[PATCH] D56000: [compiler-rt] [xray] Disable alignas() for thread_local objects on NetBSD

[Kamil Rytarowski via Phabricator via cfe-commits]

krytarowski added inline comments.


================
Comment at: lib/xray/xray_basic_logging.cc:58
 
-struct alignas(64) ThreadLocalData {
+struct
+/* TLD is not aligned properly on NetBSD, resulting in segfault */
----------------
mgorny wrote:
> krytarowski wrote:
> > Can we introduce a macro like:
> > 
> > ```
> > #if SANITIZER_NETBSD
> > #define XRAY_TLS_ALIGNAS64 /* Nor supported */
> > #else
> > #define XRAY_TLS_ALIGNED_SUPPORTED
> > #define XRAY_TLS_ALIGNAS64 alignas(64)
> > #endif
> > ```
> > 
> > And later:
> > 
> > ```
> > struct XRAY_TLS_ALIGNAS64 ThreadLocalData {
> > ```
> > 
> > and
> > 
> > ```
> > #ifdef XRAY_TLS_ALIGNED_SUPPORTED
> > static_assert(alignof(ThreadLocalData) >= 64,
> >               "ThreadLocalData must be cache line aligned.");
> > #endif
> > ```
> Maybe. Though i suppose it'd make more sense to make `64` an argument to the macro.
```
#if !SANITIZER_NETBSD
#define XRAY_TLS_ALIGNAS(x) alignas(x)
#endif
```

```
struct XRAY_TLS_ALIGNAS(64) ThreadLocalData {
```

and

```
#ifdef XRAY_TLS_ALIGNAS
static_assert(alignof(ThreadLocalData) >= 64,
              "ThreadLocalData must be cache line aligned.");
#endif
```


Repository:
  rCRT Compiler Runtime

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  https://reviews.llvm.org/D56000/new/

https://reviews.llvm.org/D56000