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

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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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10280 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2003-12-01 07:05:31 +00:00
parent d540e2c995
commit 8d1dbd2134
4 changed files with 51 additions and 14 deletions
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42
lib/Bytecode/Reader/Reader.cpp
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@ -188,7 +188,8 @@ Constant *BytecodeParser::getConstantValue(unsigned TypeSlot, unsigned Slot) {
}
}
/// ParseBasicBlock - In LLVM 1.0 bytecode files, we used to output one
/// basicblock at a time. This method reads in one of the basicblock packets.
BasicBlock *BytecodeParser::ParseBasicBlock(const unsigned char *&Buf,
const unsigned char *EndBuf,
unsigned BlockNo) {
@ -207,6 +208,38 @@ BasicBlock *BytecodeParser::ParseBasicBlock(const unsigned char *&Buf,
return BB;
}
/// ParseInstructionList - Parse all of the BasicBlock's & Instruction's in the
/// body of a function. In post 1.0 bytecode files, we no longer emit basic
/// block individually, in order to avoid per-basic-block overhead.
unsigned BytecodeParser::ParseInstructionList(Function *F,
const unsigned char *&Buf,
const unsigned char *EndBuf) {
unsigned BlockNo = 0;
std::vector<unsigned> Args;
while (Buf < EndBuf) {
BasicBlock *BB;
if (ParsedBasicBlocks.size() == BlockNo)
ParsedBasicBlocks.push_back(BB = new BasicBlock());
else if (ParsedBasicBlocks[BlockNo] == 0)
BB = ParsedBasicBlocks[BlockNo] = new BasicBlock();
else
BB = ParsedBasicBlocks[BlockNo];
++BlockNo;
F->getBasicBlockList().push_back(BB);
// Read instructions into this basic block until we get to a terminator
while (Buf < EndBuf && !BB->getTerminator())
ParseInstruction(Buf, EndBuf, Args, BB);
if (!BB->getTerminator())
throw std::string("Non-terminated basic block found!");
}
return BlockNo;
}
void BytecodeParser::ParseSymbolTable(const unsigned char *&Buf,
const unsigned char *EndBuf,
SymbolTable *ST,
@ -345,6 +378,13 @@ void BytecodeParser::materializeFunction(Function* F) {
break;
}
case BytecodeFormat::InstructionList: {
BCR_TRACE(2, "BLOCK BytecodeFormat::InstructionList: {\n");
if (BlockNum) throw std::string("Already parsed basic blocks!");
BlockNum = ParseInstructionList(F, Buf, Buf+Size);
break;
}
case BytecodeFormat::SymbolTable:
BCR_TRACE(2, "BLOCK BytecodeFormat::SymbolTable: {\n");
ParseSymbolTable(Buf, Buf+Size, &F->getSymbolTable(), F);