From: Richard Biener <richard.guenther@gmail.com>
To: Feng Xue OS <fxue@os.amperecomputing.com>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,
Thomas Schwinge <thomas@codesourcery.com>,
Jeff Law <law@redhat.com>
Subject: Re: [PATCH V8] Remove empty loop with assumed finiteness (PR tree-optimization/89713)
Date: Wed, 12 Jun 2019 09:43:00 -0000 [thread overview]
Message-ID: <CAFiYyc0Rack5sTGZ0fFfPupcZvHx+YADY3ZFNBLAEvLhgOyneg@mail.gmail.com> (raw)
In-Reply-To: <BYAPR01MB48694A530E0A6BB69410A39DF7ED0@BYAPR01MB4869.prod.exchangelabs.com>
On Tue, Jun 11, 2019 at 4:40 AM Feng Xue OS <fxue@os.amperecomputing.com> wrote:
>
> Reformat to comply with gcc coding style.
OK for trunk.
Thanks,
Richard.
> Feng
>
> ---
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index 37aab79..87cc125 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,16 @@
> +2019-06-04 Feng Xue <fxue@os.amperecomputing.com>
> +
> + PR tree-optimization/89713
> + * doc/invoke.texi (-ffinite-loops): Document new option.
> + * common.opt (-ffinite-loops): New option.
> + * tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Mark
> + IFN_GOACC_LOOP calls as necessary.
> + * tree-ssa-loop-niter.c (finite_loop_p): Assume loop with an exit
> + is finite.
> + * omp-offload.c (oacc_xform_loop): Skip lowering if return value of
> + IFN_GOACC_LOOP call is not used.
> + * opts.c (default_options_table): Enable -ffinite-loops at -O2+.
> +
> 2019-06-04 Alan Modra <amodra@gmail.com>
>
> PR target/90689
> diff --git a/gcc/common.opt b/gcc/common.opt
> index 0e72fd0..8b0e6ad 100644
> --- a/gcc/common.opt
> +++ b/gcc/common.opt
> @@ -1437,6 +1437,10 @@ ffinite-math-only
> Common Report Var(flag_finite_math_only) Optimization SetByCombined
> Assume no NaNs or infinities are generated.
>
> +ffinite-loops
> +Common Report Var(flag_finite_loops) Optimization
> +Assume that loops with an exit will terminate and not loop indefinitely.
> +
> ffixed-
> Common Joined RejectNegative Var(common_deferred_options) Defer
> -ffixed-<register> Mark <register> as being unavailable to the compiler.
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index 91c9bb8..1e12595 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -412,6 +412,7 @@ Objective-C and Objective-C++ Dialects}.
> -fdevirtualize-at-ltrans -fdse @gol
> -fearly-inlining -fipa-sra -fexpensive-optimizations -ffat-lto-objects @gol
> -ffast-math -ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
> +-ffinite-loops @gol
> -fforward-propagate -ffp-contract=@var{style} -ffunction-sections @gol
> -fgcse -fgcse-after-reload -fgcse-las -fgcse-lm -fgraphite-identity @gol
> -fgcse-sm -fhoist-adjacent-loads -fif-conversion @gol
> @@ -8282,6 +8283,7 @@ also turns on the following optimization flags:
> -fdelete-null-pointer-checks @gol
> -fdevirtualize -fdevirtualize-speculatively @gol
> -fexpensive-optimizations @gol
> +-ffinite-loops @gol
> -fgcse -fgcse-lm @gol
> -fhoist-adjacent-loads @gol
> -finline-small-functions @gol
> @@ -9503,6 +9505,15 @@ that may set @code{errno} but are otherwise free of side effects. This flag is
> enabled by default at @option{-O2} and higher if @option{-Os} is not also
> specified.
>
> +@item -ffinite-loops
> +@opindex ffinite-loops
> +@opindex fno-finite-loops
> +Assume that a loop with an exit will eventually take the exit and not loop
> +indefinitely. This allows the compiler to remove loops that otherwise have
> +no side-effects, not considering eventual endless looping as such.
> +
> +This option is enabled by default at @option{-O2}.
