c++: Fix warning on 32-bit x86

My C++17 hardware interference sizes patch caused a bogus warning on 32-bit
x86, where we have a default L1 cache line size of 0, and the front end
complained that the default constructive interference size of 64 was larger
than that.

gcc/cp/ChangeLog:

	* decl.c (cxx_init_decl_processing): Don't warn if L1 cache line
	size is smaller than maxalign.

diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index c206502..930531a 100644 (file)
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -4776,7 +4776,8 @@ cxx_init_decl_processing (void)
       if (param_construct_interfere_size < max_align)
        error ("%<--param constructive-interference-size=%d%> is less than "
               "%d", param_construct_interfere_size, max_align);
-      else if (param_construct_interfere_size > param_l1_cache_line_size)
+      else if (param_construct_interfere_size > param_l1_cache_line_size
+              && param_l1_cache_line_size >= max_align)
        warning (OPT_Winterference_size,
                 "%<--param constructive-interference-size=%d%> "
                 "is greater than %<--param l1-cache-line-size=%d%>",