[lld] [PAC][lld][AArch64][ELF] Support signed TLSDESC (PR #113817)

[Fangrui Song via llvm-commits]

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@@ -1328,6 +1328,20 @@ unsigned RelocationScanner::handleTlsRelocation(RelExpr expr, RelType type,
     return 1;
   }
 
+  // Do not optimize signed TLSDESC (as described in pauthabielf64 to LE/IE).
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MaskRay wrote:

I am concerned that AArch64 AUTH has quite intrusive changes to this function. It seems that we should make this entirely target-specific now.

https://github.com/llvm/llvm-project/pull/113817