Re: [PATCH] Fix PR59993

2014-01-31 Thread Richard Biener 
On Thu, 30 Jan 2014, Marc Glisse wrote:

 On Thu, 30 Jan 2014, Richard Biener wrote:
 
 /* Associate (p +p off1) +p off2 as (p +p (off1 + off2)).  */
 ptr = gimple_assign_rhs1 (stmt);
 off1 = gimple_assign_rhs2 (stmt);
  !   if (TREE_CODE (ptr) != SSA_NAME
  !   || !has_single_use (ptr))
   return false;
 def_stmt = SSA_NAME_DEF_STMT (ptr);
 if (!is_gimple_assign (def_stmt)
  !   || gimple_assign_rhs_code (def_stmt) != POINTER_PLUS_EXPR
  !   || !can_propagate_from (def_stmt))
   return false;
 ptr = gimple_assign_rhs1 (def_stmt);
 off2 = gimple_assign_rhs2 (def_stmt);
 
 Hello,
 
 we have 2 helpers get_prop_source_stmt and defcodefor_name in
 tree-ssa-forwprop.c, but you don't seem to like them. Do they have a
 particular drawback or is it just easier to rewrite the code than to remember
 how to use those? I am asking so I know whether I can / should use them in my
 future patches.

I don't like them too much - get_prop_source_stmt possibly causes
quadratic compile-time complexity and defcodefor_name is just
ugly ;)

To get rid of get_prop_source_stmt I'd like to move towards
keeping a simple SSA value lattice in forwprop so one can
get at the constant or SSA name a SSA name is a copy of in O(1)
(similar to the copyprop lattice).

defcodefor_name ... well, I hope to get started on a
meta-description to tree / GIMPLE pattern matching machinery
(and build our folders upon that) soon.

Richard.

Re: [PATCH] Fix PR59993

2014-01-30 Thread Jeff Law 

On 01/30/14 07:51, Richard Biener wrote:


This fixes an oversight with the (p + o1) + o2 association with
respect to abnormal-used SSA names.  I've also added a single-use
test so we don't add extra computations.

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2014-01-30  Richard Biener  rguent...@suse.de

PR tree-optimization/59993
* tree-ssa-forwprop.c (associate_pointerplus): Check we
can propagate form the earlier stmt and avoid the transform
when the intermediate result is needed.

* gcc.dg/torture/pr59993.c: New testcase.

Seems reasonable to me.
jeff

Re: [PATCH] Fix PR59993

2014-01-30 Thread Marc Glisse 

On Thu, 30 Jan 2014, Richard Biener wrote:


   /* Associate (p +p off1) +p off2 as (p +p (off1 + off2)).  */
   ptr = gimple_assign_rhs1 (stmt);
   off1 = gimple_assign_rhs2 (stmt);
!   if (TREE_CODE (ptr) != SSA_NAME
!   || !has_single_use (ptr))
 return false;
   def_stmt = SSA_NAME_DEF_STMT (ptr);
   if (!is_gimple_assign (def_stmt)
!   || gimple_assign_rhs_code (def_stmt) != POINTER_PLUS_EXPR
!   || !can_propagate_from (def_stmt))
 return false;
   ptr = gimple_assign_rhs1 (def_stmt);
   off2 = gimple_assign_rhs2 (def_stmt);


Hello,

we have 2 helpers get_prop_source_stmt and defcodefor_name in 
tree-ssa-forwprop.c, but you don't seem to like them. Do they have a 
particular drawback or is it just easier to rewrite the code than to 
remember how to use those? I am asking so I know whether I can / should 
use them in my future patches.


--
Marc Glisse