[TargetTransformInfo, API] Add a list of operands to TTI::getUserCost

The changes are a result of discussion of https://reviews.llvm.org/D33685.
It solves the following problem:

1. We can inform getGEPCost about simplified indices to help it with
   calculating the cost. But getGEPCost does not take into account the
   context which GEPs are used in.
2. We have getUserCost which can take the context into account but we cannot
   inform about simplified indices.

With the changes getUserCost will have access to additional information
as getGEPCost has.

The one parameter getUserCost is also provided.

Differential Revision: https://reviews.llvm.org/D34057

llvm-svn: 306674

llvm/include/llvm/Analysis/TargetTransformInfo.h

@@ -216,9 +216,23 @@ class TargetTransformInfo {
   /// other context they may not be folded. This routine can distinguish such
   /// cases.
   ///
+  /// \p Operands is a list of operands which can be a result of transformations
+  /// of the current operands. The number of the operands on the list must equal
+  /// to the number of the current operands the IR user has. Their order on the
+  /// list must be the same as the order of the current operands the IR user
+  /// has.
+  ///
   /// The returned cost is defined in terms of \c TargetCostConstants, see its
   /// comments for a detailed explanation of the cost values.
-  int getUserCost(const User *U) const;
+  int getUserCost(const User *U, ArrayRef<const Value *> Operands) const;
+
+  /// \brief This is a helper function which calls the two-argument getUserCost
+  /// with \p Operands which are the current operands U has.
+  int getUserCost(const User *U) const {
+    SmallVector<const Value *, 4> Operands(U->value_op_begin(),
+                                           U->value_op_end());
+    return getUserCost(U, Operands);
+  }
 
   /// \brief Return true if branch divergence exists.
   ///
@@ -824,7 +838,8 @@ class TargetTransformInfo::Concept {
                                ArrayRef<const Value *> Arguments) = 0;
   virtual unsigned getEstimatedNumberOfCaseClusters(const SwitchInst &SI,
                                                     unsigned &JTSize) = 0;
-  virtual int getUserCost(const User *U) = 0;
+  virtual int
+  getUserCost(const User *U, ArrayRef<const Value *> Operands) = 0;
   virtual bool hasBranchDivergence() = 0;
   virtual bool isSourceOfDivergence(const Value *V) = 0;
   virtual bool isAlwaysUniform(const Value *V) = 0;
@@ -1000,7 +1015,9 @@ class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
                        ArrayRef<const Value *> Arguments) override {
     return Impl.getIntrinsicCost(IID, RetTy, Arguments);
   }
-  int getUserCost(const User *U) override { return Impl.getUserCost(U); }
+  int getUserCost(const User *U, ArrayRef<const Value *> Operands) override {
+    return Impl.getUserCost(U, Operands);
+  }
   bool hasBranchDivergence() override { return Impl.hasBranchDivergence(); }
   bool isSourceOfDivergence(const Value *V) override {
     return Impl.isSourceOfDivergence(V);

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -685,14 +685,14 @@ class TargetTransformInfoImplCRTPBase : public TargetTransformInfoImplBase {
     return static_cast<T *>(this)->getIntrinsicCost(IID, RetTy, ParamTys);
   }
 
-  unsigned getUserCost(const User *U) {
+  unsigned getUserCost(const User *U, ArrayRef<const Value *> Operands) {
     if (isa<PHINode>(U))
       return TTI::TCC_Free; // Model all PHI nodes as free.
 
     if (const GEPOperator *GEP = dyn_cast<GEPOperator>(U)) {
-      SmallVector<Value *, 4> Indices(GEP->idx_begin(), GEP->idx_end());
-      return static_cast<T *>(this)->getGEPCost(
-          GEP->getSourceElementType(), GEP->getPointerOperand(), Indices);
+      return static_cast<T *>(this)->getGEPCost(GEP->getSourceElementType(),
+                                                GEP->getPointerOperand(),
+                                                Operands.drop_front());
     }
 
     if (auto CS = ImmutableCallSite(U)) {

llvm/lib/Analysis/TargetTransformInfo.cpp

@@ -89,8 +89,9 @@ TargetTransformInfo::getEstimatedNumberOfCaseClusters(const SwitchInst &SI,
   return TTIImpl->getEstimatedNumberOfCaseClusters(SI, JTSize);
 }
 
-int TargetTransformInfo::getUserCost(const User *U) const {
-  int Cost = TTIImpl->getUserCost(U);
+int TargetTransformInfo::getUserCost(const User *U,
+    ArrayRef<const Value *> Operands) const {
+  int Cost = TTIImpl->getUserCost(U, Operands);
   assert(Cost >= 0 && "TTI should not produce negative costs!");
   return Cost;
 }

llvm/lib/Target/Hexagon/HexagonTargetTransformInfo.cpp

@@ -46,8 +46,9 @@ unsigned HexagonTTIImpl::getCacheLineSize() const {
   return getST()->getL1CacheLineSize();
 }
 
-int HexagonTTIImpl::getUserCost(const User *U) {
-  auto isCastFoldedIntoLoad = [] (const CastInst *CI) -> bool {
+int HexagonTTIImpl::getUserCost(const User *U,
+                                ArrayRef<const Value *> Operands) {
+  auto isCastFoldedIntoLoad = [](const CastInst *CI) -> bool {
     if (!CI->isIntegerCast())
       return false;
     const LoadInst *LI = dyn_cast<const LoadInst>(CI->getOperand(0));
@@ -67,5 +68,5 @@ int HexagonTTIImpl::getUserCost(const User *U) {
   if (const CastInst *CI = dyn_cast<const CastInst>(U))
     if (isCastFoldedIntoLoad(CI))
       return TargetTransformInfo::TCC_Free;
-  return BaseT::getUserCost(U);
+  return BaseT::getUserCost(U, Operands);
 }

llvm/lib/Target/Hexagon/HexagonTargetTransformInfo.h

@@ -62,7 +62,7 @@ class HexagonTTIImpl : public BasicTTIImplBase<HexagonTTIImpl> {
 
   /// @}
 
-  int getUserCost(const User *U);
+  int getUserCost(const User *U, ArrayRef<const Value *> Operands);
 };
 
 } // end namespace llvm