[PATCH 0/1] MR2158: ntdll: Fix compile error on ARM64 macOS.

[Brendan Shanks (＠bshanks)]

Fix the error:
```
<inline asm>:305:2: error: conditional branch requires assembler-local label. '.L__wine_syscall_dispatcher_return' is external.
        cbnz w16, .L__wine_syscall_dispatcher_return
```

I don't know why LLVM/clang on macOS requires a local label for conditional branches.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54256

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/2158

[PATCH 1/1] ntdll: Fix compile error on ARM64 macOS.

[Brendan Shanks]

From: Brendan Shanks <bshanks(a)codeweavers.com>

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=54256
---
 dlls/ntdll/unix/signal_arm64.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/dlls/ntdll/unix/signal_arm64.c b/dlls/ntdll/unix/signal_arm64.c
index bd9818c808a..2684c1dcb67 100644
--- a/dlls/ntdll/unix/signal_arm64.c
+++ b/dlls/ntdll/unix/signal_arm64.c
@@ -1607,8 +1607,9 @@ __ASM_GLOBAL_FUNC( __wine_unix_call_dispatcher,
                    "mov x0, x2\n\t"             /* args */
                    "blr x16\n\t"
                    "ldr w16, [sp, #0x10c]\n\t"  /* frame->restore_flags */
-                   "cbnz w16, .L__wine_syscall_dispatcher_return\n\t"
-                   "ldr x18, [sp, #0x90]\n\t"
+                   "cbz w16, 1f\n\t"
+                   "b .L__wine_syscall_dispatcher_return\n"
+                   "1:\tldr x18, [sp, #0x90]\n\t"
                    "ldp x16, x17, [sp, #0xf8]\n\t"
                    "mov sp, x16\n\t"
                    "ret x17" )
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/2158

[Martin Storsjö]

> I don't know why LLVM/clang on macOS requires a local label for conditional branches.

I believe the issue is the other way around - it does require a local label for conditional branches everywhere. It's just that the definition of what is a local label is platform dependent.

On macOS/MachO, extern C symbols are all prefixed with an underscore. Local labels are symbols that don't start with an underscore, but starts with a capital `L`. This is contrary to ELF where local labels are identifiers that start with a period `.`.

I guess the proper way to handle this is to wrap this up in a macro or function, like how many other similar details are handled elsewhere.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/2158#note_23774

[Jason Millard (＠jsm174)]

Thanks for this fix. Really helped me out!

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/2158#note_24145