Remove the code from IVUsers that attempted to handle

casted induction variables in cases where the cast
isn't foldable. It ended up being a pessimization in
many cases. This could be fixed, but it would require
a bunch of complicated code in IVUsers' clients. The
advantages of this approach aren't visible enough to
justify it at this time.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73706 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/IVUsers.h

@@ -35,9 +35,9 @@ class IVStrideUse : public CallbackVH, public ilist_node<IVStrideUse> {
 public:
   IVStrideUse(IVUsersOfOneStride *parent,
               const SCEVHandle &offset,
-              Instruction* U, Value *O, bool issigned)
+              Instruction* U, Value *O)
     : CallbackVH(U), Parent(parent), Offset(offset),
-      OperandValToReplace(O), IsSigned(issigned),
+      OperandValToReplace(O),
       IsUseOfPostIncrementedValue(false) {
   }
 
@@ -57,8 +57,7 @@ public:
 
   /// getOffset - Return the offset to add to a theoeretical induction
   /// variable that starts at zero and counts up by the stride to compute
-  /// the value for the use. This always has the same type as the stride,
-  /// which may need to be casted to match the type of the use.
+  /// the value for the use. This always has the same type as the stride.
   SCEVHandle getOffset() const { return Offset; }
 
   /// setOffset - Assign a new offset to this use.
@@ -78,13 +77,6 @@ public:
     OperandValToReplace = Op;
   }
 
-  /// isSigned - The stride (and thus also the Offset) of this use may be in
-  /// a narrower type than the use itself (OperandValToReplace->getType()).
-  /// When this is the case, isSigned() indicates whether the IV expression
-  /// should be signed-extended instead of zero-extended to fit the type of
-  /// the use.
-  bool isSigned() const { return IsSigned; }
-
   /// isUseOfPostIncrementedValue - True if this should use the
   /// post-incremented version of this IV, not the preincremented version.
   /// This can only be set in special cases, such as the terminating setcc
@@ -110,10 +102,6 @@ private:
   /// that this IVStrideUse is representing.
   WeakVH OperandValToReplace;
 
-  /// IsSigned - Determines whether the replacement value is sign or
-  /// zero extended to the type of the use.
-  bool IsSigned;
-
   /// IsUseOfPostIncrementedValue - True if this should use the
   /// post-incremented version of this IV, not the preincremented version.
   bool IsUseOfPostIncrementedValue;
@@ -170,9 +158,8 @@ public:
   /// initial value and the operand that uses the IV.
   ilist<IVStrideUse> Users;
 
-  void addUser(const SCEVHandle &Offset,Instruction *User, Value *Operand,
-               bool isSigned) {
-    Users.push_back(new IVStrideUse(this, Offset, User, Operand, isSigned));
+  void addUser(const SCEVHandle &Offset, Instruction *User, Value *Operand) {
+    Users.push_back(new IVStrideUse(this, Offset, User, Operand));
   }
 };
 

lib/Analysis/IVUsers.cpp

@@ -82,11 +82,8 @@ static bool containsAddRecFromDifferentLoop(SCEVHandle S, Loop *L) {
 /// outer loop of the current loop.
 static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
                                   SCEVHandle &Start, SCEVHandle &Stride,
-                                  bool &isSigned,
                                   ScalarEvolution *SE, DominatorTree *DT) {
   SCEVHandle TheAddRec = Start;   // Initialize to zero.
-  bool isSExt = false;
-  bool isZExt = false;
 
   // If the outer level is an AddExpr, the operands are all start values except
   // for a nested AddRecExpr.
@@ -101,13 +98,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
       } else {
         Start = SE->getAddExpr(Start, AE->getOperand(i));
       }
-
-  } else if (const SCEVZeroExtendExpr *Z = dyn_cast<SCEVZeroExtendExpr>(SH)) {
-    TheAddRec = Z->getOperand();
-    isZExt = true;
-  } else if (const SCEVSignExtendExpr *S = dyn_cast<SCEVSignExtendExpr>(SH)) {
-    TheAddRec = S->getOperand();
-    isSExt = true;
   } else if (isa<SCEVAddRecExpr>(SH)) {
     TheAddRec = SH;
   } else {
@@ -131,9 +121,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
   if (containsAddRecFromDifferentLoop(AddRecStart, L))
     return false;
 
