Detect function multiversioning and sse4.2/crc32, enables i386

This fixes the build on kfreebsd-amd64, and due to the detection
of sse4.2, should also enable the sse4.2 on i386.

1 files changed, 35 insertions, 0 deletions

diff --git a/CMake/CheckCxxTarget.cmake b/CMake/CheckCxxTarget.cmake
new file mode 100644
index 000000000..373c0be4c
--- /dev/null
+++ b/CMake/CheckCxxTarget.cmake
@@ -0,0 +1,35 @@
+# CMake support for target-based function multiversioning
+#
+# Copyright (C) 2019 Canonical Ltd
+#
+# Author: Julian Andres Klode <jak@debian.org>.
+#
+# Permission is hereby granted, free of charge, to any person
+# obtaining a copy of this software and associated documentation files
+# (the "Software"), to deal in the Software without restriction,
+# including without limitation the rights to use, copy, modify, merge,
+# publish, distribute, sublicense, and/or sell copies of the Software,
+# and to permit persons to whom the Software is furnished to do so,
+# subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+
+function(check_cxx_target var target code)
+	check_cxx_source_compiles(
+	"
+	__attribute__((target(\"${target}\"))) static int foo() { ${code} return 1; }
+	__attribute__((target(\"default\"))) static int foo() { ${code} return 0; }
+	int main() { return foo(); }
+	"  ${var})
+endfunction()