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Factor matching code that is common between patterns. This works around

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GCC not jump-threading across this common code, and produces far nicer
output.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25762 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-01-29 04:25:26 +00:00
parent c7e1852d63
commit 8bc7472a0c
2 changed files with 112 additions and 35 deletions
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142
utils/TableGen/DAGISelEmitter.cpp
View File

@ -2032,9 +2032,12 @@ public:
}
} else if (IntInit *II =
dynamic_cast<IntInit*>(Child->getLeafValue())) {
emitCheck("isa<ConstantSDNode>(" + RootName + utostr(OpNo) +
") && cast<ConstantSDNode>(" + RootName + utostr(OpNo) +
")->getSignExtended() == " + itostr(II->getValue()));
emitCheck("isa<ConstantSDNode>(" + RootName + utostr(OpNo) + ")");
unsigned CTmp = TmpNo++;
emitCode("int CN"+utostr(CTmp)+" = cast<ConstantSDNode>("+
RootName + utostr(OpNo) + ")->getSignExtended();");
emitCheck("CN" + utostr(CTmp) + " == " +itostr(II->getValue()));
} else {
Child->dump();
assert(0 && "Unknown leaf type!");
@ -2530,7 +2533,7 @@ private:
/// EmitCodeForPattern - Given a pattern to match, emit code to the specified
/// stream to match the pattern, and generate the code for the match if it
/// succeeds. Returns true if the pattern is not guaranteed to match.
void DAGISelEmitter::EmitCodeForPattern(PatternToMatch &Pattern,
void DAGISelEmitter::GenerateCodeForPattern(PatternToMatch &Pattern,
std::vector<std::pair<bool, std::string> > &GeneratedCode) {
PatternCodeEmitter Emitter(*this, Pattern.getPredicates(),
Pattern.getSrcPattern(), Pattern.getDstPattern(),
@ -2581,6 +2584,95 @@ void DAGISelEmitter::EmitCodeForPattern(PatternToMatch &Pattern,
delete Pat;
}
/// EmitPatterns - Emit code for at least one pattern, but try to group common
/// code together between the patterns.
void DAGISelEmitter::EmitPatterns(std::vector<std::pair<PatternToMatch*,
std::vector<std::pair<bool, std::string> > > >
&Patterns, unsigned Indent,
std::ostream &OS) {
typedef std::pair<bool, std::string> CodeLine;
typedef std::vector<CodeLine> CodeList;
typedef std::vector<std::pair<PatternToMatch*, CodeList> > PatternList;
if (Patterns.empty()) return;
// Figure out how many patterns share the next code line:
const CodeLine &FirstCodeLine = Patterns.back().second.back();
unsigned LastMatch = Patterns.size()-1;
while (LastMatch != 0 && Patterns[LastMatch-1].second.back() == FirstCodeLine)
--LastMatch;
// If not all patterns share this line, split the list into two pieces. The
// first chunk will use this line, the second chunk won't.
if (LastMatch != 0) {
PatternList Shared(Patterns.begin()+LastMatch, Patterns.end());
PatternList Other(Patterns.begin(), Patterns.begin()+LastMatch);
// FIXME: Emit braces?
if (Shared.size() == 1) {
PatternToMatch &Pattern = *Shared.back().first;
OS << "\n" << std::string(Indent, ' ') << "// Pattern: ";
Pattern.getSrcPattern()->print(OS);
OS << "\n" << std::string(Indent, ' ') << "// Emits: ";
Pattern.getDstPattern()->print(OS);
OS << "\n";
OS << std::string(Indent, ' ') << "// Pattern complexity = "
<< getPatternSize(Pattern.getSrcPattern(), *this) << " cost = "
<< getResultPatternCost(Pattern.getDstPattern()) << "\n";
}
if (!FirstCodeLine.first) {
OS << std::string(Indent, ' ') << "{\n";
Indent += 2;
}
EmitPatterns(Shared, Indent, OS);
if (!FirstCodeLine.first) {
Indent -= 2;
OS << std::string(Indent, ' ') << "}\n";
}
if (Other.size() == 1) {
PatternToMatch &Pattern = *Other.back().first;
OS << "\n" << std::string(Indent, ' ') << "// Pattern: ";
