LLVM API Documentation

SubtargetFeature.h

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00001 //===-- llvm/Target/SubtargetFeature.h - CPU characteristics ----*- C++ -*-===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by James M. Laskey and is distributed under the 
00006 // University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file defines and manages user or tool specified CPU characteristics.
00011 // The intent is to be able to package specific features that should or should
00012 // not be used on a specific target processor.  A tool, such as llc, could, as
00013 // as example, gather chip info from the command line, a long with features
00014 // that should be used on that chip.
00015 //
00016 //===----------------------------------------------------------------------===//
00017 
00018 #ifndef LLVM_TARGET_SUBTARGETFEATURE_H
00019 #define LLVM_TARGET_SUBTARGETFEATURE_H
00020 
00021 #include <string>
00022 #include <vector>
00023 #include <iosfwd>
00024 #include "llvm/Support/DataTypes.h"
00025 
00026 namespace llvm {
00027 
00028 //===----------------------------------------------------------------------===//
00029 ///
00030 /// SubtargetFeatureKV - Used to provide key value pairs for feature and
00031 /// CPU bit flags.
00032 //
00033 struct SubtargetFeatureKV {
00034   const char *Key;                      // K-V key string
00035   const char *Desc;                     // Help descriptor
00036   uint32_t Value;                       // K-V integer value
00037   
00038   // Compare routine for std binary search
00039   bool operator<(const SubtargetFeatureKV &S) const {
00040     return strcmp(Key, S.Key) < 0;
00041   }
00042 };
00043   
00044 //===----------------------------------------------------------------------===//
00045 ///
00046 /// SubtargetInfoKV - Used to provide key value pairs for CPU and arbitrary
00047 /// pointers.
00048 //
00049 struct SubtargetInfoKV {
00050   const char *Key;                      // K-V key string
00051   void *Value;                          // K-V pointer value
00052   
00053   // Compare routine for std binary search
00054   bool operator<(const SubtargetInfoKV &S) const {
00055     return strcmp(Key, S.Key) < 0;
00056   }
00057 };
00058   
00059 //===----------------------------------------------------------------------===//
00060 ///
00061 /// SubtargetFeatures - Manages the enabling and disabling of subtarget 
00062 /// specific features.  Features are encoded as a string of the form
00063 ///   "cpu,+attr1,+attr2,-attr3,...,+attrN"
00064 /// A comma separates each feature from the next (all lowercase.)
00065 /// The first feature is always the CPU subtype (eg. pentiumm).  If the CPU
00066 /// value is "generic" then the CPU subtype should be generic for the target.
00067 /// Each of the remaining features is prefixed with + or - indicating whether
00068 /// that feature should be enabled or disabled contrary to the cpu
00069 /// specification.
00070 ///
00071 
00072 class SubtargetFeatures {
00073   std::vector<std::string> Features;    // Subtarget features as a vector
00074 public:
00075   SubtargetFeatures(const std::string &Initial = std::string());
00076 
00077   /// Features string accessors.
00078   std::string getString() const;
00079   void setString(const std::string &Initial);
00080 
00081   /// Set the CPU string.  Replaces previous setting.  Setting to "" clears CPU.
00082   void setCPU(const std::string &String);
00083   
00084   /// Setting CPU string only if no string is set.
00085   void setCPUIfNone(const std::string &String);
00086   
00087   /// Adding Features.
00088   void AddFeature(const std::string &String, bool IsEnabled = true);
00089            
00090   /// Get feature bits.
00091   uint32_t getBits(const SubtargetFeatureKV *CPUTable,
00092                          size_t CPUTableSize,
00093                    const SubtargetFeatureKV *FeatureTable,
00094                          size_t FeatureTableSize);
00095                          
00096   /// Get info pointer
00097   void *getInfo(const SubtargetInfoKV *Table, size_t TableSize);
00098   
00099   /// Print feature string.
00100   void print(std::ostream &OS) const;
00101   
00102   // Dump feature info.
00103   void dump() const;
00104 };
00105 
00106 } // End namespace llvm
00107 
00108 #endif