[clang] [llvm] [LFI][X86] Add X86 LFI target and system instruction rewrites (PR #189569)

[Fangrui Song via cfe-commits]

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@@ -1245,7 +1249,8 @@ class Triple {
 
   /// True if the target uses TLSDESC by default.
   bool hasDefaultTLSDESC() const {
-    return isAArch64() || (isAndroid() && isRISCV64()) || isOSFuchsia();
+    return isAArch64() || (isAndroid() && isRISCV64()) || isOSFuchsia() ||
+           (isX86() && isLFI());
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MaskRay wrote:

Why? Should at least be mentioned in the PR description

https://github.com/llvm/llvm-project/pull/189569