[llvm] [RISCV] Support instruction sizes up to 176-bits in disassembler. (PR #90371)

[Pengcheng Wang via llvm-commits]

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@@ -656,12 +656,44 @@ DecodeStatus RISCVDisassembler::getInstruction(MCInst &MI, uint64_t &Size,
                                                ArrayRef<uint8_t> Bytes,
                                                uint64_t Address,
                                                raw_ostream &CS) const {
-  // TODO: This will need modification when supporting instruction set
-  // extensions with instructions > 32-bits (up to 176 bits wide).
+  // It's a 16 bit instruction if bit 0 and 1 are not 0x3.
+  if ((Bytes[0] & 0x3) != 0x3)
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wangpc-pp wrote:

We can use `0b111`, `0b111111`, ..., which should be more readable.

https://github.com/llvm/llvm-project/pull/90371