[Driver] Enable outline atomics for NetBSD/aarch64

[brad0]

It looks like NetBSD 10, 11 and anything newer has the libgcc helper functions.

outline atomics were enabled by default with GCC 10 and newer.

[llvmbot]

@llvm/pr-subscribers-clang-driver

Author: Brad Smith (brad0)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/156143.diff

2 Files Affected:

• (modified) clang/lib/Driver/ToolChains/NetBSD.h (+5)
• (modified) clang/test/Driver/aarch64-features.c (+3)

diff --git a/clang/lib/Driver/ToolChains/NetBSD.h b/clang/lib/Driver/ToolChains/NetBSD.h
index 96303acaa0099..eb34032aa296f 100644
--- a/clang/lib/Driver/ToolChains/NetBSD.h
+++ b/clang/lib/Driver/ToolChains/NetBSD.h
@@ -68,6 +68,11 @@ class LLVM_LIBRARY_VISIBILITY NetBSD : public Generic_ELF {
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
 
+  bool IsAArch64OutlineAtomicsDefault(
+      const llvm::opt::ArgList &Args) const override {
+    return true;
+  }
+
   UnwindTableLevel
   getDefaultUnwindTableLevel(const llvm::opt::ArgList &Args) const override {
     return UnwindTableLevel::Asynchronous;
diff --git a/clang/test/Driver/aarch64-features.c b/clang/test/Driver/aarch64-features.c
index 05dd3bf39fae3..f97e86cbfd96f 100644
--- a/clang/test/Driver/aarch64-features.c
+++ b/clang/test/Driver/aarch64-features.c
@@ -44,6 +44,9 @@
 // RUN: %clang --target=aarch64-windows-gnu -rtlib=compiler-rt \
 // RUN: -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-OUTLINE-ATOMICS-OFF %s
 
+// RUN: %clang --target=aarch64-unknown-netbsd -rtlib=libgcc \
+// RUN: -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-OUTLINE-ATOMICS-ON %s
+
 // RUN: %clang --target=aarch64-unknown-openbsd -rtlib=compiler-rt \
 // RUN: -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-OUTLINE-ATOMICS-ON %s
 

[llvmbot]

@llvm/pr-subscribers-clang

Author: Brad Smith (brad0)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/156143.diff

2 Files Affected:

• (modified) clang/lib/Driver/ToolChains/NetBSD.h (+5)
• (modified) clang/test/Driver/aarch64-features.c (+3)

diff --git a/clang/lib/Driver/ToolChains/NetBSD.h b/clang/lib/Driver/ToolChains/NetBSD.h
index 96303acaa0099..eb34032aa296f 100644
--- a/clang/lib/Driver/ToolChains/NetBSD.h
+++ b/clang/lib/Driver/ToolChains/NetBSD.h
@@ -68,6 +68,11 @@ class LLVM_LIBRARY_VISIBILITY NetBSD : public Generic_ELF {
       const llvm::opt::ArgList &DriverArgs,
       llvm::opt::ArgStringList &CC1Args) const override;
 
+  bool IsAArch64OutlineAtomicsDefault(
+      const llvm::opt::ArgList &Args) const override {
+    return true;
+  }
+
   UnwindTableLevel
   getDefaultUnwindTableLevel(const llvm::opt::ArgList &Args) const override {
     return UnwindTableLevel::Asynchronous;
diff --git a/clang/test/Driver/aarch64-features.c b/clang/test/Driver/aarch64-features.c
index 05dd3bf39fae3..f97e86cbfd96f 100644
--- a/clang/test/Driver/aarch64-features.c
+++ b/clang/test/Driver/aarch64-features.c
@@ -44,6 +44,9 @@
 // RUN: %clang --target=aarch64-windows-gnu -rtlib=compiler-rt \
 // RUN: -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-OUTLINE-ATOMICS-OFF %s
 
+// RUN: %clang --target=aarch64-unknown-netbsd -rtlib=libgcc \
+// RUN: -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-OUTLINE-ATOMICS-ON %s
+
 // RUN: %clang --target=aarch64-unknown-openbsd -rtlib=compiler-rt \
 // RUN: -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-OUTLINE-ATOMICS-ON %s
 

[brad0]

cc @0-wiz-0

[0-wiz-0]

I am not running an aarch64 machine, but I've asked for testers on the mailing list:
https://mail-index.netbsd.org/port-arm/2025/08/30/msg009377.html

[brad0]

I am not running an aarch64 machine, but I've asked for testers on the mailing list: https://mail-index.netbsd.org/port-arm/2025/08/30/msg009377.html

Thanks. Just looking for testing and feedback.

[bsiegert]

I can test this. How do I find out if it works? Would it just fail to compile if not?

[mgorny]

I'm sorry but I'm not doing NetBSD anymore, and I don't think I can contribute any useful feedback to this. I think you need someone who understands toolchain better than I do.

[brad0]

I'm sorry but I'm not doing NetBSD anymore, and I don't think I can contribute any useful feedback to this. I think you need someone who understands toolchain better than I do.

Thanks for letting me know.

[0-wiz-0]

@brad0
Can you please let us know what kind of feedback you're interested in?
Build testing?
Code review?
Runtime testing - what in particular?
Thanks.