Emit & read more compressed bytecode by not emitting a bytecodeblock for

each basic block in function.  Instead, just emit a stream of instructions,
chopping up basic blocks based on when we find terminator instructions.  This
saves a fairly substantial chunk of bytecode space.  In stripped, sample
cases, for example, we get this reduction in size:

197.parser: 163036 -> 137180:  18.8% reduction
254.gap   : 844936 -> 689392:  22.6%
255.vortex: 621724 -> 528444:  17.7%

...

Not bad for something this simple.  :)  Note that this doesn't require a new
bytecode version number at all, though version 1.1 should not need to support
the old format.

llvm-svn: 10280

2 files changed, 7 insertions, 12 deletions

diff --git a/llvm/lib/Bytecode/Writer/Writer.cpp b/llvm/lib/Bytecode/Writer/Writer.cpp
index 9c9e1abcdd8..7fa22b81017 100644
--- a/llvm/lib/Bytecode/Writer/Writer.cpp
+++ b/llvm/lib/Bytecode/Writer/Writer.cpp
@@ -225,9 +225,13 @@ void BytecodeWriter::outputFunction(const Function *F) {
     // Output information about the constants in the function...
     outputConstants(true);
 
-    // Output basic block nodes...
-    for (Function::const_iterator I = F->begin(), E = F->end(); I != E; ++I)
-      processBasicBlock(*I);
+    {  // Output all of the instructions in the body of the function
+      BytecodeBlock ILBlock(BytecodeFormat::InstructionList, Out);
+
+      for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E;++BB)
+        for(BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I!=E;++I)
+          processInstruction(*I);
+    }
     
     // If needed, output the symbol table for the function...
     outputSymbolTable(F->getSymbolTable());
@@ -236,14 +240,6 @@ void BytecodeWriter::outputFunction(const Function *F) {
   }
 }
 
-
-void BytecodeWriter::processBasicBlock(const BasicBlock &BB) {
-  BytecodeBlock FunctionBlock(BytecodeFormat::BasicBlock, Out);
-  // Process all the instructions in the bb...
-  for(BasicBlock::const_iterator I = BB.begin(), E = BB.end(); I != E; ++I)
-    processInstruction(*I);
-}
-
 void BytecodeWriter::outputSymbolTable(const SymbolTable &MST) {
   BytecodeBlock FunctionBlock(BytecodeFormat::SymbolTable, Out);
 
diff --git a/llvm/lib/Bytecode/Writer/WriterInternals.h b/llvm/lib/Bytecode/Writer/WriterInternals.h
index 8cb4bfd8d6c..29465157c7c 100644
--- a/llvm/lib/Bytecode/Writer/WriterInternals.h
+++ b/llvm/lib/Bytecode/Writer/WriterInternals.h
@@ -36,7 +36,6 @@ public:
 protected:
   void outputConstants(bool isFunction);
   void outputFunction(const Function *F);
-  void processBasicBlock(const BasicBlock &BB);
   void processInstruction(const Instruction &I);
 
 private :