From d2810d23a9f30ae885f9bf0783f0847a12972ff3 Mon Sep 17 00:00:00 2001 From: Vitaly Chikunov Date: Fri, 18 Sep 2020 01:47:27 +0300 Subject: [PATCH] Provide cmake test if alignment requirement is strict This is based on AX_CHECK_ALIGNED_ACCESS_REQUIRED from autoconf-archive. Note, that on some arches unaligned access behavior could be changed at runtime via prctl(1). Also, unaligned memory access is still slower (and very slow on some arches) even if it's not strictly required. --- CMakeLists.txt | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/CMakeLists.txt b/CMakeLists.txt index 1d4d65b..3b8891d 100644 --- a/CMakeLists.txt +++ b/CMakeLists.txt @@ -66,6 +66,18 @@ if (ADDCARRY_U64) add_definitions(-DHAVE_ADDCARRY_U64) endif() +check_c_source_runs(" + int main(void) { + char buf[16] = { 0, 1, 2 }; + int *p = buf + 1; + int *q = buf + 2; + return (*p == *q); + } + " RELAXED_ALIGNMENT) +if (NOT RELAXED_ALIGNMENT) + add_definitions(-DSTRICT_ALIGNMENT) +endif() + set(BIN_DIRECTORY bin) # Same soversion as OpenSSL -- 2.39.5