On Tue, Jan 05, 2010 at 04:27:33PM +0100, Richard Guenther wrote:
> On Tue, Jan 5, 2010 at 4:03 PM, torbenh <[email protected]> wrote:
> > On Tue, Jan 05, 2010 at 02:46:30PM +0100, Richard Guenther wrote:
> >> On Tue, Jan 5, 2010 at 2:40 PM, torbenh <[email protected]> wrote:
> >>
> >> The -fno-alias-X things do not make much sense for user code (they
> >> have been historically used from Frontends). If restrict doesn't work
> >> for you (do you have a testcase that can reproduce your issue?)
> >> then you probably need to wait for IPA pointer analysis to be
> >> fixed in GCC 4.6.
> >
> > sorry... forget the attachment :S
>
> Yes, in this case you can fix it by making ramp static. Otherwise its
> address may be takein in another translation unit. For Fortran we
> have the DECL_RESTRICTED_P which we could expose to other
> languages via an attribute. It tells that a decl is not aliased by
> restrict qualified pointers, so
>
> struct Ramp {
> float phase;
> inline float process() { return phase++; }
> } ramp __attribute__((restrict));
>
> void fill_buffer( float * __restrict buf, size_t nframes )
> {
> for( size_t i=0; i<nframes; i++ )
> buf[i] = ramp.process();
> }
would that also work with this stuff:
template<typename ... Args>
class Mixer;
template<typename T1, typename ... Args>
class Mixer<T1, Args...> : public Block
{
private:
T1 t1 __attribute__((restrict));
Mixer<Args...> t2;
public:
inline float process() {
return t1.process() + t2.process();
}
};
template<typename T1, typename T2>
class Mixer<T1,T2> : public Block
{
private:
T1 t1 __attribute__((restrict));
T2 t2 __attribute__((restrict));
public:
inline float process() {
return t1.process() + t2.process();
}
};
Mixer<Ramp,Ramp,Ramp,Ramp> mix __attribute__((restrict))
?
i still dont understand whats the problem with -fnolias,
as in attached patch.
>
> would then be optimized as well. Can you file an enhancement
> bugreport according to this?
>
> Thanks,
> Richard.
--
torben Hohn
diff --git a/gcc/common.opt b/gcc/common.opt
index 77967f8..21eebb2 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -834,6 +834,10 @@ freschedule-modulo-scheduled-loops
Common Report Var(flag_resched_modulo_sched) Optimization
Enable/Disable the traditional scheduling in loops that already passed modulo scheduling
+fnoalias
+Common Report Var(flag_noalias) Optimization
+Assume no aliasing is happening
+
fnon-call-exceptions
Common Report Var(flag_non_call_exceptions) Optimization
Support synchronous non-call exceptions
diff --git a/gcc/opts.c b/gcc/opts.c
index 5407527..9b8639e 100644
--- a/gcc/opts.c
+++ b/gcc/opts.c
@@ -2053,6 +2053,10 @@ common_handle_option (size_t scode, const char *arg, int value,
flag_ipa_cp_clone_set = true;
break;
+ case OPT_fnoalias:
+ flag_noalias = true;
+ break;
+
case OPT_fpredictive_commoning:
flag_predictive_commoning_set = true;
break;
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index cbb43b5..0b66577 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -662,6 +662,9 @@ indirect_ref_may_alias_decl_p (tree ref1, tree ptr1,
if (!ptr_deref_may_alias_decl_p (ptr1, base2))
return false;
+ if (flag_noalias)
+ return false;
+
/* Disambiguations that rely on strict aliasing rules follow. */
if (!flag_strict_aliasing)
return true;