Pattern.getSrcPattern()->print(OS);
OS << "\n" << std::string(Indent, ' ') << "// Emits: ";
Pattern.getDstPattern()->print(OS);
OS << "\n";
OS << std::string(Indent, ' ') << "// Pattern complexity = "
<< getPatternSize(Pattern.getSrcPattern(), *this) << " cost = "
<< getResultPatternCost(Pattern.getDstPattern()) << "\n";
}
EmitPatterns(Other, Indent, OS);
return;
}
bool isPredicate = FirstCodeLine.first;
// Otherwise, every pattern in the list has this line. Emit it.
if (!isPredicate) {
// Normal code.
OS << std::string(Indent, ' ') << FirstCodeLine.second << "\n";
} else {
OS << std::string(Indent, ' ')
<< "if (" << FirstCodeLine.second << ") {\n";
Indent += 2;
}
// Remove this code from all of the patterns that share it.
for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
Patterns[i].second.pop_back();
if (Patterns[i].second.empty()) {
Patterns.erase(Patterns.begin()+i);
--i; --e;
}
}
EmitPatterns(Patterns, Indent, OS);
if (isPredicate)
OS << std::string(Indent-2, ' ') << "}\n";
}
namespace {
/// CompareByRecordName - An ordering predicate that implements less-than by
@ -2652,7 +2744,7 @@ void DAGISelEmitter::EmitInstructionSelector(std::ostream &OS) {
std::vector<std::pair<PatternToMatch*, CodeList> > CodeForPatterns;
for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
CodeList GeneratedCode;
EmitCodeForPattern(*Patterns[i], GeneratedCode);
GenerateCodeForPattern(*Patterns[i], GeneratedCode);
CodeForPatterns.push_back(std::make_pair(Patterns[i], GeneratedCode));
}
@ -2679,39 +2771,21 @@ void DAGISelEmitter::EmitInstructionSelector(std::ostream &OS) {
exit(1);
}
}
// Loop through and reverse all of the CodeList vectors, as we will be
// accessing them from their logical front, but accessing the end of a
// vector is more efficient.
for (unsigned i = 0, e = CodeForPatterns.size(); i != e; ++i) {
CodeList &GeneratedCode = CodeForPatterns[i].second;
PatternToMatch &Pattern = *CodeForPatterns[i].first;
OS << " { // Pattern: ";
Pattern.getSrcPattern()->print(OS);
OS << "\n // Emits: ";
Pattern.getDstPattern()->print(OS);
OS << "\n";
OS << " // Pattern complexity = "
<< getPatternSize(Pattern.getSrcPattern(), *this) << " cost = "
<< getResultPatternCost(Pattern.getDstPattern()) << "\n";
// Actually output the generated code now.
mightNotMatch = false;
unsigned Indent = 4;
for (unsigned j = 0, e = GeneratedCode.size(); j != e; ++j) {
if (!GeneratedCode[j].first) {
// Normal code.
OS << std::string(Indent, ' ') << GeneratedCode[j].second << "\n";
} else {
mightNotMatch = true;
OS << std::string(Indent, ' ')
<< "if (" << GeneratedCode[j].second << ") {\n";
Indent += 2;
}
}
for (; Indent != 4; Indent -= 2)
OS << std::string(Indent-2, ' ') << "}\n";
OS << " }\n";
std::reverse(GeneratedCode.begin(), GeneratedCode.end());
}
// Next, reverse the list of patterns itself for the same reason.
std::reverse(CodeForPatterns.begin(), CodeForPatterns.end());
// Emit all of the patterns now, grouped together to share code.
EmitPatterns(CodeForPatterns, 2, OS);
// If the last pattern has predicates (which could fail) emit code to catch
// the case where nothing handles a pattern.
if (mightNotMatch)

5
utils/TableGen/DAGISelEmitter.h
View File

@ -470,8 +470,11 @@ private:
std::map<std::string, Record*> &InstResults,
std::vector<Record*> &InstImpInputs,
std::vector<Record*> &InstImpResults);
void EmitCodeForPattern(PatternToMatch &Pattern,
void GenerateCodeForPattern(PatternToMatch &Pattern,
std::vector<std::pair<bool, std::string> > &GeneratedCode);
void EmitPatterns(std::vector<std::pair<PatternToMatch*,
std::vector<std::pair<bool, std::string> > > > &Patterns,
unsigned Indent, std::ostream &OS);
void EmitInstructionSelector(std::ostream &OS);
};