> +
> @item -ftree-dominator-opts
> @opindex ftree-dominator-opts
> Perform a variety of simple scalar cleanups (constant/copy
> diff --git a/gcc/omp-offload.c b/gcc/omp-offload.c
> index 97ae47b..c8a281c 100644
> --- a/gcc/omp-offload.c
> +++ b/gcc/omp-offload.c
> @@ -300,7 +300,7 @@ oacc_xform_loop (gcall *call)
> tree chunk_size = NULL_TREE;
> unsigned mask = (unsigned) TREE_INT_CST_LOW (gimple_call_arg (call, 5));
> tree lhs = gimple_call_lhs (call);
> - tree type = TREE_TYPE (lhs);
> + tree type = NULL_TREE;
> tree diff_type = TREE_TYPE (range);
> tree r = NULL_TREE;
> gimple_seq seq = NULL;
> @@ -308,6 +308,15 @@ oacc_xform_loop (gcall *call)
> unsigned outer_mask = mask & (~mask + 1); // Outermost partitioning
> unsigned inner_mask = mask & ~outer_mask; // Inner partitioning (if any)
>
> + /* Skip lowering if return value of IFN_GOACC_LOOP call is not used. */
> + if (!lhs)
> + {
> + gsi_replace_with_seq (&gsi, seq, true);
> + return;
> + }
> +
> + type = TREE_TYPE (lhs);
> +
> #ifdef ACCEL_COMPILER
> chunk_size = gimple_call_arg (call, 4);
> if (integer_minus_onep (chunk_size) /* Force static allocation. */
> diff --git a/gcc/opts.c b/gcc/opts.c
> index 64f94ac..b38bfb1 100644
> --- a/gcc/opts.c
> +++ b/gcc/opts.c
> @@ -494,6 +494,7 @@ static const struct default_options default_options_table[] =
> { OPT_LEVELS_2_PLUS, OPT_fdevirtualize, NULL, 1 },
> { OPT_LEVELS_2_PLUS, OPT_fdevirtualize_speculatively, NULL, 1 },
> { OPT_LEVELS_2_PLUS, OPT_fexpensive_optimizations, NULL, 1 },
> + { OPT_LEVELS_2_PLUS, OPT_ffinite_loops, NULL, 1 },
> { OPT_LEVELS_2_PLUS, OPT_fgcse, NULL, 1 },
> { OPT_LEVELS_2_PLUS, OPT_fhoist_adjacent_loads, NULL, 1 },
> { OPT_LEVELS_2_PLUS, OPT_findirect_inlining, NULL, 1 },
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/empty-loop.C b/gcc/testsuite/g++.dg/tree-ssa/empty-loop.C
> new file mode 100644
> index 0000000..6b1e879
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/empty-loop.C
> @@ -0,0 +1,33 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-cddce2 -ffinite-loops" } */
> +
> +#include <string>
> +#include <vector>
> +#include <list>
> +#include <set>
> +#include <map>
> +
> +using namespace std;
> +
> +int foo (vector<string> &v, list<string> &l, set<string> &s, map<int, string> &m)
> +{
> + for (vector<string>::iterator it = v.begin (); it != v.end (); ++it)
> + it->length();
> +
> + for (list<string>::iterator it = l.begin (); it != l.end (); ++it)
> + it->length();
> +
> + for (map<int, string>::iterator it = m.begin (); it != m.end (); ++it)
> + it->first + it->second.length();
> +
> + for (set<string>::iterator it0 = s.begin (); it0 != s.end(); ++it0)
> + for (vector<string>::reverse_iterator it1 = v.rbegin(); it1 != v.rend(); ++it1)
> + {
> + it0->length();
> + it1->length();
> + }
> +
> + return 0;
> +}
> +/* { dg-final { scan-tree-dump-not "if" "cddce2"} } */
> +
> diff --git a/gcc/testsuite/gcc.dg/const-1.c b/gcc/testsuite/gcc.dg/const-1.c
> index a5b2b16..2e95bd8 100644
> --- a/gcc/testsuite/gcc.dg/const-1.c
> +++ b/gcc/testsuite/gcc.dg/const-1.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile { target nonpic } } */
> -/* { dg-options "-O2 -Wsuggest-attribute=const" } */
> +/* { dg-options "-O2 -Wsuggest-attribute=const -fno-finite-loops" } */
>
> extern int extern_const(int a) __attribute__ ((const));
>
> diff --git a/gcc/testsuite/gcc.dg/graphite/graphite.exp b/gcc/testsuite/gcc.dg/graphite/graphite.exp
> index ea61446..523a955 100644
> --- a/gcc/testsuite/gcc.dg/graphite/graphite.exp
> +++ b/gcc/testsuite/gcc.dg/graphite/graphite.exp
> @@ -56,7 +56,7 @@ set vect_files [lsort [glob -nocomplain $srcdir/$subdir/vect-*.c ] ]
>
> # Tests to be compiled.
