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

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//===- 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/Support/Debug.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <cassert>
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#include <cctype>
#include <cstdlib>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Static Helper Functions
//===----------------------------------------------------------------------===//
/// hasFlag - Determine if a feature has a flag; '+' or '-'
///
static inline bool hasFlag(const 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(const StringRef Feature) {
return hasFlag(Feature) ? Feature.substr(1) : Feature;
}
/// isEnabled - Return true if enable flag; '+'.
///
static inline bool isEnabled(const StringRef Feature) {
assert(!Feature.empty() && "Empty string");
// Get first character
char Ch = Feature[0];
// Check if first character is '+' for enabled
return Ch == '+';
}
/// PrependFlag - Return a string with a prepended flag; '+' or '-'.
///
static inline std::string PrependFlag(const StringRef Feature,
bool IsEnabled) {
assert(!Feature.empty() && "Empty string");
if (hasFlag(Feature))
return Feature;
std::string Prefix = IsEnabled ? "+" : "-";
Prefix += Feature;
return Prefix;
}
/// Split - Splits a string of comma separated items in to a vector of strings.
///
static void Split(std::vector<std::string> &V, const StringRef S) {
if (S.empty())
return;
// Start at beginning of string.
size_t Pos = 0;
while (true) {
// Find the next comma
size_t Comma = S.find(',', Pos);
// If no comma found then the rest of the string is used
if (Comma == std::string::npos) {
// Add string to vector
V.push_back(S.substr(Pos));
break;
}
// Otherwise add substring to vector
V.push_back(S.substr(Pos, Comma - Pos));
// Advance to next item
Pos = Comma + 1;
}
}
/// Join a vector of strings to a string with a comma separating each element.
///
static std::string Join(const std::vector<std::string> &V) {
// Start with empty string.
std::string Result;
// If the vector is not empty
if (!V.empty()) {
// Start with the first feature
Result = V[0];
// For each successive feature
for (size_t i = 1; i < V.size(); i++) {
// Add a comma
Result += ",";
// Add the feature
Result += V[i];
}
}
// Return the features string
return Result;
}
/// Adding features.
void SubtargetFeatures::AddFeature(const StringRef String,
bool IsEnabled) {
// Don't add empty features
if (!String.empty()) {
// Convert to lowercase, prepend flag and add to vector
Features.push_back(PrependFlag(String.lower(), IsEnabled));
}
}
/// Find KV in array using binary search.
const SubtargetFeatureKV *Find(const StringRef S, const SubtargetFeatureKV *A,
size_t L) {
// Make the lower bound element we're looking for
SubtargetFeatureKV KV;
KV.Key = S.data();
// Determine the end of the array
const SubtargetFeatureKV *Hi = A + L;
// Binary search the array
const SubtargetFeatureKV *F = std::lower_bound(A, Hi, KV);
// If not found then return NULL
if (F == Hi || StringRef(F->Key) != S) return NULL;
// Return the found array item
return F;
}
/// getLongestEntryLength - Return the length of the longest entry in the table.
///
static size_t getLongestEntryLength(const SubtargetFeatureKV *Table,
size_t Size) {
size_t MaxLen = 0;
for (size_t i = 0; i < Size; i++)
MaxLen = std::max(MaxLen, std::strlen(Table[i].Key));
return MaxLen;
}
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/// Display help for feature choices.
///
static void Help(const SubtargetFeatureKV *CPUTable, size_t CPUTableSize,
const SubtargetFeatureKV *FeatTable, size_t FeatTableSize) {
// Determine the length of the longest CPU and Feature entries.
unsigned MaxCPULen = getLongestEntryLength(CPUTable, CPUTableSize);
unsigned MaxFeatLen = getLongestEntryLength(FeatTable, FeatTableSize);
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// Print the CPU table.
errs() << "Available CPUs for this target:\n\n";
for (size_t i = 0; i != CPUTableSize; i++)
errs() << format(" %-*s - %s.\n",
MaxCPULen, CPUTable[i].Key, CPUTable[i].Desc);
errs() << '\n';
// Print the Feature table.
errs() << "Available features for this target:\n\n";
for (size_t i = 0; i != FeatTableSize; i++)
errs() << format(" %-*s - %s.\n",
MaxFeatLen, FeatTable[i].Key, FeatTable[i].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";
std::exit(1);
}
//===----------------------------------------------------------------------===//
// SubtargetFeatures Implementation
//===----------------------------------------------------------------------===//
SubtargetFeatures::SubtargetFeatures(const StringRef Initial) {
// Break up string into separate features
Split(Features, Initial);
}
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std::string SubtargetFeatures::getString() const {
return Join(Features);
}
/// SetImpliedBits - For each feature that is (transitively) implied by this
/// feature, set it.
