Clang/MIPS: computeTargetTriple considering -march option

[wzssyqa]

Summary

If -march=mips32r6 or -march=mips64r6 option is given,
we should set SubArch to llvm::Triple::MipsSubArch_r6.

Thus the default triple will become

mipsisa32r6(el)-*

or

mipsisa64r6(el)-*.

[MaskRay]

Such driver changes without tests cannot be accepted. It's likely someone wants to clean up the code. Without testing they cannot know whether they would break your cases.

[brad]

@wzssyqa You see from the build that one of the tests is currently failing?

[wzssyqa]

OK, Since the CI cannot work with Phabricator shutdown timeline, I will update it and migrate it to GitHub.

[MaskRay]

In D158184#4654953, @wzssyqa wrote:

OK, Since the CI cannot work with Phabricator shutdown timeline, I will update it and migrate it to GitHub.

The CI is shared. You are not forced to migrate. Actually, I think migrating is semi-discouraged.

[jrtc27]

Actually, I think migrating is semi-discouraged.

More than that, there's the big red banner at the top that explicitly says not to do that, which you kindly added to the site after I suggested it to avoid people doing precisely this kind of migration

clang/lib/Driver/Driver.cpp

if (Args.hasFlag(options::OPT_miamcu, options::OPT_mno_iamcu, false)) {
     Target.setOS(llvm::Triple::ELFIAMCU);
     Target.setVendor(llvm::Triple::UnknownVendor);
     Target.setVendorName("intel");
   }
 
   // If target is MIPS adjust the target triple
   // accordingly to provided ABI name.
   if (Target.isMIPS()) {
+    if ((A = Args.getLastArg(options::OPT_march_EQ))) {
+      StringRef CPUName = A->getValue();
+      llvm::Triple::SubArchType subarch =
+          llvm::StringSwitch<llvm::Triple::SubArchType>(CPUName)
+              .Cases("mips32r6", "mips64r6", llvm::Triple::MipsSubArch_r6)
+              .Default(llvm::Triple::NoSubArch);
+      Target.setArch(Target.getArch(), subarch);
+    }
     if ((A = Args.getLastArg(options::OPT_mabi_EQ))) {
       StringRef ABIName = A->getValue();
       if (ABIName == "32") {
         Target = Target.get32BitArchVariant();
         if (Target.getEnvironment() == llvm::Triple::GNUABI64 ||
             Target.getEnvironment() == llvm::Triple::GNUABIN32)
           Target.setEnvironment(llvm::Triple::GNU);
       } else if (ABIName == "n32") {