CMakeDetermineCompilerABI: Detect byte order as part of check

We already detect `sizeof(void*)`.  Detect the byte order as part of the
same check.

Issue: #21392

1 files changed, 15 insertions, 0 deletions

diff --git a/Modules/CMakeDetermineCompilerABI.cmake b/Modules/CMakeDetermineCompilerABI.cmake
index 3fa99df..67c42a2a 100644
--- a/Modules/CMakeDetermineCompilerABI.cmake
+++ b/Modules/CMakeDetermineCompilerABI.cmake
@@ -77,11 +77,22 @@ function(CMAKE_DETERMINE_COMPILER_ABI lang src)
         "Detecting ${lang} compiler ABI info compiled with the following output:\n${OUTPUT}\n\n")
       file(STRINGS "${BIN}" ABI_STRINGS LIMIT_COUNT 32 REGEX "INFO:[A-Za-z0-9_]+\\[[^]]*\\]")
       set(ABI_SIZEOF_DPTR "NOTFOUND")
+      set(ABI_BYTE_ORDER "NOTFOUND")
       set(ABI_NAME "NOTFOUND")
       foreach(info ${ABI_STRINGS})
         if("${info}" MATCHES "INFO:sizeof_dptr\\[0*([^]]*)\\]" AND NOT ABI_SIZEOF_DPTR)
           set(ABI_SIZEOF_DPTR "${CMAKE_MATCH_1}")
         endif()
+        if("${info}" MATCHES "INFO:byte_order\\[(BIG_ENDIAN|LITTLE_ENDIAN)\\]")
+          set(byte_order "${CMAKE_MATCH_1}")
+          if(ABI_BYTE_ORDER STREQUAL "NOTFOUND")
+            # Tentatively use the value because this is the first occurrence.
+            set(ABI_BYTE_ORDER "${byte_order}")
+          elseif(NOT ABI_BYTE_ORDER STREQUAL "${byte_order}")
+            # Drop value because multiple occurrences do not match.
+            set(ABI_BYTE_ORDER "")
+          endif()
+        endif()
         if("${info}" MATCHES "INFO:abi\\[([^]]*)\\]" AND NOT ABI_NAME)
           set(ABI_NAME "${CMAKE_MATCH_1}")
         endif()
@@ -93,6 +104,10 @@ function(CMAKE_DETERMINE_COMPILER_ABI lang src)
         set(CMAKE_${lang}_SIZEOF_DATA_PTR "${CMAKE_${lang}_SIZEOF_DATA_PTR_DEFAULT}" PARENT_SCOPE)
       endif()
 
+      if(ABI_BYTE_ORDER)
+        set(CMAKE_${lang}_BYTE_ORDER "${ABI_BYTE_ORDER}" PARENT_SCOPE)
+      endif()
+
       if(ABI_NAME)
         set(CMAKE_${lang}_COMPILER_ABI "${ABI_NAME}" PARENT_SCOPE)
       endif()