[ThinLTO] NFC: Merge duplicated functions together (#82421)

Author: jansvoboda11

llvm/include/llvm/LTO/LTO.h

@@ -75,6 +75,8 @@ void computeLTOCacheKey(
 
 namespace lto {
 
+StringLiteral getThinLTODefaultCPU(const Triple &TheTriple);
+
 /// Given the original \p Path to an output file, replace any path
 /// prefix matching \p OldPrefix with \p NewPrefix. Also, create the
 /// resulting directory if it does not yet exist.

llvm/lib/LTO/LTO.cpp

@@ -1557,6 +1557,21 @@ ThinBackend lto::createInProcessThinBackend(ThreadPoolStrategy Parallelism,
       };
 }
 
+StringLiteral lto::getThinLTODefaultCPU(const Triple &TheTriple) {
+  if (!TheTriple.isOSDarwin())
+    return "";
+  if (TheTriple.getArch() == Triple::x86_64)
+    return "core2";
+  if (TheTriple.getArch() == Triple::x86)
+    return "yonah";
+  if (TheTriple.isArm64e())
+    return "apple-a12";
+  if (TheTriple.getArch() == Triple::aarch64 ||
+      TheTriple.getArch() == Triple::aarch64_32)
+    return "cyclone";
+  return "";
+}
+
 // Given the original \p Path to an output file, replace any path
 // prefix matching \p OldPrefix with \p NewPrefix. Also, create the
 // resulting directory if it does not yet exist.

llvm/lib/LTO/LTOCodeGenerator.cpp

@@ -409,18 +409,8 @@ bool LTOCodeGenerator::determineTarget() {
   SubtargetFeatures Features(join(Config.MAttrs, ""));
   Features.getDefaultSubtargetFeatures(Triple);
   FeatureStr = Features.getString();
-  // Set a default CPU for Darwin triples.
-  if (Config.CPU.empty() && Triple.isOSDarwin()) {
-    if (Triple.getArch() == llvm::Triple::x86_64)
-      Config.CPU = "core2";
-    else if (Triple.getArch() == llvm::Triple::x86)
-      Config.CPU = "yonah";
-    else if (Triple.isArm64e())
-      Config.CPU = "apple-a12";
-    else if (Triple.getArch() == llvm::Triple::aarch64 ||
-             Triple.getArch() == llvm::Triple::aarch64_32)
-      Config.CPU = "cyclone";
-  }
+  if (Config.CPU.empty())
+    Config.CPU = lto::getThinLTODefaultCPU(Triple);
 
   // If data-sections is not explicitly set or unset, set data-sections by
   // default to match the behaviour of lld and gold plugin.

llvm/lib/LTO/ThinLTOCodeGenerator.cpp

@@ -539,17 +539,8 @@ static void resolvePrevailingInIndex(
 // Initialize the TargetMachine builder for a given Triple
 static void initTMBuilder(TargetMachineBuilder &TMBuilder,
                           const Triple &TheTriple) {
-  // Set a default CPU for Darwin triples (copied from LTOCodeGenerator).
-  // FIXME this looks pretty terrible...
-  if (TMBuilder.MCpu.empty() && TheTriple.isOSDarwin()) {
-    if (TheTriple.getArch() == llvm::Triple::x86_64)
-      TMBuilder.MCpu = "core2";
-    else if (TheTriple.getArch() == llvm::Triple::x86)
-      TMBuilder.MCpu = "yonah";
-    else if (TheTriple.getArch() == llvm::Triple::aarch64 ||
-             TheTriple.getArch() == llvm::Triple::aarch64_32)
-      TMBuilder.MCpu = "cyclone";
-  }
+  if (TMBuilder.MCpu.empty())
+    TMBuilder.MCpu = lto::getThinLTODefaultCPU(TheTriple);
   TMBuilder.TheTriple = std::move(TheTriple);
 }