[TableGen] More named sub-operands work.

Commit a538d1f13a13 first added support for named sub-operands in
CodeEmitterGen. We now add a few more features to that, enabling
further target cleanups.

1. Adds support for handling an EncoderMethod in a sub-operand in
CodeEmitterGen. Previously, the specified encoder of a sub-operand was
ignored, and only the default used.

2. Adds support for sub-operands in DecoderEmitter, along with support
for tied sub-operands.

The changes to the decoder required a few minor tweaks to a few
targets, where existing brokeness was exposed. In order to keep this
patch small, I left FIXMEs which will be addressed in upcoming
patches. (Except MIPS16, since its object file emission/decoding is
totally broken).

Differential Revision: https://reviews.llvm.org/D137653

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
index cb2a0c4..b4e6b32 100644
--- a/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
+++ b/llvm/lib/Target/ARM/Disassembler/ARMDisassembler.cpp
@@ -629,6 +629,9 @@ static DecodeStatus DecodeVPTMaskOperand(MCInst &Inst, unsigned Val,
 static DecodeStatus DecodeVpredROperand(MCInst &Inst, unsigned Val,
                                         uint64_t Address,
                                         const MCDisassembler *Decoder);
+static DecodeStatus DecodeVpredNOperand(MCInst &Inst, unsigned Val,
+                                        uint64_t Address,
+                                        const MCDisassembler *Decoder);
 static DecodeStatus
 DecodeRestrictedIPredicateOperand(MCInst &Inst, unsigned Val, uint64_t Address,
                                   const MCDisassembler *Decoder);
@@ -6544,6 +6547,17 @@ static DecodeStatus DecodeVpredROperand(MCInst &Inst, unsigned RegNo,
   return MCDisassembler::Success;
 }
 
+[[maybe_unused]] static DecodeStatus
+DecodeVpredNOperand(MCInst &Inst, unsigned RegNo, uint64_t Address,
+                    const MCDisassembler *Decoder) {
+  // Similar to above, we want to ensure that no operands are added for the
+  // vpred operands. (This is marked "maybe_unused" for the moment; because
+  // DecoderEmitter currently (wrongly) omits operands with no instruction bits,
+  // the decoder doesn't actually call it yet. That will be addressed in a
+  // future change.)
+  return MCDisassembler::Success;
+}
+
 static DecodeStatus
 DecodeRestrictedIPredicateOperand(MCInst &Inst, unsigned Val, uint64_t Address,
                                   const MCDisassembler *Decoder) {