Generalize ScalarEvolution to be able to analyze GEPs when

TargetData is not present. It still uses TargetData when available.
This generalization also fixed some limitations in the TargetData
case; the attached testcase covers this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79344 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 96 insertions, 2 deletions

diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h
index b98f535217..558cd011f5 100644
--- a/include/llvm/Analysis/ScalarEvolution.h
+++ b/include/llvm/Analysis/ScalarEvolution.h
@@ -433,6 +433,8 @@ namespace llvm {
     const SCEV *getUMaxExpr(SmallVectorImpl<const SCEV *> &Operands);
     const SCEV *getSMinExpr(const SCEV *LHS, const SCEV *RHS);
     const SCEV *getUMinExpr(const SCEV *LHS, const SCEV *RHS);
+    const SCEV *getFieldOffsetExpr(const StructType *STy, unsigned FieldNo);
+    const SCEV *getAllocSizeExpr(const Type *AllocTy);
     const SCEV *getUnknown(Value *V);
     const SCEV *getCouldNotCompute();
 
diff --git a/include/llvm/Analysis/ScalarEvolutionExpander.h b/include/llvm/Analysis/ScalarEvolutionExpander.h
index 9266bf9713..cc0204b6fa 100644
--- a/include/llvm/Analysis/ScalarEvolutionExpander.h
+++ b/include/llvm/Analysis/ScalarEvolutionExpander.h
@@ -115,6 +115,10 @@ namespace llvm {
 
     Value *visitUMaxExpr(const SCEVUMaxExpr *S);
 
+    Value *visitFieldOffsetExpr(const SCEVFieldOffsetExpr *S);
+
+    Value *visitAllocSizeExpr(const SCEVAllocSizeExpr *S);
+
     Value *visitUnknown(const SCEVUnknown *S) {
       return S->getValue();
     }
diff --git a/include/llvm/Analysis/ScalarEvolutionExpressions.h b/include/llvm/Analysis/ScalarEvolutionExpressions.h
index 99df1dfefc..35372be126 100644
--- a/include/llvm/Analysis/ScalarEvolutionExpressions.h
+++ b/include/llvm/Analysis/ScalarEvolutionExpressions.h
@@ -26,8 +26,8 @@ namespace llvm {
     // These should be ordered in terms of increasing complexity to make the
     // folders simpler.
     scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
-    scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr, scUnknown,
-    scCouldNotCompute
+    scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
+    scFieldOffset, scAllocSize, scUnknown, scCouldNotCompute
   };
 
   //===--------------------------------------------------------------------===//
@@ -488,6 +488,90 @@ namespace llvm {
     }
   };
 
+  //===--------------------------------------------------------------------===//
+  /// SCEVTargetDataConstant - This node is the base class for representing
+  /// target-dependent values in a target-independent way.
+  ///
+  class SCEVTargetDataConstant : public SCEV {
+  protected:
+    const Type *Ty;
+    SCEVTargetDataConstant(const FoldingSetNodeID &ID, enum SCEVTypes T,
+                           const Type *ty) :
+      SCEV(ID, T), Ty(ty) {}
+
+  public:
+    virtual bool isLoopInvariant(const Loop *) const { return true; }
+    virtual bool hasComputableLoopEvolution(const Loop *) const {
+      return false; // not computable
+    }
+
+    virtual bool hasOperand(const SCEV *) const {
+      return false;
+    }
+
+    bool dominates(BasicBlock *, DominatorTree *) const {
+      return true;
+    }
+
+    virtual const Type *getType() const { return Ty; }
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static inline bool classof(const SCEVTargetDataConstant *S) { return true; }
+    static inline bool classof(const SCEV *S) {
+      return S->getSCEVType() == scFieldOffset ||
+             S->getSCEVType() == scAllocSize;
+    }
+  };
+
+  //===--------------------------------------------------------------------===//
+  /// SCEVFieldOffsetExpr - This node represents an offsetof expression.
+  ///
+  class SCEVFieldOffsetExpr : public SCEVTargetDataConstant {
+    friend class ScalarEvolution;
+
+    const StructType *STy;
+    unsigned FieldNo;
+    SCEVFieldOffsetExpr(const FoldingSetNodeID &ID, const Type *ty,
+                        const StructType *sty, unsigned fieldno) :
+      SCEVTargetDataConstant(ID, scFieldOffset, ty),
+      STy(sty), FieldNo(fieldno) {}
+
+  public:
+    const StructType *getStructType() const { return STy; }
+    unsigned getFieldNo() const { return FieldNo; }
+
+    virtual void print(raw_ostream &OS) const;
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static inline bool classof(const SCEVFieldOffsetExpr *S) { return true; }
+    static inline bool classof(const SCEV *S) {
+      return S->getSCEVType() == scFieldOffset;
+    }
+  };
+
+  //===--------------------------------------------------------------------===//
+  /// SCEVAllocSize - This node represents a sizeof expression.
+  ///
+  class SCEVAllocSizeExpr : public SCEVTargetDataConstant {
+    friend class ScalarEvolution;
+
+    const Type *AllocTy;
+    SCEVAllocSizeExpr(const FoldingSetNodeID &ID,
+                      const Type *ty, const Type *allocty) :
+      SCEVTargetDataConstant(ID, scAllocSize, ty),
+      AllocTy(allocty) {}
+
+  public:
+    const Type *getAllocType() const { return AllocTy; }
+
+    virtual void print(raw_ostream &OS) const;
+
+    /// Methods for support type inquiry through isa, cast, and dyn_cast:
+    static inline bool classof(const SCEVAllocSizeExpr *S) { return true; }
+    static inline bool classof(const SCEV *S) {
+      return S->getSCEVType() == scAllocSize;
+    }
+  };
 
   //===--------------------------------------------------------------------===//
   /// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV
@@ -552,6 +636,10 @@ namespace llvm {
         return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
       case scUMaxExpr:
         return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
+      case scFieldOffset:
+        return ((SC*)this)->visitFieldOffsetExpr((const SCEVFieldOffsetExpr*)S);
+      case scAllocSize:
+        return ((SC*)this)->visitAllocSizeExpr((const SCEVAllocSizeExpr*)S);
       case scUnknown:
         return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
       case scCouldNotCompute: