Break SCEVExpander out of IndVarSimplify into its own .h/.cpp file so that

other passes may use it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22557 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/ScalarEvolutionExpander.h

@@ -0,0 +1,180 @@
+//===---- llvm/Analysis/ScalarEvolutionExpander.h - SCEV Exprs --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the classes used to generate code from scalar expressions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
+#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPANDER_H
+
+#include "llvm/BasicBlock.h"
+#include "llvm/Constants.h"
+#include "llvm/Instructions.h"
+#include "llvm/Type.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionExpressions.h"
+#include "llvm/Support/CFG.h"
+
+namespace llvm {
+  /// SCEVExpander - This class uses information about analyze scalars to
+  /// rewrite expressions in canonical form.
+  ///
+  /// Clients should create an instance of this class when rewriting is needed,
+  /// and destroying it when finished to allow the release of the associated
+  /// memory.
+  struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
+    ScalarEvolution &SE;
+    LoopInfo &LI;
+    std::map<SCEVHandle, Value*> InsertedExpressions;
+    std::set<Instruction*> InsertedInstructions;
+
+    Instruction *InsertPt;
+
+    friend struct SCEVVisitor<SCEVExpander, Value*>;
+  public:
+    SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {}
+
+    /// clear - Erase the contents of the InsertedExpressions map so that users
+    /// trying to expand the same expression into multiple BasicBlocks or 
+    /// different places within the same BasicBlock can do so.
+    void clear() { InsertedExpressions.clear(); }
+    
+    /// isInsertedInstruction - Return true if the specified instruction was
+    /// inserted by the code rewriter.  If so, the client should not modify the
+    /// instruction.
+    bool isInsertedInstruction(Instruction *I) const {
+      return InsertedInstructions.count(I);
+    }
+
+    /// getOrInsertCanonicalInductionVariable - This method returns the
+    /// canonical induction variable of the specified type for the specified
+    /// loop (inserting one if there is none).  A canonical induction variable
+    /// starts at zero and steps by one on each iteration.
+    Value *getOrInsertCanonicalInductionVariable(const Loop *L, const Type *Ty){
+      assert((Ty->isInteger() || Ty->isFloatingPoint()) &&
+             "Can only insert integer or floating point induction variables!");
+      SCEVHandle H = SCEVAddRecExpr::get(SCEVUnknown::getIntegerSCEV(0, Ty),
+                                         SCEVUnknown::getIntegerSCEV(1, Ty), L);
+      return expand(H);
+    }
+
+    /// addInsertedValue - Remember the specified instruction as being the
+    /// canonical form for the specified SCEV.
+    void addInsertedValue(Instruction *I, SCEV *S) {
+      InsertedExpressions[S] = (Value*)I;
+      InsertedInstructions.insert(I);
+    }
+
+    /// expandCodeFor - Insert code to directly compute the specified SCEV
+    /// expression into the program.  The inserted code is inserted into the
+    /// specified block.
+    ///
+    /// If a particular value sign is required, a type may be specified for the
+    /// result.
+    Value *expandCodeFor(SCEVHandle SH, Instruction *IP, const Type *Ty = 0) {
+      // Expand the code for this SCEV.
+      this->InsertPt = IP;
+      return expandInTy(SH, Ty);
+    }
+
+  protected:
+    Value *expand(SCEV *S) {
+      // Check to see if we already expanded this.
+      std::map<SCEVHandle, Value*>::iterator I = InsertedExpressions.find(S);
+      if (I != InsertedExpressions.end())
+        return I->second;
+
+      Value *V = visit(S);
+      InsertedExpressions[S] = V;
+      return V;
+    }
+
+    Value *expandInTy(SCEV *S, const Type *Ty) {
+      Value *V = expand(S);
+      if (Ty && V->getType() != Ty) {
+        // FIXME: keep track of the cast instruction.
+        if (Constant *C = dyn_cast<Constant>(V))
+          return ConstantExpr::getCast(C, Ty);
+        else if (Instruction *I = dyn_cast<Instruction>(V)) {
+          // Check to see if there is already a cast.  If there is, use it.
+          for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
+               UI != E; ++UI) {
+            if ((*UI)->getType() == Ty)
+              if (CastInst *CI = dyn_cast<CastInst>(cast<Instruction>(*UI))) {
+                BasicBlock::iterator It = I; ++It;
+                if (isa<InvokeInst>(I))
+                  It = cast<InvokeInst>(I)->getNormalDest()->begin();
+                while (isa<PHINode>(It)) ++It;
+                if (It != BasicBlock::iterator(CI)) {
+                  // Splice the cast immediately after the operand in question.
+                  BasicBlock::InstListType &InstList =
+                    It->getParent()->getInstList();
+                  InstList.splice(It, CI->getParent()->getInstList(), CI);
+                }
+                return CI;
+              }
+          }
+          BasicBlock::iterator IP = I; ++IP;
+          if (InvokeInst *II = dyn_cast<InvokeInst>(I))
+            IP = II->getNormalDest()->begin();
+          while (isa<PHINode>(IP)) ++IP;
+          return new CastInst(V, Ty, V->getName(), IP);
+        } else {
+          // FIXME: check to see if there is already a cast!
+          return new CastInst(V, Ty, V->getName(), InsertPt);
+        }
+      }
+      return V;
+    }
+
+    Value *visitConstant(SCEVConstant *S) {
+      return S->getValue();
+    }
+
+    Value *visitTruncateExpr(SCEVTruncateExpr *S) {
+      Value *V = expand(S->getOperand());
+      return new CastInst(V, S->getType(), "tmp.", InsertPt);
+    }
+
+    Value *visitZeroExtendExpr(SCEVZeroExtendExpr *S) {
+      Value *V = expandInTy(S->getOperand(),S->getType()->getUnsignedVersion());
+      return new CastInst(V, S->getType(), "tmp.", InsertPt);
+    }
+
+    Value *visitAddExpr(SCEVAddExpr *S) {
+      const Type *Ty = S->getType();
+      Value *V = expandInTy(S->getOperand(S->getNumOperands()-1), Ty);
+
+      // Emit a bunch of add instructions
+      for (int i = S->getNumOperands()-2; i >= 0; --i)
+        V = BinaryOperator::createAdd(V, expandInTy(S->getOperand(i), Ty),
+                                      "tmp.", InsertPt);
+      return V;
+    }
+
+    Value *visitMulExpr(SCEVMulExpr *S);
+
+    Value *visitUDivExpr(SCEVUDivExpr *S) {
+      const Type *Ty = S->getType();
+      Value *LHS = expandInTy(S->getLHS(), Ty);
+      Value *RHS = expandInTy(S->getRHS(), Ty);
+      return BinaryOperator::createDiv(LHS, RHS, "tmp.", InsertPt);
+    }
+
+    Value *visitAddRecExpr(SCEVAddRecExpr *S);
+
+    Value *visitUnknown(SCEVUnknown *S) {
+      return S->getValue();
+    }
+  };
+}
+
+#endif
+