Fix warnings about the `native` target-cpu

This fixes a regression from #53031 where specifying `-C target-cpu=native` is
printing a lot of warnings from LLVM about `native` being an unknown CPU. It
turns out that `native` is indeed an unknown CPU and we have to perform a
mapping to an actual CPU name, but this mapping is only performed in one
location rather than all locations we inform LLVM about the target CPU.

This commit centralizes the mapping of `native` to LLVM's value of the native
CPU, ensuring that all locations we inform LLVM about the `target-cpu` it's
never `native`.

Closes #53322

1 files changed, 7 insertions, 6 deletions

diff --git a/src/rustllvm/PassWrapper.cpp b/src/rustllvm/PassWrapper.cpp
index 46825efeee2..09befdaae37 100644
--- a/src/rustllvm/PassWrapper.cpp
+++ b/src/rustllvm/PassWrapper.cpp
@@ -359,6 +359,12 @@ extern "C" void LLVMRustPrintTargetFeatures(LLVMTargetMachineRef) {
 }
 #endif
 
+extern "C" const char* LLVMRustGetHostCPUName(size_t *len) {
+  StringRef Name = sys::getHostCPUName();
+  *len = Name.size();
+  return Name.data();
+}
+
 extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     const char *TripleStr, const char *CPU, const char *Feature,
     LLVMRustCodeModel RustCM, LLVMRustRelocMode RustReloc,
@@ -381,11 +387,6 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
     return nullptr;
   }
 
-  StringRef RealCPU = CPU;
-  if (RealCPU == "native") {
-    RealCPU = sys::getHostCPUName();
-  }
-
   TargetOptions Options;
 
   Options.FloatABIType = FloatABI::Default;
@@ -417,7 +418,7 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine(
   if (RustCM != LLVMRustCodeModel::None)
     CM = fromRust(RustCM);
   TargetMachine *TM = TheTarget->createTargetMachine(
-      Trip.getTriple(), RealCPU, Feature, Options, RM, CM, OptLevel);
+      Trip.getTriple(), CPU, Feature, Options, RM, CM, OptLevel);
   return wrap(TM);
 }