[compiler-rt] [compiler-rt][builtins][test][darwin] Fix some compiler-rt builtins tests on Apple platforms (PR #207895)

[Ian Anderson via llvm-commits]

https://github.com/ian-twilightcoder created https://github.com/llvm/llvm-project/pull/207895

Skip the rounding mode parts of scalbn{f} due to underflow behavior in libm.

Mark enable_execute_stack_test.c unsupported on Apple arm64 platforms because they don't support an executable stack.

Assisted-by: Claude Code

>From b577d43909e02d8f310af6411df79e54a83910e5 Mon Sep 17 00:00:00 2001
From: Ian Anderson <iana at apple.com>
Date: Mon, 6 Jul 2026 16:31:13 -0700
Subject: [PATCH] [compiler-rt][builtins][test][darwin] Fix some compiler-rt
 builtins tests on Apple platforms

Skip the rounding mode parts of scalbn{f} due to underflow behavior in libm.

Mark enable_execute_stack_test.c unsupported on Apple arm64 platforms because they don't support an executable stack.

Assisted-by: Claude Code
---
 compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c   | 4 +++-
 compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c  | 4 +++-
 compiler-rt/test/builtins/Unit/enable_execute_stack_test.c | 3 +++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c
index 9124601c0bb2e..18e886b502650 100644
--- a/compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_scalbn_test.c
@@ -63,11 +63,13 @@ int main() {
     defined(__i386__) || defined(__x86_64__)
 // Skip these tests on Windows because the UCRT scalbn function always behaves
 // as if the default rounding mode is set (FE_TONEAREST).
+// Also skip on Apple because the libm scalbn flushes underflow to zero
+// regardless of the rounding mode.
 // Also skip for newlib because although its scalbn function does respect the
 // rounding mode, where the tests trigger an underflow or overflow using a
 // large exponent the result is rounded in the opposite direction to that which
 // would be expected in the (FE_UPWARD) and (FE_DOWNWARD) modes.
-#  if !defined(_WIN32) && !defined(_NEWLIB_VERSION)
+#  if !defined(_WIN32) && !defined(__APPLE__) && !defined(_NEWLIB_VERSION)
   fesetround(FE_UPWARD);
   if (iterate_cases("FE_UPWARD")) return 1;
 
diff --git a/compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c b/compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c
index 3ffdde6aed3f2..1debed725fc38 100644
--- a/compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c
+++ b/compiler-rt/test/builtins/Unit/compiler_rt_scalbnf_test.c
@@ -62,11 +62,13 @@ int main() {
     defined(__i386__) || defined(__x86_64__)
 // Skip these tests on Windows because the UCRT scalbnf function always behaves
 // as if the default rounding mode is set (FE_TONEAREST).
+// Also skip on Apple because the libm scalbnf flushes underflow to zero
+// regardless of the rounding mode.
 // Also skip for newlib because although its scalbnf function does respect the
 // rounding mode, where the tests trigger an underflow or overflow using a
 // large exponent the result is rounded in the opposite direction to that which
 // would be expected in the (FE_UPWARD) and (FE_DOWNWARD) modes.
-#  if !defined(_WIN32) && !defined(_NEWLIB_VERSION)
+#  if !defined(_WIN32) && !defined(__APPLE__) && !defined(_NEWLIB_VERSION)
   fesetround(FE_UPWARD);
   if (iterate_cases("FE_UPWARD")) return 1;
 
diff --git a/compiler-rt/test/builtins/Unit/enable_execute_stack_test.c b/compiler-rt/test/builtins/Unit/enable_execute_stack_test.c
index b3cb4df005ca5..138d56eb560d0 100644
--- a/compiler-rt/test/builtins/Unit/enable_execute_stack_test.c
+++ b/compiler-rt/test/builtins/Unit/enable_execute_stack_test.c
@@ -2,6 +2,9 @@
 // RUN: %clang_builtins %s %librt -o %t && %run_nomprotect %t
 // REQUIRES: librt_has_enable_execute_stack
 
+// Apple platforms don't allow an executable stack on arm64.
+// UNSUPPORTED: darwin && target={{arm64.*}}
+
 #include <stdio.h>
 #include <string.h>
 #include <stdint.h>