llvm-project/llvm/lib/MC/SubtargetFeature.cpp

310 lines
9.4 KiB
C++

//===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the SubtargetFeature interface.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
#include <cctype>
#include <cstdlib>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Static Helper Functions
//===----------------------------------------------------------------------===//
/// hasFlag - Determine if a feature has a flag; '+' or '-'
///
static inline 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 =='-';
}
/// StripFlag - Return string stripped of flag.
///
static inline std::string StripFlag(StringRef Feature) {
return hasFlag(Feature) ? Feature.substr(1) : Feature;
}
/// isEnabled - 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 == '+';
}
/// Split - Splits a string of comma separated items in to a vector of strings.
///
static void Split(std::vector<std::string> &V, StringRef S) {
SmallVector<StringRef, 3> Tmp;
S.split(Tmp, ',', -1, false /* KeepEmpty */);
V.assign(Tmp.begin(), Tmp.end());
}
/// Adding features.
void SubtargetFeatures::AddFeature(StringRef String, bool Enable) {
// Don't add empty features.
if (!String.empty())
// Convert to lowercase, prepend flag if we don't already have a flag.
Features.push_back(hasFlag(String) ? String.lower()
: (Enable ? "+" : "-") + String.lower());
}
/// Find KV in array using binary search.
static const SubtargetFeatureKV *Find(StringRef S,
ArrayRef<SubtargetFeatureKV> A) {
// Binary search the array
auto F = std::lower_bound(A.begin(), A.end(), S);
// If not found then return NULL
if (F == A.end() || StringRef(F->Key) != S) return nullptr;
// Return the found array item
return F;
}
/// getLongestEntryLength - Return the length of the longest entry in the table.
///
static size_t getLongestEntryLength(ArrayRef<SubtargetFeatureKV> Table) {
size_t MaxLen = 0;
for (auto &I : Table)
MaxLen = std::max(MaxLen, std::strlen(I.Key));
return MaxLen;
}
/// Display help for feature choices.
///
static void Help(ArrayRef<SubtargetFeatureKV> CPUTable,
ArrayRef<SubtargetFeatureKV> FeatTable) {
// Determine the length of the longest CPU and Feature entries.
unsigned MaxCPULen = getLongestEntryLength(CPUTable);
unsigned MaxFeatLen = getLongestEntryLength(FeatTable);
// Print the CPU table.
errs() << "Available CPUs for this target:\n\n";
for (auto &CPU : CPUTable)
errs() << format(" %-*s - %s.\n", MaxCPULen, CPU.Key, CPU.Desc);
errs() << '\n';
// Print the Feature table.
errs() << "Available features for this target:\n\n";
for (auto &Feature : FeatTable)
errs() << format(" %-*s - %s.\n", MaxFeatLen, Feature.Key, Feature.Desc);
errs() << '\n';
errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
"For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
}
//===----------------------------------------------------------------------===//
// SubtargetFeatures Implementation
//===----------------------------------------------------------------------===//
SubtargetFeatures::SubtargetFeatures(StringRef Initial) {
// Break up string into separate features
Split(Features, Initial);
}
std::string SubtargetFeatures::getString() const {
return join(Features.begin(), Features.end(), ",");
}
/// SetImpliedBits - For each feature that is (transitively) implied by this
/// feature, set it.
///
static
void SetImpliedBits(FeatureBitset &Bits, const SubtargetFeatureKV *FeatureEntry,
ArrayRef<SubtargetFeatureKV> FeatureTable) {
for (auto &FE : FeatureTable) {
if (FeatureEntry->Value == FE.Value) continue;
if ((FeatureEntry->Implies & FE.Value).any()) {
Bits |= FE.Value;
SetImpliedBits(Bits, &FE, FeatureTable);
}
}
}
/// ClearImpliedBits - For each feature that (transitively) implies this
/// feature, clear it.
