On Fri, Jun 06, 2014 at 09:08:17AM +0400, Yury Gribov wrote:
> Build_check_stmt is now unified for const/variable lengths
> but I'd still prefer to treat the use_calls case specially
> because calling single __asan_loadN is more space-efficient
> than emitting two separate calls with a length check.
That is not what I meant.
1) instrument_mem_region_access/instrument_strlen should use a single
build_check_stmt call instead of two that they do now,
both for use_calls case and !use_calls case, the difference
is just that instrument_mem_region_access needs to guard
it against len == 0, while for use_calls it doesn't have to,
it seems __asan_{load,store}N handles length of 0 correctly
(still, the caller shouldn't update_mem_ref_hash_table
if length might be zero, even in the use_calls case)
2) passing always a tree length to build_check_stmt and then
recreating size_in_bytes out of it is ugly, just add a new
tree parameter, if it is non-NULL, the length is variable,
and real_size_in_bytes should be 1, and the code additionally
has to compute length - 1 at runtime and add the result,
otherwise it just keeps adding precomputed constant
Jakub
