Save another 30K from 176.gcc by encoding the compaction table a bit more
intelligently.
llvm-svn: 10918
diff --git a/llvm/lib/Bytecode/Writer/Writer.cpp b/llvm/lib/Bytecode/Writer/Writer.cpp
index d0b04d2..a55508e 100644
--- a/llvm/lib/Bytecode/Writer/Writer.cpp
+++ b/llvm/lib/Bytecode/Writer/Writer.cpp
@@ -293,12 +293,24 @@
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);
}