This new class provides support for platform specific "features". The intent

is to manage processor specific attributes from the command line.  See examples
of use in llc/lli and PowerPCTargetSubtarget.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23191 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Laskey 2005-09-01 21:36:18 +00:00
parent 75592e4137
commit b3302db18a
2 changed files with 318 additions and 0 deletions

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//===-- llvm/Target/SubtargetFeature.h - CPU characteristics ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Jim Laskey and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines and manages user or tool specified CPU characteristics.
// The intent is to be able to package specific features that should or should
// not be used on a specific target processor. A tool, such as llc, could, as
// as example, gather chip info from the command line, a long with features
// that should be used on that chip.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_TARGET_SUBTARGETFEATURE_H
#define LLVM_TARGET_SUBTARGETFEATURE_H
#include <string>
#include <vector>
#include <iostream>
#include <cassert>
namespace llvm {
//===----------------------------------------------------------------------===//
///
/// SubtargetFeatureKV - Used to provide key value pairs for feature and
/// CPU bit flags.
//
struct SubtargetFeatureKV {
const char *Key; // K-V key string
uint32_t Value; // K-V integer value
// Compare routine for std binary search
bool operator<(const std::string &S) const {
return strcmp(Key, S.c_str()) < 0;
}
};
//===----------------------------------------------------------------------===//
///
/// SubtargetFeatures - Manages the enabling and disabling of subtarget
/// specific features. Features are encoded as a string of the form
/// "cpu,+attr1,+attr2,-attr3,...,+attrN"
/// A comma separates each feature from the next (all lowercase.)
/// The first feature is always the CPU subtype (eg. pentiumm). If the CPU
/// value is "generic" then the CPU subtype should be generic for the target.
/// Each of the remaining features is prefixed with + or - indicating whether
/// that feature should be enabled or disabled contrary to the cpu
/// specification.
///
class SubtargetFeatures {
private:
std::vector<std::string> Features; // Subtarget features as a vector
// Determine if a feature has a flag; '+' or '-'
static inline bool hasFlag(const std::string &Feature) {
assert(!Feature.empty() && "Empty string");
// Get first character
char Ch = Feature[0];
// Check if first character is '+' or '-' flag
return Ch == '+' || Ch =='-';
}
// Return true if enable flag; '+'.
static inline bool isEnabled(const std::string &Feature) {
assert(!Feature.empty() && "Empty string");
// Get first character
char Ch = Feature[0];
// Check if first character is '+' for enabled
return Ch == '+';
}
// Return a string with a prepended flag; '+' or '-'.
static inline std::string PrependFlag(const std::string &Feature,
bool IsEnabled) {
assert(!Feature.empty() && "Empty string");
if (hasFlag(Feature)) return Feature;
return std::string(IsEnabled ? "+" : "-") + Feature;
}
// Return string stripped of flag.
static inline std::string StripFlag(const std::string &Feature) {
return hasFlag(Feature) ? Feature.substr(1) : Feature;
}
/// Splits a string of comma separated items in to a vector of strings.
static void Split(std::vector<std::string> &V, const std::string &S);
/// Join a vector of strings into a string with a comma separating each
/// item.
static std::string Join(const std::vector<std::string> &V);
/// Convert a string to lowercase.
static std::string toLower(const std::string &S);
/// Find item in array using binary search.
static const SubtargetFeatureKV *Find(const std::string &S,
const SubtargetFeatureKV *A, size_t L);
public:
/// Ctor.
SubtargetFeatures(const std::string Initial = std::string()) {
// Break up string into separate features
Split(Features, Initial);
}
/// Features string accessors.
inline std::string getString() const { return Join(Features); }
void setString(const std::string &Initial) {
// Throw out old features
Features.clear();
// Break up string into separate features
Split(Features, toLower(Initial));
}
/// Setting CPU string. Replaces previous setting. Setting to "" clears CPU.
void setCPU(std::string String) { Features[0] = toLower(String); }
/// Adding Features.
void AddFeature(const std::string &String, bool IsEnabled = true);
/// Parse feature string for quick usage.
static uint32_t Parse(const std::string &String,
const std::string &DefaultCPU,
const SubtargetFeatureKV *CPUTable,
size_t CPUTableSize,
const SubtargetFeatureKV *FeatureTable,
size_t FeatureTableSize);
/// Print feature string.
void print(std::ostream &OS) const;
// Dump feature info.
void dump() const;
};
} // End namespace llvm
#endif

