[lld] [lld] Add thunks for hexagon (PR #111217)

[Fangrui Song via llvm-commits]

================
@@ -2129,17 +2129,44 @@ void ThunkCreator::mergeThunks(ArrayRef<OutputSection *> outputSections) {
       });
 }
 
-static int64_t getPCBias(Ctx &ctx, RelType type) {
-  if (ctx.arg.emachine != EM_ARM)
-    return 0;
-  switch (type) {
-  case R_ARM_THM_JUMP19:
-  case R_ARM_THM_JUMP24:
-  case R_ARM_THM_CALL:
-    return 4;
-  default:
-    return 8;
+constexpr uint32_t HEXAGON_MASK_END_PACKET = 3 << 14;
+constexpr uint32_t HEXAGON_END_OF_PACKET = 3 << 14;
+constexpr uint32_t HEXAGON_END_OF_DUPLEX = 0 << 14;
+
+// Return the distance between the packet start and the instruction in the
+// relocation.
+static int getHexagonPacketOffset(const InputSection &isec,
+                                  const Relocation &rel) {
+  const ArrayRef<uint8_t> SectContents = isec.content();
----------------
MaskRay wrote:

lld uses the `variableName` naming convention.

The most common convention uses `sec` for InputSection and `data` for section content.
(We use `osec` for `OutputSection`, and `sec` is for InputSection. Some old code might not stick with the convention.)

https://github.com/llvm/llvm-project/pull/111217