[AMDGPU] Put back ProperlyAlighedRC helper functions

Putting back the functions that are recently deleted
as they were found unused. They are needed for
implementing subreg reload during RA.

llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp

diff --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
index 3efdad6..4777e06 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -3882,6 +3882,28 @@
   return true;
 }
 
+const TargetRegisterClass *
+SIRegisterInfo::getProperlyAlignedRC(const TargetRegisterClass *RC) const {
+  if (!RC || !ST.needsAlignedVGPRs())
+    return RC;
+
+  unsigned Size = getRegSizeInBits(*RC);
+  if (Size <= 32)
+    return RC;
+
+  if (RC == &AMDGPU::VS_64RegClass)
+    return &AMDGPU::VS_64_Align2RegClass;
+
+  if (isVGPRClass(RC))
+    return getAlignedVGPRClassForBitWidth(Size);
+  if (isAGPRClass(RC))
+    return getAlignedAGPRClassForBitWidth(Size);
+  if (isVectorSuperClass(RC))
+    return getAlignedVectorSuperClassForBitWidth(Size);
+
+  return RC;
+}
+
 ArrayRef<MCPhysReg>
 SIRegisterInfo::getAllSGPR128(const MachineFunction &MF) const {
   return ArrayRef(AMDGPU::SGPR_128RegClass.begin(), ST.getMaxNumSGPRs(MF) / 4);

llvm/lib/Target/AMDGPU/SIRegisterInfo.h

diff --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.h b/llvm/lib/Target/AMDGPU/SIRegisterInfo.h
index 2e2916f..4c8e217 100644
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.h
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.h
@@ -431,6 +431,11 @@
   // the subtarget.
   bool isProperlyAlignedRC(const TargetRegisterClass &RC) const;
 
+  // Given \p RC returns corresponding aligned register class if required
+  // by the subtarget.
+  const TargetRegisterClass *
+  getProperlyAlignedRC(const TargetRegisterClass *RC) const;
+
   /// Return all SGPR128 which satisfy the waves per execution unit requirement
   /// of the subtarget.
   ArrayRef<MCPhysReg> getAllSGPR128(const MachineFunction &MF) const;