[AIX][TLS] Relax front end diagnostics to accept the local-exec TLS model

[amyk]

Summary

This patch relaxes the front end AIX diagnostics added in D102070 to accept the
local-exec TLS model, as we plan to support this model in a series of future patches.

The diagnostics are relaxed when local-exec is used as a compiler option to -ftls-model=*
and in the __attribute__((tls_model("local-exec"))) attribute.

[aaron.ballman]

LGTM!

clang/lib/Frontend/CompilerInvocation.cpp

if (A->getOption().matches(OPT_mlink_builtin_bitcode)) {
       F.Internalize = true;
     }
     Opts.LinkBitcodeFiles.push_back(F);
   }
 
   if (Arg *A = Args.getLastArg(OPT_ftlsmodel_EQ)) {
     if (T.isOSAIX()) {
       StringRef Name = A->getValue();
-      if (Name != "global-dynamic")
+      if (Name != "global-dynamic" && Name != "local-exec")
         Diags.Report(diag::err_aix_unsupported_tls_model) << Name;
     }
   }
 
   if (Arg *A = Args.getLastArg(OPT_fdenormal_fp_math_EQ)) {
     StringRef Val = A->getValue();
     Opts.FPDenormalMode = llvm::parseDenormalFPAttribute(Val);
     Opts.FP32DenormalMode = Opts.FPDenormalMode;

clang/lib/Sema/SemaDeclAttr.cpp

static void handleTLSModelAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   // Check that the value.
   if (Model != "global-dynamic" && Model != "local-dynamic"
       && Model != "initial-exec" && Model != "local-exec") {
     S.Diag(LiteralLoc, diag::err_attr_tlsmodel_arg);
     return;
   }
 
   if (S.Context.getTargetInfo().getTriple().isOSAIX() &&
-      Model != "global-dynamic") {
+      Model != "global-dynamic" && Model != "local-exec") {
     S.Diag(LiteralLoc, diag::err_aix_attr_unsupported_tls_model) << Model;
     return;
   }
 
   D->addAttr(::new (S.Context) TLSModelAttr(S.Context, AL, Model));
 }
 
 static void handleRestrictAttr(Sema &S, Decl *D, const ParsedAttr &AL) {

clang/test/CodeGen/PowerPC/aix-tls-model.cpp

 // RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
 // RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=global-dynamic -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
 // RUN: not %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=local-dynamic -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-LD-ERROR
 // RUN: not %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=initial-exec -emit-llvm  2>&1 | FileCheck %s -check-prefix=CHECK-IE-ERROR
-// RUN: not %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=local-exec -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-LE-ERROR
+// RUN: %clang_cc1 %s -triple powerpc-unknown-aix -target-cpu pwr8 -ftls-model=local-exec -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-LE
 // RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
 // RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=global-dynamic -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-GD
 // RUN: not %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=local-dynamic -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-LD-ERROR
 // RUN: not %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=initial-exec -emit-llvm  2>&1 | FileCheck %s -check-prefix=CHECK-IE-ERROR
-// RUN: not %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=local-exec -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-LE-ERROR
+// RUN: %clang_cc1 %s -triple powerpc64-unknown-aix -target-cpu pwr8 -ftls-model=local-exec -emit-llvm -o - | FileCheck %s -check-prefix=CHECK-LE
 
 int z1 = 0;
 int z2;
 int __thread x;
 int f() {
   static int __thread y;
   return y++;
 }
 
 // CHECK-GD: @z1 ={{.*}} global i32 0
 // CHECK-GD: @z2 ={{.*}} global i32 0
 // CHECK-GD: @x ={{.*}} thread_local global i32 0
 // CHECK-GD: @_ZZ1fvE1y = internal thread_local global i32 0
 // CHECK-LD-ERROR:  error: TLS model 'local-dynamic' is not yet supported on AIX
 // CHECK-IE-ERROR:  error: TLS model 'initial-exec' is not yet supported on AIX
-// CHECK-LE-ERROR:  error: TLS model 'local-exec' is not yet supported on AIX
+// CHECK-LE: @z1 ={{.*}} global i32 0
+// CHECK-LE: @z2 ={{.*}} global i32 0
+// CHECK-LE: @x ={{.*}} thread_local(localexec) global i32 0
+// CHECK-LE: @_ZZ1fvE1y = internal thread_local(localexec) global i32 0

clang/test/Sema/aix-attr-tls_model.c

 // RUN: %clang_cc1 -triple powerpc64-unknown-aix -target-cpu pwr8 -verify -fsyntax-only %s
 // RUN: %clang_cc1 -triple powerpc-unknown-aix -target-cpu pwr8 -verify -fsyntax-only %s
 
 #if !__has_attribute(tls_model)
 #error "Should support tls_model attribute"
 #endif
 
 static __thread int y __attribute((tls_model("global-dynamic"))); // no-warning
 static __thread int y __attribute((tls_model("local-dynamic"))); // expected-error {{TLS model 'local-dynamic' is not yet supported on AIX}}
 static __thread int y __attribute((tls_model("initial-exec"))); // expected-error {{TLS model 'initial-exec' is not yet supported on AIX}}
-static __thread int y __attribute((tls_model("local-exec"))); // expected-error {{TLS model 'local-exec' is not yet supported on AIX}}
+static __thread int y __attribute((tls_model("local-exec"))); // no-warning