On Tue, 3 May 2016, Christophe Lyon wrote:
> On 2 May 2016 at 19:01, Jan Hubicka <hubi...@ucw.cz> wrote:
> >> On Thu, 21 Apr 2016, Jan Hubicka wrote:
> >>
> >> > Hi,
> >> > this patch implements the long promised logic to inline across
> >> > -ffast-math
> >> > boundary when eitehr caller or callee has no fp operations in it. This
> >> > is
> >> > needed to resolve code quality regression on Firefox with LTO where
> >> > -O3/-O2/-Ofast flags are combined and we fail to inline a lot of comdats
> >> > otherwise.
> >> >
> >> > Bootstrapped/regtested x86_64-linux. Ricahrd, I would like to know your
> >> > opinion
> >> > on fp_expression_p predicate - it is bit ugly but I do not know how to
> >> > implement
> >> > it better.
> >> >
> >> > We still won't inline -O1 code into -O2+ because flag_strict_overflow
> >> > differs.
> >> > I will implement similar logic for overflows incrementally. Similarly
> >> > flag_errno_math
> >> > can be handled better, but I am not sure it matters - I think wast
> >> > majority of time
> >> > users set errno_math in sync with other -ffast-math implied flags.
> >>
> >> Note that for reasons PR70586 shows (const functions having possible
> >> trapping side-effect because of FP math or division) we'd like to
> >> have sth like "uses FP math" "uses possibly trapping integer math"
> >> "uses integer math with undefined overflow" on a per function level
> >> and propagated alongside pure/const/nothrow state.
> >>
> >> So maybe you can fit that into a more suitable place than just the
> >> inliner (which of course is interested in "uses FP math locally",
> >> not the transitive answer we need for PR70586).
> >
> > We don't really have much more suitable place - ipa-inline-analysis is
> > doing most of the analysis of function body that is usefull for IPA passes,
> > not only for inliner. It should be renamed perhaps to something like
> > function_body_summary. I will do that later this stage1.
> >
> > For PR70686 in addition to transitive answer we will need to know that
> > the transformation is win. Const function may take a lot of time and
> > introducing new call on code path that did not used it previously is
> > bad idea unless we know that the function is very cheap (which may
> > be true only for fast builtins, I don't know)
> >
> > This patch impleemnts the suggested check for presence of FP parameters.
> > We can play with special casing the moves incrementally.
> >
> > Bootstrapped/regtested x86_64-linux.
> >
> > Index: testsuite/ChangeLog
> > ===================================================================
> > --- testsuite/ChangeLog (revision 235765)
> > +++ testsuite/ChangeLog (working copy)
> > @@ -1,3 +1,7 @@
> > +2016-05-02 Jan Hubicka <hubi...@ucw.cz>
> > +
> > + * gcc.dg/ipa/inline-8.c: New testcase.
> > +
> > 2016-05-02 Jakub Jelinek <ja...@redhat.com>
> >
> > PR rtl-optimization/70467
> > Index: testsuite/gcc.dg/ipa/inline-8.c
> > ===================================================================
> > --- testsuite/gcc.dg/ipa/inline-8.c (revision 0)
> > +++ testsuite/gcc.dg/ipa/inline-8.c (working copy)
> > @@ -0,0 +1,36 @@
> > +/* Verify that we do not inline isnanf test info -ffast-math code but that
> > we
> > + do inline trivial functions across -Ofast boundary. */
> > +/* { dg-do run } */
> > +/* { dg-options "-O2" } */
> > +#include <math.h>
> > +/* Can't be inlined because isnanf will be optimized out. */
> > +int
> > +cmp (float a)
> > +{
> > + return isnanf (a);
>
> Hi,
>
> This new testcase does not pass on bare-metal configs (using newlib), because:
> warning: implicit declaration of function 'isnanf'
> [-Wimplicit-function-declaration]
> warning: incompatible implicit declaration of built-in function 'isnanf'
>
> I'm not sure what's the appropriate dg-require to avoid this?
c99_runtime I guess.
Richard.
> Christophe
>
> > +}
> > +/* Can be inlined. */
> > +int
> > +move (int a)
> > +{
> > + return a;
> > +}
> > +float a;
> > +void
> > +set ()
> > +{
> > + a=nan("");
> > +}
> > +float b;
> > +__attribute__ ((optimize("Ofast")))
> > +int
> > +main()
> > +{
> > + b++;
> > + if (cmp(a))
> > + __builtin_abort ();
> > + float a = move (1);
> > + if (!__builtin_constant_p (a))
> > + __builtin_abort ();
> > + return 0;
> > +}
> > Index: ChangeLog
> > ===================================================================
> > --- ChangeLog (revision 235765)
> > +++ ChangeLog (working copy)
> > @@ -1,3 +1,18 @@
> > +2016-05-02 Jan Hubicka <hubi...@ucw.cz>
> > +
> > + * ipa-inline-analysis.c (reset_inline_summary): Clear fp_expressions
> > + (dump_inline_summary): Dump it.
