FuncToLLVM.cpp | Explore in Territory

//===- FuncToLLVM.cpp - Func to LLVM dialect conversion -------------------===//
//
// 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 file implements a pass to convert MLIR Func and builtin dialects
// into the LLVM IR dialect.
//
//===----------------------------------------------------------------------===//

#include "mlir/Conversion/FuncToLLVM/ConvertFuncToLLVMPass.h"

#include "mlir/Analysis/DataLayoutAnalysis.h"
#include "mlir/Conversion/ArithToLLVM/ArithToLLVM.h"
#include "mlir/Conversion/ControlFlowToLLVM/ControlFlowToLLVM.h"
#include "mlir/Conversion/ConvertToLLVM/ToLLVMInterface.h"
#include "mlir/Conversion/FuncToLLVM/ConvertFuncToLLVM.h"
#include "mlir/Conversion/LLVMCommon/ConversionTarget.h"
#include "mlir/Conversion/LLVMCommon/Pattern.h"
#include "mlir/Conversion/LLVMCommon/VectorPattern.h"
#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/Dialect/LLVMIR/FunctionCallUtils.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/Dialect/LLVMIR/LLVMTypes.h"
#include "mlir/Dialect/Utils/StaticValueUtils.h"
#include "mlir/IR/Attributes.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/BuiltinAttributeInterfaces.h"
#include "mlir/IR/BuiltinAttributes.h"
#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/IRMapping.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/IR/SymbolTable.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/Transforms/DialectConversion.h"
#include "mlir/Transforms/Passes.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/TypeSwitch.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FormatVariadic.h"
#include <algorithm>
#include <functional>
#include <optional>

namespace mlir {
#define GEN_PASS_DEF_CONVERTFUNCTOLLVMPASS
#define GEN_PASS_DEF_SETLLVMMODULEDATALAYOUTPASS
#include "mlir/Conversion/Passes.h.inc"
} // namespace mlir

usingnamespacemlir;

#define PASS_NAME …

static constexpr StringRef varargsAttrName = …;
static constexpr StringRef linkageAttrName = …;
static constexpr StringRef barePtrAttrName = …;

/// Return `true` if the `op` should use bare pointer calling convention.
static bool shouldUseBarePtrCallConv(Operation *op,
                                     const LLVMTypeConverter *typeConverter) { … }

/// Only retain those attributes that are not constructed by
/// `LLVMFuncOp::build`.
static void filterFuncAttributes(FunctionOpInterface func,
                                 SmallVectorImpl<NamedAttribute> &result) { … }

/// Propagate argument/results attributes.
static void propagateArgResAttrs(OpBuilder &builder, bool resultStructType,
                                 FunctionOpInterface funcOp,
                                 LLVM::LLVMFuncOp wrapperFuncOp) { … }

/// Creates an auxiliary function with pointer-to-memref-descriptor-struct
/// arguments instead of unpacked arguments. This function can be called from C
/// by passing a pointer to a C struct corresponding to a memref descriptor.
/// Similarly, returned memrefs are passed via pointers to a C struct that is
/// passed as additional argument.
/// Internally, the auxiliary function unpacks the descriptor into individual
/// components and forwards them to `newFuncOp` and forwards the results to
/// the extra arguments.
static void wrapForExternalCallers(OpBuilder &rewriter, Location loc,
                                   const LLVMTypeConverter &typeConverter,
                                   FunctionOpInterface funcOp,
                                   LLVM::LLVMFuncOp newFuncOp) { … }

/// Creates an auxiliary function with pointer-to-memref-descriptor-struct
/// arguments instead of unpacked arguments. Creates a body for the (external)
/// `newFuncOp` that allocates a memref descriptor on stack, packs the
/// individual arguments into this descriptor and passes a pointer to it into
/// the auxiliary function. If the result of the function cannot be directly
/// returned, we write it to a special first argument that provides a pointer
/// to a corresponding struct. This auxiliary external function is now
/// compatible with functions defined in C using pointers to C structs
/// corresponding to a memref descriptor.
static void wrapExternalFunction(OpBuilder &builder, Location loc,
                                 const LLVMTypeConverter &typeConverter,
                                 FunctionOpInterface funcOp,
                                 LLVM::LLVMFuncOp newFuncOp) { … }

/// Inserts `llvm.load` ops in the function body to restore the expected pointee
/// value from `llvm.byval`/`llvm.byref` function arguments that were converted
/// to LLVM pointer types.
static void restoreByValRefArgumentType(
    ConversionPatternRewriter &rewriter, const LLVMTypeConverter &typeConverter,
    ArrayRef<std::optional<NamedAttribute>> byValRefNonPtrAttrs,
    LLVM::LLVMFuncOp funcOp) { … }

FailureOr<LLVM::LLVMFuncOp>
mlir::convertFuncOpToLLVMFuncOp(FunctionOpInterface funcOp,
                                ConversionPatternRewriter &rewriter,
                                const LLVMTypeConverter &converter) { … }

namespace {

/// FuncOp legalization pattern that converts MemRef arguments to pointers to
/// MemRef descriptors (LLVM struct data types) containing all the MemRef type
/// information.
struct FuncOpConversion : public ConvertOpToLLVMPattern<func::FuncOp> { … };

struct ConstantOpLowering : public ConvertOpToLLVMPattern<func::ConstantOp> { … };

// A CallOp automatically promotes MemRefType to a sequence of alloca/store and
// passes the pointer to the MemRef across function boundaries.
template <typename CallOpType>
struct CallOpInterfaceLowering : public ConvertOpToLLVMPattern<CallOpType> { … };

class CallOpLowering : public CallOpInterfaceLowering<func::CallOp> { … };

struct CallIndirectOpLowering
    : public CallOpInterfaceLowering<func::CallIndirectOp> { … };

struct UnrealizedConversionCastOpLowering
    : public ConvertOpToLLVMPattern<UnrealizedConversionCastOp> { … };

// Special lowering pattern for `ReturnOps`.  Unlike all other operations,
// `ReturnOp` interacts with the function signature and must have as many
// operands as the function has return values.  Because in LLVM IR, functions
// can only return 0 or 1 value, we pack multiple values into a structure type.
// Emit `UndefOp` followed by `InsertValueOp`s to create such structure if
// necessary before returning it
struct ReturnOpLowering : public ConvertOpToLLVMPattern<func::ReturnOp> { … };
} // namespace

void mlir::populateFuncToLLVMFuncOpConversionPattern(
    LLVMTypeConverter &converter, RewritePatternSet &patterns) { … }

void mlir::populateFuncToLLVMConversionPatterns(
    LLVMTypeConverter &converter, RewritePatternSet &patterns,
    const SymbolTable *symbolTable) { … }

namespace {
/// A pass converting Func operations into the LLVM IR dialect.
struct ConvertFuncToLLVMPass
    : public impl::ConvertFuncToLLVMPassBase<ConvertFuncToLLVMPass> { … };

struct SetLLVMModuleDataLayoutPass
    : public impl::SetLLVMModuleDataLayoutPassBase<
          SetLLVMModuleDataLayoutPass> { … };
} // namespace

//===----------------------------------------------------------------------===//
// ConvertToLLVMPatternInterface implementation
//===----------------------------------------------------------------------===//

namespace {
/// Implement the interface to convert Func to LLVM.
struct FuncToLLVMDialectInterface : public ConvertToLLVMPatternInterface { … };
} // namespace

void mlir::registerConvertFuncToLLVMInterface(DialectRegistry &registry) { … }
llvm/mlir/lib/Conversion/FuncToLLVM/FuncToLLVM.cpp
