[OpenMP][macOS] Add the implementation of __divdc3 and __divsc3

Apple Silicon macOS doesn't have the two functions coming with their `libgcc`.
This causes a link error when compiling OpenMP. `compiler-rt` has the
implementation of the two functions but users may not always have that enabled,
either when using the system compiler or building LLVM manually.

This patch simply adds the imlementation of the two functions and only includes
them on Apple Silicon macOS.

Fix #54596.

openmp/runtime/src/CMakeLists.txt

@@ -113,6 +113,10 @@ else()
     else()
       libomp_append(LIBOMP_GNUASMFILES z_Linux_asm.S) # Unix assembly file
     endif()
+    # Apple Silicon macOS doesn't have certain functions. We need to implement them.
+    if(APPLE AND ${LIBOMP_ARCH} STREQUAL "aarch64")
+      libomp_append(LIBOMP_GNUASMFILES z_macOS_util.cpp)
+    endif()
   endif()
   libomp_append(LIBOMP_CXXFILES thirdparty/ittnotify/ittnotify_static.cpp LIBOMP_USE_ITT_NOTIFY)
   libomp_append(LIBOMP_CXXFILES kmp_debugger.cpp LIBOMP_USE_DEBUGGER)

openmp/runtime/src/z_macOS_util.cpp

@@ -0,0 +1,102 @@
+/*
+ * z_macOS_util.cpp -- platform specific routines.
+ */
+
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <cmath>
+
+#define _ISNANd std::isnan
+#define _ISNANf std::isnan
+#define _ISINFd std::isinf
+#define _ISINFf std::isinf
+#define _ISFINITEd std::isfinite
+#define _ISFINITEf std::isfinite
+#define _COPYSIGNd std::copysign
+#define _COPYSIGNf std::copysign
+#define _SCALBNd std::scalbn
+#define _SCALBNf std::scalbn
+#define _ABSd std::abs
+#define _ABSf std::abs
+#define _LOGBd std::logb
+#define _LOGBf std::logb
+#define _fmaxd std::fmax
+#define _fmaxf std::fmax
+
+extern "C" {
+
+double _Complex __divdc3(double __a, double __b, double __c, double __d) {
+  int __ilogbw = 0;
+  // Can't use std::max, because that's defined in <algorithm>, and we don't
+  // want to pull that in for every compile.  The CUDA headers define
+  // ::max(float, float) and ::max(double, double), which is sufficient for us.
+  double __logbw = _LOGBd(_fmaxd(_ABSd(__c), _ABSd(__d)));
+  if (_ISFINITEd(__logbw)) {
+    __ilogbw = (int)__logbw;
+    __c = _SCALBNd(__c, -__ilogbw);
+    __d = _SCALBNd(__d, -__ilogbw);
+  }
+  double __denom = __c * __c + __d * __d;
+  double _Complex z;
+  __real__(z) = _SCALBNd((__a * __c + __b * __d) / __denom, -__ilogbw);
+  __imag__(z) = _SCALBNd((__b * __c - __a * __d) / __denom, -__ilogbw);
+  if (_ISNANd(__real__(z)) && _ISNANd(__imag__(z))) {
+    if ((__denom == 0.0) && (!_ISNANd(__a) || !_ISNANd(__b))) {
+      __real__(z) = _COPYSIGNd(__builtin_huge_val(), __c) * __a;
+      __imag__(z) = _COPYSIGNd(__builtin_huge_val(), __c) * __b;
+    } else if ((_ISINFd(__a) || _ISINFd(__b)) && _ISFINITEd(__c) &&
+               _ISFINITEd(__d)) {
+      __a = _COPYSIGNd(_ISINFd(__a) ? 1.0 : 0.0, __a);
+      __b = _COPYSIGNd(_ISINFd(__b) ? 1.0 : 0.0, __b);
+      __real__(z) = __builtin_huge_val() * (__a * __c + __b * __d);
+      __imag__(z) = __builtin_huge_val() * (__b * __c - __a * __d);
+    } else if (_ISINFd(__logbw) && __logbw > 0.0 && _ISFINITEd(__a) &&
+               _ISFINITEd(__b)) {
+      __c = _COPYSIGNd(_ISINFd(__c) ? 1.0 : 0.0, __c);
+      __d = _COPYSIGNd(_ISINFd(__d) ? 1.0 : 0.0, __d);
+      __real__(z) = 0.0 * (__a * __c + __b * __d);
+      __imag__(z) = 0.0 * (__b * __c - __a * __d);
+    }
+  }
+  return z;
+}
+
+float _Complex __divsc3(float __a, float __b, float __c, float __d) {
+  int __ilogbw = 0;
+  float __logbw = _LOGBf(_fmaxf(_ABSf(__c), _ABSf(__d)));
+  if (_ISFINITEf(__logbw)) {
+    __ilogbw = (int)__logbw;
+    __c = _SCALBNf(__c, -__ilogbw);
+    __d = _SCALBNf(__d, -__ilogbw);
+  }
+  float __denom = __c * __c + __d * __d;
+  float _Complex z;
+  __real__(z) = _SCALBNf((__a * __c + __b * __d) / __denom, -__ilogbw);
+  __imag__(z) = _SCALBNf((__b * __c - __a * __d) / __denom, -__ilogbw);
+  if (_ISNANf(__real__(z)) && _ISNANf(__imag__(z))) {
+    if ((__denom == 0) && (!_ISNANf(__a) || !_ISNANf(__b))) {
+      __real__(z) = _COPYSIGNf(__builtin_huge_valf(), __c) * __a;
+      __imag__(z) = _COPYSIGNf(__builtin_huge_valf(), __c) * __b;
+    } else if ((_ISINFf(__a) || _ISINFf(__b)) && _ISFINITEf(__c) &&
+               _ISFINITEf(__d)) {
+      __a = _COPYSIGNf(_ISINFf(__a) ? 1 : 0, __a);
+      __b = _COPYSIGNf(_ISINFf(__b) ? 1 : 0, __b);
+      __real__(z) = __builtin_huge_valf() * (__a * __c + __b * __d);
+      __imag__(z) = __builtin_huge_valf() * (__b * __c - __a * __d);
+    } else if (_ISINFf(__logbw) && __logbw > 0 && _ISFINITEf(__a) &&
+               _ISFINITEf(__b)) {
+      __c = _COPYSIGNf(_ISINFf(__c) ? 1 : 0, __c);
+      __d = _COPYSIGNf(_ISINFf(__d) ? 1 : 0, __d);
+      __real__(z) = 0 * (__a * __c + __b * __d);
+      __imag__(z) = 0 * (__b * __c - __a * __d);
+    }
+  }
+  return z;
+}
+}