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llvm-mirror/lib/MC/SubtargetFeature.cpp
Evan Cheng c9e252df68 Change createAsmParser to take a MCSubtargetInfo instead of triple,
CPU, and feature string. Parsing some asm directives can change
subtarget state (e.g. .code 16) and it must be reflected in other
modules (e.g. MCCodeEmitter). That is, the MCSubtargetInfo instance
must be shared.

llvm-svn: 134795
2011-07-09 05:47:46 +00:00

398 lines
12 KiB
C++

//===- 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/raw_ostream.h"
#include "llvm/ADT/StringExtras.h"
#include <algorithm>
#include <cassert>
#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(LowercaseString(String), IsEnabled));
}
}
/// Find KV in array using binary search.
template<typename T> const T *Find(const StringRef S, const T *A, size_t L) {
// Make the lower bound element we're looking for
T KV;
KV.Key = S.data();
// Determine the end of the array
const T *Hi = A + L;
// Binary search the array
const T *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;
}
/// 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);
// Print the CPU table.
errs() << "Available CPUs for this target:\n\n";
for (size_t i = 0; i != CPUTableSize; i++)
errs() << " " << CPUTable[i].Key
<< std::string(MaxCPULen - std::strlen(CPUTable[i].Key), ' ')
<< " - " << CPUTable[i].Desc << ".\n";
errs() << "\n";
// Print the Feature table.
errs() << "Available features for this target:\n\n";
for (size_t i = 0; i != FeatTableSize; i++)
errs() << " " << FeatTable[i].Key
<< std::string(MaxFeatLen - std::strlen(FeatTable[i].Key), ' ')
<< " - " << FeatTable[i].Desc << ".\n";
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);
}
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;
}
/// Get scheduling itinerary of a CPU.
void *SubtargetFeatures::getItinerary(const StringRef CPU,
const SubtargetInfoKV *Table,
size_t TableSize) {
assert(Table && "missing table");
#ifndef NDEBUG
for (size_t i = 1; i < TableSize; i++) {
assert(strcmp(Table[i - 1].Key, Table[i].Key) < 0 && "Table is not sorted");
}
#endif
// Find entry
const SubtargetInfoKV *Entry = Find(CPU, Table, TableSize);
if (Entry) {
return Entry->Value;
} else {
errs() << "'" << CPU
<< "' is not a recognized processor for this target"
<< " (ignoring processor)\n";
return NULL;
}
}
/// 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";
}
/// dump - Dump feature info.
///
void SubtargetFeatures::dump() const {
print(dbgs());
}
/// 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");
}
}
}