[AIX] Diagnose thinLTO usage in clang on AIX.

[Xiangling_L]

clang/lib/Driver/Driver.cpp

4006

I would suggest a better way to specify the target is to use err_drv_unsupported_opt_for_target like above rather than hardcoding.

[w2yehia]

clang/lib/Driver/Driver.cpp

4006

using err_drv_unsupported_opt_for_target requires an option spelling, which implies we need an option present. Here I wanted to diagnose that thinLTO is not supported on AIX regardless of how we reached the decision that LTOMode is LTOK_Thin (for example, maybe -flto will start implying LTOK_Thin)

So we have two options:

1. diagnose thinLTO in general: I can change the diagnostics to the following (which is kinda ugly but couldn't find a shorter way without introducing a new diagnostics message):

Diag(diag::err_drv_clang_unsupported)
    << ("thinLTO on target '" + RawTriple.str() + "'").c_str();

2. diagnose -flto=thin option only:

if (Arg *A = C.getArgs().getLastArg(options::OPT_flto_EQ))
  if (!strcmp(A->getValue(), "thin"))
     Diag(diag::err_drv_unsupported_opt_for_target)
         << (A->getSpelling() + std::string("thin")).c_str() 
         << RawTriple.str();

Please, let me know which you prefer and whether there's another way to do this.
Thanks.

[Xiangling_L]

clang/lib/Driver/Driver.cpp

4006

Thanks for your explanation and all possibilities provided. I think it makes sense to keep what you already have in this patch.
Just one more thing, based on this patch, I think a confusing part is that you put diagnose into aix-err-options.c file but the diagnose is not about which option AIX doesn't support. And as you mentioned, you'd like to diagnose that thinLTO is not supported on AIX regardless of how we reached the decision. Should we create a new test file for it?

[w2yehia]

moved the testcase to its own file as per reviewer's suggestion.

[Xiangling_L]

LGTM. thanks

clang/lib/Driver/Driver.cpp

if (FinalOutput) {
 
     if (NumOutputs > 1) {
       Diag(clang::diag::err_drv_output_argument_with_multiple_files);
       FinalOutput = nullptr;
     }
   }
 
   const llvm::Triple &RawTriple = C.getDefaultToolChain().getTriple();
-  if (RawTriple.isOSAIX())
+  if (RawTriple.isOSAIX()) {
     if (Arg *A = C.getArgs().getLastArg(options::OPT_G))
       Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getSpelling() << RawTriple.str();
+    if (LTOMode == LTOK_Thin)
+      Diag(diag::err_drv_clang_unsupported) << "thinLTO on AIX";
+  }
 
   // Collect the list of architectures.
   llvm::StringSet<> ArchNames;
   if (RawTriple.isOSBinFormatMachO())
     for (const Arg *A : C.getArgs())
       if (A->getOption().matches(options::OPT_arch))
         ArchNames.insert(A->getValue());
 

clang/test/Driver/aix-unsupported-features.c

+// RUN: %clang -target powerpc-ibm-aix-xcoff -### -flto=thin 2>&1 %s | \
+// RUN:   FileCheck --check-prefix=CHECKTHINLTO %s
+// RUN: %clang -target powerpc64-ibm-aix-xcoff -### -flto=thin 2>&1 %s | \
+// RUN:   FileCheck --check-prefix=CHECKTHINLTO %s
+
+// CHECKTHINLTO: error: the clang compiler does not support 'thinLTO on AIX'
+