> Hello.
>
> I've been working on a patch that would cope with target and optimization
> (read PerFunction)
> in a proper way. I came to following test-case (slightly modified
> ./gcc/testsuite/gcc.c-torture/execute/alias-1.c):
>
> int val;
>
> int *ptr = &val;
> float *ptr2 = &val;
>
> static
> __attribute__((always_inline, optimize ("-fno-strict-aliasing")))
> typepun ()
> {
> *ptr2=0;
> }
>
> main()
> {
> *ptr=1;
> typepun ();
> if (*ptr)
> __builtin_abort ();
> }
>
> $ gcc -O2 /tmp/always-inline.c -fdump-tree-all-details && ./a.out
> Aborted (core dumped)
>
> Problem is that einline does:
>
> Inlining typepun into main (always_inline).
> Estimating body: typepun/3
> Known to be false: not inlined
> size:2 time:2
> Dropping flag_strict_aliasing on main:4 <<---- here is strict_aliasing drop
> Accounting size:2.00, time:2.00 on predicate:(true)
>
> However fre1 does not still check for flag_strict_aliasing. Is it bug or not?
> I did an experimental fix, but I guess there will me multiple places where
> the
> flag is checked.
Aha, I think the problem is that once we modify strict aliasing of cfun, we need
to re-set the global optimization attributes, becuase those are still copies
from
the original declaration.
>
> Second question:
> Current ipa-inline.c code contains question sophisticated
> check_{match,maybe_up,maybe_down} and
> it's following by:
>
> /* When user added an attribute to the callee honor it. */
> else if (lookup_attribute ("optimize", DECL_ATTRIBUTES (callee->decl))
> && opts_for_fn (caller->decl) != opts_for_fn (callee->decl))
> {
> e->inline_failed = CIF_OPTIMIZATION_MISMATCH;
> inlinable = false;
> }
>
> I think it's very strict, as when one uses __attribute__((optimize)) with a
> param that matches with
> command line arguments, it will return false. What if we remove the hunk?
I am not quite sure. If you have function A with optimization attribute and
you inline it to function b
with same command line parameters, it may enable to inline it into function C
where A would not be inlined
because of the explicit optimization attribute.
If we relax this check, we will need to copy the optimization attribute from A
to B at the time
we inline into B.
>
> Thanks,
> Martin
> diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
> index 871fa121fd0..da38e4fab69 100644
> --- a/gcc/tree-ssa-alias.c
> +++ b/gcc/tree-ssa-alias.c
> @@ -986,7 +986,7 @@ ncr_compar (const void *field1_, const void *field2_)
> static bool
> nonoverlapping_component_refs_p (const_tree x, const_tree y)
> {
> - if (!flag_strict_aliasing
> + if (!opts_for_fn (current_function_decl)->x_flag_strict_aliasing
This should not be necessary. Einline ought to update global opts.
I suppose when decl modified is cfun one needs to reset current_funcion_decl
to NULL and then set it again so the global flags changing machinery notices
this
change.
Honza
t
> || !x || !y
> || TREE_CODE (x) != COMPONENT_REF
> || TREE_CODE (y) != COMPONENT_REF)
> @@ -1167,7 +1167,7 @@ indirect_ref_may_alias_decl_p (tree ref1
> ATTRIBUTE_UNUSED, tree base1,
> return false;
>
> /* Disambiguations that rely on strict aliasing rules follow. */
> - if (!flag_strict_aliasing || !tbaa_p)
> + if (!opts_for_fn (current_function_decl)->x_flag_strict_aliasing ||
> !tbaa_p)
> return true;
>
> ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
> @@ -1334,7 +1334,7 @@ indirect_refs_may_alias_p (tree ref1 ATTRIBUTE_UNUSED,
> tree base1,
> return false;
>
> /* Disambiguations that rely on strict aliasing rules follow. */
> - if (!flag_strict_aliasing || !tbaa_p)
> + if (!opts_for_fn (current_function_decl)->x_flag_strict_aliasing ||
> !tbaa_p)
> return true;
>
> ptrtype1 = TREE_TYPE (TREE_OPERAND (base1, 1));
> @@ -1508,7 +1508,7 @@ refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool
> tbaa_p)
>
> /* First defer to TBAA if possible. */
> if (tbaa_p
> - && flag_strict_aliasing
> + && opts_for_fn (current_function_decl)->x_flag_strict_aliasing
> && !alias_sets_conflict_p (ao_ref_alias_set (ref1),
> ao_ref_alias_set (ref2)))
> return false;