> set dg-do-what-default compile
> -dg-runtest $scop_files "" "-O2 -fgraphite -fdump-tree-graphite-all"
> +dg-runtest $scop_files "" "-O2 -fgraphite -fdump-tree-graphite-all -fno-finite-loops"
> dg-runtest $id_files "" "-O2 -fgraphite-identity -ffast-math -fdump-tree-graphite-details"
>
> # Tests to be run.
> diff --git a/gcc/testsuite/gcc.dg/loop-unswitch-1.c b/gcc/testsuite/gcc.dg/loop-unswitch-1.c
> index f6fc41d..de2fb2c 100644
> --- a/gcc/testsuite/gcc.dg/loop-unswitch-1.c
> +++ b/gcc/testsuite/gcc.dg/loop-unswitch-1.c
> @@ -1,6 +1,6 @@
> /* For PR rtl-optimization/27735 */
> /* { dg-do compile } */
> -/* { dg-options "-O2 -funswitch-loops -fdump-tree-unswitch-details" } */
> +/* { dg-options "-O2 -funswitch-loops -fdump-tree-unswitch-details -fno-finite-loops" } */
>
> void set_color(void);
> void xml_colorize_line(unsigned int *p, int state)
> diff --git a/gcc/testsuite/gcc.dg/predict-9.c b/gcc/testsuite/gcc.dg/predict-9.c
> index 7e5ba08..f491c51 100644
> --- a/gcc/testsuite/gcc.dg/predict-9.c
> +++ b/gcc/testsuite/gcc.dg/predict-9.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdisable-tree-evrp -fdump-tree-profile_estimate" } */
> +/* { dg-options "-O2 -fdisable-tree-evrp -fdump-tree-profile_estimate -fno-finite-loops" } */
>
> extern int global;
> extern int global2;
> diff --git a/gcc/testsuite/gcc.dg/pure-2.c b/gcc/testsuite/gcc.dg/pure-2.c
> index fe6e2bc..318cfd1 100644
> --- a/gcc/testsuite/gcc.dg/pure-2.c
> +++ b/gcc/testsuite/gcc.dg/pure-2.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -Wsuggest-attribute=pure" } */
> +/* { dg-options "-O2 -Wsuggest-attribute=pure -fno-finite-loops" } */
> /* { dg-add-options bind_pic_locally } */
>
> extern int extern_const(int a) __attribute__ ((pure));
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/20040211-1.c b/gcc/testsuite/gcc.dg/tree-ssa/20040211-1.c
> index d289e5d..a9bdf26 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/20040211-1.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/20040211-1.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-tree-cddce2" } */
> +/* { dg-options "-O2 -fdump-tree-cddce2 -fno-finite-loops" } */
>
> struct rtx_def;
> typedef struct rtx_def *rtx;
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dce-2.c b/gcc/testsuite/gcc.dg/tree-ssa/dce-2.c
> new file mode 100644
> index 0000000..18c1ddb
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/dce-2.c
> @@ -0,0 +1,37 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-cddce1 -ffinite-loops" } */
> +
> +typedef struct list {
> + char pad[15];
> + struct list *next;
> +} list;
> +
> +int data;
> +
> +list *head, *tail;
> +
> +int __attribute__((pure)) pfn (int);
> +
> +int foo (unsigned u, int s)
> +{
> + unsigned i;
> + list *p;
> + int j;
> +
> + for (i = 0; i < u; i += 2)
> + ;
> +
> + for (p = head; p; p = p->next)
> + ;
> +
> + for (j = data; j & s; j = pfn (j + 3))
> + ;
> +
> + for (p = head; p != tail; p = p->next)
> + for (j = data + 1; j > s; j = pfn (j + 2))
> + ;
> +
> + return 0;
> +}
> +/* { dg-final { scan-tree-dump-not "if" "cddce1"} } */
> +
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/loop-10.c b/gcc/testsuite/gcc.dg/tree-ssa/loop-10.c
> index a29c9fb..3d05ad2 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/loop-10.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/loop-10.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* { dg-options "-O2 -fdump-tree-optimized -fno-finite-loops" } */
> /* { dg-require-effective-target int32plus } */
>
> int bar (void);
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c b/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c
> index e9b4f26..187c084 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fsplit-paths -fno-tree-cselim -fdump-tree-split-paths-details -w" } */
> +/* { dg-options "-O2 -fsplit-paths -fno-tree-cselim -fdump-tree-split-paths-details -w -fno-finite-loops" } */
>
> struct __sFILE
> {
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-12.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-12.c
> index d829b04..6752676 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-12.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-12.c
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-tree-thread2-details -fdump-tree-thread3-details -fdump-tree-thread4-details" } */
> +/* { dg-options "-O2 -fdump-tree-thread2-details -fdump-tree-thread3-details -fdump-tree-thread4-details -fno-finite-loops" } */
> /* { dg-final { scan-tree-dump "FSM" "thread2" } } */
> /* { dg-final { scan-tree-dump "FSM" "thread3" } } */
> /* { dg-final { scan-tree-dump "FSM" "thread4" { xfail *-*-* } } } */
> diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
> index 2478219..a38899e 100644
> --- a/gcc/tree-ssa-dce.c
> +++ b/gcc/tree-ssa-dce.c
> @@ -245,6 +245,17 @@ mark_stmt_if_obviously_necessary (gimple *stmt, bool aggressive)
> mark_stmt_necessary (stmt, true);
> return;
> }
> + /* IFN_GOACC_LOOP calls are necessary in that they are used to
> + represent parameter (i.e. step, bound) of a lowered OpenACC
> + partitioned loop. But this kind of partitioned loop might not
> + survive from aggressive loop removal for it has loop exit and
> + is assumed to be finite. Therefore, we need to explicitly mark
> + these calls. (An example is libgomp.oacc-c-c++-common/pr84955.c) */
> + if (gimple_call_internal_p (stmt, IFN_GOACC_LOOP))
> + {
> + mark_stmt_necessary (stmt, true);
> + return;
> + }
> if (!gimple_call_lhs (stmt))
> return;
> break;
> diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
> index 470b6a2..9b9cb41 100644
> --- a/gcc/tree-ssa-loop-niter.c
> +++ b/gcc/tree-ssa-loop-niter.c
> @@ -2798,6 +2798,27 @@ finite_loop_p (struct loop *loop)
> loop->num);
> return true;
> }
> +
> + if (flag_finite_loops)
> + {
> + unsigned i;
> + vec<edge> exits = get_loop_exit_edges (loop);
> + edge ex;
> +
> + /* If the loop has a normal exit, we can assume it will terminate. */
> + FOR_EACH_VEC_ELT (exits, i, ex)
> + if (!(ex->flags & (EDGE_EH | EDGE_ABNORMAL | EDGE_FAKE)))
> + {
> + exits.release ();
> + if (dump_file)
> + fprintf (dump_file, "Assume loop %i to be finite: it has an exit "
> + "and -ffinite-loops is on.\n", loop->num);
> + return true;
> + }
> +
> + exits.release ();
> + }
> +
> return false;
> }
>
> diff --git a/libgomp/testsuite/libgomp.oacc-c-c++-common/pr84955-1.c b/libgomp/testsuite/libgomp.oacc-c-c++-common/pr84955-1.c
> new file mode 100644
> index 0000000..44767cd
> --- /dev/null
> +++ b/libgomp/testsuite/libgomp.oacc-c-c++-common/pr84955-1.c
> @@ -0,0 +1,31 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-cddce2 -ffinite-loops" } */
> +
> +int
> +f1 (void)
> +{
> + int i, j;
> +
> +#pragma acc parallel loop tile(2,3)
> + for (i = 1; i < 10; i++)
> + for (j = 1; j < 10; j++)
> + for (;;)
> + ;
> +
> + return i + j;
> +}
> +
> +int
> +f2 (void)
> +{
> + int i, j, k;
> +
> +#pragma acc parallel loop tile(2,3)
> + for (i = 1; i < 10; i++)
> + for (j = 1; j < 10; j++)
> + for (k = 1; k < 10; k++)
> + ;
> +
> + return i + j;
> +}
> +/* { dg-final { scan-tree-dump-not "if" "cddce2"} } */
> --
> 1.8.3.1
next prev parent reply other threads:[~2019-06-12 9:43 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-17 4:17 [PATCH] " Feng Xue OS
2019-05-17 16:47 ` Jeff Law
2019-05-17 18:50 ` Richard Biener
2019-05-18 14:00 ` Marc Glisse
2019-05-20 7:50 ` Richard Biener
2019-05-20 8:27 ` Feng Xue OS
2019-05-20 9:19 ` Richard Biener
2019-05-20 9:48 ` Feng Xue OS
2019-05-20 11:54 ` Richard Biener
2019-05-20 14:00 ` Feng Xue OS
2019-05-20 14:04 ` Richard Biener
2019-05-20 14:51 ` Feng Xue OS
2019-05-21 10:12 ` Richard Biener
2019-05-21 14:24 ` Richard Biener
2019-05-22 13:44 ` Michael Matz
2019-05-24 16:02 ` [PATCH V3] " Feng Xue OS
2019-05-24 9:15 ` [PATCH V2] " Feng Xue OS
2019-05-29 11:16 ` Richard Biener
2019-06-04 6:49 ` [PATCH V4] " Feng Xue OS
2019-06-04 8:24 ` Marc Glisse
2019-06-04 15:16 ` [PATCH V5] " Feng Xue OS
2019-06-04 15:24 ` [PATCH V6] " Feng Xue OS
2019-06-05 11:05 ` Richard Biener
2019-06-06 10:00 ` [PATCH V7] " Feng Xue OS
2019-06-11 2:40 ` [PATCH V8] " Feng Xue OS
2019-06-12 9:43 ` Richard Biener [this message]
2019-06-15 12:05 ` [committed][nvptx, libgomp] Update pr85381-{2,4}.c test-cases Tom de Vries
2019-05-20 13:04 ` [PATCH] Remove empty loop with assumed finiteness (PR tree-optimization/89713) Marc Glisse
2019-05-20 13:26 ` Richard Biener
2019-05-20 14:49 ` Michael Matz
2019-05-21 8:06 ` Marc Glisse
2020-04-01 13:36 ` [PATCH][RFC] c/94392 - only enable -ffinite-loops for C++ Richard Biener
2020-04-01 13:47 ` Jakub Jelinek
2020-04-01 13:52 ` Richard Biener
2020-04-01 15:56 ` Jan Hubicka
2020-04-01 16:59 ` Richard Biener
2020-04-01 19:15 ` Jason Merrill
2020-04-02 9:12 ` Richard Biener
2020-04-02 9:17 ` Jakub Jelinek
2020-04-02 9:41 ` Richard Biener
2020-04-03 8:29 ` Revert "[nvptx, libgomp] Update pr85381-{2, 4}.c test-cases" [PR89713, PR94392] (was: [PATCH][RFC] c/94392 - only enable -ffinite-loops for C++) Thomas Schwinge
2020-04-03 9:36 ` Revert "[nvptx, libgomp] Update pr85381-{2,4}.c " Richard Biener
2020-04-03 10:34 ` Jakub Jelinek
2020-10-30 14:09 ` Revert "[nvptx, libgomp] Update pr85381-{2, 4}.c " Thomas Schwinge
2020-10-30 14:16 ` Revert "[nvptx, libgomp] Update pr85381-{2,4}.c " Jakub Jelinek
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