[LLVM][LTO][NFC] Resolve FIXME in ThinLTOCodeGenerator.cpp

[gAlfonso-bit]

Summary

Made the complicated if statements into a switch statement.

[steven_wu]

+ mehdi

I think the FIXME is about not duplicating code from LTOCodeGenerator, not how terrible if statement looks.

[steven_wu]

That is said, I am fine with the clean up but this probably doesn't resolve FIXME.

[gAlfonso-bit]

This comment was removed by gAlfonso-bit.

[gAlfonso-bit]

Mirrored changes into LTOCodeGenerator.cpp, since the original code was from there.

[steven_wu]

Can you unify the duplicated code or just put the FIXME back saying need to fix the duplicated code in the future?

Does the original code break any linter? Or it is just an attempt to rewrite the code using switch?

[jrtc27]

llvm/lib/LTO/LTOCodeGenerator.cpp

347 ↗

(On Diff #364993)

You've deleted this

[gAlfonso-bit]

Readded arm64e detection

[gAlfonso-bit]

In D107473#2934894, @steven_wu wrote:

Can you unify the duplicated code or just put the FIXME back saying need to fix the duplicated code in the future?

Does the original code break any linter? Or it is just an attempt to rewrite the code using switch?

Should I just have the logic in a function? If I do, should I assume macOS is the target and cpu is empty or should I add those checks in the function?

llvm/lib/LTO/ThinLTOCodeGenerator.cpp

 #include "llvm/IR/Verifier.h"
 #include "llvm/IRReader/IRReader.h"
 #include "llvm/LTO/LTO.h"
-#include "llvm/LTO/SummaryBasedOptimizations.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/Object/IRObjectFile.h"
 #include "llvm/Passes/PassBuilder.h"

 #include "llvm/Support/Error.h"
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/Path.h"
-#include "llvm/Support/SHA1.h"
 #include "llvm/Support/SmallVectorMemoryBuffer.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Support/ThreadPool.h"

 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)
+    switch (TheTriple.getArch()) {
+    case llvm::Triple::x86_64:
       TMBuilder.MCpu = "core2";
-    else if (TheTriple.getArch() == llvm::Triple::x86)
+      break;
+    case llvm::Triple::x86:
       TMBuilder.MCpu = "yonah";
-    else if (TheTriple.getArch() == llvm::Triple::aarch64 ||
-             TheTriple.getArch() == llvm::Triple::aarch64_32)
+      break;
+    case llvm::Triple::aarch64:
+    case llvm::Triple::aarch64_32:
       TMBuilder.MCpu = "cyclone";
+      break;
+    }
   }
   TMBuilder.TheTriple = std::move(TheTriple);
 }