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Change encoding of instruction operands in bitcode binaries to be relative

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to the instruction position.  The old encoding would give an absolute
ID which counts up within a function, and only resets at the next function.

I.e., Instead of having:

... = icmp eq i32 n-1, n-2
br i1 ..., label %bb1, label %bb2

it will now be roughly:

... = icmp eq i32 1, 2
br i1 1, label %bb1, label %bb2

This makes it so that ids remain relatively small and can be encoded
in fewer bits.

With this encoding, forward reference operands will be given
negative-valued IDs.  Use signed VBRs for the most common case
of forward references, which is phi instructions.

To retain backward compatibility we bump the bitcode version
from 0 to 1 to distinguish between the different encodings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165739 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jan Wen Voung
2012-10-11 20:20:40 +00:00
parent 81eb88f7d2
commit d9a3bad448
5 changed files with 236 additions and 91 deletions
Download Patch File Download Diff File Expand all files Collapse all files

86
lib/Bitcode/Reader/BitcodeReader.cpp
View File

@@ -891,9 +891,9 @@ bool BitcodeReader::ParseMetadata() {
}
}
/// DecodeSignRotatedValue - Decode a signed value stored with the sign bit in
/// decodeSignRotatedValue - Decode a signed value stored with the sign bit in
/// the LSB for dense VBR encoding.
static uint64_t DecodeSignRotatedValue(uint64_t V) {
uint64_t BitcodeReader::decodeSignRotatedValue(uint64_t V) {
if ((V & 1) == 0)
return V >> 1;
if (V != 1)
@@ -943,7 +943,7 @@ bool BitcodeReader::ResolveGlobalAndAliasInits() {
static APInt ReadWideAPInt(ArrayRef<uint64_t> Vals, unsigned TypeBits) {
SmallVector<uint64_t, 8> Words(Vals.size());
std::transform(Vals.begin(), Vals.end(), Words.begin(),
DecodeSignRotatedValue);
BitcodeReader::decodeSignRotatedValue);
return APInt(TypeBits, Words);
}
@@ -997,7 +997,7 @@ bool BitcodeReader::ParseConstants() {
case bitc::CST_CODE_INTEGER: // INTEGER: [intval]
if (!CurTy->isIntegerTy() || Record.empty())
return Error("Invalid CST_INTEGER record");
V = ConstantInt::get(CurTy, DecodeSignRotatedValue(Record[0]));
V = ConstantInt::get(CurTy, decodeSignRotatedValue(Record[0]));
break;
case bitc::CST_CODE_WIDE_INTEGER: {// WIDE_INTEGER: [n x intval]
if (!CurTy->isIntegerTy() || Record.empty())
@@ -1524,13 +1524,22 @@ bool BitcodeReader::ParseModule(bool Resume) {
// Read a record.
switch (Stream.ReadRecord(Code, Record)) {
default: break; // Default behavior, ignore unknown content.
case bitc::MODULE_CODE_VERSION: // VERSION: [version#]
case bitc::MODULE_CODE_VERSION: { // VERSION: [version#]
if (Record.size() < 1)
return Error("Malformed MODULE_CODE_VERSION");
// Only version #0 is supported so far.
if (Record[0] != 0)
return Error("Unknown bitstream version!");
// Only version #0 and #1 are supported so far.
unsigned module_version = Record[0];
switch (module_version) {
default: return Error("Unknown bitstream version!");
case 0:
UseRelativeIDs = false;
break;
case 1:
UseRelativeIDs = true;
break;
}
break;
}
case bitc::MODULE_CODE_TRIPLE: { // TRIPLE: [strchr x N]
std::string S;
if (ConvertToString(Record, 0, S))
@@ -1797,13 +1806,6 @@ bool BitcodeReader::ParseModuleTriple(std::string &Triple) {
// Read a record.
switch (Stream.ReadRecord(Code, Record)) {
default: break; // Default behavior, ignore unknown content.
case bitc::MODULE_CODE_VERSION: // VERSION: [version#]
if (Record.size() < 1)
return Error("Malformed MODULE_CODE_VERSION");
// Only version #0 is supported so far.
if (Record[0] != 0)
return Error("Unknown bitstream version!");
break;
case bitc::MODULE_CODE_TRIPLE: { // TRIPLE: [strchr x N]
std::string S;
