[llvm-commits] [llvm] r55102 - in /llvm/trunk/lib/Bitcode/Reader: BitcodeReader.cpp BitcodeReader.h
Chris Lattner
sabre at nondot.org
Wed Aug 20 19:34:16 PDT 2008
Author: lattner
Date: Wed Aug 20 21:34:16 2008
New Revision: 55102
URL: http://llvm.org/viewvc/llvm-project?rev=55102&view=rev
Log:
recommit bcreader, handling packed structs correctly. Apparently
people want fast *and* correct. Sheesh.
Modified:
llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp
llvm/trunk/lib/Bitcode/Reader/BitcodeReader.h
Modified: llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp?rev=55102&r1=55101&r2=55102&view=diff
==============================================================================
--- llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp (original)
+++ llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp Wed Aug 20 21:34:16 2008
@@ -133,6 +133,15 @@
: ConstantExpr(Ty, Instruction::UserOp1, &Op<0>(), 1) {
Op<0>() = UndefValue::get(Type::Int32Ty);
}
+
+ /// @brief Methods to support type inquiry through isa, cast, and dyn_cast.
+ static inline bool classof(const ConstantPlaceHolder *) { return true; }
+ static bool classof(const Value *V) {
+ return isa<ConstantExpr>(V) &&
+ cast<ConstantExpr>(V)->getOpcode() == Instruction::UserOp1;
+ }
+
+
/// Provide fast operand accessors
DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
};
@@ -205,6 +214,86 @@
return V;
}
+/// ResolveConstantForwardRefs - Once all constants are read, this method bulk
+/// resolves any forward references. The idea behind this is that we sometimes
+/// get constants (such as large arrays) which reference *many* forward ref
+/// constants. Replacing each of these causes a lot of thrashing when
+/// building/reuniquing the constant. Instead of doing this, we look at all the
+/// uses and rewrite all the place holders at once for any constant that uses
+/// a placeholder.
+void BitcodeReaderValueList::ResolveConstantForwardRefs() {
+ // Sort the values by-pointer so that they are efficient to look up with a
+ // binary search.
+ std::sort(ResolveConstants.begin(), ResolveConstants.end());
+
+ SmallVector<Constant*, 64> NewOps;
+
+ while (!ResolveConstants.empty()) {
+ Value *RealVal = getOperand(ResolveConstants.back().second);
+ Constant *Placeholder = ResolveConstants.back().first;
+ ResolveConstants.pop_back();
+
+ // Loop over all users of the placeholder, updating them to reference the
+ // new value. If they reference more than one placeholder, update them all
+ // at once.
+ while (!Placeholder->use_empty()) {
+ User *U = Placeholder->use_back();
+ // If the using object isn't uniqued, just update the operands. This
+ // handles instructions and initializers for global variables.
+ if (!isa<Constant>(U) || isa<GlobalValue>(U)) {
+ U->replaceUsesOfWith(Placeholder, RealVal);
+ continue;
+ }
+
+ // Otherwise, we have a constant that uses the placeholder. Replace that
+ // constant with a new constant that has *all* placeholder uses updated.
+ Constant *UserC = cast<Constant>(U);
+ for (User::op_iterator I = UserC->op_begin(), E = UserC->op_end();
+ I != E; ++I) {
+ Value *NewOp;
+ if (!isa<ConstantPlaceHolder>(*I)) {
+ // Not a placeholder reference.
+ NewOp = *I;
+ } else if (*I == Placeholder) {
+ // Common case is that it just references this one placeholder.
+ NewOp = RealVal;
+ } else {
+ // Otherwise, look up the placeholder in ResolveConstants.
+ ResolveConstantsTy::iterator It =
+ std::lower_bound(ResolveConstants.begin(), ResolveConstants.end(),
+ std::pair<Constant*, unsigned>(cast<Constant>(*I),
+ 0));
+ assert(It != ResolveConstants.end() && It->first == *I);
+ NewOp = this->getOperand(It->second);
+ }
+
+ NewOps.push_back(cast<Constant>(NewOp));
+ }
+
+ // Make the new constant.
+ Constant *NewC;
+ if (ConstantArray *UserCA = dyn_cast<ConstantArray>(UserC)) {
+ NewC = ConstantArray::get(UserCA->getType(), &NewOps[0], NewOps.size());
+ } else if (ConstantStruct *UserCS = dyn_cast<ConstantStruct>(UserC)) {
+ NewC = ConstantStruct::get(&NewOps[0], NewOps.size(),
+ UserCS->getType()->isPacked());
+ } else if (isa<ConstantVector>(UserC)) {
+ NewC = ConstantVector::get(&NewOps[0], NewOps.size());
+ } else {
+ // Must be a constant expression.
