[lld] [lld][AArch64][ELF][PAC] Support `.relr.auth.dyn` section (PR #87635)

[Daniil Kovalev via llvm-commits]

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@@ -1445,9 +1445,33 @@ template <class ELFT> void Writer<ELFT>::finalizeAddressDependentContent() {
       in.mipsGot->updateAllocSize();
 
     for (Partition &part : partitions) {
+      // The R_AARCH64_AUTH_RELATIVE has a smaller addend field as bits [63:32]
+      // encode the signing schema. We've put relocations in .relr.auth.dyn
+      // during RelocationScanner::processAux, but the target VA for some of
+      // them might be wider than 32 bits. We can only know the final VA at this
+      // point, so move relocations with large values from .relr.auth.dyn to
+      // .rela.dyn.
+      if (part.relrAuthDyn) {
+        auto it = llvm::remove_if(
+            part.relrAuthDyn->relocs, [&part](const RelativeReloc &elem) {
+              const Relocation &reloc = elem.inputSec->relocs()[elem.relocIdx];
+              if (isInt<32>(reloc.sym->getVA(reloc.addend)))
+                return false;
+              part.relaDyn->addReloc({R_AARCH64_AUTH_RELATIVE, elem.inputSec,
+                                      reloc.offset,
+                                      DynamicReloc::AddendOnlyWithTargetVA,
+                                      *reloc.sym, reloc.addend, R_ABS});
+              // See also AArch64::relocate
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kovdan01 wrote:

Moved to the previous one, see e68efcf46ebf0abdeec9f1fd5ed6a14e51e07e42

https://github.com/llvm/llvm-project/pull/87635