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//===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This file implements the SubtargetFeature interface.
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//===----------------------------------------------------------------------===//
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#include "llvm/Target/SubtargetFeature.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/ADT/StringExtras.h"
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//===----------------------------------------------------------------------===//
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// Static Helper Functions
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//===----------------------------------------------------------------------===//
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/// hasFlag - Determine if a feature has a flag; '+' or '-'
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static inline bool hasFlag(const std::string &Feature) {
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assert(!Feature.empty() && "Empty string");
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// Get first character
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// Check if first character is '+' or '-' flag
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return Ch == '+' || Ch =='-';
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/// StripFlag - Return string stripped of flag.
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static inline std::string StripFlag(const std::string &Feature) {
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return hasFlag(Feature) ? Feature.substr(1) : Feature;
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/// isEnabled - Return true if enable flag; '+'.
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static inline bool isEnabled(const std::string &Feature) {
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assert(!Feature.empty() && "Empty string");
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// Get first character
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// Check if first character is '+' for enabled
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/// PrependFlag - Return a string with a prepended flag; '+' or '-'.
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static inline std::string PrependFlag(const std::string &Feature,
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assert(!Feature.empty() && "Empty string");
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if (hasFlag(Feature)) return Feature;
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return std::string(IsEnabled ? "+" : "-") + Feature;
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/// Split - Splits a string of comma separated items in to a vector of strings.
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static void Split(std::vector<std::string> &V, const std::string &S) {
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// Start at beginning of string.
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// Find the next comma
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size_t Comma = S.find(',', Pos);
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// If no comma found then the rest of the string is used
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if (Comma == std::string::npos) {
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// Add string to vector
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V.push_back(S.substr(Pos));
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// Otherwise add substring to vector
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V.push_back(S.substr(Pos, Comma - Pos));
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// Advance to next item
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/// Join a vector of strings to a string with a comma separating each element.
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static std::string Join(const std::vector<std::string> &V) {
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// Start with empty string.
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// If the vector is not empty
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// Start with the CPU feature
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// For each successive feature
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for (size_t i = 1; i < V.size(); i++) {
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// Return the features string
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void SubtargetFeatures::AddFeature(const std::string &String,
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// Don't add empty features
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if (!String.empty()) {
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// Convert to lowercase, prepend flag and add to vector
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Features.push_back(PrependFlag(LowercaseString(String), IsEnabled));
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/// Find KV in array using binary search.
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template<typename T> const T *Find(const std::string &S, const T *A, size_t L) {
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// Make the lower bound element we're looking for
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// Determine the end of the array
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// Binary search the array
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const T *F = std::lower_bound(A, Hi, KV);
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// If not found then return NULL
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if (F == Hi || std::string(F->Key) != S) return NULL;
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// Return the found array item
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/// getLongestEntryLength - Return the length of the longest entry in the table.
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static size_t getLongestEntryLength(const SubtargetFeatureKV *Table,
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for (size_t i = 0; i < Size; i++)
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MaxLen = std::max(MaxLen, std::strlen(Table[i].Key));
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/// Display help for feature choices.
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static void Help(const SubtargetFeatureKV *CPUTable, size_t CPUTableSize,
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const SubtargetFeatureKV *FeatTable, size_t FeatTableSize) {
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// Determine the length of the longest CPU and Feature entries.
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unsigned MaxCPULen = getLongestEntryLength(CPUTable, CPUTableSize);
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unsigned MaxFeatLen = getLongestEntryLength(FeatTable, FeatTableSize);
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// Print the CPU table.
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errs() << "Available CPUs for this target:\n\n";
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for (size_t i = 0; i != CPUTableSize; i++)
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errs() << " " << CPUTable[i].Key
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<< std::string(MaxCPULen - std::strlen(CPUTable[i].Key), ' ')
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<< " - " << CPUTable[i].Desc << ".\n";
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// Print the Feature table.
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errs() << "Available features for this target:\n\n";
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for (size_t i = 0; i != FeatTableSize; i++)
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errs() << " " << FeatTable[i].Key
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<< std::string(MaxFeatLen - std::strlen(FeatTable[i].Key), ' ')
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<< " - " << FeatTable[i].Desc << ".\n";
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errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
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<< "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
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//===----------------------------------------------------------------------===//
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// SubtargetFeatures Implementation
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//===----------------------------------------------------------------------===//
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SubtargetFeatures::SubtargetFeatures(const std::string &Initial) {
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// Break up string into separate features
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Split(Features, Initial);
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std::string SubtargetFeatures::getString() const {
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return Join(Features);
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void SubtargetFeatures::setString(const std::string &Initial) {
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// Throw out old features
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// Break up string into separate features
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Split(Features, LowercaseString(Initial));
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/// setCPU - Set the CPU string. Replaces previous setting. Setting to ""
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void SubtargetFeatures::setCPU(const std::string &String) {
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Features[0] = LowercaseString(String);
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/// setCPUIfNone - Setting CPU string only if no string is set.
