From b8b40e2fb98895eba6d490afd798794a53529770 Mon Sep 17 00:00:00 2001
From: Jon Roelofs <jonathan_roelofs@apple.com>
Date: Tue, 19 Dec 2023 11:17:04 -0700
Subject: [PATCH] Revert "[builtins][arm64] Implement
 __init_cpu_features_resolver on Apple platforms (#75636)"

This reverts commit 17aa5201710325ac4b8ccc95bb7954fea8e14849.
---
 compiler-rt/lib/builtins/cpu_model/aarch64.c  |  4 +-
 .../builtins/cpu_model/aarch64/fmv/apple.inc  | 69 -------------------
 2 files changed, 1 insertion(+), 72 deletions(-)
 delete mode 100644 compiler-rt/lib/builtins/cpu_model/aarch64/fmv/apple.inc

diff --git a/compiler-rt/lib/builtins/cpu_model/aarch64.c b/compiler-rt/lib/builtins/cpu_model/aarch64.c
index 73e8453e3833ca..3ed2a85e3413a9 100644
--- a/compiler-rt/lib/builtins/cpu_model/aarch64.c
+++ b/compiler-rt/lib/builtins/cpu_model/aarch64.c
@@ -123,9 +123,7 @@ struct {
 
 // The formatter wants to re-order these includes, but doing so is incorrect:
 // clang-format off
-#if defined(__APPLE__)
-#include "aarch64/fmv/apple.inc"
-#elif defined(__FreeBSD__)
+#if defined(__FreeBSD__)
 #include "aarch64/fmv/mrs.inc"
 #include "aarch64/fmv/freebsd.inc"
 #elif defined(__Fuchsia__)
diff --git a/compiler-rt/lib/builtins/cpu_model/aarch64/fmv/apple.inc b/compiler-rt/lib/builtins/cpu_model/aarch64/fmv/apple.inc
deleted file mode 100644
index 79d4ac70bd1b6d..00000000000000
--- a/compiler-rt/lib/builtins/cpu_model/aarch64/fmv/apple.inc
+++ /dev/null
@@ -1,69 +0,0 @@
-#include <TargetConditionals.h>
-#if TARGET_OS_OSX || TARGET_OS_IPHONE
-#include <dispatch/dispatch.h>
-#include <sys/sysctl.h>
-
-static bool isKnownAndSupported(const char *name) {
-  int32_t val = 0;
-  size_t size = sizeof(val);
-  if (sysctlbyname(name, &val, &size, NULL, 0))
-    return false;
-  return val;
-}
-
-void __init_cpu_features_resolver(void) {
-  // On Darwin platforms, this may be called concurrently by multiple threads
-  // because the resolvers that use it are called lazily at runtime (unlike on
-  // ELF platforms, where IFuncs are resolved serially at load time).  This
-  // function's effect on __aarch64_cpu_features should be idempotent, but even
-  // so we need dispatch_once to resolve the race condition.  Dispatch is
-  // available through libSystem, which we need anyway for the sysctl, so this
-  // does not add a new dependency.
-
-  static dispatch_once_t onceToken = 0;
-  dispatch_once(&onceToken, ^{
-    // https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics
-    static struct {
-      const char *sysctl_name;
-      enum CPUFeatures feature;
-    } features[] = {
-        {"hw.optional.arm.FEAT_FlagM", FEAT_FLAGM},
-        {"hw.optional.arm.FEAT_FlagM2", FEAT_FLAGM2},
-        {"hw.optional.arm.FEAT_FHM", FEAT_FP16FML},
-        {"hw.optional.arm.FEAT_DotProd", FEAT_DOTPROD},
-        {"hw.optional.arm.FEAT_RDM", FEAT_RDM},
-        {"hw.optional.arm.FEAT_LSE", FEAT_LSE},
-        {"hw.optional.floatingpoint", FEAT_FP},
-        {"hw.optional.AdvSIMD", FEAT_SIMD},
-        {"hw.optional.armv8_crc32", FEAT_CRC},
-        {"hw.optional.arm.FEAT_SHA1", FEAT_SHA1},
-        {"hw.optional.arm.FEAT_SHA256", FEAT_SHA2},
-        {"hw.optional.arm.FEAT_SHA3", FEAT_SHA3},
-        {"hw.optional.arm.FEAT_AES", FEAT_AES},
-        {"hw.optional.arm.FEAT_PMULL", FEAT_PMULL},
-        {"hw.optional.arm.FEAT_FP16", FEAT_FP16},
-        {"hw.optional.arm.FEAT_DIT", FEAT_DIT},
-        {"hw.optional.arm.FEAT_DPB", FEAT_DPB},
-        {"hw.optional.arm.FEAT_DPB2", FEAT_DPB2},
-        {"hw.optional.arm.FEAT_JSCVT", FEAT_JSCVT},
-        {"hw.optional.arm.FEAT_FCMA", FEAT_FCMA},
-        {"hw.optional.arm.FEAT_LRCPC", FEAT_RCPC},
-        {"hw.optional.arm.FEAT_LRCPC2", FEAT_RCPC2},
-        {"hw.optional.arm.FEAT_FRINTTS", FEAT_FRINTTS},
-        {"hw.optional.arm.FEAT_I8MM", FEAT_I8MM},
-        {"hw.optional.arm.FEAT_BF16", FEAT_BF16},
-        {"hw.optional.arm.FEAT_SB", FEAT_SB},
-        {"hw.optional.arm.FEAT_SPECRES", FEAT_PREDRES},
-        {"hw.optional.arm.FEAT_SSBS", FEAT_SSBS2},
-        {"hw.optional.arm.FEAT_BTI", FEAT_BTI},
-    };
-
-    for (size_t I = 0, E = sizeof(features) / sizeof(features[0]); I != E; ++I)
-      if (isKnownAndSupported(features[I].sysctl_name))
-        __aarch64_cpu_features.features |= (1ULL << features[I].feature);
-
-    __aarch64_cpu_features.features |= (1ULL << FEAT_INIT);
-  });
-}
-
-#endif // TARGET_OS_OSX || TARGET_OS_IPHONE