[lld] [LLD][COFF] Add basic ARM64X dynamic relocations support (PR #118035)

[Jacek Caban via llvm-commits]

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@@ -1147,4 +1148,81 @@ uint32_t ImportThunkChunkARM64EC::extendRanges() {
   return sizeof(arm64Thunk) - sizeof(uint32_t);
 }
 
+size_t Arm64XDynamicRelocEntry::getSize() const {
+  switch (type) {
+  case IMAGE_DVRT_ARM64X_FIXUP_TYPE_VALUE:
+    return sizeof(uint16_t) + size; // A header and a payload.
+  case IMAGE_DVRT_ARM64X_FIXUP_TYPE_DELTA:
+  case IMAGE_DVRT_ARM64X_FIXUP_TYPE_ZEROFILL:
+    llvm_unreachable("unsupported type");
+  }
+}
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cjacek wrote:

I created #122382 for a fix, sorry about that. The current `llvm_unreachable()` will be removed one ARM64X support is more complete. Those two reloc types are needed for the shared IAT.

https://github.com/llvm/llvm-project/pull/118035