[clang] [llvm] [RISCV] Added the MIPS prefetch extensions for MIPS RV64 P8700. (PR #145647)

[Craig Topper via cfe-commits]

================
@@ -535,6 +535,19 @@ static DecodeStatus decodeRTZArg(MCInst &Inst, uint32_t Imm, int64_t Address,
   Inst.addOperand(MCOperand::createImm(Imm));
   return MCDisassembler::Success;
 }
+template <int Bits>
+static DecodeStatus DecodeSImm(MCInst &Inst, uint64_t Imm, uint64_t Address,
+                               const MCDisassembler *Decoder) {
+  if (Imm & ~((1LL << Bits) - 1))
+    return MCDisassembler::Fail;
+
+  // Imm is a signed immediate, so sign extend it.
+  if (Imm & (1 << (Bits - 1)))
+    Imm |= ~((1LL << Bits) - 1);
----------------
topperc wrote:

Please use the SignExtend utility in MathExtras.h

https://github.com/llvm/llvm-project/pull/145647