[clang] [llvm] [RISCV] Add support for getHostCPUFeatures using hwprobe (PR #94352)

[Philip Reames via cfe-commits]

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@@ -83,8 +83,14 @@ void riscv::getRISCVTargetFeatures(const Driver &D, const llvm::Triple &Triple,
   // and other features (ex. mirco architecture feature) from mcpu
   if (Arg *A = Args.getLastArg(options::OPT_mcpu_EQ)) {
     StringRef CPU = A->getValue();
-    if (CPU == "native")
+    if (CPU == "native") {
       CPU = llvm::sys::getHostCPUName();
+      llvm::StringMap<bool> HostFeatures;
+      if (llvm::sys::getHostCPUFeatures(HostFeatures))
+        for (auto &F : HostFeatures)
+          Features.push_back(
+              Args.MakeArgString((F.second ? "+" : "-") + F.first()));
+    }
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preames wrote:

Do we also need to update riscv::getRISCVArch?  There's analogous logic there for getting features from mcpu native.

https://github.com/llvm/llvm-project/pull/94352