> > + (fp_expression_p): New predicate.
> > + (estimate_function_body_sizes): Use it.
> > + (inline_merge_summary): Merge fp_expressions.
> > + (inline_read_section): Read fp_expressions.
> > + (inline_write_summary): Write fp_expressions.
> > + * ipa-inline.c (can_inline_edge_p): Permit inlining across fp math
> > + codegen boundary if either caller or callee is !fp_expressions.
> > + * ipa-inline.h (inline_summary): Add fp_expressions.
> > + * ipa-inline-transform.c (inline_call): When inlining
> > !fp_expressions
> > + to fp_expressions be sure the fp generation flags are updated.
> > +
> > 2016-05-02 Jakub Jelinek <ja...@redhat.com>
> >
> > PR rtl-optimization/70467
> > Index: ipa-inline-analysis.c
> > ===================================================================
> > --- ipa-inline-analysis.c (revision 235693)
> > +++ ipa-inline-analysis.c (working copy)
> > @@ -850,7 +850,8 @@ evaluate_conditions_for_known_args (stru
> > if (known_aggs.exists ())
> > {
> > agg = known_aggs[c->operand_num];
> > - val = ipa_find_agg_cst_for_param (agg, c->offset, c->by_ref);
> > + val = ipa_find_agg_cst_for_param (agg,
> > known_vals[c->operand_num],
> > + c->offset, c->by_ref);
> > }
> > else
> > val = NULL_TREE;
> > @@ -1069,6 +1070,7 @@ reset_inline_summary (struct cgraph_node
> > reset_inline_edge_summary (e);
> > for (e = node->indirect_calls; e; e = e->next_callee)
> > reset_inline_edge_summary (e);
> > + info->fp_expressions = false;
> > }
> >
> > /* Hook that is called by cgraph.c when a node is removed. */
> > @@ -1423,6 +1425,8 @@ dump_inline_summary (FILE *f, struct cgr
> > fprintf (f, " inlinable");
> > if (s->contains_cilk_spawn)
> > fprintf (f, " contains_cilk_spawn");
> > + if (s->fp_expressions)
> > + fprintf (f, " fp_expression");
> > fprintf (f, "\n self time: %i\n", s->self_time);
> > fprintf (f, " global time: %i\n", s->time);
> > fprintf (f, " self size: %i\n", s->self_size);
> > @@ -2459,6 +2463,21 @@ clobber_only_eh_bb_p (basic_block bb, bo
> > return true;
> > }
> >
> > +/* Return true if STMT compute a floating point expression that may be
> > affected
> > + by -ffast-math and similar flags. */
> > +
> > +static bool
> > +fp_expression_p (gimple *stmt)
> > +{
> > + ssa_op_iter i;
> > + tree op;
> > +
> > + FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF|SSA_OP_USE)
> > + if (FLOAT_TYPE_P (TREE_TYPE (op)))
> > + return true;
> > + return false;
> > +}
> > +
> > /* Compute function body size parameters for NODE.
