[PATCH 7/7] Libsanitizer merge from upstream r249633.

[Jakub Jelinek]

On Tue, Oct 13, 2015 at 02:22:36PM +0300, Maxim Ostapenko wrote:
> This is the final patch. Force libsanitizer to use an old ABI for ubsan
> float cast data descriptors, because for some exprs (e.g. that type of
> tcc_declaration) we can't get the right location for now. I'm not sure about
> this, perhaps it should be fixed in GCC somehow.

I don't like this (neither the heuristics on the libubsan, it wouldn't be a
big deal to add a new library entrypoint).
If because of the heuristics you need to ensure that the SourceLocation is
always known, then either you check in ubsan.c whether expand_location
gives you NULL xloc.file and in that case use old style float cast overflow
(without location) - i.e. pass 0, NULL, otherwise you use new style, i.e.
pass 1, &loc.  Or arrange through some special option to emit something like
{ "<unknown>", 0, 0 } instead of { NULL, 0, 0 } for the float cast case.
And, regardless of this, any progress in making sure we have fewer cases
with UNKNOWN_LOCATION on this will not hurt.  I think at this point I'd
prefer the first choice, i.e. using old style for locations without
filename, and new style otherwise.

> 2015-10-13  Maxim Ostapenko  <m.ostapenko@partner.samsung.com>
> 
> 	* ubsan/ubsan_handlers.cc (looksLikeFloatCastOverflowDataV1): Always
> 	return true for now.
> 
> Index: libsanitizer/ubsan/ubsan_handlers.cc
> ===================================================================
> --- libsanitizer/ubsan/ubsan_handlers.cc	(revision 250059)
> +++ libsanitizer/ubsan/ubsan_handlers.cc	(working copy)
> @@ -307,6 +307,9 @@
>  }
>  
>  static bool looksLikeFloatCastOverflowDataV1(void *Data) {
> +  // (TODO): propagate SourceLocation into DataDescriptor and use this
> +  // heuristic than.
> +  return true;
>    // First field is either a pointer to filename or a pointer to a
>    // TypeDescriptor.
>    u8 *FilenameOrTypeDescriptor;


	Jakub