Change encoding of instruction operands in bitcode binaries to be relative
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
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index 8860ef0..1a3a7b0 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -891,9 +891,9 @@
}
}
-/// 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 @@
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 @@
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 @@
// 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 @@
// 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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
}
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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 @@
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");
diff --git a/lib/Bitcode/Reader/BitcodeReader.h b/lib/Bitcode/Reader/BitcodeReader.h
index e7c4e94..c5e9799 100644
--- a/lib/Bitcode/Reader/BitcodeReader.h
+++ b/lib/Bitcode/Reader/BitcodeReader.h
@@ -179,18 +179,27 @@
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 @@
/// @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 @@
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 @@
} 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();