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llvm-mc/AsmMatcher: Tweak string matcher.

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- Track whether we need to insert an explicit 'break'.

 - Invert conditional when matching a single prefix to reduce
   nesting/bracing/breaking.

 - wc -l of X86GenAsmMatcher.inc decreased by 10%. :)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@78513 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Daniel Dunbar 2009-08-08 22:57:25 +00:00
parent 76eb6f5685
commit 72ffae90ce
1 changed files with 28 additions and 26 deletions
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54
utils/TableGen/AsmMatcherEmitter.cpp
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@ -734,7 +734,9 @@ FindFirstNonCommonLetter(const std::vector<const StringPair*> &Matches) {
/// EmitStringMatcherForChar - Given a set of strings that are known to be the
/// same length and whose characters leading up to CharNo are the same, emit
/// code to verify that CharNo and later are the same.
static void EmitStringMatcherForChar(const std::string &StrVariableName,
///
/// \return - True if control can leave the emitted code fragment.
static bool EmitStringMatcherForChar(const std::string &StrVariableName,
const std::vector<const StringPair*> &Matches,
unsigned CharNo, unsigned IndentCount,
raw_ostream &OS) {
@ -749,7 +751,7 @@ static void EmitStringMatcherForChar(const std::string &StrVariableName,
// FIXME: If Matches[0].first has embeded \n, this will be bad.
OS << Indent << Matches[0]->second << "\t // \"" << Matches[0]->first
<< "\"\n";
return;
return false;
}
// Bucket the matches by the character we are comparing.
@ -766,24 +768,24 @@ static void EmitStringMatcherForChar(const std::string &StrVariableName,
unsigned FirstNonCommonLetter = FindFirstNonCommonLetter(Matches);
unsigned NumChars = FirstNonCommonLetter-CharNo;
// Emit code to break out if the prefix doesn't match.
if (NumChars == 1) {
// Do the comparison with if (Str[1] == 'f')
// Do the comparison with if (Str[1] != 'f')
// FIXME: Need to escape general characters.
OS << Indent << "if (" << StrVariableName << "[" << CharNo << "] == '"
<< Matches[0]->first[CharNo] << "') {\n";
OS << Indent << "if (" << StrVariableName << "[" << CharNo << "] != '"
<< Matches[0]->first[CharNo] << "')\n";
OS << Indent << " break;\n";
} else {
// Do the comparison with if (Str.substr(1,3) == "foo").
OS << Indent << "if (" << StrVariableName << ".substr(" << CharNo << ","
<< NumChars << ") == \"";
// Do the comparison with if (Str.substr(1,3) != "foo").
// FIXME: Need to escape general strings.
OS << Matches[0]->first.substr(CharNo, NumChars) << "\") {\n";
OS << Indent << "if (" << StrVariableName << ".substr(" << CharNo << ","
<< NumChars << ") != \"";
OS << Matches[0]->first.substr(CharNo, NumChars) << "\")\n";
OS << Indent << " break;";
}
EmitStringMatcherForChar(StrVariableName, Matches, FirstNonCommonLetter,
IndentCount+1, OS);
OS << Indent << "}\n";
return;
return EmitStringMatcherForChar(StrVariableName, Matches,
FirstNonCommonLetter, IndentCount, OS);
}
// Otherwise, we have multiple possible things, emit a switch on the
@ -796,21 +798,23 @@ static void EmitStringMatcherForChar(const std::string &StrVariableName,
// TODO: escape hard stuff (like \n) if we ever care about it.
OS << Indent << "case '" << LI->first << "':\t // "
<< LI->second.size() << " strings to match.\n";
EmitStringMatcherForChar(StrVariableName, LI->second, CharNo+1,
IndentCount+1, OS);
OS << Indent << " break;\n";
if (EmitStringMatcherForChar(StrVariableName, LI->second, CharNo+1,
IndentCount+1, OS))
OS << Indent << " break;\n";
}
OS << Indent << "}\n";
return true;
}
/// EmitStringMatcher - Given a list of strings and code to execute when they
/// match, output a simple switch tree to classify the input string. If a
/// match is found, the code in Vals[i].second is executed. This code should do
/// a return to avoid falling through. If nothing matches, execution falls
/// through. StrVariableName is the name of teh variable to test.
/// match, output a simple switch tree to classify the input string.
///
/// If a match is found, the code in Vals[i].second is executed; control must
/// not exit this code fragment. If nothing matches, execution falls through.
///
/// \param StrVariableName - The name of the variable to test.
static void EmitStringMatcher(const std::string &StrVariableName,
const std::vector<StringPair> &Matches,
raw_ostream &OS) {
@ -825,16 +829,14 @@ static void EmitStringMatcher(const std::string &StrVariableName,
OS << " switch (" << StrVariableName << ".size()) {\n";
OS << " default: break;\n";
for (std::map<unsigned, std::vector<const StringPair*> >::iterator LI =
MatchesByLength.begin(), E = MatchesByLength.end(); LI != E; ++LI) {
OS << " case " << LI->first << ":\t // " << LI->second.size()
<< " strings to match.\n";
EmitStringMatcherForChar(StrVariableName, LI->second, 0, 0, OS);
OS << " break;\n";
if (EmitStringMatcherForChar(StrVariableName, LI->second, 0, 0, OS))
OS << " break;\n";
}
OS << " }\n";
}