//===- llvm/MC/SubtargetFeature.h - CPU characteristics ---------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
/// \file Defines and manages user or tool specified CPU characteristics.
/// The intent is to be able to package specific features that should or should
/// not be used on a specific target processor. A tool, such as llc, could, as
/// as example, gather chip info from the command line, a long with features
/// that should be used on that chip.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_SUBTARGETFEATURE_H
#define LLVM_MC_SUBTARGETFEATURE_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/MathExtras.h"
#include <array>
#include <initializer_list>
#include <string>
#include <vector>
namespace llvm {
class raw_ostream;
class Triple;
const unsigned MAX_SUBTARGET_WORDS = 4;
const unsigned MAX_SUBTARGET_FEATURES = MAX_SUBTARGET_WORDS * 64;
/// Container class for subtarget features.
/// This is a constexpr reimplementation of a subset of std::bitset. It would be
/// nice to use std::bitset directly, but it doesn't support constant
/// initialization.
class FeatureBitset {
static_assert((MAX_SUBTARGET_FEATURES % 64) == 0,
"Should be a multiple of 64!");
std::array<uint64_t, MAX_SUBTARGET_WORDS> Bits{};
protected:
constexpr FeatureBitset(const std::array<uint64_t, MAX_SUBTARGET_WORDS> &B)
: Bits{B} {}
public:
constexpr FeatureBitset() = default;
constexpr FeatureBitset(std::initializer_list<unsigned> Init) {
for (auto I : Init)
set(I);
}
FeatureBitset &set() {
std::fill(std::begin(Bits), std::end(Bits), -1ULL);
return *this;
}
constexpr FeatureBitset &set(unsigned I) {
// GCC <6.2 crashes if this is written in a single statement.
uint64_t NewBits = Bits[I / 64] | (uint64_t(1) << (I % 64));
Bits[I / 64] = NewBits;
return *this;
}
constexpr FeatureBitset &reset(unsigned I) {
// GCC <6.2 crashes if this is written in a single statement.
uint64_t NewBits = Bits[I / 64] & ~(uint64_t(1) << (I % 64));
Bits[I / 64] = NewBits;
return *this;
}
constexpr FeatureBitset &flip(unsigned I) {
// GCC <6.2 crashes if this is written in a single statement.
uint64_t NewBits = Bits[I / 64] ^ (uint64_t(1) << (I % 64));
Bits[I / 64] = NewBits;
return *this;
}
constexpr bool operator[](unsigned I) const {
uint64_t Mask = uint64_t(1) << (I % 64);
return (Bits[I / 64] & Mask) != 0;
}
constexpr bool test(unsigned I) const { return (*this)[I]; }
constexpr size_t size() const { return MAX_SUBTARGET_FEATURES; }
bool any() const {
return llvm::any_of(Bits, [](uint64_t I) { return I != 0; });
}
bool none() const { return !any(); }
size_t count() const {
size_t Count = 0;
for (auto B : Bits)
Count += llvm::popcount(B);
return Count;
}
constexpr FeatureBitset &operator^=(const FeatureBitset &RHS) {
for (unsigned I = 0, E = Bits.size(); I != E; ++I) {
Bits[I] ^= RHS.Bits[I];
}
return *this;
}
constexpr FeatureBitset operator^(const FeatureBitset &RHS) const {
FeatureBitset Result = *this;
Result ^= RHS;
return Result;
}
constexpr FeatureBitset &operator&=(const FeatureBitset &RHS) {
for (unsigned I = 0, E = Bits.size(); I != E; ++I) {
Bits[I] &= RHS.Bits[I];
}
return *this;
}
constexpr FeatureBitset operator&(const FeatureBitset &RHS) const {
FeatureBitset Result = *this;
Result &= RHS;
return Result;
}
constexpr FeatureBitset &operator|=(const FeatureBitset &RHS) {
for (unsigned I = 0, E = Bits.size(); I != E; ++I) {
Bits[I] |= RHS.Bits[I];
}
return *this;
}
constexpr FeatureBitset operator|(const FeatureBitset &RHS) const {
FeatureBitset Result = *this;
Result |= RHS;
return Result;
}
constexpr FeatureBitset operator~() const {
FeatureBitset Result = *this;
for (auto &B : Result.Bits)
B = ~B;
return Result;
}
bool operator==(const FeatureBitset &RHS) const {
return std::equal(std::begin(Bits), std::end(Bits), std::begin(RHS.Bits));
}
bool operator!=(const FeatureBitset &RHS) const { return !(*this == RHS); }
bool operator < (const FeatureBitset &Other) const {
for (unsigned I = 0, E = size(); I != E; ++I) {
bool LHS = test(I), RHS = Other.test(I);
if (LHS != RHS)
return LHS < RHS;
}
return false;
}
};
/// Class used to store the subtarget bits in the tables created by tablegen.
class FeatureBitArray : public FeatureBitset {
public:
constexpr FeatureBitArray(const std::array<uint64_t, MAX_SUBTARGET_WORDS> &B)
: FeatureBitset(B) {}
const FeatureBitset &getAsBitset() const { return *this; }
};
//===----------------------------------------------------------------------===//
/// Manages the enabling and disabling of subtarget specific features.
///
/// Features are encoded as a string of the form
/// "+attr1,+attr2,-attr3,...,+attrN"
/// A comma separates each feature from the next (all lowercase.)
/// Each of the remaining features is prefixed with + or - indicating whether
/// that feature should be enabled or disabled contrary to the cpu
/// specification.
class SubtargetFeatures {
std::vector<std::string> Features; ///< Subtarget features as a vector
public:
explicit SubtargetFeatures(StringRef Initial = "");
/// Returns features as a string.
std::string getString() const;
/// Adds Features.
void AddFeature(StringRef String, bool Enable = true);
void addFeaturesVector(const ArrayRef<std::string> OtherFeatures);
/// Returns the vector of individual subtarget features.
const std::vector<std::string> &getFeatures() const { return Features; }
/// Prints feature string.
void print(raw_ostream &OS) const;
// Dumps feature info.
void dump() const;
/// Adds the default features for the specified target triple.
void getDefaultSubtargetFeatures(const Triple& Triple);
/// Determine if a feature has a flag; '+' or '-'
static bool hasFlag(StringRef Feature) {
assert(!Feature.empty() && "Empty string");
// Get first character
char Ch = Feature[0];
// Check if first character is '+' or '-' flag
return Ch == '+' || Ch =='-';
}
/// Return string stripped of flag.
static StringRef StripFlag(StringRef Feature) {
return hasFlag(Feature) ? Feature.substr(1) : Feature;
}
/// Return true if enable flag; '+'.
static inline bool isEnabled(StringRef Feature) {
assert(!Feature.empty() && "Empty string");
// Get first character
char Ch = Feature[0];
// Check if first character is '+' for enabled
return Ch == '+';
}
/// Splits a string of comma separated items in to a vector of strings.
static void Split(std::vector<std::string> &V, StringRef S);
};
} // end namespace llvm
#endif // LLVM_MC_SUBTARGETFEATURE_H