[clang] [Clang][BPF] Add __bpf_cpu_version__ macro (PR #71856)

[via cfe-commits]

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@@ -29,6 +29,14 @@ void BPFTargetInfo::getTargetDefines(const LangOptions &Opts,
                                      MacroBuilder &Builder) const {
   Builder.defineMacro("__bpf__");
   Builder.defineMacro("__BPF__");
+
+  std::string CPU = getTargetOpts().CPU;
+  if (CPU == "probe")
+    Builder.defineMacro("__bpf_cpu_version__", "0");
+  else if (CPU.empty() || CPU == "generic")
+    Builder.defineMacro("__bpf_cpu_version__", "1");
+  else
+    Builder.defineMacro("__bpf_cpu_version__", CPU.substr(1));
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yonghong-song wrote:

Some architectures prefer small case (x86, pcc, loongarch, riscv) while some other architectures (arm, etc.) prefer upper case. Yes, we can use capitol cases for all the proposed macros.
For BPF_CPU_VERSION, I would like __BPF_CPU_VERSION. Basically adding '__' as prefix. What do you think?

https://github.com/llvm/llvm-project/pull/71856