diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -908,11 +908,10 @@
       TRI->getRegClass(FoldDesc.operands()[0].RegClass);
 
   // Split 64-bit constants into 32-bits for folding.
-  if (UseOp.getSubReg() && AMDGPU::getRegBitWidth(FoldRC->getID()) == 64) {
+  if (UseOp.getSubReg() && AMDGPU::getRegBitWidth(*FoldRC) == 64) {
     Register UseReg = UseOp.getReg();
     const TargetRegisterClass *UseRC = MRI->getRegClass(UseReg);
-
-    if (AMDGPU::getRegBitWidth(UseRC->getID()) != 64)
+    if (AMDGPU::getRegBitWidth(*UseRC) != 64)
       return;
 
     APInt Imm(64, OpToFold.getImm());
diff --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -2882,7 +2882,7 @@
     if (MRI.getRegClass(FalseReg) != RC)
       return false;
 
-    int NumInsts = AMDGPU::getRegBitWidth(RC->getID()) / 32;
+    int NumInsts = AMDGPU::getRegBitWidth(*RC) / 32;
     CondCycles = TrueCycles = FalseCycles = NumInsts; // ???
 
     // Limit to equal cost for branch vs. N v_cndmask_b32s.
@@ -2897,7 +2897,7 @@
     if (MRI.getRegClass(FalseReg) != RC)
       return false;
 
-    int NumInsts = AMDGPU::getRegBitWidth(RC->getID()) / 32;
+    int NumInsts = AMDGPU::getRegBitWidth(*RC) / 32;
 
     // Multiples of 8 can do s_cselect_b64
     if (NumInsts % 2 == 0)
diff --git a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
--- a/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
@@ -1310,7 +1310,7 @@
   const TargetRegisterClass *RC = getRegClassForReg(MF->getRegInfo(), ValueReg);
   // On gfx90a+ AGPR is a regular VGPR acceptable for loads and stores.
   const bool IsAGPR = !ST.hasGFX90AInsts() && isAGPRClass(RC);
-  const unsigned RegWidth = AMDGPU::getRegBitWidth(RC->getID()) / 8;
+  const unsigned RegWidth = AMDGPU::getRegBitWidth(*RC) / 8;
 
   // Always use 4 byte operations for AGPRs because we need to scavenge
   // a temporary VGPR.
@@ -2904,7 +2904,7 @@
 
 ArrayRef<int16_t> SIRegisterInfo::getRegSplitParts(const TargetRegisterClass *RC,
                                                    unsigned EltSize) const {
-  const unsigned RegBitWidth = AMDGPU::getRegBitWidth(*RC->MC);
+  const unsigned RegBitWidth = AMDGPU::getRegBitWidth(*RC);
   assert(RegBitWidth >= 32 && RegBitWidth <= 1024);
 
   const unsigned RegDWORDs = RegBitWidth / 32;
@@ -3209,4 +3209,4 @@
     break;
   }
   return 0;
-}
\ No newline at end of file
+}
diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
@@ -31,6 +31,7 @@
 class MCRegisterInfo;
 class MCSubtargetInfo;
 class StringRef;
+class TargetRegisterClass;
 class Triple;
 class raw_ostream;
 
@@ -1178,6 +1179,9 @@
 /// Get the size in bits of a register from the register class \p RC.
 unsigned getRegBitWidth(const MCRegisterClass &RC);
 
+/// Get the size in bits of a register from the register class \p RC.
+unsigned getRegBitWidth(const TargetRegisterClass &RC);
+
 /// Get size of register operand
 unsigned getRegOperandSize(const MCRegisterInfo *MRI, const MCInstrDesc &Desc,
                            unsigned OpNo);
diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.cpp
@@ -12,6 +12,7 @@
 #include "AMDKernelCodeT.h"
 #include "MCTargetDesc/AMDGPUMCTargetDesc.h"
 #include "llvm/BinaryFormat/ELF.h"
+#include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
@@ -2367,11 +2368,15 @@
   return getRegBitWidth(RC.getID());
 }
 
+unsigned getRegBitWidth(const TargetRegisterClass &RC) {
+  return getRegBitWidth(RC.getID());
+}
+
 unsigned getRegOperandSize(const MCRegisterInfo *MRI, const MCInstrDesc &Desc,
                            unsigned OpNo) {
   assert(OpNo < Desc.NumOperands);
   unsigned RCID = Desc.operands()[OpNo].RegClass;
-  return getRegBitWidth(MRI->getRegClass(RCID)) / 8;
+  return getRegBitWidth(RCID) / 8;
 }
 
 bool isInlinableLiteral64(int64_t Literal, bool HasInv2Pi) {