On Tue, Oct 16, 2012 at 11:39 AM, Eric Botcazou <ebotca...@adacore.com> wrote: >> As I'm not sure how to best do that I suggest we do a more proper RTL >> DSE hack by adding a 'libcall-call-escape'-set which we can add to >> instead of calling mark_addressable this late. We need to add all >> partitions of a decl here, of course, and we need to query it from >> can_escape. > > That doesn't pertain only to libcalls though, mark_addressable can also be > called for regular calls if arguments are callee-copied. And mark_addressable > has also been called from expand_asm_operands for ages.
Hm, I see ... >> Well, it just means that the enhanced DSE is fragile :/ > > Maybe, but the current implementation is the outcome of a discussion between > Easwaran and you IIRC. In any case, before attempting to rewrite everything, > here is another approach that patches things up by extending the usage of the > TREE_ADDRESSABLE bit from the vars in a partition to the artificial pointer to > that partition, i.e. the bit is set on the artificial pointer if it is set on > at least one variable in the partition. Ok, I like that a lot more - can_escape now properly checks all partition vars and the use of TREE_ADDRESSABLE on the SSA-NAME is a nice idea. Less ideal is the mark_addressable change but I can't see any better way to deal with late addressable markings ... > Tested on x86_64-suse-linux. ... thus, ok! Thanks, Richard. > > PR rtl-optimization/54870 > * tree.h (TREE_ADDRESSABLE): Document special usage of SSA_NAME. > * cfgexpand.c (update_alias_info_with_stack_vars ): Set it on the > SSA_NAME pointer that points to a partition if there is at least > one variable with it set in the partition. > * dse.c (local_variable_can_escape): New predicate. > (can_escape): Call it. > * gimplify.c (mark_addressable): If this is a partitioned decl, mark > the SSA_NAME pointer that points to a partition as well. > > > -- > Eric Botcazou