+ NewC = cast<ConstantExpr>(UserC)->getWithOperands(&NewOps[0],
+ NewOps.size());
+ }
+
+ UserC->replaceAllUsesWith(NewC);
+ UserC->destroyConstant();
+ NewOps.clear();
+ }
+
+ delete Placeholder;
+ }
+}
+
const Type *BitcodeReader::getTypeByID(unsigned ID, bool isTypeTable) {
// If the TypeID is in range, return it.
@@ -602,14 +691,8 @@
unsigned NextCstNo = ValueList.size();
while (1) {
unsigned Code = Stream.ReadCode();
- if (Code == bitc::END_BLOCK) {
- if (NextCstNo != ValueList.size())
- return Error("Invalid constant reference!");
-
- if (Stream.ReadBlockEnd())
- return Error("Error at end of constants block");
- return false;
- }
+ if (Code == bitc::END_BLOCK)
+ break;
if (Code == bitc::ENTER_SUBBLOCK) {
// No known subblocks, always skip them.
@@ -852,6 +935,17 @@
ValueList.AssignValue(V, NextCstNo);
++NextCstNo;
}
+
+ if (NextCstNo != ValueList.size())
+ return Error("Invalid constant reference!");
+
+ if (Stream.ReadBlockEnd())
+ return Error("Error at end of constants block");
+
+ // Once all the constants have been read, go through and resolve forward
+ // references.
+ ValueList.ResolveConstantForwardRefs();
+ return false;
}
/// RememberAndSkipFunctionBody - When we see the block for a function body,
Modified: llvm/trunk/lib/Bitcode/Reader/BitcodeReader.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Bitcode/Reader/BitcodeReader.h?rev=55102&r1=55101&r2=55102&view=diff
==============================================================================
--- llvm/trunk/lib/Bitcode/Reader/BitcodeReader.h (original)
+++ llvm/trunk/lib/Bitcode/Reader/BitcodeReader.h Wed Aug 20 21:34:16 2008
@@ -32,9 +32,22 @@
class BitcodeReaderValueList : public User {
unsigned Capacity;
+
+ /// ResolveConstants - As we resolve forward-referenced constants, we add
+ /// information about them to this vector. This allows us to resolve them in
+ /// bulk instead of resolving each reference at a time. See the code in
+ /// ResolveConstantForwardRefs for more information about this.
+ ///
+ /// The key of this vector is the placeholder constant, the value is the slot
+ /// number that holds the resolved value.
+ typedef std::vector<std::pair<Constant*, unsigned> > ResolveConstantsTy;
+ ResolveConstantsTy ResolveConstants;
public:
BitcodeReaderValueList() : User(Type::VoidTy, Value::ArgumentVal, 0, 0)
, Capacity(0) {}
+ ~BitcodeReaderValueList() {
+ assert(ResolveConstants.empty() && "Constants not resolved?");
+ }
/// Provide fast operand accessors
DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
@@ -50,6 +63,7 @@
}
void clear() {
+ assert(ResolveConstants.empty() && "Constants not resolved?");
if (OperandList) dropHungoffUses(OperandList);
Capacity = 0;
}
@@ -73,15 +87,26 @@
if (Idx == size()) {
push_back(V);
} else if (Value *OldV = getOperand(Idx)) {
- // If there was a forward reference to this value, replace it.
- setOperand(Idx, V);
- OldV->replaceAllUsesWith(V);
- delete OldV;
+ // Handle constants and non-constants (e.g. instrs) differently for
+ // efficiency.
+ if (Constant *PHC = dyn_cast<Constant>(OldV)) {
+ ResolveConstants.push_back(std::make_pair(PHC, Idx));
+ setOperand(Idx, V);
+ } else {
+ // If there was a forward reference to this value, replace it.
+ setOperand(Idx, V);
+ OldV->replaceAllUsesWith(V);
+ delete OldV;
+ }
} else {
initVal(Idx, V);
}
}
+ /// ResolveConstantForwardRefs - Once all constants are read, this method bulk
+ /// resolves any forward references.
+ void ResolveConstantForwardRefs();
+
private:
void initVal(unsigned Idx, Value *V) {
if (Idx >= size()) {
@@ -94,7 +119,8 @@
};
template <>
-struct OperandTraits<BitcodeReaderValueList> : HungoffOperandTraits</*16 FIXME*/> {
+struct OperandTraits<BitcodeReaderValueList>
+ : HungoffOperandTraits</*16 FIXME*/> {
};
DEFINE_TRANSPARENT_OPERAND_ACCESSORS(BitcodeReaderValueList, Value)
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