[clang] [clang] fix uefi target for aarch64 & x86_64 (PR #120632)

[Tristan Ross via cfe-commits]

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@@ -790,7 +790,9 @@ template <typename Target>
 class LLVM_LIBRARY_VISIBILITY UEFITargetInfo : public OSTargetInfo<Target> {
 protected:
   void getOSDefines(const LangOptions &Opts, const llvm::Triple &Triple,
-                    MacroBuilder &Builder) const override {}
+                    MacroBuilder &Builder) const override {
+    Builder.defineMacro("__UEFI__");
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RossComputerGuy wrote:

I'm not familiar with any other toolchains supporting UEFI targets. LLVM would be the first I think. I know zig has some UEFI support but it's based on Windows stuff and they have their own stdlib for the language. But as far as C goes, LLVM would be the first.

https://github.com/llvm/llvm-project/pull/120632