> > When EARLY is true, we compute only simple summaries without
> > non-trivial predicates to drive the early inliner. */
> > @@ -2733,6 +2752,13 @@ estimate_function_body_sizes (struct cgr
> > this_time * (2 - prob), &p);
> > }
> >
> > + if (!info->fp_expressions && fp_expression_p (stmt))
> > + {
> > + info->fp_expressions = true;
> > + if (dump_file)
> > + fprintf (dump_file, " fp_expression set\n");
> > + }
> > +
> > gcc_assert (time >= 0);
> > gcc_assert (size >= 0);
> > }
> > @@ -3577,6 +3603,8 @@ inline_merge_summary (struct cgraph_edge
> > else
> > toplev_predicate = true_predicate ();
> >
> > + info->fp_expressions |= callee_info->fp_expressions;
> > +
> > if (callee_info->conds)
> > evaluate_properties_for_edge (edge, true, &clause, NULL, NULL, NULL);
> > if (ipa_node_params_sum && callee_info->conds)
> > @@ -4229,6 +4257,7 @@ inline_read_section (struct lto_file_dec
> > bp = streamer_read_bitpack (&ib);
> > info->inlinable = bp_unpack_value (&bp, 1);
> > info->contains_cilk_spawn = bp_unpack_value (&bp, 1);
> > + info->fp_expressions = bp_unpack_value (&bp, 1);
> >
> > count2 = streamer_read_uhwi (&ib);
> > gcc_assert (!info->conds);
> > @@ -4395,6 +4424,7 @@ inline_write_summary (void)
> > bp = bitpack_create (ob->main_stream);
> > bp_pack_value (&bp, info->inlinable, 1);
> > bp_pack_value (&bp, info->contains_cilk_spawn, 1);
> > + bp_pack_value (&bp, info->fp_expressions, 1);
> > streamer_write_bitpack (&bp);
> > streamer_write_uhwi (ob, vec_safe_length (info->conds));
> > for (i = 0; vec_safe_iterate (info->conds, i, &c); i++)
> > Index: ipa-inline.c
> > ===================================================================
> > --- ipa-inline.c (revision 235693)
> > +++ ipa-inline.c (working copy)
> > @@ -338,7 +338,7 @@ can_inline_edge_p (struct cgraph_edge *e
> > else if (e->call_stmt_cannot_inline_p)
> > {
> > if (e->inline_failed != CIF_FUNCTION_NOT_OPTIMIZED)
> > - e->inline_failed = CIF_MISMATCHED_ARGUMENTS;
> > + e->inline_failed = e->caller->thunk.thunk_p ? CIF_THUNK :
> > CIF_MISMATCHED_ARGUMENTS;
> > inlinable = false;
> > }
> > /* Don't inline if the functions have different EH personalities. */
> > @@ -396,6 +396,8 @@ can_inline_edge_p (struct cgraph_edge *e
> > (DECL_DISREGARD_INLINE_LIMITS (callee->decl)
> > && lookup_attribute ("always_inline",
> > DECL_ATTRIBUTES (callee->decl)));
> > + inline_summary *caller_info = inline_summaries->get (caller);
> > + inline_summary *callee_info = inline_summaries->get (callee);
> >
> > /* Until GCC 4.9 we did not check the semantics alterning flags
> > bellow and inline across optimization boundry.
> > @@ -417,16 +419,21 @@ can_inline_edge_p (struct cgraph_edge *e
> > == !opt_for_fn (callee->decl, optimize) ||
> > !always_inline))
> > || check_match (flag_wrapv)
> > || check_match (flag_trapv)
> > - /* Strictly speaking only when the callee uses FP math. */
> > - || check_maybe_up (flag_rounding_math)
> > - || check_maybe_up (flag_trapping_math)
> > - || check_maybe_down (flag_unsafe_math_optimizations)
> > - || check_maybe_down (flag_finite_math_only)
> > - || check_maybe_up (flag_signaling_nans)
> > - || check_maybe_down (flag_cx_limited_range)
> > - || check_maybe_up (flag_signed_zeros)
> > - || check_maybe_down (flag_associative_math)
> > - || check_maybe_down (flag_reciprocal_math)
> > + /* When caller or callee does FP math, be sure FP codegen
> > flags
> > + compatible. */
> > + || ((caller_info->fp_expressions &&
> > callee_info->fp_expressions)
> > + && (check_maybe_up (flag_rounding_math)
> > + || check_maybe_up (flag_trapping_math)
> > + || check_maybe_down (flag_unsafe_math_optimizations)
> > + || check_maybe_down (flag_finite_math_only)
> > + || check_maybe_up (flag_signaling_nans)
> > + || check_maybe_down (flag_cx_limited_range)
> > + || check_maybe_up (flag_signed_zeros)
> > + || check_maybe_down (flag_associative_math)
> > + || check_maybe_down (flag_reciprocal_math)
> > + /* Strictly speaking only when the callee contains
> > function
> > + calls that may end up setting errno. */
> > + || check_maybe_up (flag_errno_math)))
> > /* We do not want to make code compiled with exceptions to be
> > brought into a non-EH function unless we know that the
> > callee
> > does not throw.
> > @@ -435,9 +442,6 @@ can_inline_edge_p (struct cgraph_edge *e
> > && DECL_FUNCTION_PERSONALITY (callee->decl))
> > || (check_maybe_up (flag_exceptions)
> > && DECL_FUNCTION_PERSONALITY (callee->decl))
> > - /* Strictly speaking only when the callee contains function
> > - calls that may end up setting errno. */
> > - || check_maybe_up (flag_errno_math)
> > /* When devirtualization is diabled for callee, it is not safe
> > to inline it as we possibly mangled the type info.