///
static
void SetImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
const SubtargetFeatureKV *FeatureTable,
size_t FeatureTableSize) {
for (size_t i = 0; i < FeatureTableSize; ++i) {
const SubtargetFeatureKV &FE = FeatureTable[i];
if (FeatureEntry->Value == FE.Value) continue;
if (FeatureEntry->Implies & FE.Value) {
Bits |= FE.Value;
SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
}
}
}
/// ClearImpliedBits - For each feature that (transitively) implies this
/// feature, clear it.
///
static
void ClearImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
const SubtargetFeatureKV *FeatureTable,
size_t FeatureTableSize) {
for (size_t i = 0; i < FeatureTableSize; ++i) {
const SubtargetFeatureKV &FE = FeatureTable[i];
if (FeatureEntry->Value == FE.Value) continue;
if (FE.Implies & FeatureEntry->Value) {
Bits &= ~FE.Value;
ClearImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
}
}
}
/// ToggleFeature - Toggle a feature and returns the newly updated feature
/// bits.
uint64_t
SubtargetFeatures::ToggleFeature(uint64_t Bits, const StringRef Feature,
const SubtargetFeatureKV *FeatureTable,
size_t FeatureTableSize) {
// Find feature in table.
const SubtargetFeatureKV *FeatureEntry =
Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
// 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, FeatureTableSize);
} else {
Bits |= FeatureEntry->Value;
// For each feature that this implies, set it.
SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
}
} else {
errs() << "'" << Feature
<< "' is not a recognized feature for this target"
<< " (ignoring feature)\n";
}
return Bits;
}
/// getFeatureBits - Get feature bits a CPU.
///
uint64_t SubtargetFeatures::getFeatureBits(const StringRef CPU,
const SubtargetFeatureKV *CPUTable,
size_t CPUTableSize,
const SubtargetFeatureKV *FeatureTable,
size_t FeatureTableSize) {
if (!FeatureTableSize || !CPUTableSize)
return 0;
#ifndef NDEBUG
for (size_t i = 1; i < CPUTableSize; i++) {
assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 &&
"CPU table is not sorted");
}
for (size_t i = 1; i < FeatureTableSize; i++) {
assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 &&
"CPU features table is not sorted");
}
#endif
uint64_t Bits = 0; // Resulting bits
// Check if help is needed
if (CPU == "help")
Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
// Find CPU entry if CPU name is specified.
if (!CPU.empty()) {
const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable, CPUTableSize);
// 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 (size_t i = 0; i < FeatureTableSize; ++i) {
const SubtargetFeatureKV &FE = FeatureTable[i];
if (CPUEntry->Value & FE.Value)
SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
}
} else {
errs() << "'" << CPU
<< "' is not a recognized processor for this target"
<< " (ignoring processor)\n";
}
}
// Iterate through each feature
for (size_t i = 0, E = Features.size(); i < E; i++) {
const StringRef Feature = Features[i];
// Check for help
if (Feature == "+help")
Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
// Find feature in table.
const SubtargetFeatureKV *FeatureEntry =
Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
// 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, FeatureTableSize);
} else {
Bits &= ~FeatureEntry->Value;
// For each feature that implies this, clear it.
ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
}
} else {
errs() << "'" << Feature
<< "' is not a recognized feature for this target"
<< " (ignoring feature)\n";
}
}
return Bits;
}
/// print - Print feature string.
///
void SubtargetFeatures::print(raw_ostream &OS) const {
for (size_t i = 0, e = Features.size(); i != e; ++i)
OS << Features[i] << " ";
OS << "\n";
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
/// dump - Dump feature info.
///
void SubtargetFeatures::dump() const {
print(dbgs());
}
#endif
/// getDefaultSubtargetFeatures - Return a string listing the features
/// associated with the 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");
}
}
}