Build system: Allow user to enable Intel CET

MSVC:
https://docs.microsoft.com/en-us/cpp/build/reference/guard-enable-eh-continuation-metadata?view=msvc-170
https://docs.microsoft.com/en-us/cpp/build/reference/cetcompat?view=msvc-170

GCC:
https://gcc.gnu.org/onlinedocs/gcc-11.2.0/gcc/Instrumentation-Options.html

Clang:
Don't know where's the documentation but should use
the same parameter with GCC.

Change-Id: I654618e45743a5ad1394c930932b9d0044572725
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

cmake/QtInternalTargets.cmake

@@ -278,6 +278,21 @@ if (GCC AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL "9.2")
     target_compile_options(PlatformCommonInternal INTERFACE $<$<COMPILE_LANGUAGE:CXX>:-Wsuggest-override>)
 endif()
 
+if(QT_FEATURE_intelcet)
+    if(MSVC)
+        target_compile_options(PlatformCommonInternal INTERFACE
+            -guard:ehcont
+        )
+        target_link_options(PlatformCommonInternal INTERFACE
+            -guard:ehcont -CETCOMPAT
+        )
+    else()
+        target_compile_options(PlatformCommonInternal INTERFACE
+            -fcf-protection
+        )
+    endif()
+endif()
+
 if(QT_FEATURE_force_asserts)
     target_compile_definitions(PlatformCommonInternal INTERFACE QT_FORCE_ASSERTS)
 endif()

config_help.txt

@@ -137,6 +137,7 @@ Build options:
 
   -pch ................. Use precompiled headers [auto]
   -ltcg ................ Use Link Time Code Generation [no]
+  -intelcet ............ Use Intel Control-flow Enforcement Technology [no]
   -linker [bfd,gold,lld,mold]
                          Force use of the GNU ld, GNU gold, LLVM/LLD or mold
                          linker instead of default one (GCC and clang only)

configure.cmake

@@ -1034,7 +1034,7 @@ qt_feature("relocatable" PRIVATE
 )
 qt_feature("intelcet" PRIVATE
     LABEL "Using Intel CET"
-    CONDITION TEST_intelcet
+    CONDITION ( INPUT_intelcet STREQUAL yes ) OR TEST_intelcet
 )
 qt_configure_add_summary_build_type_and_config()
 qt_configure_add_summary_section(NAME "Build options")
@@ -1085,6 +1085,7 @@ qt_configure_add_summary_entry(
 qt_configure_add_summary_entry(ARGS "relocatable")
 qt_configure_add_summary_entry(ARGS "precompile_header")
 qt_configure_add_summary_entry(ARGS "ltcg")
+qt_configure_add_summary_entry(ARGS "intelcet")
 qt_configure_add_summary_section(NAME "Target compiler supports")
 qt_configure_add_summary_entry(
     TYPE "featureList"

qt_cmdline.cmake

@@ -67,6 +67,7 @@ qt_commandline_option(incredibuild-xge TYPE boolean NAME incredibuild_xge)
 qt_commandline_option(libudev TYPE boolean)
 qt_commandline_option(linker TYPE optionalString VALUES bfd gold lld mold)
 qt_commandline_option(ltcg TYPE boolean)
+qt_commandline_option(intelcet TYPE boolean)
 # special case begin
 qt_commandline_option(make TYPE addString VALUES examples libs tests tools
                       benchmarks manual-tests minimal-static-tests)