[llvm] [JITLink][AArch32] Add TableGen Backend for Instr Encodings (PR #76996)

[Stefan Gränitz via llvm-commits]

================
@@ -164,17 +164,77 @@ struct HalfWords {
   const uint16_t Lo; // Second halfword
 };
 
+enum InstrName {
+
+#define GET_INSTR(name, opcode, opcode_mask, imm_mask, reg_mask) name,
+
+#include "llvm/ExecutionEngine/JITLink/JITLinkAArch32.inc"
+#undef GET_INSTR
+  INSTR_COUNT,
+  NONE = INSTR_COUNT,
+};
+
+constexpr InstrName getInstrFromJITLinkEdgeKind(Edge::Kind Kind) {
+  switch (Kind) {
+  case Arm_Call:
+    return InstrName::NONE;
+  case aarch32::Arm_Jump24:
+    return InstrName::NONE;
+  case aarch32::Arm_MovwAbsNC:
+    return InstrName::MOVi16;
+  case aarch32::Arm_MovtAbs:
+    return InstrName::MOVTi16;
+  case aarch32::Thumb_Call:
+    return InstrName::NONE;
+  case aarch32::Thumb_Jump24:
+    return InstrName::NONE;
+  case aarch32::Thumb_MovwAbsNC:
+  case aarch32::Thumb_MovwPrelNC:
+    return InstrName::t2MOVi16;
+  case aarch32::Thumb_MovtAbs:
+  case aarch32::Thumb_MovtPrel:
+    return InstrName::t2MOVTi16;
+  default:
+    return InstrName::NONE;
+  }
+}
+
+struct InstrInfo {
+  uint32_t Opcode;
+  uint32_t OpcodeMask;
+  uint32_t ImmMask;
+  uint32_t RegMask;
+};
+
+static constexpr InstrInfo InstrTable[INSTR_COUNT] = {
+#define GET_INSTR(name, opcode, opcode_mask, imm_mask, reg_mask)               \
+  {opcode, opcode_mask, imm_mask, reg_mask},
+#include "llvm/ExecutionEngine/JITLink/JITLinkAArch32.inc"
+#undef GET_INSTR
+};
+
 /// FixupInfo base class is required for dynamic lookups.
 struct FixupInfoBase {
   static const FixupInfoBase *getDynFixupInfo(Edge::Kind K);
   virtual ~FixupInfoBase() {}
 };
 
-/// FixupInfo checks for Arm edge kinds work on 32-bit words
-struct FixupInfoArm : public FixupInfoBase {
+struct FixupInfoArmBase : public FixupInfoBase {
   bool (*checkOpcode)(uint32_t Wd) = nullptr;
 };
 
+/// FixupInfo checks for Arm edge kinds work on 32-bit words
+template <EdgeKind_aarch32 Kind> struct FixupInfoArm : public FixupInfoArmBase {
+  static constexpr uint32_t Opcode =
+      InstrTable[getInstrFromJITLinkEdgeKind(Kind)].Opcode;
----------------
weliveindetail wrote:

Can we turn these into something like `getTableGenInfoArm(Kind).Opcode`? Then `getInstrFromJITLinkEdgeKind()` could become an implementation detail and for Thumb we can also convert to `HalfWords` in there.

https://github.com/llvm/llvm-project/pull/76996