224 lines
9.4 KiB
C++
224 lines
9.4 KiB
C++
//===-- MathToLibm.cpp - conversion from Math to libm calls ---------------===//
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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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#include "mlir/Conversion/MathToLibm/MathToLibm.h"
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#include "mlir/Dialect/Arith/IR/Arith.h"
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#include "mlir/Dialect/Func/IR/FuncOps.h"
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#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
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#include "mlir/Dialect/Math/IR/Math.h"
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#include "mlir/Dialect/Utils/IndexingUtils.h"
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#include "mlir/Dialect/Vector/IR/VectorOps.h"
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#include "mlir/Dialect/Vector/Utils/VectorUtils.h"
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#include "mlir/IR/BuiltinDialect.h"
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#include "mlir/IR/PatternMatch.h"
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#include "mlir/Pass/Pass.h"
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namespace mlir {
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#define GEN_PASS_DEF_CONVERTMATHTOLIBM
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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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// Pattern to convert vector operations to scalar operations. This is needed as
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// libm calls require scalars.
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template <typename Op>
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struct VecOpToScalarOp : public OpRewritePattern<Op> {
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public:
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using OpRewritePattern<Op>::OpRewritePattern;
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LogicalResult matchAndRewrite(Op op, PatternRewriter &rewriter) const final;
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};
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// Pattern to promote an op of a smaller floating point type to F32.
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template <typename Op>
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struct PromoteOpToF32 : public OpRewritePattern<Op> {
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public:
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using OpRewritePattern<Op>::OpRewritePattern;
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LogicalResult matchAndRewrite(Op op, PatternRewriter &rewriter) const final;
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};
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// Pattern to convert scalar math operations to calls to libm functions.
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// Additionally the libm function signatures are declared.
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template <typename Op>
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struct ScalarOpToLibmCall : public OpRewritePattern<Op> {
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public:
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using OpRewritePattern<Op>::OpRewritePattern;
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ScalarOpToLibmCall<Op>(MLIRContext *context, StringRef floatFunc,
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StringRef doubleFunc, PatternBenefit benefit)
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: OpRewritePattern<Op>(context, benefit), floatFunc(floatFunc),
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doubleFunc(doubleFunc){};
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LogicalResult matchAndRewrite(Op op, PatternRewriter &rewriter) const final;
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private:
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std::string floatFunc, doubleFunc;
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};
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} // namespace
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template <typename Op>
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LogicalResult
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VecOpToScalarOp<Op>::matchAndRewrite(Op op, PatternRewriter &rewriter) const {
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auto opType = op.getType();
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auto loc = op.getLoc();
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auto vecType = opType.template dyn_cast<VectorType>();
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if (!vecType)
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return failure();
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if (!vecType.hasRank())
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return failure();
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auto shape = vecType.getShape();
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int64_t numElements = vecType.getNumElements();
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Value result = rewriter.create<arith::ConstantOp>(
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loc, DenseElementsAttr::get(
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vecType, FloatAttr::get(vecType.getElementType(), 0.0)));
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SmallVector<int64_t> strides = computeStrides(shape);
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for (auto linearIndex = 0; linearIndex < numElements; ++linearIndex) {
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SmallVector<int64_t> positions = delinearize(strides, linearIndex);
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SmallVector<Value> operands;
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for (auto input : op->getOperands())
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operands.push_back(
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rewriter.create<vector::ExtractOp>(loc, input, positions));
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Value scalarOp =
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rewriter.create<Op>(loc, vecType.getElementType(), operands);
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result =
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rewriter.create<vector::InsertOp>(loc, scalarOp, result, positions);
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}
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rewriter.replaceOp(op, {result});
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return success();
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}
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template <typename Op>
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LogicalResult
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PromoteOpToF32<Op>::matchAndRewrite(Op op, PatternRewriter &rewriter) const {
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auto opType = op.getType();
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if (!opType.template isa<Float16Type, BFloat16Type>())
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return failure();
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auto loc = op.getLoc();
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auto f32 = rewriter.getF32Type();
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auto extendedOperands = llvm::to_vector(
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llvm::map_range(op->getOperands(), [&](Value operand) -> Value {
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return rewriter.create<arith::ExtFOp>(loc, f32, operand);
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}));
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auto newOp = rewriter.create<Op>(loc, f32, extendedOperands);
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rewriter.replaceOpWithNewOp<arith::TruncFOp>(op, opType, newOp);
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return success();
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}
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template <typename Op>
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LogicalResult
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ScalarOpToLibmCall<Op>::matchAndRewrite(Op op,
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PatternRewriter &rewriter) const {
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auto module = SymbolTable::getNearestSymbolTable(op);
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auto type = op.getType();
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if (!type.template isa<Float32Type, Float64Type>())
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return failure();
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auto name = type.getIntOrFloatBitWidth() == 64 ? doubleFunc : floatFunc;
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auto opFunc = dyn_cast_or_null<SymbolOpInterface>(
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SymbolTable::lookupSymbolIn(module, name));
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// Forward declare function if it hasn't already been
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if (!opFunc) {
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OpBuilder::InsertionGuard guard(rewriter);
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rewriter.setInsertionPointToStart(&module->getRegion(0).front());
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auto opFunctionTy = FunctionType::get(
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rewriter.getContext(), op->getOperandTypes(), op->getResultTypes());
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opFunc = rewriter.create<func::FuncOp>(rewriter.getUnknownLoc(), name,
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opFunctionTy);
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opFunc.setPrivate();
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// By definition Math dialect operations imply LLVM's "readnone"
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// function attribute, so we can set it here to provide more
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// optimization opportunities (e.g. LICM) for backends targeting LLVM IR.