///
static
void ClearImpliedBits(FeatureBitset &Bits,
const SubtargetFeatureKV *FeatureEntry,
ArrayRef<SubtargetFeatureKV> FeatureTable) {
for (auto &FE : FeatureTable) {
if (FeatureEntry->Value == FE.Value) continue;
if ((FE.Implies & FeatureEntry->Value).any()) {
Bits &= ~FE.Value;
ClearImpliedBits(Bits, &FE, FeatureTable);
}
}
}
/// ToggleFeature - Toggle a feature and update the feature bits.
void
SubtargetFeatures::ToggleFeature(FeatureBitset &Bits, StringRef Feature,
ArrayRef<SubtargetFeatureKV> FeatureTable) {
// Find feature in table.
const SubtargetFeatureKV *FeatureEntry =
Find(StripFlag(Feature), FeatureTable);
// If there is a match
if (FeatureEntry) {
if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
Bits &= ~FeatureEntry->Value;
// For each feature that implies this, clear it.
ClearImpliedBits(Bits, FeatureEntry, FeatureTable);
} else {
Bits |= FeatureEntry->Value;
// For each feature that this implies, set it.
SetImpliedBits(Bits, FeatureEntry, FeatureTable);
}
} else {
errs() << "'" << Feature
<< "' is not a recognized feature for this target"
<< " (ignoring feature)\n";
}
}
void SubtargetFeatures::ApplyFeatureFlag(FeatureBitset &Bits, StringRef Feature,
ArrayRef<SubtargetFeatureKV> FeatureTable) {
assert(hasFlag(Feature));
// Find feature in table.
const SubtargetFeatureKV *FeatureEntry =
Find(StripFlag(Feature), FeatureTable);
// If there is a match
if (FeatureEntry) {
// Enable/disable feature in bits
if (isEnabled(Feature)) {
Bits |= FeatureEntry->Value;
// For each feature that this implies, set it.
SetImpliedBits(Bits, FeatureEntry, FeatureTable);
} else {
Bits &= ~FeatureEntry->Value;
// For each feature that implies this, clear it.
ClearImpliedBits(Bits, FeatureEntry, FeatureTable);
}
} else {
errs() << "'" << Feature
<< "' is not a recognized feature for this target"
<< " (ignoring feature)\n";
}
}
/// getFeatureBits - Get feature bits a CPU.
///
FeatureBitset
SubtargetFeatures::getFeatureBits(StringRef CPU,
ArrayRef<SubtargetFeatureKV> CPUTable,
ArrayRef<SubtargetFeatureKV> FeatureTable) {
if (CPUTable.empty() || FeatureTable.empty())
return FeatureBitset();
#ifndef NDEBUG
assert(std::is_sorted(std::begin(CPUTable), std::end(CPUTable)) &&
"CPU table is not sorted");
assert(std::is_sorted(std::begin(FeatureTable), std::end(FeatureTable)) &&
"CPU features table is not sorted");
#endif
// Resulting bits
FeatureBitset Bits;
// Check if help is needed
if (CPU == "help")
Help(CPUTable, FeatureTable);
// Find CPU entry if CPU name is specified.
else if (!CPU.empty()) {
const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable);
// If there is a match
if (CPUEntry) {
// Set base feature bits
Bits = CPUEntry->Value;
// Set the feature implied by this CPU feature, if any.
for (auto &FE : FeatureTable) {
if ((CPUEntry->Value & FE.Value).any())
SetImpliedBits(Bits, &FE, FeatureTable);
}
} else {
errs() << "'" << CPU
<< "' is not a recognized processor for this target"
<< " (ignoring processor)\n";
}
}
// Iterate through each feature
for (auto &Feature : Features) {
// Check for help
if (Feature == "+help")
Help(CPUTable, FeatureTable);
ApplyFeatureFlag(Bits, Feature, FeatureTable);
}
return Bits;
}
/// print - Print feature string.
///
void SubtargetFeatures::print(raw_ostream &OS) const {
for (auto &F : Features)
OS << F << " ";
OS << "\n";
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
/// dump - Dump feature info.
///
void SubtargetFeatures::dump() const {
print(dbgs());
}
#endif
/// Adds the default features for the specified target triple.
///
/// FIXME: This is an inelegant way of specifying the features of a
/// subtarget. It would be better if we could encode this information
/// into the IR. See <rdar://5972456>.
///
void SubtargetFeatures::getDefaultSubtargetFeatures(const Triple& Triple) {
if (Triple.getVendor() == Triple::Apple) {
if (Triple.getArch() == Triple::ppc) {
// powerpc-apple-*
AddFeature("altivec");
} else if (Triple.getArch() == Triple::ppc64) {
// powerpc64-apple-*
AddFeature("64bit");
AddFeature("altivec");
}
}
}