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Save another 30K from 176.gcc by encoding the compaction table a bit more

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intelligently.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10918 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-01-18 22:35:34 +00:00
parent 33522d4f25
commit 241024381f
2 changed files with 32 additions and 7 deletions
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21
lib/Bytecode/Reader/Reader.cpp
View File

@ -496,8 +496,22 @@ void BytecodeParser::ParseCompactionTable(const unsigned char *&Buf,
const unsigned char *End) {
while (Buf != End) {
unsigned NumEntries = read_vbr_uint(Buf, End);
unsigned Ty = read_vbr_uint(Buf, End);
unsigned NumEntries;
unsigned Ty;
NumEntries = read_vbr_uint(Buf, End);
switch (NumEntries & 3) {
case 0:
case 1:
case 2:
Ty = NumEntries >> 2;
NumEntries &= 3;
break;
case 3:
NumEntries >>= 2;
Ty = read_vbr_uint(Buf, End);
break;
}
if (Ty >= CompactionTable.size())
CompactionTable.resize(Ty+1);
@ -513,11 +527,10 @@ void BytecodeParser::ParseCompactionTable(const unsigned char *&Buf,
CompactionTable.resize(NumEntries+Type::FirstDerivedTyID);
} else {
assert(NumEntries != 0 && "Cannot read zero entries!");
const Type *Typ = getType(Ty);
// Push the implicit zero
CompactionTable[Ty].push_back(Constant::getNullValue(Typ));
for (unsigned i = 1; i != NumEntries; ++i) {
for (unsigned i = 0; i != NumEntries; ++i) {
Value *V = getGlobalTableValue(Typ, read_vbr_uint(Buf, End));
CompactionTable[Ty].push_back(V);
}

18
lib/Bytecode/Writer/Writer.cpp
View File

@ -293,12 +293,24 @@ void BytecodeWriter::outputCompactionTablePlane(unsigned PlaneNo,
assert(StartNo < End && "Cannot emit negative range!");
assert(StartNo < Plane.size() && End <= Plane.size());
output_vbr(unsigned(End-StartNo), Out); // Output the number of things.
output_vbr(PlaneNo, Out); // Emit the type plane this is
// Do not emit the null initializer!
if (PlaneNo != Type::TypeTyID) ++StartNo;
// Figure out which encoding to use. By far the most common case we have is
// to emit 0-2 entries in a compaction table plane.
switch (End-StartNo) {
case 0: // Avoid emitting two vbr's if possible.
case 1:
case 2:
output_vbr((PlaneNo << 2) | End-StartNo, Out);
break;
default:
// Output the number of things.
output_vbr((unsigned(End-StartNo) << 2) | 3, Out);
output_vbr(PlaneNo, Out); // Emit the type plane this is
break;
}
for (unsigned i = StartNo; i != End; ++i)
output_vbr(Table.getGlobalSlot(Plane[i]), Out);
}