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void SubtargetFeatures::setCPUIfNone(const std::string &String) {
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if (Features[0].empty()) setCPU(String);
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/// getCPU - Returns current CPU.
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const std::string & SubtargetFeatures::getCPU() const {
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/// SetImpliedBits - For each feature that is (transitively) implied by this
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void SetImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
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const SubtargetFeatureKV *FeatureTable,
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size_t FeatureTableSize) {
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for (size_t i = 0; i < FeatureTableSize; ++i) {
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const SubtargetFeatureKV &FE = FeatureTable[i];
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if (FeatureEntry->Value == FE.Value) continue;
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if (FeatureEntry->Implies & FE.Value) {
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SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
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/// ClearImpliedBits - For each feature that (transitively) implies this
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/// feature, clear it.
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void ClearImpliedBits(uint32_t &Bits, const SubtargetFeatureKV *FeatureEntry,
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const SubtargetFeatureKV *FeatureTable,
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size_t FeatureTableSize) {
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for (size_t i = 0; i < FeatureTableSize; ++i) {
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const SubtargetFeatureKV &FE = FeatureTable[i];
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if (FeatureEntry->Value == FE.Value) continue;
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if (FE.Implies & FeatureEntry->Value) {
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ClearImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
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/// getBits - Get feature bits.
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uint32_t SubtargetFeatures::getBits(const SubtargetFeatureKV *CPUTable,
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const SubtargetFeatureKV *FeatureTable,
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size_t FeatureTableSize) {
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assert(CPUTable && "missing CPU table");
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assert(FeatureTable && "missing features table");
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for (size_t i = 1; i < CPUTableSize; i++) {
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assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 &&
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"CPU table is not sorted");
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for (size_t i = 1; i < FeatureTableSize; i++) {
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assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 &&
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"CPU features table is not sorted");
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uint32_t Bits = 0; // Resulting bits
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// Check if help is needed
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if (Features[0] == "help")
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Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
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const SubtargetFeatureKV *CPUEntry =
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Find(Features[0], CPUTable, CPUTableSize);
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// If there is a match
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// Set base feature bits
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Bits = CPUEntry->Value;
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// Set the feature implied by this CPU feature, if any.
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for (size_t i = 0; i < FeatureTableSize; ++i) {
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const SubtargetFeatureKV &FE = FeatureTable[i];
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if (CPUEntry->Value & FE.Value)
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SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
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errs() << "'" << Features[0]
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<< "' is not a recognized processor for this target"
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<< " (ignoring processor)\n";
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// Iterate through each feature
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for (size_t i = 1; i < Features.size(); i++) {
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const std::string &Feature = Features[i];
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if (Feature == "+help")
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Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
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// Find feature in table.
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const SubtargetFeatureKV *FeatureEntry =
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Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
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// If there is a match
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// Enable/disable feature in bits
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if (isEnabled(Feature)) {
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Bits |= FeatureEntry->Value;
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// For each feature that this implies, set it.
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SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
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Bits &= ~FeatureEntry->Value;
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// For each feature that implies this, clear it.
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ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
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errs() << "'" << Feature
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<< "' is not a recognized feature for this target"
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<< " (ignoring feature)\n";
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void *SubtargetFeatures::getInfo(const SubtargetInfoKV *Table,
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assert(Table && "missing table");
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for (size_t i = 1; i < TableSize; i++) {
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assert(strcmp(Table[i - 1].Key, Table[i].Key) < 0 && "Table is not sorted");
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const SubtargetInfoKV *Entry = Find(Features[0], Table, TableSize);
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errs() << "'" << Features[0]
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<< "' is not a recognized processor for this target"
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<< " (ignoring processor)\n";
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/// print - Print feature string.
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void SubtargetFeatures::print(raw_ostream &OS) const {
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for (size_t i = 0, e = Features.size(); i != e; ++i)
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OS << Features[i] << " ";
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/// dump - Dump feature info.
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void SubtargetFeatures::dump() const {
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/// getDefaultSubtargetFeatures - Return a string listing the features
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/// associated with the target triple.
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/// FIXME: This is an inelegant way of specifying the features of a
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/// subtarget. It would be better if we could encode this information
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/// into the IR. See <rdar://5972456>.
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void SubtargetFeatures::getDefaultSubtargetFeatures(const std::string &CPU,
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const Triple& Triple) {
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if (Triple.getVendor() == Triple::Apple) {
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if (Triple.getArch() == Triple::ppc) {
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AddFeature("altivec");
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} else if (Triple.getArch() == Triple::ppc64) {
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AddFeature("altivec");