-  if (isSExt || isZExt)
-    Start = SE->getTruncateExpr(Start, AddRec->getType());
-
   Start = SE->getAddExpr(Start, AddRecStart);
 
   // If stride is an instruction, make sure it dominates the loop preheader.
@@ -148,7 +135,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
   }
 
   Stride = AddRecStride;
-  isSigned = isSExt;
   return true;
 }
 
@@ -218,9 +204,8 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
   Loop *UseLoop = LI->getLoopFor(I->getParent());
   SCEVHandle Start = SE->getIntegerSCEV(0, ISE->getType());
   SCEVHandle Stride = Start;
-  bool isSigned = false; // Arbitrary initial value - pacifies compiler.
 
-  if (!getSCEVStartAndStride(ISE, L, UseLoop, Start, Stride, isSigned, SE, DT))
+  if (!getSCEVStartAndStride(ISE, L, UseLoop, Start, Stride, SE, DT))
     return false;  // Non-reducible symbolic expression, bail out.
 
   SmallPtrSet<Instruction *, 4> UniqueUsers;
@@ -271,11 +256,11 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
         // The value used will be incremented by the stride more than we are
         // expecting, so subtract this off.
         SCEVHandle NewStart = SE->getMinusSCEV(Start, Stride);
-        StrideUses->addUser(NewStart, User, I, isSigned);
+        StrideUses->addUser(NewStart, User, I);
         StrideUses->Users.back().setIsUseOfPostIncrementedValue(true);
         DOUT << "   USING POSTINC SCEV, START=" << *NewStart<< "\n";
       } else {
-        StrideUses->addUser(Start, User, I, isSigned);
+        StrideUses->addUser(Start, User, I);
       }
     }
   }
@@ -312,7 +297,6 @@ bool IVUsers::runOnLoop(Loop *l, LPPassManager &LPM) {
 /// getReplacementExpr - Return a SCEV expression which computes the
 /// value of the OperandValToReplace of the given IVStrideUse.
 SCEVHandle IVUsers::getReplacementExpr(const IVStrideUse &U) const {
-  const Type *UseTy = U.getOperandValToReplace()->getType();
   // Start with zero.
   SCEVHandle RetVal = SE->getIntegerSCEV(0, U.getParent()->Stride->getType());
   // Create the basic add recurrence.
@@ -329,14 +313,6 @@ SCEVHandle IVUsers::getReplacementExpr(const IVStrideUse &U) const {
     if (ExitVal->isLoopInvariant(L))
       RetVal = ExitVal;
   }
-  // Promote the result to the type of the use.
-  if (SE->getTypeSizeInBits(RetVal->getType()) !=
-      SE->getTypeSizeInBits(UseTy)) {
-    if (U.isSigned())
-      RetVal = SE->getSignExtendExpr(RetVal, UseTy);
-    else
-      RetVal = SE->getZeroExtendExpr(RetVal, UseTy);
-  }
   return RetVal;
 }
 

lib/Transforms/Scalar/LoopStrengthReduce.cpp

@@ -336,13 +336,6 @@ namespace {
     /// EmittedBase.
     Value *OperandValToReplace;
 