> > Allow early inlining of always inlines. */
> > Index: ipa-inline.h
> > ===================================================================
> > --- ipa-inline.h (revision 235693)
> > +++ ipa-inline.h (working copy)
> > @@ -132,6 +132,8 @@ struct GTY(()) inline_summary
> > /* True wen there is only one caller of the function before small
> > function
> > inlining. */
> > unsigned int single_caller : 1;
> > + /* True if function contains any floating point expressions. */
> > + unsigned int fp_expressions : 1;
> >
> > /* Information about function that will result after applying all the
> > inline decisions present in the callgraph. Generally kept up to
> > Index: ipa-inline-transform.c
> > ===================================================================
> > --- ipa-inline-transform.c (revision 235693)
> > +++ ipa-inline-transform.c (working copy)
> > @@ -338,6 +338,63 @@ inline_call (struct cgraph_edge *e, bool
> > DECL_FUNCTION_SPECIFIC_OPTIMIZATION (to->decl)
> > = build_optimization_node (&opts);
> > }
> > + inline_summary *caller_info = inline_summaries->get (to);
> > + inline_summary *callee_info = inline_summaries->get (callee);
> > + if (!caller_info->fp_expressions && callee_info->fp_expressions)
> > + {
> > + caller_info->fp_expressions = true;
> > + if (opt_for_fn (callee->decl, flag_rounding_math)
> > + != opt_for_fn (to->decl, flag_rounding_math)
> > + || opt_for_fn (callee->decl, flag_trapping_math)
> > + != opt_for_fn (to->decl, flag_trapping_math)
> > + || opt_for_fn (callee->decl, flag_unsafe_math_optimizations)
> > + != opt_for_fn (to->decl, flag_unsafe_math_optimizations)
> > + || opt_for_fn (callee->decl, flag_finite_math_only)
> > + != opt_for_fn (to->decl, flag_finite_math_only)
> > + || opt_for_fn (callee->decl, flag_signaling_nans)
> > + != opt_for_fn (to->decl, flag_signaling_nans)
> > + || opt_for_fn (callee->decl, flag_cx_limited_range)
> > + != opt_for_fn (to->decl, flag_cx_limited_range)
> > + || opt_for_fn (callee->decl, flag_signed_zeros)
> > + != opt_for_fn (to->decl, flag_signed_zeros)
> > + || opt_for_fn (callee->decl, flag_associative_math)
> > + != opt_for_fn (to->decl, flag_associative_math)
> > + || opt_for_fn (callee->decl, flag_reciprocal_math)
> > + != opt_for_fn (to->decl, flag_reciprocal_math)
> > + || opt_for_fn (callee->decl, flag_errno_math)
> > + != opt_for_fn (to->decl, flag_errno_math))
> > + {
> > + struct gcc_options opts = global_options;
> > +
> > + cl_optimization_restore (&opts, opts_for_fn (to->decl));
> > + opts.x_flag_rounding_math
> > + = opt_for_fn (callee->decl, flag_rounding_math);
> > + opts.x_flag_trapping_math
> > + = opt_for_fn (callee->decl, flag_trapping_math);
> > + opts.x_flag_unsafe_math_optimizations
> > + = opt_for_fn (callee->decl, flag_unsafe_math_optimizations);
> > + opts.x_flag_finite_math_only
> > + = opt_for_fn (callee->decl, flag_finite_math_only);
> > + opts.x_flag_signaling_nans
> > + = opt_for_fn (callee->decl, flag_signaling_nans);
> > + opts.x_flag_cx_limited_range
> > + = opt_for_fn (callee->decl, flag_cx_limited_range);
> > + opts.x_flag_signed_zeros
> > + = opt_for_fn (callee->decl, flag_signed_zeros);
> > + opts.x_flag_associative_math
> > + = opt_for_fn (callee->decl, flag_associative_math);
> > + opts.x_flag_reciprocal_math
> > + = opt_for_fn (callee->decl, flag_reciprocal_math);
> > + opts.x_flag_errno_math
> > + = opt_for_fn (callee->decl, flag_errno_math);
> > + if (dump_file)
> > + fprintf (dump_file, "Copying FP flags from %s:%i to %s:%i\n",
> > + callee->name (), callee->order, to->name (),
> > to->order);
> > + build_optimization_node (&opts);
> > + DECL_FUNCTION_SPECIFIC_OPTIMIZATION (to->decl)
> > + = build_optimization_node (&opts);
> > + }
> > + }
> >
> > /* If aliases are involved, redirect edge to the actual destination and
> > possibly remove the aliases. */
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
