[compiler-rt] 4e731ab - [compiler-rt][AArch64] Initialize __aarch64_have_lse_atomics for Fuchsia

[Roland McGrath via llvm-commits]

Author: Roland McGrath
Date: 2022-03-28T11:49:31-07:00
New Revision: 4e731abc55681751b5d736b613f7720e50eb1ad4

URL: https://github.com/llvm/llvm-project/commit/4e731abc55681751b5d736b613f7720e50eb1ad4
DIFF: https://github.com/llvm/llvm-project/commit/4e731abc55681751b5d736b613f7720e50eb1ad4.diff

LOG: [compiler-rt][AArch64] Initialize __aarch64_have_lse_atomics for Fuchsia

Use Fuchsia's zx_system_get_features API to determine
whether LSE atomics are available on the machine.

Reviewed By: abrachet

Differential Revision: https://reviews.llvm.org/D118839

Added: 
    

Modified: 
    compiler-rt/lib/builtins/cpu_model.c

Removed: 
    


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diff  --git a/compiler-rt/lib/builtins/cpu_model.c b/compiler-rt/lib/builtins/cpu_model.c
index c5913f763dd24..7651e84f876c0 100644
--- a/compiler-rt/lib/builtins/cpu_model.c
+++ b/compiler-rt/lib/builtins/cpu_model.c
@@ -801,12 +801,23 @@ _Bool __aarch64_have_lse_atomics
 #if defined(__ANDROID__)
 #include <string.h>
 #include <sys/system_properties.h>
+#elif defined(__Fuchsia__)
+#include <zircon/features.h>
+#include <zircon/syscalls.h>
 #endif
 static void CONSTRUCTOR_ATTRIBUTE init_have_lse_atomics(void) {
 #if defined(__FreeBSD__)
   unsigned long hwcap;
   int result = elf_aux_info(AT_HWCAP, &hwcap, sizeof hwcap);
   __aarch64_have_lse_atomics = result == 0 && (hwcap & HWCAP_ATOMICS) != 0;
+#elif defined(__Fuchsia__)
+  // This ensures the vDSO is a direct link-time dependency of anything that
+  // needs this initializer code.
+#pragma comment(lib, "zircon")
+  uint32_t features;
+  zx_status_t status = _zx_system_get_features(ZX_FEATURE_KIND_CPU, &features);
+  __aarch64_have_lse_atomics =
+      status == ZX_OK && (features & ZX_ARM64_FEATURE_ISA_ATOMICS) != 0;
 #else
   unsigned long hwcap = getauxval(AT_HWCAP);
   _Bool result = (hwcap & HWCAP_ATOMICS) != 0;