Revert 54786. It's not checking for overflows, etc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54813 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 37a93e114a0963fedb5249593863cc07fb0b36c2..04faa0aa50819d3201fd89ab2348f044a3bd52d3 100644 (file)
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -45,7 +45,6 @@ STATISTIC(NumReduced ,    "Number of GEPs strength reduced");
 STATISTIC(NumInserted,    "Number of PHIs inserted");
 STATISTIC(NumVariable,    "Number of PHIs with variable strides");
 STATISTIC(NumEliminated , "Number of strides eliminated");
-STATISTIC(NumShadow , "Number of Shdow IVs optimized");
 
 namespace {
 
@@ -178,10 +177,6 @@ private:
                                   IVStrideUse* &CondUse,
                                   const SCEVHandle* &CondStride);
     void OptimizeIndvars(Loop *L);
-
-    /// OptimizeShadowIV - If IV is used in a int-to-float cast
-    /// inside the loop then try to eliminate the cast opeation.
-    void OptimizeShadowIV(Loop *L);
     bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse,
                        const SCEVHandle *&CondStride);
     bool RequiresTypeConversion(const Type *Ty, const Type *NewTy);
@@ -1694,108 +1689,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
   return Cond;
 }
 
-/// OptimizeShadowIV - If IV is used in a int-to-float cast
-/// inside the loop then try to eliminate the cast opeation.
-void LoopStrengthReduce::OptimizeShadowIV(Loop *L) {
-
-  for (unsigned Stride = 0, e = StrideOrder.size(); Stride != e;
-       ++Stride) {
-    std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI = 
-      IVUsesByStride.find(StrideOrder[Stride]);
-    assert(SI != IVUsesByStride.end() && "Stride doesn't exist!");
-    
-    for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(),
-           E = SI->second.Users.end(); UI != E; /* empty */) {
-      std::vector<IVStrideUse>::iterator CandidateUI = UI;
-      UI++;
-      Instruction *ShadowUse = CandidateUI->User;
-      const Type *DestTy = NULL;
-
-      /* If shadow use is a int->float cast then insert a second IV
-         to elminate this cast.
-
-           for (unsigned i = 0; i < n; ++i) 
-             foo((double)i);
-
-         is trnasformed into
-
-           double d = 0.0;
-           for (unsigned i = 0; i < n; ++i, ++d) 
-             foo(d);
-      */
-      UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->User);
-      if (UCast) 
-        DestTy = UCast->getDestTy();
-      else {
-        SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->User);
-        if (!SCast) continue;
-        DestTy = SCast->getDestTy();
-      }
-      
-      PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));
-      if (!PH) continue;
-      if (PH->getNumIncomingValues() != 2) continue;
-
-      unsigned Entry, Latch;
-      if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {
-        Entry = 0;
-        Latch = 1;
-      } else {
-        Entry = 1;
-        Latch = 0;
-      }
-        
-      ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
-      if (!Init) continue;
-      ConstantFP *NewInit = ConstantFP::get(DestTy, Init->getZExtValue());
-
-      BinaryOperator *Incr = 
-        dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));
-      if (!Incr) continue;
-      if (Incr->getOpcode() != Instruction::Add
-          && Incr->getOpcode() != Instruction::Sub)
-        continue;
-
-      /* Initialize new IV, double d = 0.0 in above example. */
-      ConstantInt *C = NULL;
-      if (Incr->getOperand(0) == PH)
-        C = dyn_cast<ConstantInt>(Incr->getOperand(1));
-      else if (Incr->getOperand(1) == PH)
-        C = dyn_cast<ConstantInt>(Incr->getOperand(0));
-      else
-        continue;
-
-      if (!C) continue;
-
-      /* create new icnrement. '++d' in above example. */
-      ConstantFP *CFP = ConstantFP::get(DestTy, C->getZExtValue());
-      BinaryOperator *NewIncr = 
-        BinaryOperator::Create(Incr->getOpcode(),
-                               NewInit, CFP, "IV.S.next.", Incr);
-
-      /* Add new PHINode. */
-      PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH);
-      NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));
-      NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));
-
-      /* Remove cast operation */
-      ShadowUse->replaceAllUsesWith(NewPH);
-      ShadowUse->eraseFromParent();
-      SI->second.Users.erase(CandidateUI);
-      NumShadow++;
-      break;
-    }
-  }
-}
-
 // OptimizeIndvars - Now that IVUsesByStride is set up with all of the indvar
 // uses in the loop, look to see if we can eliminate some, in favor of using
 // common indvars for the different uses.
 void LoopStrengthReduce::OptimizeIndvars(Loop *L) {
   // TODO: implement optzns here.
 
-  OptimizeShadowIV(L);
-
   // Finally, get the terminating condition for the loop if possible.  If we
   // can, we want to change it to use a post-incremented version of its
   // induction variable, to allow coalescing the live ranges for the IV into

diff --git a/test/Transforms/LoopStrengthReduce/2008-08-14-ShadowIV.ll b/test/Transforms/LoopStrengthReduce/2008-08-14-ShadowIV.ll
index 681c9be1675ab71932fa91b68649d4eb8cc72260..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391 100644 (file)
--- a/test/Transforms/LoopStrengthReduce/2008-08-14-ShadowIV.ll
+++ b/test/Transforms/LoopStrengthReduce/2008-08-14-ShadowIV.ll
@@ -1,27 +0,0 @@
-; RUN: llvm-as < %s | opt -loop-reduce | llvm-dis | grep "phi double"
-
-define void @foobar(i32 %n) nounwind {
-entry:
-       icmp eq i32 %n, 0               ; <i1>:0 [#uses=2]
-       br i1 %0, label %return, label %bb.nph
-
-bb.nph:                ; preds = %entry
-       %umax = select i1 %0, i32 1, i32 %n             ; <i32> [#uses=1]
-       br label %bb
-
-bb:            ; preds = %bb, %bb.nph
-       %i.03 = phi i32 [ 0, %bb.nph ], [ %indvar.next, %bb ]           ; <i32> [#uses=3]
-       tail call void @bar( i32 %i.03 ) nounwind
-       uitofp i32 %i.03 to double              ; <double>:1 [#uses=1]
-       tail call void @foo( double %1 ) nounwind
-       %indvar.next = add i32 %i.03, 1         ; <i32> [#uses=2]
-       %exitcond = icmp eq i32 %indvar.next, %umax             ; <i1> [#uses=1]
-       br i1 %exitcond, label %return, label %bb
-
-return:                ; preds = %bb, %entry
-       ret void
-}
-
-declare void @bar(i32)
-
-declare void @foo(double)