-    /// isSigned - The stride (and thus also the Base) of this use may be in
-    /// a narrower type than the use itself (OperandValToReplace->getType()).
-    /// When this is the case, the isSigned field indicates whether the
-    /// IV expression should be signed-extended instead of zero-extended to
-    /// fit the type of the use.
-    bool isSigned;
-
     /// Imm - The immediate value that should be added to the base immediately
     /// before Inst, because it will be folded into the imm field of the
     /// instruction.  This is also sometimes used for loop-variant values that
@@ -363,7 +356,6 @@ namespace {
     BasedUser(IVStrideUse &IVSU, ScalarEvolution *se)
       : SE(se), Base(IVSU.getOffset()), Inst(IVSU.getUser()),
         OperandValToReplace(IVSU.getOperandValToReplace()),
-        isSigned(IVSU.isSigned()),
         Imm(SE->getIntegerSCEV(0, Base->getType())), 
         isUseOfPostIncrementedValue(IVSU.isUseOfPostIncrementedValue()) {}
 
@@ -428,11 +420,6 @@ Value *BasedUser::InsertCodeForBaseAtPosition(const SCEVHandle &NewBase,
     NewValSCEV = SE->getAddExpr(NewValSCEV, Imm);
   }
 
-  if (isSigned)
-    NewValSCEV = SE->getTruncateOrSignExtend(NewValSCEV, Ty);
-  else
-    NewValSCEV = SE->getTruncateOrZeroExtend(NewValSCEV, Ty);
-
   return Rewriter.expandCodeFor(NewValSCEV, Ty, IP);
 }
 
@@ -2047,7 +2034,7 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
     OldCond->replaceAllUsesWith(Cond);
     OldCond->eraseFromParent();
 
-    IU->IVUsesByStride[*NewStride]->addUser(NewOffset, Cond, NewCmpLHS, false);
+    IU->IVUsesByStride[*NewStride]->addUser(NewOffset, Cond, NewCmpLHS);
     CondUse = &IU->IVUsesByStride[*NewStride]->Users.back();
     CondStride = NewStride;
     ++NumEliminated;
@@ -2397,8 +2384,7 @@ void LoopStrengthReduce::OptimizeLoopTermCond(Loop *L) {
       
       // Clone the IVUse, as the old use still exists!
       IU->IVUsesByStride[*CondStride]->addUser(CondUse->getOffset(), Cond,
-                                              CondUse->getOperandValToReplace(),
-                                               false);
+                                             CondUse->getOperandValToReplace());
       CondUse = &IU->IVUsesByStride[*CondStride]->Users.back();
     }
   }

test/CodeGen/X86/iv-users-in-other-loops.ll

@@ -1,11 +1,11 @@
 ; RUN: llvm-as < %s | llc -march=x86-64 -f -o %t
 ; RUN: grep inc %t | count 1
 ; RUN: grep dec %t | count 2
-; RUN: grep addq %t | count 8
-; RUN: grep addb %t | count 2
-; RUN: grep leaq %t | count 12
-; RUN: grep leal %t | count 2
-; RUN: grep movq %t | count 4
+; RUN: grep addq %t | count 13
+; RUN: not grep addb %t
+; RUN: grep leaq %t | count 8
+; RUN: grep leal %t | count 4
+; RUN: grep movq %t | count 5
 
 ; IV users in each of the loops from other loops shouldn't cause LSR
 ; to insert new induction variables. Previously it would create a

test/Transforms/IndVarSimplify/masked-iv.ll

@@ -1,4 +1,6 @@
-; RUN: llvm-as < %s | opt -indvars | llvm-dis | grep trunc | count 1
+; RUN: llvm-as < %s | opt -indvars | llvm-dis > %t
+; RUN: not grep trunc %t
+; RUN: grep and %t | count 1
 
 ; Indvars should do the IV arithmetic in the canonical IV type (i64),
 ; and only use one truncation.

test/Transforms/IndVarSimplify/shrunk-constant.ll

@@ -1,4 +1,5 @@
-; RUN: llvm-as < %s | opt -iv-users -analyze -disable-output | grep store
+; RUN: llvm-as < %s | opt -scalar-evolution -analyze -disable-output \
+; RUN:  | grep {\\-->  (zext i4 {-7,+,-8}<loop> to i32)}
 
 define fastcc void @foo() nounwind {
 entry: