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?
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. */