if (ConvertToString(Record, 0, S))
@@ -2016,7 +2018,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *LHS, *RHS;
if (getValueTypePair(Record, OpNum, NextValueNo, LHS) ||
getValue(Record, OpNum, LHS->getType(), RHS) ||
popValue(Record, OpNum, NextValueNo, LHS->getType(), RHS) ||
OpNum+1 > Record.size())
return Error("Invalid BINOP record");
@@ -2131,8 +2133,8 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *TrueVal, *FalseVal, *Cond;
if (getValueTypePair(Record, OpNum, NextValueNo, TrueVal) ||
getValue(Record, OpNum, TrueVal->getType(), FalseVal) ||
getValue(Record, OpNum, Type::getInt1Ty(Context), Cond))
popValue(Record, OpNum, NextValueNo, TrueVal->getType(), FalseVal) ||
popValue(Record, OpNum, NextValueNo, Type::getInt1Ty(Context), Cond))
return Error("Invalid SELECT record");
I = SelectInst::Create(Cond, TrueVal, FalseVal);
@@ -2146,7 +2148,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *TrueVal, *FalseVal, *Cond;
if (getValueTypePair(Record, OpNum, NextValueNo, TrueVal) ||
getValue(Record, OpNum, TrueVal->getType(), FalseVal) ||
popValue(Record, OpNum, NextValueNo, TrueVal->getType(), FalseVal) ||
getValueTypePair(Record, OpNum, NextValueNo, Cond))
return Error("Invalid SELECT record");
@@ -2171,7 +2173,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Vec, *Idx;
if (getValueTypePair(Record, OpNum, NextValueNo, Vec) ||
getValue(Record, OpNum, Type::getInt32Ty(Context), Idx))
popValue(Record, OpNum, NextValueNo, Type::getInt32Ty(Context), Idx))
return Error("Invalid EXTRACTELT record");
I = ExtractElementInst::Create(Vec, Idx);
InstructionList.push_back(I);
@@ -2182,9 +2184,9 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Vec, *Elt, *Idx;
if (getValueTypePair(Record, OpNum, NextValueNo, Vec) ||
getValue(Record, OpNum,
popValue(Record, OpNum, NextValueNo,
cast<VectorType>(Vec->getType())->getElementType(), Elt) ||
getValue(Record, OpNum, Type::getInt32Ty(Context), Idx))
popValue(Record, OpNum, NextValueNo, Type::getInt32Ty(Context), Idx))
return Error("Invalid INSERTELT record");
I = InsertElementInst::Create(Vec, Elt, Idx);
InstructionList.push_back(I);
@@ -2195,7 +2197,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Vec1, *Vec2, *Mask;
if (getValueTypePair(Record, OpNum, NextValueNo, Vec1) ||
getValue(Record, OpNum, Vec1->getType(), Vec2))
popValue(Record, OpNum, NextValueNo, Vec1->getType(), Vec2))
return Error("Invalid SHUFFLEVEC record");
if (getValueTypePair(Record, OpNum, NextValueNo, Mask))
@@ -2215,7 +2217,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *LHS, *RHS;
if (getValueTypePair(Record, OpNum, NextValueNo, LHS) ||
getValue(Record, OpNum, LHS->getType(), RHS) ||
popValue(Record, OpNum, NextValueNo, LHS->getType(), RHS) ||
OpNum+1 != Record.size())
return Error("Invalid CMP record");
@@ -2260,7 +2262,8 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
}
else {
BasicBlock *FalseDest = getBasicBlock(Record[1]);
Value *Cond = getFnValueByID(Record[2], Type::getInt1Ty(Context));
Value *Cond = getValue(Record, 2, NextValueNo,
Type::getInt1Ty(Context));
if (FalseDest == 0 || Cond == 0)
return Error("Invalid BR record");
I = BranchInst::Create(TrueDest, FalseDest, Cond);
@@ -2276,7 +2279,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
Type *OpTy = getTypeByID(Record[1]);
unsigned ValueBitWidth = cast<IntegerType>(OpTy)->getBitWidth();
Value *Cond = getFnValueByID(Record[2], OpTy);
Value *Cond = getValue(Record, 2, NextValueNo, OpTy);
BasicBlock *Default = getBasicBlock(Record[3]);
if (OpTy == 0 || Cond == 0 || Default == 0)
return Error("Invalid SWITCH record");
@@ -2331,7 +2334,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
if (Record.size() < 3 || (Record.size() & 1) == 0)
return Error("Invalid SWITCH record");
Type *OpTy = getTypeByID(Record[0]);
Value *Cond = getFnValueByID(Record[1], OpTy);
