[RISCV] MC layer support for the standard RV32D instruction set extension

As the FPR32 and FPR64 registers have the same names, use 
validateTargetOperandClass in RISCVAsmParser to coerce a parsed FPR32 to an 
FPR64 when necessary. The rest of this patch is very similar to the RV32F 
patch.

Differential Revision: https://reviews.llvm.org/D39895

llvm-svn: 320023

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
index 0f186004a4f..2649f1b3729 100644
--- a/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
+++ b/llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp
@@ -105,6 +105,31 @@ static DecodeStatus DecodeFPR32RegisterClass(MCInst &Inst, uint64_t RegNo,
   return MCDisassembler::Success;
 }
 
+static const unsigned FPR64DecoderTable[] = {
+  RISCV::F0_64,  RISCV::F1_64,  RISCV::F2_64,  RISCV::F3_64,
+  RISCV::F4_64,  RISCV::F5_64,  RISCV::F6_64,  RISCV::F7_64,
+  RISCV::F8_64,  RISCV::F9_64,  RISCV::F10_64, RISCV::F11_64,
+  RISCV::F12_64, RISCV::F13_64, RISCV::F14_64, RISCV::F15_64,
+  RISCV::F16_64, RISCV::F17_64, RISCV::F18_64, RISCV::F19_64,
+  RISCV::F20_64, RISCV::F21_64, RISCV::F22_64, RISCV::F23_64,
+  RISCV::F24_64, RISCV::F25_64, RISCV::F26_64, RISCV::F27_64,
+  RISCV::F28_64, RISCV::F29_64, RISCV::F30_64, RISCV::F31_64
+};
+
+static DecodeStatus DecodeFPR64RegisterClass(MCInst &Inst, uint64_t RegNo,
+                                             uint64_t Address,
+                                             const void *Decoder) {
+  if (RegNo > sizeof(FPR64DecoderTable))
+    return MCDisassembler::Fail;
+
+  // We must define our own mapping from RegNo to register identifier.
+  // Accessing index RegNo in the register class will work in the case that
+  // registers were added in ascending order, but not in general.
+  unsigned Reg = FPR64DecoderTable[RegNo];
+  Inst.addOperand(MCOperand::createReg(Reg));
+  return MCDisassembler::Success;
+}
+
 template <unsigned N>
 static DecodeStatus decodeUImmOperand(MCInst &Inst, uint64_t Imm,
                                       int64_t Address, const void *Decoder) {