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[HW] Improve name legalization speed. [NFC] (#1166) 

Improve name legalization speed.  Improves HWLegalizeNames by about 4%.  The fast path is an early check that the name is valid and has no temporary strings. The slow path removes some redundant checks on legalized names.
This commit is contained in:
Andrew Lenharth 2021-05-28 09:55:24 -05:00 committed by GitHub
parent 73d0132f31
commit 35bd44f920
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 34 additions and 34 deletions
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68
lib/Dialect/SV/SVDialect.cpp
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@ -68,25 +68,32 @@ static llvm::ManagedStatic<StringSet<>, ReservedWordsCreator> reservedWords;
StringRef circt::sv::resolveKeywordConflict(StringRef origName,
llvm::StringSet<> &recordNames,
size_t &nextGeneratedNameID) {
auto name = origName;
// Get the list of reserved words we need to avoid. We could prepopulate this
// into the used words cache, but it is large and immutable, so we just query
// it when needed.
SmallVector<char, 16> nameBuffer(name.begin(), name.end());
// Fast path: name is valid
if (!reservedWords->count(origName)) {
auto itAndInserted = recordNames.insert(origName);
if (itAndInserted.second)
return itAndInserted.first->getKey();
}
// We need to mutate the name, get the copy ready.
SmallString<16> nameBuffer(origName.begin(), origName.end());
nameBuffer.push_back('_');
auto baseSize = nameBuffer.size();
while (1) {
// Loop until we get a name that is not a keyword and is unique.
if (!reservedWords->count(name)) {
auto itAndInserted = recordNames.insert(name);
if (itAndInserted.second)
return itAndInserted.first->getKey();
}
// We need to auto-unique it.
auto suffix = llvm::utostr(nextGeneratedNameID++);
nameBuffer.append(suffix.begin(), suffix.end());
name = StringRef(nameBuffer.data(), nameBuffer.size());
// The name may be unique. No keywords have an underscore followed by a
// number, so don't check that again.
auto itAndInserted = recordNames.insert(nameBuffer);
if (itAndInserted.second)
return itAndInserted.first->getKey();
// Chop off the suffix and try again until we get a unique name..
nameBuffer.resize(baseSize);
@ -107,39 +114,32 @@ static bool isValidVerilogCharacter(char ch) {
StringRef circt::sv::legalizeName(StringRef name,
llvm::StringSet<> &recordNames,
size_t &nextGeneratedNameID) {
// Fastest path: empty name.
if (name.empty())
name = "_T";
return resolveKeywordConflict("_T", recordNames, nextGeneratedNameID);
// Check to see if the name consists of all-valid identifiers. If not, we
// need to escape them.
// Check that the name is valid as the semi-fast path.
if (llvm::all_of(name, isValidVerilogCharacter) &&
isValidVerilogCharacterFirst(name.front()))
return resolveKeywordConflict(name, recordNames, nextGeneratedNameID);
// The name consists of at least one invalid character. Escape it.
SmallString<16> tmpName;
if (!isValidVerilogCharacterFirst(name.front()) && name.front() != ' ' &&
name.front() != '.')
tmpName += '_';
for (char ch : name) {
if (isValidVerilogCharacter(ch))
continue;
// Otherwise, we need to escape it.
SmallString<16> tmpName;
for (char ch : name) {
if (isValidVerilogCharacter(ch))
tmpName += ch;
else if (ch == ' ' || ch == '.')
tmpName += '_';
else {
tmpName += llvm::utohexstr((unsigned char)ch);
}
tmpName += ch;
else if (ch == ' ' || ch == '.')
tmpName += '_';
else {
tmpName += llvm::utohexstr((unsigned char)ch);
}
return legalizeName(tmpName, recordNames, nextGeneratedNameID);
}
// Check to see if this name is valid. The first character cannot be a
// number or some other weird thing. If it is, start with an underscore.
if (!isValidVerilogCharacterFirst(name.front())) {
SmallString<16> tmpName("_");
tmpName += name;
return legalizeName(tmpName, recordNames, nextGeneratedNameID);
}
// Make sure the new valid name does not conflict with any existing names.
return resolveKeywordConflict(name, recordNames, nextGeneratedNameID);
return resolveKeywordConflict(tmpName, recordNames, nextGeneratedNameID);
}
/// Check if a name is valid for use in SV output by only containing characters