[AIX] Improve option processing for mabi=vec-extabi and mabi=vec=defaul

[ZarkoCA]

Summary

Opening this revision to better address comments by @hubert.reinterpretcast in https://reviews.llvm.org/rGcaaaebcde462

[hubert.reinterpretcast]

LGTM; thanks!

clang/lib/Driver/ToolChains/Clang.cpp

for (const Arg *A : Args.filtered(options::OPT_frewrite_map_file,
       } else {
         CmdArgs.push_back("-frewrite-map-file");
         CmdArgs.push_back(A->getValue());
         A->claim();
       }
     }
   }
 
-  if (Triple.isOSAIX() && Args.hasArg(options::OPT_maltivec)) {
-    if (Args.getLastArg(options::OPT_mabi_EQ_vec_extabi)) {
-      CmdArgs.push_back("-mabi=vec-extabi");
-    } else {
-      D.Diag(diag::err_aix_default_altivec_abi);
-    }
-  }
-
   if (Arg *A = Args.getLastArg(options::OPT_mabi_EQ_vec_extabi,
                                options::OPT_mabi_EQ_vec_default)) {
     if (!Triple.isOSAIX())
       D.Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getSpelling() << RawTriple.str();
-    if (A->getOption().getID() == options::OPT_mabi_EQ_vec_default)
-      D.Diag(diag::err_aix_default_altivec_abi);
     if (A->getOption().getID() == options::OPT_mabi_EQ_vec_extabi)
       CmdArgs.push_back("-mabi=vec-extabi");
+    else
+      D.Diag(diag::err_aix_default_altivec_abi);
   }
 
   if (Arg *A = Args.getLastArg(options::OPT_Wframe_larger_than_EQ)) {
     StringRef v = A->getValue();
     CmdArgs.push_back("-mllvm");
     CmdArgs.push_back(Args.MakeArgString("-warn-stack-size=" + v));
     A->claim();
   }

clang/test/CodeGen/altivec.c

 // RUN: %clang_cc1 -target-feature +altivec -triple powerpc-unknown-unknown -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-BE
 // RUN: %clang_cc1 -target-feature +altivec -triple powerpcle-unknown-unknown -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-LE
 // RUN: %clang_cc1 -target-feature +altivec -triple powerpc64-unknown-unknown -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-BE
 // RUN: %clang_cc1 -target-feature +altivec -triple powerpc64le-unknown-unknown -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-LE
 // RUN: %clang_cc1 -target-feature +altivec -mabi=vec-extabi -target-cpu pwr8 -triple powerpc-unknown-aix -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-BE
 // RUN: %clang_cc1 -target-feature +altivec -mabi=vec-extabi -target-cpu pwr8 -triple powerpc64-unknown-aix -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-BE
 // RUN: not %clang_cc1 -target-feature +altivec -mabi=vec-default -target-cpu pwr8 -triple powerpc-unknown-aix -emit-llvm %s 2>&1 | FileCheck %s --check-prefix=AIX-ERROR
 // RUN: not %clang_cc1 -target-feature +altivec -mabi=vec-default -target-cpu pwr8 -triple powerpc64-unknown-aix -emit-llvm %s 2>&1 | FileCheck %s --check-prefix=AIX-ERROR
-
-// RUN: not %clang -S -emit-llvm -maltivec -mcpu=pwr8 -target powerpc-unknown-aix %s 2>&1 | FileCheck %s --check-prefix=AIX-ERROR
-// RUN: not %clang -S -emit-llvm -maltivec -mcpu=pwr8 -target powerpc64-unknown-aix %s 2>&1 | FileCheck %s --check-prefix=AIX-ERROR 
 // RUN: %clang -S -emit-llvm -maltivec -mabi=vec-extabi -mcpu=pwr8 -target powerpc-unknown-aix %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-BE
 // RUN: %clang -S -emit-llvm -maltivec -mabi=vec-extabi -mcpu=pwr8 -target powerpc64-unknown-aix %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-BE
 // RUN: not %clang -S -emit-llvm -maltivec -mabi=vec-default -mcpu=pwr8 -triple powerpc-unknown-aix -emit-llvm %s 2>&1 | FileCheck %s --check-prefix=AIX-ERROR
 // RUN: not %clang -S -emit-llvm -maltivec -mabi=vec-default -mcpu=pwr8 -triple powerpc64-unknown-aix -emit-llvm %s 2>&1 | FileCheck %s --check-prefix=AIX-ERROR
 // Check initialization
 
 vector int test0 = (vector int)(1);       // CHECK: @test0 ={{.*}} global <4 x i32> <i32 1, i32 1, i32 1, i32 1>
 vector float test1 = (vector float)(1.0); // CHECK: @test1 ={{.*}} global <4 x float> <float 1.000000e+{{0+}}, float 1.000000e+{{0+}}, float 1.000000e+{{0+}}, float 1.000000e+{{0+}}>