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// This will have to be changed, when strict FP behavior is supported
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// by Math dialect.
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opFunc->setAttr(LLVM::LLVMDialect::getReadnoneAttrName(),
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UnitAttr::get(rewriter.getContext()));
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}
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assert(isa<FunctionOpInterface>(SymbolTable::lookupSymbolIn(module, name)));
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rewriter.replaceOpWithNewOp<func::CallOp>(op, name, op.getType(),
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op->getOperands());
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return success();
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}
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void mlir::populateMathToLibmConversionPatterns(
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RewritePatternSet &patterns, PatternBenefit benefit,
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llvm::Optional<PatternBenefit> log1pBenefit) {
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patterns.add<VecOpToScalarOp<math::Atan2Op>, VecOpToScalarOp<math::ExpM1Op>,
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VecOpToScalarOp<math::TanhOp>, VecOpToScalarOp<math::CosOp>,
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VecOpToScalarOp<math::SinOp>, VecOpToScalarOp<math::ErfOp>,
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VecOpToScalarOp<math::RoundEvenOp>,
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VecOpToScalarOp<math::RoundOp>, VecOpToScalarOp<math::AtanOp>,
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VecOpToScalarOp<math::TanOp>, VecOpToScalarOp<math::TruncOp>>(
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patterns.getContext(), benefit);
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patterns.add<PromoteOpToF32<math::Atan2Op>, PromoteOpToF32<math::ExpM1Op>,
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PromoteOpToF32<math::TanhOp>, PromoteOpToF32<math::CosOp>,
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PromoteOpToF32<math::SinOp>, PromoteOpToF32<math::ErfOp>,
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PromoteOpToF32<math::RoundEvenOp>, PromoteOpToF32<math::RoundOp>,
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PromoteOpToF32<math::AtanOp>, PromoteOpToF32<math::TanOp>,
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PromoteOpToF32<math::TruncOp>>(patterns.getContext(), benefit);
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patterns.add<ScalarOpToLibmCall<math::AtanOp>>(patterns.getContext(), "atanf",
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"atan", benefit);
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patterns.add<ScalarOpToLibmCall<math::Atan2Op>>(patterns.getContext(),
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"atan2f", "atan2", benefit);
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patterns.add<ScalarOpToLibmCall<math::ErfOp>>(patterns.getContext(), "erff",
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"erf", benefit);
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patterns.add<ScalarOpToLibmCall<math::ExpM1Op>>(patterns.getContext(),
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"expm1f", "expm1", benefit);
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patterns.add<ScalarOpToLibmCall<math::TanOp>>(patterns.getContext(), "tanf",
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"tan", benefit);
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patterns.add<ScalarOpToLibmCall<math::TanhOp>>(patterns.getContext(), "tanhf",
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"tanh", benefit);
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patterns.add<ScalarOpToLibmCall<math::RoundEvenOp>>(
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patterns.getContext(), "roundevenf", "roundeven", benefit);
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patterns.add<ScalarOpToLibmCall<math::RoundOp>>(patterns.getContext(),
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"roundf", "round", benefit);
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patterns.add<ScalarOpToLibmCall<math::CosOp>>(patterns.getContext(), "cosf",
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"cos", benefit);
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patterns.add<ScalarOpToLibmCall<math::SinOp>>(patterns.getContext(), "sinf",
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"sin", benefit);
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patterns.add<ScalarOpToLibmCall<math::Log1pOp>>(
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patterns.getContext(), "log1pf", "log1p", log1pBenefit.value_or(benefit));
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patterns.add<ScalarOpToLibmCall<math::FloorOp>>(patterns.getContext(),
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"floorf", "floor", benefit);
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patterns.add<ScalarOpToLibmCall<math::CeilOp>>(patterns.getContext(), "ceilf",
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"ceil", benefit);
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patterns.add<ScalarOpToLibmCall<math::TruncOp>>(patterns.getContext(),
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"truncf", "trunc", benefit);
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}
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namespace {
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struct ConvertMathToLibmPass
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: public impl::ConvertMathToLibmBase<ConvertMathToLibmPass> {
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void runOnOperation() override;
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};
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} // namespace
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void ConvertMathToLibmPass::runOnOperation() {
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auto module = getOperation();
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RewritePatternSet patterns(&getContext());
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populateMathToLibmConversionPatterns(patterns, /*benefit=*/1);
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ConversionTarget target(getContext());
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target.addLegalDialect<arith::ArithDialect, BuiltinDialect, func::FuncDialect,
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vector::VectorDialect>();
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target.addIllegalDialect<math::MathDialect>();
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if (failed(applyPartialConversion(module, target, std::move(patterns))))
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signalPassFailure();
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}
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std::unique_ptr<OperationPass<ModuleOp>> mlir::createConvertMathToLibmPass() {
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return std::make_unique<ConvertMathToLibmPass>();
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}
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