| Message ID | 20151114181044.GA1297@jaguar.atmel.com |
|---|---|
| State | New |
| Headers | show |
On Sat, 14 Nov 2015, Senthil Kumar Selvaraj wrote: > 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.selvaraj@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.selvaraj@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.selvaraj@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)))))) Please use TYPE_PRECISION (...) and GET_MODE_PRECISION (word_mode) and add a comment as to what we are testing here and why. Btw, ideally we'd factor out a bool desired_pro_or_demotion_p (tree to_type, tree from_type) {} function somewhere as we have similar tests throughout the compiler that we might want to unify (and also have a central place to eventually add a target hook if ever desired). In fact in other places we also check that the type we promote/demote to matches its mode precision or the type we promote/demote from already does not. I'd suggest tree.[ch] for that function. Please also add a testcase. Thanks, Richard. > { > value_range *vr = get_value_range (innerop); > > > Regards > Senthil > > > > Richard. > > > > >Richard? > > > > > >Regards > > >Senthil > > >> > > >> -- > > >> Marc Glisse > > > > > >
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);