Value *Cond = getValue(Record, 1, NextValueNo, OpTy);
BasicBlock *Default = getBasicBlock(Record[2]);
if (OpTy == 0 || Cond == 0 || Default == 0)
return Error("Invalid SWITCH record");
@@ -2355,7 +2358,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
if (Record.size() < 2)
return Error("Invalid INDIRECTBR record");
Type *OpTy = getTypeByID(Record[0]);
Value *Address = getFnValueByID(Record[1], OpTy);
Value *Address = getValue(Record, 1, NextValueNo, OpTy);
if (OpTy == 0 || Address == 0)
return Error("Invalid INDIRECTBR record");
unsigned NumDests = Record.size()-2;
@@ -2397,7 +2400,8 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
SmallVector<Value*, 16> Ops;
for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i, ++OpNum) {
Ops.push_back(getFnValueByID(Record[OpNum], FTy->getParamType(i)));
Ops.push_back(getValue(Record, OpNum, NextValueNo,
FTy->getParamType(i)));
if (Ops.back() == 0) return Error("Invalid INVOKE record");
}
@@ -2444,7 +2448,14 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
InstructionList.push_back(PN);
for (unsigned i = 0, e = Record.size()-1; i != e; i += 2) {
Value *V = getFnValueByID(Record[1+i], Ty);
Value *V;
// With the new function encoding, it is possible that operands have
// negative IDs (for forward references). Use a signed VBR
// representation to keep the encoding small.
if (UseRelativeIDs)
V = getValueSigned(Record, 1+i, NextValueNo, Ty);
else
V = getValue(Record, 1+i, NextValueNo, Ty);
BasicBlock *BB = getBasicBlock(Record[2+i]);
if (!V || !BB) return Error("Invalid PHI record");
PN->addIncoming(V, BB);
@@ -2542,7 +2553,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Val, *Ptr;
if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
getValue(Record, OpNum,
popValue(Record, OpNum, NextValueNo,
cast<PointerType>(Ptr->getType())->getElementType(), Val) ||
OpNum+2 != Record.size())
return Error("Invalid STORE record");
@@ -2556,7 +2567,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Val, *Ptr;
if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
getValue(Record, OpNum,
popValue(Record, OpNum, NextValueNo,
cast<PointerType>(Ptr->getType())->getElementType(), Val) ||
OpNum+4 != Record.size())
return Error("Invalid STOREATOMIC record");
@@ -2579,9 +2590,9 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Ptr, *Cmp, *New;
if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
getValue(Record, OpNum,
popValue(Record, OpNum, NextValueNo,
cast<PointerType>(Ptr->getType())->getElementType(), Cmp) ||
getValue(Record, OpNum,
popValue(Record, OpNum, NextValueNo,
cast<PointerType>(Ptr->getType())->getElementType(), New) ||
OpNum+3 != Record.size())
return Error("Invalid CMPXCHG record");
@@ -2599,7 +2610,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
unsigned OpNum = 0;
Value *Ptr, *Val;
if (getValueTypePair(Record, OpNum, NextValueNo, Ptr) ||
getValue(Record, OpNum,
popValue(Record, OpNum, NextValueNo,
cast<PointerType>(Ptr->getType())->getElementType(), Val) ||
OpNum+4 != Record.size())
return Error("Invalid ATOMICRMW record");
@@ -2653,7 +2664,8 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
if (FTy->getParamType(i)->isLabelTy())
Args.push_back(getBasicBlock(Record[OpNum]));
else
Args.push_back(getFnValueByID(Record[OpNum], FTy->getParamType(i)));
Args.push_back(getValue(Record, OpNum, NextValueNo,
FTy->getParamType(i)));
if (Args.back() == 0) return Error("Invalid CALL record");
}
@@ -2682,7 +2694,7 @@ bool BitcodeReader::ParseFunctionBody(Function *F) {
if (Record.size() < 3)
return Error("Invalid VAARG record");
Type *OpTy = getTypeByID(Record[0]);
Value *Op = getFnValueByID(Record[1], OpTy);
Value *Op = getValue(Record, 1, NextValueNo, OpTy);
Type *ResTy = getTypeByID(Record[2]);
if (!OpTy || !Op || !ResTy)
return Error("Invalid VAARG record");

