Revert "[SLP]Reduce number of alternate instruction, where possible"

This reverts commit d5a7a48.

That commit triggers failed asserts, see
#123360 for details.

Author: mstorsjo

llvm/include/llvm/Analysis/TargetTransformInfo.h

@@ -1759,10 +1759,6 @@ class TargetTransformInfo {
   /// scalable version of the vectorized loop.
   bool preferFixedOverScalableIfEqualCost() const;
 
-  /// \returns True if target prefers SLP vectorizer with altermate opcode
-  /// vectorization, false - otherwise.
-  bool preferAlternateOpcodeVectorization() const;
-
   /// \returns True if the target prefers reductions in loop.
   bool preferInLoopReduction(unsigned Opcode, Type *Ty,
                              ReductionFlags Flags) const;
@@ -2310,7 +2306,6 @@ class TargetTransformInfo::Concept {
                                         unsigned ChainSizeInBytes,
                                         VectorType *VecTy) const = 0;
   virtual bool preferFixedOverScalableIfEqualCost() const = 0;
-  virtual bool preferAlternateOpcodeVectorization() const = 0;
   virtual bool preferInLoopReduction(unsigned Opcode, Type *Ty,
                                      ReductionFlags) const = 0;
   virtual bool preferPredicatedReductionSelect(unsigned Opcode, Type *Ty,
@@ -3111,9 +3106,6 @@ class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
   bool preferFixedOverScalableIfEqualCost() const override {
     return Impl.preferFixedOverScalableIfEqualCost();
   }
-  bool preferAlternateOpcodeVectorization() const override {
-    return Impl.preferAlternateOpcodeVectorization();
-  }
   bool preferInLoopReduction(unsigned Opcode, Type *Ty,
                              ReductionFlags Flags) const override {
     return Impl.preferInLoopReduction(Opcode, Ty, Flags);

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -989,8 +989,6 @@ class TargetTransformInfoImplBase {
 
   bool preferFixedOverScalableIfEqualCost() const { return false; }
 
-  bool preferAlternateOpcodeVectorization() const { return true; }
-
   bool preferInLoopReduction(unsigned Opcode, Type *Ty,
                              TTI::ReductionFlags Flags) const {
     return false;

llvm/lib/Analysis/TargetTransformInfo.cpp

@@ -1360,10 +1360,6 @@ bool TargetTransformInfo::preferFixedOverScalableIfEqualCost() const {
   return TTIImpl->preferFixedOverScalableIfEqualCost();
 }
 
-bool TargetTransformInfo::preferAlternateOpcodeVectorization() const {
-  return TTIImpl->preferAlternateOpcodeVectorization();
-}
-
 bool TargetTransformInfo::preferInLoopReduction(unsigned Opcode, Type *Ty,
                                                 ReductionFlags Flags) const {
   return TTIImpl->preferInLoopReduction(Opcode, Ty, Flags);

llvm/lib/Target/RISCV/RISCVTargetTransformInfo.h

@@ -111,8 +111,6 @@ class RISCVTTIImpl : public BasicTTIImplBase<RISCVTTIImpl> {
 
   unsigned getMaximumVF(unsigned ElemWidth, unsigned Opcode) const;
 
-  bool preferAlternateOpcodeVectorization() const { return false; }
-
   bool preferEpilogueVectorization() const {
     // Epilogue vectorization is usually unprofitable - tail folding or
     // a smaller VF would have been better.  This a blunt hammer - we

llvm/lib/Target/X86/X86TargetTransformInfo.h

@@ -292,7 +292,6 @@ class X86TTIImpl : public BasicTTIImplBase<X86TTIImpl> {
 
   TTI::MemCmpExpansionOptions enableMemCmpExpansion(bool OptSize,
                                                     bool IsZeroCmp) const;
-  bool preferAlternateOpcodeVectorization() const { return false; }
   bool prefersVectorizedAddressing() const;
   bool supportsEfficientVectorElementLoadStore() const;
   bool enableInterleavedAccessVectorization();