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If these blocks are empty, there is no reason to even emit the bytecode blocks.

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This saves about 15K in 176.gcc, coupled with another patch that I'm working on.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10889 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-01-15 21:06:57 +00:00
parent d5c59d5c84
commit 0baa0af861
2 changed files with 24 additions and 8 deletions
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6
lib/Bytecode/Writer/Writer.cpp
View File

@ -164,7 +164,8 @@ void BytecodeWriter::outputConstantsInPlane(const std::vector<const Value*>
void BytecodeWriter::outputConstants(bool isFunction) {
ConstantTotalBytes -= Out.size();
if (isFunction) FunctionConstantTotalBytes -= Out.size();
BytecodeBlock CPool(BytecodeFormat::ConstantPool, Out);
BytecodeBlock CPool(BytecodeFormat::ConstantPool, Out,
true /* Elide block if empty */);
unsigned NumPlanes = Table.getNumPlanes();
@ -286,7 +287,8 @@ void BytecodeWriter::outputSymbolTable(const SymbolTable &MST) {
SymTabBytes -= Out.size();
BytecodeBlock SymTabBlock(BytecodeFormat::SymbolTable, Out);
BytecodeBlock SymTabBlock(BytecodeFormat::SymbolTable, Out,
true/* ElideIfEmpty*/);
for (SymbolTable::const_iterator TI = MST.begin(); TI != MST.end(); ++TI) {
SymbolTable::type_const_iterator I = MST.type_begin(TI->first);

26
lib/Bytecode/Writer/WriterInternals.h
View File

@ -50,27 +50,41 @@ private:
// BytecodeBlock - Little helper class that helps us do backpatching of bytecode
// block sizes really easily. It backpatches when it goes out of scope.
//
/// BytecodeBlock - Little helper class is used by the bytecode writer to help
/// do backpatching of bytecode block sizes really easily. It backpatches when
/// it goes out of scope.
///
class BytecodeBlock {
unsigned Loc;
std::deque<unsigned char> &Out;
/// ElideIfEmpty - If this is true and the bytecode block ends up being empty,
/// the block can remove itself from the output stream entirely.
bool ElideIfEmpty;
BytecodeBlock(const BytecodeBlock &); // do not implement
void operator=(const BytecodeBlock &); // do not implement
public:
inline BytecodeBlock(unsigned ID, std::deque<unsigned char> &o) : Out(o) {
inline BytecodeBlock(unsigned ID, std::deque<unsigned char> &o,
bool elideIfEmpty = false)
: Out(o), ElideIfEmpty(elideIfEmpty) {
output(ID, Out);
output((unsigned)0, Out); // Reserve the space for the block size...
output(0U, Out); // Reserve the space for the block size...
Loc = Out.size();
}
inline ~BytecodeBlock() { // Do backpatch when block goes out
// of scope...
if (Loc == Out.size() && ElideIfEmpty) {
// If the block is empty, and we are allowed to, do not emit the block at
// all!
Out.resize(Out.size()-8);
return;
}
//cerr << "OldLoc = " << Loc << " NewLoc = " << NewLoc << " diff = "
// << (NewLoc-Loc) << endl;
output((unsigned)(Out.size()-Loc), Out, (int)Loc-4);
output(unsigned(Out.size()-Loc), Out, int(Loc-4));
align32(Out); // Blocks must ALWAYS be aligned
}
};