GlobalISel: Remove dead code

Generic code should probably not introduce G_INSERT/G_EXTRACT. The
mirror unpackRegs should also be removed, but AMDGPU still has a use
remaining which needs to be fixed.

Author: arsenm

llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h

@@ -251,16 +251,6 @@ class CallLowering {
                          SmallVectorImpl<ArgInfo> &SplitArgs,
                          const DataLayout &DL, CallingConv::ID CallConv) const;
 
-  /// Generate instructions for packing \p SrcRegs into one big register
-  /// corresponding to the aggregate type \p PackedTy.
-  ///
-  /// \param SrcRegs should contain one virtual register for each base type in
-  ///                \p PackedTy, as returned by computeValueLLTs.
-  ///
-  /// \return The packed register.
-  Register packRegs(ArrayRef<Register> SrcRegs, Type *PackedTy,
-                    MachineIRBuilder &MIRBuilder) const;
-
   /// Generate instructions for unpacking \p SrcReg into the \p DstRegs
   /// corresponding to the aggregate type \p PackedTy.
   ///

llvm/lib/CodeGen/GlobalISel/CallLowering.cpp

@@ -224,31 +224,6 @@ void CallLowering::splitToValueTypes(const ArgInfo &OrigArg,
   SplitArgs.back().Flags[0].setInConsecutiveRegsLast();
 }
 
-Register CallLowering::packRegs(ArrayRef<Register> SrcRegs, Type *PackedTy,
-                                MachineIRBuilder &MIRBuilder) const {
-  assert(SrcRegs.size() > 1 && "Nothing to pack");
-
-  const DataLayout &DL = MIRBuilder.getMF().getDataLayout();
-  MachineRegisterInfo *MRI = MIRBuilder.getMRI();
-
-  LLT PackedLLT = getLLTForType(*PackedTy, DL);
-
-  SmallVector<LLT, 8> LLTs;
-  SmallVector<uint64_t, 8> Offsets;
-  computeValueLLTs(DL, *PackedTy, LLTs, &Offsets);
-  assert(LLTs.size() == SrcRegs.size() && "Regs / types mismatch");
-
-  Register Dst = MRI->createGenericVirtualRegister(PackedLLT);
-  MIRBuilder.buildUndef(Dst);
-  for (unsigned i = 0; i < SrcRegs.size(); ++i) {
-    Register NewDst = MRI->createGenericVirtualRegister(PackedLLT);
-    MIRBuilder.buildInsert(NewDst, Dst, SrcRegs[i], Offsets[i]);
-    Dst = NewDst;
-  }
-
-  return Dst;
-}
-
 void CallLowering::unpackRegs(ArrayRef<Register> DstRegs, Register SrcReg,
                               Type *PackedTy,
                               MachineIRBuilder &MIRBuilder) const {