On Thu, May 19, 2011 at 2:48 PM, Kai Tietz <ktiet...@googlemail.com> wrote: > Hello, > > This patch improves reassociation folding for comparision. It expands > expressions within binary-AND/OR expression like (X | Y) == 0 to (X == > 0 && Y == 0) > and (X | Y) != 0 to (X != 0 || Y != 0). This is necessary to allow > better reassociation > on weak pre-folded logical expressions. This unfolding gets undone > anyway later by pass, > so no disadvantage gets introduced. > Also while going through BB-list, it tries to do some little > type-sinking for SSA sequences > like "D1 = (type) bool1; D2 = (type) bool2; D3 = D1 & D2;' to 'D1 = > bool1 & bool2; D2 = (type) D1;'. > This folding has the advantage to see better through intermediate > results with none-boolean type. > The function eliminate_redundant_comparison () got reworded so, that > doesn't break in all cases. > It now continues to find duplicates and tries to find inverse variant > (folded to constant). By this > change we don't combine possible weak optimizations too fast, before > we can find and handle > inverse or duplicates.
sinking casting belongs not here but instead to tree-ssa-forwprop. I'm not sure that a != 0 | b != 0 is the better canonical variant than a | b != 0 though. is_boolean_compatible_type_p looks like a strange remanent. Richard. > ChangeLog > > * tree-ssa-reassoc.c (ii: New > helper. > (is_ior_ne_eq_cmp): Likewise. > (build_inner_expand_ne_eq_cmp): Likewise. > (build_expand_ne_eq_cmp): Likewise. > (sink_cast_and_expand): Likewise. > (build_and_add_sum): Add forward declaration. > (remove_visited_stmt_chain): Likewise. > (build_and_add_sum): Allow generation of unary expression. > (eliminate_redundant_comparison): Rework this routine. > (break_up_subtract_bb): Rename to break_up_operation_bb. > Additional do logical unfolding for optimization and > primitive type-sinking for type-casts on boolean-kind > (do_reassoc): Rename break_up_subtract_bb to break_up_operation_bb. > > ChangeLog > > * gcc.dg/binop-tand1.c > * gcc.dg/binop-tand2.c > * gcc.dg/binop-tand3.c > * gcc.dg/binop-tand4.c > * gcc.dg/binop-tor1.c > * gcc.dg/binop-tor2.c > * gcc.dg/binop-tor3.c > * gcc.dg/binop-tor4.c > * gcc.dg/binop-tor5.c > > Bootstrapped and tested for x86_64-pc-linux-gnu for all standard > languages plus ADA and Obj-C++. > Ok for apply? > > Regards, > Kai >
