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//===--- EnumPayload.h - Payload management for 'enum' Types ----*- C++ -*-===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#ifndef SWIFT_IRGEN_ENUMPAYLOAD_H
#define SWIFT_IRGEN_ENUMPAYLOAD_H
#include "IRGenModule.h"
#include "Explosion.h"
#include "TypeInfo.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/ADT/PointerEmbeddedInt.h"
#include "llvm/ADT/PointerUnion.h"
#include <utility>
namespace swift {
namespace irgen {
/// A description of how to represent an enum payload as a value.
/// A payload can either use a generic word-chunked representation,
/// or attempt to follow the explosion schema of one of its payload
/// types.
/// TODO: the current code only ever uses the generic word-chunked
/// representation, it might be better if it used an appropriate
/// explosion schema instead.
class EnumPayloadSchema {
// A size in bits less than 0 indicates that the payload size is
// dynamic.
const int64_t BitSize;
public:
/// Create a new schema with a dynamic size.
EnumPayloadSchema() : BitSize(-1) {}
/// Create a new schema with the given fixed size in bits.
explicit EnumPayloadSchema(unsigned bits)
: BitSize(static_cast<int64_t>(bits)) {}
/// Report whether the schema has a fixed size.
explicit operator bool() const {
return BitSize >= 0;
}
/// Invoke a functor for each element type in the schema.
template<typename TypeFn /* void(llvm::Type *schemaType) */>
void forEachType(IRGenModule &IGM, TypeFn &&fn) const {
assert(BitSize >= 0 && "payload size must not be dynamic");
// Chunk into pointer-sized integer values.
int64_t bitSize = BitSize;
int64_t pointerSize = IGM.getPointerSize().getValueInBits();
while (bitSize >= pointerSize) {
fn(IGM.SizeTy);
bitSize -= pointerSize;
}
if (bitSize > 0)
fn(llvm::IntegerType::get(IGM.getLLVMContext(), bitSize));
}
};
/// Is a switch default destination unreachable?
enum IsUnreachable_t: bool {
IsNotUnreachable = false,
IsUnreachable = true,
};
using SwitchDefaultDest
= llvm::PointerIntPair<llvm::BasicBlock*, 1, IsUnreachable_t>;
/// An enum payload value. The payload is represented as an explosion of
/// integers and pointers that together represent the bit pattern of
/// the payload.
class EnumPayload {
public:
/// A value, or the type of a zero value in the payload.
using LazyValue = llvm::PointerUnion<llvm::Value *, llvm::Type *>;
mutable SmallVector<LazyValue, 2> PayloadValues;
mutable llvm::Type *StorageType = nullptr;
EnumPayload() = default;
/// Generate a "zero" enum payload.
static EnumPayload zero(IRGenModule &IGM,
EnumPayloadSchema schema);
/// Generate an enum payload containing the given bit pattern.
static EnumPayload fromBitPattern(IRGenModule &IGM,
const APInt &bitPattern,
EnumPayloadSchema schema);
/// Insert a value into the enum payload.
///
/// The current payload value at the given offset is assumed to be zero.
/// If \p numBitsUsedInValue is non-negative denotes the actual number of bits
/// that need storing in \p value otherwise the full bit-width of \p value
/// will be stored.
void insertValue(IRGenModule &IGM,
IRBuilder &builder,
llvm::Value *value, unsigned bitOffset);
/// Extract a value from the enum payload.
llvm::Value *extractValue(IRGenFunction &IGF,
llvm::Type *type, unsigned bitOffset) const;
/// Take an enum payload out of an explosion.
static EnumPayload fromExplosion(IRGenModule &IGM,
Explosion &in,
EnumPayloadSchema schema);
/// Add the payload to an explosion.
void explode(IRGenModule &IGM, Explosion &out) const;
/// Pack into another enum payload.
void packIntoEnumPayload(IRGenModule &IGM,
IRBuilder &builder,
EnumPayload &dest,
unsigned bitOffset) const;
/// Unpack from another enum payload.
static EnumPayload unpackFromEnumPayload(IRGenFunction &IGF,
const EnumPayload &src,
unsigned bitOffset,
EnumPayloadSchema schema);
/// Load an enum payload from memory.
static EnumPayload load(IRGenFunction &IGF, Address address,
EnumPayloadSchema schema);
/// Store an enum payload to memory.
void store(IRGenFunction &IGF, Address address) const;
/// Emit a switch over specific bit patterns for the payload.
/// The value will be tested as if AND-ed against the given mask.
void emitSwitch(IRGenFunction &IGF,
const APInt &mask,
ArrayRef<std::pair<APInt, llvm::BasicBlock*>> cases,
SwitchDefaultDest dflt) const;
/// Emit an equality comparison operation that payload & mask == value.
llvm::Value *emitCompare(IRGenFunction &IGF,
const APInt &mask,
const APInt &value) const;
/// Apply an AND mask to the payload.
void emitApplyAndMask(IRGenFunction &IGF, const APInt &mask);
/// Apply an OR mask to the payload.
void emitApplyOrMask(IRGenModule &IGM,
IRBuilder &builder, const APInt &mask);
/// Apply an OR mask to the payload.
void emitApplyOrMask(IRGenFunction &IGF, EnumPayload mask);
/// Scatter the bits in value to the bit positions indicated by the
/// mask. The new bits are added using OR, so an emitApplyAndMask
/// call should be used first if existing bits need to be cleared.
void emitScatterBits(IRGenModule &IGM,
IRBuilder &builder,
const APInt &mask,
llvm::Value *value);
/// Gather bits from an enum payload based on a spare bit mask.
llvm::Value *emitGatherSpareBits(IRGenFunction &IGF,
const SpareBitVector &spareBits,
unsigned firstBitOffset,
unsigned bitWidth) const;
void print(llvm::raw_ostream &OS);
void dump();
private:
/// Calculate the total number of bits this payload requires.
/// This will always be a multiple of 8.
unsigned getAllocSizeInBits(const llvm::DataLayout &DL) const;
};
}
}
#endif