67
lib/Bitcode/Reader/BitcodeReader.h
View File

@@ -179,18 +179,27 @@ class BitcodeReader : public GVMaterializer {
typedef std::pair<unsigned, GlobalVariable*> BlockAddrRefTy;
DenseMap<Function*, std::vector<BlockAddrRefTy> > BlockAddrFwdRefs;
/// UseRelativeIDs - Indicates that we are using a new encoding for
/// instrunction operands where most operands in the current
/// FUNCTION_BLOCK are encoded relative to the instruction number,
/// for a more compact encoding. Some instruction operands are not
/// relative to the instruction ID: basic block numbers, and types.
/// Once the old style function blocks have been phased out, we would
/// not need this flag.
bool UseRelativeIDs;
public:
explicit BitcodeReader(MemoryBuffer *buffer, LLVMContext &C)
: Context(C), TheModule(0), Buffer(buffer), BufferOwned(false),
LazyStreamer(0), NextUnreadBit(0), SeenValueSymbolTable(false),
ErrorString(0), ValueList(C), MDValueList(C),
SeenFirstFunctionBody(false) {
SeenFirstFunctionBody(false), UseRelativeIDs(false) {
}
explicit BitcodeReader(DataStreamer *streamer, LLVMContext &C)
: Context(C), TheModule(0), Buffer(0), BufferOwned(false),
LazyStreamer(streamer), NextUnreadBit(0), SeenValueSymbolTable(false),
ErrorString(0), ValueList(C), MDValueList(C),
SeenFirstFunctionBody(false) {
SeenFirstFunctionBody(false), UseRelativeIDs(false) {
}
~BitcodeReader() {
FreeState();
@@ -223,6 +232,9 @@ public:
/// @brief Cheap mechanism to just extract module triple
/// @returns true if an error occurred.
bool ParseTriple(std::string &Triple);
static uint64_t decodeSignRotatedValue(uint64_t V);
private:
Type *getTypeByID(unsigned ID);
Value *getFnValueByID(unsigned ID, Type *Ty) {
@@ -247,6 +259,9 @@ private:
unsigned InstNum, Value *&ResVal) {
if (Slot == Record.size()) return true;
unsigned ValNo = (unsigned)Record[Slot++];
// Adjust the ValNo, if it was encoded relative to the InstNum.
if (UseRelativeIDs)
ValNo = InstNum - ValNo;
if (ValNo < InstNum) {
// If this is not a forward reference, just return the value we already
// have.
@@ -255,20 +270,54 @@ private:
} else if (Slot == Record.size()) {
return true;
}
unsigned TypeNo = (unsigned)Record[Slot++];
ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
return ResVal == 0;
}
bool getValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
Type *Ty, Value *&ResVal) {
if (Slot == Record.size()) return true;
unsigned ValNo = (unsigned)Record[Slot++];
ResVal = getFnValueByID(ValNo, Ty);
/// popValue - Read a value out of the specified record from slot 'Slot'.
/// Increment Slot past the number of slots used by the value in the record.
/// Return true if there is an error.
bool popValue(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
unsigned InstNum, Type *Ty, Value *&ResVal) {
if (getValue(Record, Slot, InstNum, Ty, ResVal))
return true;
// All values currently take a single record slot.
++Slot;
return false;
}
/// getValue -- Like popValue, but does not increment the Slot number.
bool getValue(SmallVector<uint64_t, 64> &Record, unsigned Slot,
unsigned InstNum, Type *Ty, Value *&ResVal) {
ResVal = getValue(Record, Slot, InstNum, Ty);
return ResVal == 0;
}
/// getValue -- Version of getValue that returns ResVal directly,
/// or 0 if there is an error.
Value *getValue(SmallVector<uint64_t, 64> &Record, unsigned Slot,
unsigned InstNum, Type *Ty) {
if (Slot == Record.size()) return 0;
unsigned ValNo = (unsigned)Record[Slot];
// Adjust the ValNo, if it was encoded relative to the InstNum.
if (UseRelativeIDs)
ValNo = InstNum - ValNo;
return getFnValueByID(ValNo, Ty);
}
/// getValueSigned -- Like getValue, but decodes signed VBRs.
Value *getValueSigned(SmallVector<uint64_t, 64> &Record, unsigned Slot,
unsigned InstNum, Type *Ty) {
if (Slot == Record.size()) return 0;
unsigned ValNo = (unsigned)decodeSignRotatedValue(Record[Slot]);
// Adjust the ValNo, if it was encoded relative to the InstNum.
if (UseRelativeIDs)
ValNo = InstNum - ValNo;
return getFnValueByID(ValNo, Ty);
}
bool ParseModule(bool Resume);
bool ParseAttributeBlock();
bool ParseTypeTable();