//
//===----------------------------------------------------------------------===//
//
-// The MachineConstantPool class keeps track of constants referenced by a
-// function which must be spilled to memory. This is used for constants which
-// are unable to be used directly as operands to instructions, which typically
-// include floating point and large integer constants.
-//
-// Instructions reference the address of these constant pool constants through
-// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
-// code, these virtual address references are converted to refer to the
-// address of the function constant pool values.
+/// @file This file declares the MachineConstantPool class which is an abstract
+/// constant pool to keep track of constants referenced by a function.
//
//===----------------------------------------------------------------------===//
namespace llvm {
class Constant;
+class TargetData;
+/// This class is a data container for one entry in a MachineConstantPool.
+/// It contains a pointer to the value and an offset from the start of
+/// the constant pool.
+/// @brief An entry in a MachineConstantPool
+struct MachineConstantPoolEntry {
+ Constant *Val; ///< The constant itself.
+ unsigned Offset; ///< The offset of the constant from the start of the pool.
+ MachineConstantPoolEntry(Constant *V, unsigned O) : Val(V), Offset(O) {}
+};
+
+/// The MachineConstantPool class keeps track of constants referenced by a
+/// function which must be spilled to memory. This is used for constants which
+/// are unable to be used directly as operands to instructions, which typically
+/// include floating point and large integer constants.
+///
+/// Instructions reference the address of these constant pool constants through
+/// the use of MO_ConstantPoolIndex values. When emitting assembly or machine
+/// code, these virtual address references are converted to refer to the
+/// address of the function constant pool values.
+/// @brief The machine constant pool.
class MachineConstantPool {
- std::vector<std::pair<Constant*,unsigned> > Constants;
+ const TargetData *TD; ///< The machine's TargetData.
+ unsigned PoolAlignment; ///< The alignment for the pool.
+ std::vector<MachineConstantPoolEntry> Constants; ///< The pool of constants.
public:
-
+ /// @brief The only constructor.
+ MachineConstantPool(const TargetData *td) : TD(td), PoolAlignment(1) {}
+
+ /// getConstantPoolAlignment - Return the log2 of the alignment required by
+ /// the whole constant pool, of which the first element must be aligned.
+ unsigned getConstantPoolAlignment() const { return PoolAlignment; }
+
/// getConstantPoolIndex - Create a new entry in the constant pool or return
/// an existing one. User must specify an alignment in bytes for the object.
- ///
- unsigned getConstantPoolIndex(Constant *C, unsigned Alignment) {
- // Check to see if we already have this constant.
- //
- // FIXME, this could be made much more efficient for large constant pools.
- for (unsigned i = 0, e = Constants.size(); i != e; ++i)
- if (Constants[i].first == C && Constants[i].second >= Alignment)
- return i;
- Constants.push_back(std::make_pair(C, Alignment));
- return Constants.size()-1;
- }
-
+ unsigned getConstantPoolIndex(Constant *C, unsigned Alignment);
+
/// isEmpty - Return true if this constant pool contains no constants.
- ///
bool isEmpty() const { return Constants.empty(); }
- const std::vector<std::pair<Constant*,unsigned> > &getConstants() const {
+ const std::vector<MachineConstantPoolEntry> &getConstants() const {
return Constants;
}
/// print - Used by the MachineFunction printer to print information about
- /// stack objects. Implemented in MachineFunction.cpp
+ /// constant pool objects. Implemented in MachineFunction.cpp
///
void print(std::ostream &OS) const;
/// dump - Call print(std::cerr) to be called from the debugger.
+ ///
void dump() const;
};