Index: llvm/lib/Target/RISCV/RISCV.td
===================================================================
--- llvm/lib/Target/RISCV/RISCV.td
+++ llvm/lib/Target/RISCV/RISCV.td
@@ -179,8 +179,8 @@
                        AssemblerPredicate<(all_of (not Feature64Bit)),
                        "RV32I Base Instruction Set">;
 
+// RV32 uses DefaultMode.
 def RV64           : HwMode<"+64bit">;
-def RV32           : HwMode<"-64bit">;
 
 def FeatureRV32E
     : SubtargetFeature<"e", "IsRV32E", "true",
Index: llvm/lib/Target/RISCV/RISCVRegisterInfo.td
===================================================================
--- llvm/lib/Target/RISCV/RISCVRegisterInfo.td
+++ llvm/lib/Target/RISCV/RISCVRegisterInfo.td
@@ -97,8 +97,8 @@
   }
 }
 
-def XLenVT : ValueTypeByHwMode<[RV32, RV64, DefaultMode],
-                               [i32,  i64,  i32]>;
+def XLenVT : ValueTypeByHwMode<[RV64, DefaultMode/*RV32*/],
+                               [i64,  i32]>;
 
 // The order of registers represents the preferred allocation sequence.
 // Registers are listed in the order caller-save, callee-save, specials.
@@ -111,14 +111,14 @@
     (sequence "X%u", 0, 4)
   )> {
   let RegInfos = RegInfoByHwMode<
-      [RV32,              RV64,              DefaultMode],
-      [RegInfo<32,32,32>, RegInfo<64,64,64>, RegInfo<32,32,32>]>;
+      [RV64,              DefaultMode/*RV32*/],
+      [RegInfo<64,64,64>, RegInfo<32,32,32>]>;
 }
 
 def GPRX0 : RegisterClass<"RISCV", [XLenVT], 32, (add X0)> {
   let RegInfos = RegInfoByHwMode<
-      [RV32,              RV64,              DefaultMode],
-      [RegInfo<32,32,32>, RegInfo<64,64,64>, RegInfo<32,32,32>]>;
+      [RV64,              DefaultMode/*RV32*/],
+      [RegInfo<64,64,64>, RegInfo<32,32,32>]>;
 }
 
 // The order of registers represents the preferred allocation sequence.
@@ -132,8 +132,8 @@
     (sequence "X%u", 1, 4)
   )> {
   let RegInfos = RegInfoByHwMode<
-      [RV32,              RV64,              DefaultMode],
-      [RegInfo<32,32,32>, RegInfo<64,64,64>, RegInfo<32,32,32>]>;
+      [RV64,              DefaultMode/*RV32*/],
+      [RegInfo<64,64,64>, RegInfo<32,32,32>]>;
 }
 
 def GPRNoX0X2 : RegisterClass<"RISCV", [XLenVT], 32, (add
@@ -145,8 +145,8 @@
     X1, X3, X4
   )> {
   let RegInfos = RegInfoByHwMode<
-      [RV32,              RV64,              DefaultMode],
-      [RegInfo<32,32,32>, RegInfo<64,64,64>, RegInfo<32,32,32>]>;
+      [RV64,              DefaultMode/*RV32*/],
+      [RegInfo<64,64,64>, RegInfo<32,32,32>]>;
 }
 
 def GPRC : RegisterClass<"RISCV", [XLenVT], 32, (add
@@ -154,8 +154,8 @@
     (sequence "X%u", 8, 9)
   )> {
   let RegInfos = RegInfoByHwMode<
-      [RV32,              RV64,              DefaultMode],
-      [RegInfo<32,32,32>, RegInfo<64,64,64>, RegInfo<32,32,32>]>;
+      [RV64,              DefaultMode/*RV32*/],
+      [RegInfo<64,64,64>, RegInfo<32,32,32>]>;
 }
 
 // For indirect tail calls, we can't use callee-saved registers, as they are
@@ -167,14 +167,14 @@
     (sequence "X%u", 28, 31)
   )> {
   let RegInfos = RegInfoByHwMode<
-      [RV32,              RV64,              DefaultMode],
-      [RegInfo<32,32,32>, RegInfo<64,64,64>, RegInfo<32,32,32>]>;
+      [RV64,              DefaultMode/*RV32*/],
+      [RegInfo<64,64,64>, RegInfo<32,32,32>]>;
 }
 
 def SP : RegisterClass<"RISCV", [XLenVT], 32, (add X2)> {
   let RegInfos = RegInfoByHwMode<
-      [RV32,              RV64,              DefaultMode],
-      [RegInfo<32,32,32>, RegInfo<64,64,64>, RegInfo<32,32,32>]>;
+      [RV64,              DefaultMode/*RV32*/],
+      [RegInfo<64,64,64>, RegInfo<32,32,32>]>;
 }
 
 // Floating point registers