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//===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Jim Laskey and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the SubtargetFeature interface.
//
//===----------------------------------------------------------------------===//
#include "llvm/Target/SubtargetFeature.h"
#include <string>
#include <algorithm>
#include <vector>
#include <cassert>
using namespace llvm;
/// Splits a string of comma separated items in to a vector of strings.
void SubtargetFeatures::Split(std::vector<std::string> &V,
const std::string &S) {
// 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 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.
std::string SubtargetFeatures::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 CPU 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;
}
/// Convert a string to lowercase.
std::string SubtargetFeatures::toLower(const std::string &S) {
// Copy the string
std::string Result = S;
// For each character in string
for (size_t i = 0; i < Result.size(); i++) {
// Convert character to lowercase
Result[i] = std::tolower(Result[i]);
}
// Return the lowercased string
return Result;
}
/// Adding features.
void SubtargetFeatures::AddFeature(const std::string &String,
bool IsEnabled) {
// Don't add empty features
if (!String.empty()) {
// Convert to lowercase, prepend flag and add to vector
Features.push_back(PrependFlag(toLower(String), IsEnabled));
}
}
/// Find item in array using binary search.
const SubtargetFeatureKV *
SubtargetFeatures::Find(const std::string &S,
const SubtargetFeatureKV *A, size_t L) {
// Determine the end of the array
const SubtargetFeatureKV *Hi = A + L;
// Binary search the array
const SubtargetFeatureKV *F = std::lower_bound(A, Hi, S);
// If not found then return NULL
if (F == Hi || std::string(F->Key) != S) return NULL;
// Return the found array item
return F;
}
/// Parse feature string for quick usage.
uint32_t SubtargetFeatures::Parse(const std::string &String,
const std::string &DefaultCPU,
const SubtargetFeatureKV *CPUTable,
size_t CPUTableSize,
const SubtargetFeatureKV *FeatureTable,
size_t FeatureTableSize) {
assert(CPUTable && "missing CPU table");
assert(FeatureTable && "missing features table");
#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
std::vector<std::string> Features; // Subtarget features as a vector
uint32_t Bits = 0; // Resulting bits
// Split up features
Split(Features, String);
// Check if default is needed
if (Features[0].empty()) Features[0] = DefaultCPU;
// Find CPU entry
const SubtargetFeatureKV *CPUEntry =
Find(Features[0], CPUTable, CPUTableSize);
// If there is a match
if (CPUEntry) {
// Set base feature bits
Bits = CPUEntry->Value;
} else {
std::cerr << Features[0]
<< " is not a recognized processor for this target"
<< " (ignoring processor)"
<< "\n";
}
// Iterate through each feature
for (size_t i = 1; i < Features.size(); i++) {
// Get next feature
const std::string &Feature = Features[i];
// 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;
else Bits &= ~FeatureEntry->Value;
} else {
std::cerr << Feature
<< " is not a recognized feature for this target"
<< " (ignoring feature)"
<< "\n";
}
}
return Bits;
}
/// Print feature string.
void SubtargetFeatures::print(std::ostream &OS) const {
for (size_t i = 0; i < Features.size(); i++) {
OS << Features[i] << " ";
}
OS << "\n";
}
/// Dump feature info.
void SubtargetFeatures::dump() const {
print(std::cerr);
}