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      1 //===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===//
      2 //
      3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
      4 // See https://llvm.org/LICENSE.txt for license information.
      5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
      6 //
      7 //===----------------------------------------------------------------------===//
      8 //
      9 /// \file Implements the SubtargetFeature interface.
     10 //
     11 //===----------------------------------------------------------------------===//
     12 
     13 #include "llvm/MC/SubtargetFeature.h"
     14 #include "llvm/ADT/SmallVector.h"
     15 #include "llvm/ADT/StringExtras.h"
     16 #include "llvm/ADT/StringRef.h"
     17 #include "llvm/ADT/Triple.h"
     18 #include "llvm/Config/llvm-config.h"
     19 #include "llvm/Support/Compiler.h"
     20 #include "llvm/Support/Debug.h"
     21 #include "llvm/Support/raw_ostream.h"
     22 #include <algorithm>
     23 #include <cassert>
     24 #include <cstddef>
     25 #include <cstring>
     26 #include <iterator>
     27 #include <string>
     28 #include <vector>
     29 
     30 using namespace llvm;
     31 
     32 /// Splits a string of comma separated items in to a vector of strings.
     33 void SubtargetFeatures::Split(std::vector<std::string> &V, StringRef S) {
     34   SmallVector<StringRef, 3> Tmp;
     35   S.split(Tmp, ',', -1, false /* KeepEmpty */);
     36   V.reserve(Tmp.size());
     37   for (StringRef T : Tmp)
     38     V.push_back(std::string(T));
     39 }
     40 
     41 void SubtargetFeatures::AddFeature(StringRef String, bool Enable) {
     42   // Don't add empty features.
     43   if (!String.empty())
     44     // Convert to lowercase, prepend flag if we don't already have a flag.
     45     Features.push_back(hasFlag(String) ? String.lower()
     46                                        : (Enable ? "+" : "-") + String.lower());
     47 }
     48 
     49 SubtargetFeatures::SubtargetFeatures(StringRef Initial) {
     50   // Break up string into separate features
     51   Split(Features, Initial);
     52 }
     53 
     54 std::string SubtargetFeatures::getString() const {
     55   return join(Features.begin(), Features.end(), ",");
     56 }
     57 
     58 void SubtargetFeatures::print(raw_ostream &OS) const {
     59   for (auto &F : Features)
     60     OS << F << " ";
     61   OS << "\n";
     62 }
     63 
     64 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
     65 LLVM_DUMP_METHOD void SubtargetFeatures::dump() const {
     66   print(dbgs());
     67 }
     68 #endif
     69 
     70 void SubtargetFeatures::getDefaultSubtargetFeatures(const Triple& Triple) {
     71   // FIXME: This is an inelegant way of specifying the features of a
     72   // subtarget. It would be better if we could encode this information
     73   // into the IR. See <rdar://5972456>.
     74   if (Triple.getVendor() == Triple::Apple) {
     75     if (Triple.getArch() == Triple::ppc) {
     76       // powerpc-apple-*
     77       AddFeature("altivec");
     78     } else if (Triple.getArch() == Triple::ppc64) {
     79       // powerpc64-apple-*
     80       AddFeature("64bit");
     81       AddFeature("altivec");
     82     }
     83   }
     84 }
     85