[lld] [lld][Hexagon] Fix TLS GD PLT to only create PLT entry for __tls_get_addr (PR #180297)

[Fangrui Song via llvm-commits]

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@@ -978,7 +978,25 @@ void RelocScan::process(RelExpr expr, RelType type, uint64_t offset,
         sym.setFlags(NEEDS_GOT | NEEDS_GOT_NONAUTH);
     }
   } else if (needsPlt(expr)) {
-    sym.setFlags(NEEDS_PLT);
+    // For Hexagon TLS GD PLT relocations (call foo at GDPLT), the PLT entry should
+    // be for __tls_get_addr, not the TLS symbol. Create __tls_get_addr here
+    // with NEEDS_PLT so its PLT entry is created during postScanRelocations.
+    // hexagonTLSSymbolUpdate() will rebind the relocations later.
+    if (ctx.arg.emachine == EM_HEXAGON && sym.isTls() &&
+        (type == R_HEX_GD_PLT_B22_PCREL || type == R_HEX_GD_PLT_B22_PCREL_X ||
+         type == R_HEX_GD_PLT_B32_PCREL_X)) {
+      Symbol *s = ctx.symtab->find("__tls_get_addr");
+      if (!s) {
+        s = ctx.symtab->addSymbol(Undefined{ctx.internalFile, "__tls_get_addr",
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MaskRay wrote:

Relocation scanning is parallel, so adding a symbol to `ctx.symtab` is unsafe.

If you need custom logic, do it in Hexagon.cpp instead of in this generic code. I've created #181596 to isolate target-specific special cases.

https://github.com/llvm/llvm-project/pull/180297