From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 80474 invoked by alias); 12 Jun 2019 09:43:15 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 80460 invoked by uid 89); 12 Jun 2019 09:43:15 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-14.5 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.1 spammy=Xue, xue, finiteness, sk:wsugges X-HELO: mail-lj1-f194.google.com Received: from mail-lj1-f194.google.com (HELO mail-lj1-f194.google.com) (209.85.208.194) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 12 Jun 2019 09:43:12 +0000 Received: by mail-lj1-f194.google.com with SMTP id h10so8636180ljg.0 for ; Wed, 12 Jun 2019 02:43:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=0XEgqssNN3FZ7bduBVuoyBVXT5pPKtDWqXr8Rn6rgGk=; b=Ewpa2l0Ipu1OIzOEzRM805OtVO5HUcJGkws0s1v6GdG44kDnPM3tnAL7tyH/NlZp+/ sv2fNkj/kMbY7NEm47VJBWwoqpv5B5z/p9XRNg9exLr0SR/+pIoRHw614mA9IYSmnGWu 5x5o/FMGfxcPBUEEi7JNAKEx9B5M7G1UkCKNRYO0uJrCpMFnKbmqs6c9MUwdNgyacmQi y7OTfLv1xpHPF3a/fKyCSDNyizJCBmXRUKb4vYjpipCVkaf4aajJXxxWpr2FEicU8bpG 2ofUMNvtzyLzEFFoByhSIA6NLiL4eSb7CUnY0XtWItCAMT0vffEdOwBpI0ZNyQ3ChaEJ CJhQ== MIME-Version: 1.0 References: In-Reply-To: From: Richard Biener Date: Wed, 12 Jun 2019 09:43:00 -0000 Message-ID: Subject: Re: [PATCH V8] Remove empty loop with assumed finiteness (PR tree-optimization/89713) To: Feng Xue OS Cc: "gcc-patches@gcc.gnu.org" , Thomas Schwinge , Jeff Law Content-Type: text/plain; charset="UTF-8" X-IsSubscribed: yes X-SW-Source: 2019-06/txt/msg00691.txt.bz2 On Tue, Jun 11, 2019 at 4:40 AM Feng Xue OS 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 > + > + 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 > > 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- Mark 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 > +#include > +#include > +#include > +#include > + > +using namespace std; > + > +int foo (vector &v, list &l, set &s, map &m) > +{ > + for (vector::iterator it = v.begin (); it != v.end (); ++it) > + it->length(); > + > + for (list::iterator it = l.begin (); it != l.end (); ++it) > + it->length(); > + > + for (map::iterator it = m.begin (); it != m.end (); ++it) > + it->first + it->second.length(); > + > + for (set::iterator it0 = s.begin (); it0 != s.end(); ++it0) > + for (vector::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 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