[clang][FMV] Allow declaration of function versions in namespaces.

clang/lib/CodeGen/CodeGenModule.cpp

@@ -4150,7 +4150,7 @@ llvm::GlobalValue::LinkageTypes getMultiversionLinkage(CodeGenModule &CGM,
 }
 
 static FunctionDecl *createDefaultTargetVersionFrom(const FunctionDecl *FD) {
-  DeclContext *DeclCtx = FD->getASTContext().getTranslationUnitDecl();
+  auto *DeclCtx = const_cast<DeclContext *>(FD->getDeclContext());
   TypeSourceInfo *TInfo = FD->getTypeSourceInfo();
   StorageClass SC = FD->getStorageClass();
   DeclarationName Name = FD->getNameInfo().getName();

clang/lib/Sema/SemaDecl.cpp

@@ -11868,8 +11868,8 @@ static bool CheckMultiVersionFunction(Sema &S, FunctionDecl *NewFD,
     return false;
 
   if (!OldDecl || !OldDecl->getAsFunction() ||
-      OldDecl->getDeclContext()->getRedeclContext() !=
-          NewFD->getDeclContext()->getRedeclContext()) {
+      !OldDecl->getDeclContext()->getRedeclContext()->Equals(
+          NewFD->getDeclContext()->getRedeclContext())) {
     // If there's no previous declaration, AND this isn't attempting to cause
     // multiversioning, this isn't an error condition.
     if (MVKind == MultiVersionKind::None)

clang/test/CodeGenCXX/fmv-namespace.cpp

@@ -0,0 +1,93 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --check-globals all --include-generated-funcs --version 5
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -emit-llvm %s -o - | FileCheck %s
+
+namespace Name {
+int __attribute((target_version("default"))) foo() { return 0; }
+}
+
+namespace Name {
+int __attribute((target_version("sve"))) foo() { return 1; }
+}
+
+int bar() { return Name::foo(); }
+
+namespace OtherName {
+int __attribute((target_version("sve"))) foo() { return 2; }
+}
+
+int baz() { return OtherName::foo(); }
+
+//.
+// CHECK: @__aarch64_cpu_features = external dso_local global { i64 }
+// CHECK: @_ZN4Name3fooEv.ifunc = weak_odr alias i32 (), ptr @_ZN4Name3fooEv
+// CHECK: @_ZN9OtherName3fooEv.ifunc = weak_odr alias i32 (), ptr @_ZN9OtherName3fooEv
+// CHECK: @_ZN4Name3fooEv = weak_odr ifunc i32 (), ptr @_ZN4Name3fooEv.resolver
+// CHECK: @_ZN9OtherName3fooEv = weak_odr ifunc i32 (), ptr @_ZN9OtherName3fooEv.resolver
+//.
+// CHECK-LABEL: define dso_local noundef i32 @_ZN4Name3fooEv.default(
+// CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    ret i32 0
+//
+//
+// CHECK-LABEL: define dso_local noundef i32 @_ZN4Name3fooEv._Msve(
+// CHECK-SAME: ) #[[ATTR1:[0-9]+]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    ret i32 1
+//
+//
+// CHECK-LABEL: define dso_local noundef i32 @_Z3barv(
+// CHECK-SAME: ) #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[CALL:%.*]] = call noundef i32 @_ZN4Name3fooEv()
+// CHECK-NEXT:    ret i32 [[CALL]]
+//
+//
+// CHECK-LABEL: define weak_odr ptr @_ZN4Name3fooEv.resolver() comdat {
+// CHECK-NEXT:  [[RESOLVER_ENTRY:.*:]]
+// CHECK-NEXT:    call void @__init_cpu_features_resolver()
+// CHECK-NEXT:    [[TMP0:%.*]] = load i64, ptr @__aarch64_cpu_features, align 8
+// CHECK-NEXT:    [[TMP1:%.*]] = and i64 [[TMP0]], 1073741824
+// CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i64 [[TMP1]], 1073741824
+// CHECK-NEXT:    [[TMP3:%.*]] = and i1 true, [[TMP2]]
+// CHECK-NEXT:    br i1 [[TMP3]], label %[[RESOLVER_RETURN:.*]], label %[[RESOLVER_ELSE:.*]]
+// CHECK:       [[RESOLVER_RETURN]]:
+// CHECK-NEXT:    ret ptr @_ZN4Name3fooEv._Msve
+// CHECK:       [[RESOLVER_ELSE]]:
+// CHECK-NEXT:    ret ptr @_ZN4Name3fooEv.default
+//
+//
+// CHECK-LABEL: define dso_local noundef i32 @_ZN9OtherName3fooEv._Msve(
+// CHECK-SAME: ) #[[ATTR1]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    ret i32 2
+//
+//
+// CHECK-LABEL: define dso_local noundef i32 @_Z3bazv(
+// CHECK-SAME: ) #[[ATTR0]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[CALL:%.*]] = call noundef i32 @_ZN9OtherName3fooEv()
+// CHECK-NEXT:    ret i32 [[CALL]]
+//
+//
+// CHECK-LABEL: define weak_odr ptr @_ZN9OtherName3fooEv.resolver() comdat {
+// CHECK-NEXT:  [[RESOLVER_ENTRY:.*:]]
+// CHECK-NEXT:    call void @__init_cpu_features_resolver()
+// CHECK-NEXT:    [[TMP0:%.*]] = load i64, ptr @__aarch64_cpu_features, align 8
+// CHECK-NEXT:    [[TMP1:%.*]] = and i64 [[TMP0]], 1073741824
+// CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i64 [[TMP1]], 1073741824
+// CHECK-NEXT:    [[TMP3:%.*]] = and i1 true, [[TMP2]]
+// CHECK-NEXT:    br i1 [[TMP3]], label %[[RESOLVER_RETURN:.*]], label %[[RESOLVER_ELSE:.*]]
+// CHECK:       [[RESOLVER_RETURN]]:
+// CHECK-NEXT:    ret ptr @_ZN9OtherName3fooEv._Msve
+// CHECK:       [[RESOLVER_ELSE]]:
+// CHECK-NEXT:    ret ptr @_ZN9OtherName3fooEv.default
+//
+//.
+// CHECK: attributes #[[ATTR0]] = { mustprogress noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+// CHECK: attributes #[[ATTR1]] = { mustprogress noinline nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-features"="+fp-armv8,+fullfp16,+neon,+sve" }
+// CHECK: attributes #[[ATTR2:[0-9]+]] = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+//.
+// CHECK: [[META0:![0-9]+]] = !{i32 1, !"wchar_size", i32 4}
+// CHECK: [[META1:![0-9]+]] = !{!"{{.*}}clang version {{.*}}"}
+//.

clang/test/Sema/fmv-namespace.cpp

@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -triple aarch64-linux-gnu  -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+namespace Name {
+int __attribute((target_version("default"))) foo() { return 0; }
+}
+
+namespace Name {
+int __attribute((target_version("sve"))) foo() { return 1; }
+}
+
+int bar() { return Name::foo(); }