On 16/03/2018 20:37, Martin Storsjö wrote:
With GCC, request it to maintain 16 byte alignment, and the existing entry points already align it via attribute_align_arg.With clang, do the same as for mingw; disable the aligned stack and let the assembly functions that require it do the alignment instead. --- configure | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/configure b/configure index 95e6006440..78a2065208 100755 --- a/configure +++ b/configure @@ -4957,16 +4957,34 @@ elif enabled gcc; then check_cflags -Werror=format-security check_cflags -fdiagnostics-color=auto enabled extra_warnings || check_disable_warning -Wno-maybe-uninitialized + if enabled x86_32; then + case $target_os in + *bsd*) + # BSDs don't guarantee a 16 byte aligned stack, but we can + # request GCC to try to maintain 16 byte alignment throughout + # function calls. Library entry points that might call assembly + # functions align the stack. (The parameter means 2^4 bytes.) + check_cflags -mpreferred-stack-boundary=4 + ;; + esac + fi elif enabled llvm_gcc; then check_cflags -mllvm -stack-alignment=16 elif enabled clang; then - if [ "$target_os" = "mingw32" -o "$target_os" = "win32" ] && enabled x86_32; then + if enabled x86_32; then # Clang doesn't support maintaining alignment without assuming the # same alignment in every function. If 16 byte alignment would be # enabled, one would also have to either add attribute_align_arg on # every single entry point into the libraries or enable -mstackrealign # (doing stack realignment in every single function). - disable aligned_stack + case $target_os in + mingw32|win32|*bsd*) + disable aligned_stack + ;; + *) + check_cflags -mllvm -stack-alignment=16 + ;; + esac else check_cflags -mllvm -stack-alignment=16 fi
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