[lld] [LLD][ELF][AArch64] Add BTI Aware long branch thunks (PR #108989)

[Fangrui Song via llvm-commits]

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@@ -578,6 +622,48 @@ void AArch64ADRPThunk::addSymbols(ThunkSection &isec) {
   addSymbol("$x", STT_NOTYPE, 0, isec);
 }
 
+void AArch64BTILandingPadThunk::addSymbols(ThunkSection &isec) {
+  addSymbol(saver().save("__AArch64BTIThunk_" + destination.getName()),
+            STT_FUNC, 0, isec);
+  addSymbol("$x", STT_NOTYPE, 0, isec);
+}
+
+InputSection *AArch64BTILandingPadThunk::getTargetInputSection() const {
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MaskRay wrote:

This function is not needed.

Relocations.cpp calls `ts = getISThunkSec(targetsec)` without checking `getTargetInputSection`.

https://github.com/llvm/llvm-project/pull/108989