[lld] [LLD][COFF] Use EC symbol table for CHPE metadata (PR #120328)

[Jacek Caban via llvm-commits]

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@@ -2688,6 +2693,21 @@ void Writer::prepareLoadConfig(SymbolTable &symtab, T *loadConfig) {
       loadConfig->DynamicValueRelocTableSection = relocSec->sectionIndex;
       loadConfig->DynamicValueRelocTableOffset =
           ctx.dynamicRelocs->getRVA() - relocSec->getRVA();
+
+      // On ARM64X, only the EC version of the load config contains
+      // CHPEMetadataPointer. Copy its value to the native load config.
+      if (!symtab.isEC() && ctx.hybridSymtab->loadConfigSize >=
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cjacek wrote:

We currently create dynamic relocations only when the target is ARM64X, so checking `hybridSymtab` and `dynamicRelocs` amounts to the same thing. In theory, this could change in the future if we add support for other dynamic relocation types. I'll update it to use a separate branch to avoid relying on this assumption, which should also make the code a bit cleaner.

https://github.com/llvm/llvm-project/pull/120328