Require Xcode >= 11.2 on macOS 10.15 (Catalina)
- As detailed in a previous CL, Xcode 11.0-1 exhibited a -fstack-check
bug on 10.15 Catalina that broke alignment for at least AVX
instructions causing segfaults from within Eigen.
- As Xcode 11.2 fixes this issue, and is probably a more reliable fix
than -fno-stack-check, we now require the user update in this case.
Change-Id: I482748fe5f40f82e7daf4da133cdfabbd95ffc89
diff --git a/CMakeLists.txt b/CMakeLists.txt
index dc01b7d..f8cc86f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -80,6 +80,10 @@
include(AddCompileFlagsIfSupported)
include(UpdateCacheVariable)
+# Xcode 11.0-1 with macOS 10.15 (Catalina) broke alignment.
+include(DetectBrokenStackCheckMacOSXcodePairing)
+detect_broken_stack_check_macos_xcode_pairing()
+
# Set up the git hook to make Gerrit Change-Id: lines in commit messages.
include(AddGerritCommitHook)
add_gerrit_commit_hook(${Ceres_SOURCE_DIR} ${Ceres_BINARY_DIR})
diff --git a/cmake/DetectSIMDHostileStackCheckMacOSXcodePairing.cmake b/cmake/DetectBrokenStackCheckMacOSXcodePairing.cmake
similarity index 60%
rename from cmake/DetectSIMDHostileStackCheckMacOSXcodePairing.cmake
rename to cmake/DetectBrokenStackCheckMacOSXcodePairing.cmake
index d5384d2..151e28c 100644
--- a/cmake/DetectSIMDHostileStackCheckMacOSXcodePairing.cmake
+++ b/cmake/DetectBrokenStackCheckMacOSXcodePairing.cmake
@@ -28,14 +28,19 @@
#
# Author: alexs.mac@gmail.com (Alex Stewart)
-# As detailed in [1] the combination of macOS 10.15.x (Catalina) and Xcode 11
-# (up to at least 10.15.1 / Xcode 11.1) enables by default -fstack-check which
+# As detailed in [1] the combination of macOS 10.15.x (Catalina) and
+# Xcode 11.0-1 enables by default a broken version of -fstack-check which
# can break the alignment requirements for SIMD instructions resulting in
-# segfaults from within Eigen.
+# segfaults from within Eigen. This issue was apparently fixed in Xcode 11.2
+# despite not appearing in the official release notes.
+#
+# Although this can be worked around by compiling with -fno-stack-check, we
+# instead prevent generation as the update to Xcode 11.2 is free and failing
+# to include -fno-stack-check *everywhere* could still result in random
+# segfaults.
#
# [1]: https://forums.developer.apple.com/thread/121887
-function(detect_simd_hostile_stack_check_macos_xcode_pairing OUT_VAR)
- set(${OUT_VAR} FALSE PARENT_SCOPE)
+function(detect_broken_stack_check_macos_xcode_pairing)
if (NOT APPLE)
return()
endif()
@@ -45,6 +50,13 @@
ERROR_QUIET
OUTPUT_STRIP_TRAILING_WHITESPACE)
+ if (MACOS_VERSION VERSION_LESS 10.15)
+ # Only 10.15 (Catalina) is likely to be affected, irrespective of the Xcode
+ # version. Although it is possible to recreate the issue on 10.14 (Mojave)
+ # and Xcode 11.0-1 if -fstack-check is forced on, this is not the default.
+ return()
+ endif()
+
execute_process(COMMAND xcodebuild -version
OUTPUT_VARIABLE XCODE_VERSION
ERROR_QUIET
@@ -52,25 +64,20 @@
string(REGEX MATCH "Xcode [0-9\\.]+" XCODE_VERSION "${XCODE_VERSION}")
string(REGEX REPLACE "Xcode ([0-9\\.]+)" "\\1" XCODE_VERSION "${XCODE_VERSION}")
- include(CheckCXXSourceRuns)
- set(CMAKE_REQUIRED_FLAGS "-mavx -O3")
- # Minimal test case taken from [1], author: snowcat, segfaults if
- # -fstack-check is enabled by default on affected macOS / Xcode pairing.
- check_cxx_source_runs(
- "int main(void) {
- register char a __asm(\"rbx\") = 0;
- char b[5000];
- char c[100] = {0};
- asm volatile(\"\" : : \"r,m\"(a), \"r,m\"(b), \"r,m\"(c) : \"memory\");
- return 0;
- }"
- BROKEN_STACK_CHECK_DISABLED_BY_DEFAULT)
-
- if (NOT BROKEN_STACK_CHECK_DISABLED_BY_DEFAULT)
- message("-- Detected macOS version: ${MACOS_VERSION} and Xcode version: "
- "${XCODE_VERSION} with SIMD-hostile -fstack-check enabled by default. "
- "Unless -fno-stack-check is used, segfaults may occur in any code that "
- "uses SIMD instructions.")
- set(${OUT_VAR} TRUE PARENT_SCOPE)
- endif()
+ if ((XCODE_VERSION VERSION_EQUAL 11.0) OR
+ (XCODE_VERSION VERSION_EQUAL 11.1))
+ message(FATAL_ERROR "Detected macOS version: ${MACOS_VERSION} and "
+ "Xcode version: ${XCODE_VERSION} which combined exhibit an "
+ "-fstack-check bug which can break alignment requirements for at least "
+ "AVX instructions as detailed here [1]."
+ "\n"
+ "This bug affected Xcode 11.0 and 11.1 but only when used with 10.15 "
+ "(Catalina), and was fixed in Xcode 11.2. Without the fix in place, "
+ "random segfaults will occur in Eigen operations used by Ceres that use "
+ "AVX instructions."
+ "\n"
+ "Please update to at least Xcode 11.2."
+ "\n"
+ "[1]: https://forums.developer.apple.com/thread/121887")
+ endif()
endfunction()
diff --git a/internal/ceres/CMakeLists.txt b/internal/ceres/CMakeLists.txt
index 15770ad..148b058 100644
--- a/internal/ceres/CMakeLists.txt
+++ b/internal/ceres/CMakeLists.txt
@@ -349,15 +349,6 @@
target_include_directories(ceres PUBLIC ${INC_DIR})
endforeach()
-include(DetectSIMDHostileStackCheckMacOSXcodePairing)
-detect_simd_hostile_stack_check_macos_xcode_pairing(
- MUST_DISABLE_STACK_CHECK)
-if (MUST_DISABLE_STACK_CHECK)
- message("-- Explicitly disabling -fstack-check in Ceres target (both "
- "for Ceres and for clients) to avoid breaking SIMD alignment.")
- target_compile_options(ceres PUBLIC "-fno-stack-check")
-endif()
-
install(TARGETS ceres
EXPORT CeresExport
RUNTIME DESTINATION bin
