
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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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#ifndef MLIR_CONVERSION_GPUCOMMON_OPTOFUNCCALLLOWERING_H_
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#define MLIR_CONVERSION_GPUCOMMON_OPTOFUNCCALLLOWERING_H_
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#include "mlir/Conversion/StandardToLLVM/ConvertStandardToLLVM.h"
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#include "mlir/Dialect/GPU/GPUDialect.h"
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#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
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#include "mlir/Dialect/StandardOps/IR/Ops.h"
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#include "mlir/IR/Builders.h"
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namespace mlir {
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/// Rewriting that replace SourceOp with a CallOp to `f32Func` or `f64Func`
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/// depending on the element type that Op operates upon. The function
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/// declaration is added in case it was not added before.
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///
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/// If the input values are of f16 type, the value is first casted to f32, the
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/// function called and then the result casted back.
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///
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/// Example with NVVM:
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/// %exp_f32 = std.exp %arg_f32 : f32
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///
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/// will be transformed into
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/// llvm.call @__nv_expf(%arg_f32) : (f32) -> f32
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template <typename SourceOp>
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struct OpToFuncCallLowering : public ConvertOpToLLVMPattern<SourceOp> {
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public:
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explicit OpToFuncCallLowering(LLVMTypeConverter &lowering_, StringRef f32Func,
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StringRef f64Func)
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: ConvertOpToLLVMPattern<SourceOp>(lowering_), f32Func(f32Func),
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f64Func(f64Func) {}
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LogicalResult
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matchAndRewrite(SourceOp op, ArrayRef<Value> operands,
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ConversionPatternRewriter &rewriter) const override {
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using LLVM::LLVMFuncOp;
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static_assert(
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std::is_base_of<OpTrait::OneResult<SourceOp>, SourceOp>::value,
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"expected single result op");
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static_assert(std::is_base_of<OpTrait::SameOperandsAndResultType<SourceOp>,
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SourceOp>::value,
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"expected op with same operand and result types");
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SmallVector<Value, 1> castedOperands;
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for (Value operand : operands)
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castedOperands.push_back(maybeCast(operand, rewriter));
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Type resultType = castedOperands.front().getType();
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Type funcType = getFunctionType(resultType, castedOperands);
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StringRef funcName = getFunctionName(
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funcType.cast<LLVM::LLVMFunctionType>().getReturnType());
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if (funcName.empty())
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return failure();
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LLVMFuncOp funcOp = appendOrGetFuncOp(funcName, funcType, op);
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auto callOp = rewriter.create<LLVM::CallOp>(
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op->getLoc(), resultType, rewriter.getSymbolRefAttr(funcOp),
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castedOperands);
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if (resultType == operands.front().getType()) {
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rewriter.replaceOp(op, {callOp.getResult(0)});
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return success();
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}
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Value truncated = rewriter.create<LLVM::FPTruncOp>(
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op->getLoc(), operands.front().getType(), callOp.getResult(0));
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rewriter.replaceOp(op, {truncated});
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return success();
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}
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private:
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Value maybeCast(Value operand, PatternRewriter &rewriter) const {
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Type type = operand.getType();
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if (!type.isa<Float16Type>())
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return operand;
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return rewriter.create<LLVM::FPExtOp>(
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operand.getLoc(), Float32Type::get(rewriter.getContext()), operand);
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}
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Type getFunctionType(Type resultType, ArrayRef<Value> operands) const {
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SmallVector<Type, 1> operandTypes;
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for (Value operand : operands) {
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operandTypes.push_back(operand.getType());
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}
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return LLVM::LLVMFunctionType::get(resultType, operandTypes);
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}
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StringRef getFunctionName(Type type) const {
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if (type.isa<Float32Type>())
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return f32Func;
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if (type.isa<Float64Type>())
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return f64Func;
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return "";
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}
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LLVM::LLVMFuncOp appendOrGetFuncOp(StringRef funcName, Type funcType,
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Operation *op) const {
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using LLVM::LLVMFuncOp;
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Operation *funcOp = SymbolTable::lookupNearestSymbolFrom(op, funcName);
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if (funcOp)
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return cast<LLVMFuncOp>(*funcOp);
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mlir::OpBuilder b(op->getParentOfType<LLVMFuncOp>());
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return b.create<LLVMFuncOp>(op->getLoc(), funcName, funcType);
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}
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const std::string f32Func;
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const std::string f64Func;
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};
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} // namespace mlir
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#endif // MLIR_CONVERSION_GPUCOMMON_OPTOFUNCCALLLOWERING_H_
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