[ThinLTO][AIX] Enable thinLTO on AIX

[w2yehia]

Summary

Starting from AIX 7.2 TL5 SP6 and AIX 7.3 TODO the system linker supports thinLTO.

[ZarkoCA]

Personal preference style nit but LGTM.

clang/lib/Driver/ToolChains/CommonArgs.cpp

674–677

Above is a refactor nit.

[w2yehia]

clang/lib/Driver/ToolChains/CommonArgs.cpp

674–677

I wanted to avoid touching the CmdArgs.push_bac... line to preserve git blame. Also, the suggested version is more lines.

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() && 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/lib/Driver/ToolChains/CommonArgs.cpp

if (!OOpt.empty()) {
         CmdArgs.push_back(Args.MakeArgString(Twine("--lto-CGO") + OOpt));
     }
   }
 
   if (Args.hasArg(options::OPT_gsplit_dwarf))
     CmdArgs.push_back(Args.MakeArgString(
         Twine(PluginOptPrefix) + "dwo_dir=" + Output.getFilename() + "_dwo"));
 
-  if (IsThinLTO)
+  if (IsThinLTO && !IsOSAIX)
     CmdArgs.push_back(Args.MakeArgString(Twine(PluginOptPrefix) + "thinlto"));
+  else if (IsThinLTO && IsOSAIX)
+    CmdArgs.push_back(Args.MakeArgString(Twine("-bdbg:thinlto")));
+
 
   StringRef Parallelism = getLTOParallelism(Args, D);
   if (!Parallelism.empty())
     CmdArgs.push_back(
         Args.MakeArgString(Twine(PluginOptPrefix) + "jobs=" + Parallelism));
 
   // If an explicit debugger tuning argument appeared, pass it along.
   if (Arg *A =

clang/test/CodeGen/thinlto-backend-option.ll

 ; Test to ensure -mllvm work when invoking the ThinLTO backend path.
 
 ; This test uses a non-existent backend option to test that backend options are
 ; being parsed. While it's more important that the existing options are parsed
 ; than that this error is produced, this provides a reliable way to test this
 ; scenario independent of any particular backend options that may exist now or
 ; in the future.
 
-; XFAIL: target={{.*}}-aix{{.*}}
-
 ; RUN: %clang -flto=thin -c -o %t.o %s
 ; RUN: llvm-lto -thinlto -o %t %t.o
 ; RUN: not %clang_cc1 -x ir %t.o -fthinlto-index=%t.thinlto.bc -mllvm -nonexistent -emit-obj -o /dev/null 2>&1 | FileCheck %s -check-prefix=UNKNOWN
 ; UNKNOWN: clang (LLVM option parsing): Unknown command line argument '-nonexistent'
 
 ; RUN: not %clang_cc1 -flto=thinfoo 2>&1 | FileCheck %s -check-prefix=INVALID
 ; INVALID: error: invalid value 'thinfoo' in '-flto=thinfoo'

clang/test/CodeGen/thinlto-emit-llvm.c

-// XFAIL: target={{.*}}-aix{{.*}}
-
 // Test to ensure -emit-llvm and -emit-llvm-bc work when invoking the
 // ThinLTO backend path.
 // RUN: %clang -O2 %s -flto=thin -c -o %t.o
 // RUN: llvm-lto -thinlto -o %t %t.o
 // RUN: %clang_cc1 -O2 -x ir %t.o -fthinlto-index=%t.thinlto.bc -emit-llvm -o - | FileCheck %s
 // RUN: %clang_cc1 -O2 -x ir %t.o -fthinlto-index=%t.thinlto.bc -emit-llvm-bc -o - | llvm-dis -o - | FileCheck %s
 
 // CHECK: define{{.*}} void @foo()
 void foo(void) {
 }

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'
-

clang/test/Driver/thinlto_backend.c

-// XFAIL: target={{.*}}-aix{{.*}}
-
 // RUN: %clang -O2 %s -flto=thin -c -o %t.o
 // RUN: llvm-lto -thinlto -o %t %t.o
 
 // -fthinlto_index should be passed to cc1
 // RUN: %clang -O2 -o %t1.o -x ir %t.o -c -fthinlto-index=%t.thinlto.bc -### \
 // RUN:     2>&1 | FileCheck %s -check-prefix=CHECK-THINLTOBE-ACTION
 // CHECK-THINLTOBE-ACTION: -fthinlto-index=
 // CHECK-THINLTOBE-ACTION-SAME: {{"?-x"? "?ir"?}}

clang/test/Integration/thinlto_profile_sample_accurate.c

-// XFAIL: target={{.*}}-aix{{.*}}
-
 // Test to ensure -emit-llvm profile-sample-accurate is honored in ThinLTO.
 // RUN: %clang -O2 %s -flto=thin -fprofile-sample-accurate -c -o %t.o
 // RUN: llvm-lto -thinlto -o %t %t.o
 // RUN: %clang_cc1 -O2 -x ir %t.o -fthinlto-index=%t.thinlto.bc -emit-llvm -o - | FileCheck %s
 
 // CHECK: define{{.*}} void @foo()
 // CHECK: attributes{{.*}} "profile-sample-accurate"
 void foo(void) {
 }