On Sat, Nov 14, 2015 at 09:57:40AM +0100, Richard Biener wrote: > On November 14, 2015 9:49:28 AM GMT+01:00, Senthil Kumar Selvaraj > <senthil_kumar.selva...@atmel.com> wrote: > >On Sat, Nov 14, 2015 at 09:13:41AM +0100, Marc Glisse wrote: > >> On Sat, 14 Nov 2015, Senthil Kumar Selvaraj wrote: > >> > >> >This patch came out of a discussion held in the gcc mailing list > >> >(https://gcc.gnu.org/ml/gcc/2015-11/msg00067.html). > >> > > >> >The patch restricts folding of conditional exprs with lhs previously > >> >set by a type conversion to occur only if the source of the type > >> >conversion's mode is word mode or smaller. > >> > > >> >Bootstrapped and reg tested on x86_64 (with > >--enable-languages=c,c++). > >> > > >> >If ok, could you commit please? I don't have commit access. > >> > > >> >Regards > >> >Senthil > >> > > >> >gcc/ChangeLog > >> > > >> >2015-11-11 Senthil Kumar Selvaraj > ><senthil_kumar.selva...@atmel.com> > >> > > >> > * tree-vrp.c (simplify_cond_using_ranges): Fold only > >> > if innerop's mode is word_mode or smaller. > >> > > >> > > >> >diff --git gcc/tree-vrp.c gcc/tree-vrp.c > >> >index e2393e4..c139bc6 100644 > >> >--- gcc/tree-vrp.c > >> >+++ gcc/tree-vrp.c > >> >@@ -9467,6 +9467,8 @@ simplify_cond_using_ranges (gcond *stmt) > >> > innerop = gimple_assign_rhs1 (def_stmt); > >> > > >> > if (TREE_CODE (innerop) == SSA_NAME > >> >+ && (GET_MODE_SIZE(TYPE_MODE(TREE_TYPE(innerop))) > >> >+ <= GET_MODE_SIZE(word_mode)) > >> > && !POINTER_TYPE_P (TREE_TYPE (innerop))) > >> > { > >> > value_range *vr = get_value_range (innerop); > >> > >> I thought the result of the discussion was that the transformation is > >ok if > >> either it is narrowing or it widens but to something no bigger than > >> word_mode. So you should have 2 comparisons, or 1 with a max. > > > >Hmm, I came to the opposite conclusion - I thought Richard only okayed > >"widening upto word-mode", not the narrowing. > > I didn't mean to suggest narrowing is not OK. In fact narrowing is always OK.
My bad. Here's a revised patch that checks for both conditions, using max as Marc suggested to limit to word_mode or narrowing conversions. Bootstrapped and regtested for x86_64 with c and c++. Is this ok? If yes, would you commit it for me please? I don't have commit access. gcc/ChangeLog 2015-11-14 Senthil Kumar Selvaraj <senthil_kumar.selva...@atmel.com> * tree-vrp.c (simplify_cond_using_ranges): Fold only if innerop's mode smaller or equal to word_mode or op0's mode. diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index e2393e4..cfd90e7 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -9467,7 +9467,10 @@ simplify_cond_using_ranges (gcond *stmt) innerop = gimple_assign_rhs1 (def_stmt); if (TREE_CODE (innerop) == SSA_NAME - && !POINTER_TYPE_P (TREE_TYPE (innerop))) + && !POINTER_TYPE_P (TREE_TYPE (innerop)) + && (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (innerop))) + <= std::max (GET_MODE_SIZE (word_mode), + GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0)))))) { value_range *vr = get_value_range (innerop); Regards Senthil > > Richard. > > >Richard? > > > >Regards > >Senthil > >> > >> -- > >> Marc Glisse > >