#ifndef LLVM_TRANSFORMS_UTILS_SSAUPDATER_H
#define LLVM_TRANSFORMS_UTILS_SSAUPDATER_H
+#include "llvm/ADT/StringRef.h"
+
namespace llvm {
- class Value;
class BasicBlock;
+ class Instruction;
+ class LoadInst;
+ template<typename T> class SmallVectorImpl;
+ template<typename T> class SSAUpdaterTraits;
+ class PHINode;
+ class Type;
class Use;
-
+ class Value;
+
/// SSAUpdater - This class updates SSA form for a set of values defined in
/// multiple blocks. This is used when code duplication or another unstructured
/// transformation wants to rewrite a set of uses of one value with uses of a
/// set of values.
class SSAUpdater {
+ friend class SSAUpdaterTraits<SSAUpdater>;
+
+private:
/// AvailableVals - This keeps track of which value to use on a per-block
- /// basis. When we insert PHI nodes, we keep track of them here. We use
- /// WeakVH's for the value of the map because we RAUW PHI nodes when we
- /// eliminate them, and want the WeakVH to track this.
- //typedef DenseMap<BasicBlock*, TrackingVH<Value> > AvailableValsTy;
+ /// basis. When we insert PHI nodes, we keep track of them here.
+ //typedef DenseMap<BasicBlock*, Value*> AvailableValsTy;
void *AV;
-
- /// PrototypeValue is an arbitrary representative value, which we derive names
- /// and a type for PHI nodes.
- Value *PrototypeValue;
-
- /// IncomingPredInfo - We use this as scratch space when doing our recursive
- /// walk. This should only be used in GetValueInBlockInternal, normally it
- /// should be empty.
- //std::vector<std::pair<BasicBlock*, TrackingVH<Value> > > IncomingPredInfo;
- void *IPI;
+
+ /// ProtoType holds the type of the values being rewritten.
+ Type *ProtoType;
+
+ // PHI nodes are given a name based on ProtoName.
+ std::string ProtoName;
+
+ /// InsertedPHIs - If this is non-null, the SSAUpdater adds all PHI nodes that
+ /// it creates to the vector.
+ SmallVectorImpl<PHINode*> *InsertedPHIs;
+
public:
- SSAUpdater();
+ /// SSAUpdater constructor. If InsertedPHIs is specified, it will be filled
+ /// in with all PHI Nodes created by rewriting.
+ explicit SSAUpdater(SmallVectorImpl<PHINode*> *InsertedPHIs = 0);
~SSAUpdater();
-
+
/// Initialize - Reset this object to get ready for a new set of SSA
- /// updates. ProtoValue is the value used to name PHI nodes.
- void Initialize(Value *ProtoValue);
-
- /// AddAvailableValue - Indicate that a rewritten value is available in the
- /// specified block with the specified value.
+ /// updates with type 'Ty'. PHI nodes get a name based on 'Name'.
+ void Initialize(Type *Ty, StringRef Name);
+
+ /// AddAvailableValue - Indicate that a rewritten value is available at the
+ /// end of the specified block with the specified value.
void AddAvailableValue(BasicBlock *BB, Value *V);
-
+
+ /// HasValueForBlock - Return true if the SSAUpdater already has a value for
+ /// the specified block.
+ bool HasValueForBlock(BasicBlock *BB) const;
+
/// GetValueAtEndOfBlock - Construct SSA form, materializing a value that is
/// live at the end of the specified block.
Value *GetValueAtEndOfBlock(BasicBlock *BB);
-
+
+ /// GetValueInMiddleOfBlock - Construct SSA form, materializing a value that
+ /// is live in the middle of the specified block.
+ ///
+ /// GetValueInMiddleOfBlock is the same as GetValueAtEndOfBlock except in one
+ /// important case: if there is a definition of the rewritten value after the
+ /// 'use' in BB. Consider code like this:
+ ///
+ /// X1 = ...
+ /// SomeBB:
+ /// use(X)
+ /// X2 = ...
+ /// br Cond, SomeBB, OutBB
+ ///
+ /// In this case, there are two values (X1 and X2) added to the AvailableVals
+ /// set by the client of the rewriter, and those values are both live out of
+ /// their respective blocks. However, the use of X happens in the *middle* of
+ /// a block. Because of this, we need to insert a new PHI node in SomeBB to
+ /// merge the appropriate values, and this value isn't live out of the block.
+ ///
+ Value *GetValueInMiddleOfBlock(BasicBlock *BB);
+
/// RewriteUse - Rewrite a use of the symbolic value. This handles PHI nodes,
- /// which use their value in the corresponding predecessor.
+ /// which use their value in the corresponding predecessor. Note that this
+ /// will not work if the use is supposed to be rewritten to a value defined in
+ /// the same block as the use, but above it. Any 'AddAvailableValue's added
+ /// for the use's block will be considered to be below it.
void RewriteUse(Use &U);
-
+
+ /// RewriteUseAfterInsertions - Rewrite a use, just like RewriteUse. However,
+ /// this version of the method can rewrite uses in the same block as a
+ /// definition, because it assumes that all uses of a value are below any
+ /// inserted values.
+ void RewriteUseAfterInsertions(Use &U);
+
private:
Value *GetValueAtEndOfBlockInternal(BasicBlock *BB);
+
void operator=(const SSAUpdater&); // DO NOT IMPLEMENT
SSAUpdater(const SSAUpdater&); // DO NOT IMPLEMENT
};
+
+/// LoadAndStorePromoter - This little helper class provides a convenient way to
+/// promote a collection of loads and stores into SSA Form using the SSAUpdater.
+/// This handles complexities that SSAUpdater doesn't, such as multiple loads
+/// and stores in one block.
+///
+/// Clients of this class are expected to subclass this and implement the
+/// virtual methods.
+///
+class LoadAndStorePromoter {
+protected:
+ SSAUpdater &SSA;
+public:
+ LoadAndStorePromoter(const SmallVectorImpl<Instruction*> &Insts,
+ SSAUpdater &S, StringRef Name = StringRef());
+ virtual ~LoadAndStorePromoter() {}
+
+ /// run - This does the promotion. Insts is a list of loads and stores to
+ /// promote, and Name is the basename for the PHIs to insert. After this is
+ /// complete, the loads and stores are removed from the code.
+ void run(const SmallVectorImpl<Instruction*> &Insts) const;
+
+
+ /// Return true if the specified instruction is in the Inst list (which was
+ /// passed into the run method). Clients should implement this with a more
+ /// efficient version if possible.
+ virtual bool isInstInList(Instruction *I,
+ const SmallVectorImpl<Instruction*> &Insts) const;
+
+ /// doExtraRewritesBeforeFinalDeletion - This hook is invoked after all the
+ /// stores are found and inserted as available values, but
+ virtual void doExtraRewritesBeforeFinalDeletion() const {
+ }
+
+ /// replaceLoadWithValue - Clients can choose to implement this to get
+ /// notified right before a load is RAUW'd another value.
+ virtual void replaceLoadWithValue(LoadInst *LI, Value *V) const {
+ }
+
+ /// This is called before each instruction is deleted.
+ virtual void instructionDeleted(Instruction *I) const {
+ }
+
+ /// updateDebugInfo - This is called to update debug info associated with the
+ /// instruction.
+ virtual void updateDebugInfo(Instruction *I) const {
+ }
+};
} // End llvm namespace
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