From c29c92c789d93848cc1c929838771bfc68cb272c Mon Sep 17 00:00:00 2001 From: Feng Xue Date: Thu, 13 Jun 2019 04:17:42 +0000 Subject: [PATCH] PR tree-optimization/89713 - Assume loop with an exit is finite gcc/ChangeLog: * 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+. gcc/testsuite/ChangeLog: * g++.dg/tree-ssa/empty-loop.C: New test. * gcc.dg/tree-ssa/dce-2.c: New test. * gcc.dg/const-1.c: Add -fno-finite-loops option. * gcc.dg/graphite/graphite.exp: Likewise. * gcc.dg/loop-unswitch-1.c: Likewise. * gcc.dg/predict-9.c: Likewise. * gcc.dg/pure-2.c: Likewise. * gcc.dg/tree-ssa/20040211-1.c: Likewise. * gcc.dg/tree-ssa/loop-10.c: Likewise. * gcc.dg/tree-ssa/split-path-6.c: Likewise. * gcc.dg/tree-ssa/ssa-thread-12.c: Likewise. libgomp/ChangeLog: * testsuite/libgomp.oacc-c-c++-common/pr84955-1.c: New test. From-SVN: r272234 --- gcc/ChangeLog | 13 +++++++ gcc/common.opt | 4 ++ gcc/doc/invoke.texi | 11 ++++++ gcc/omp-offload.c | 11 +++++- gcc/opts.c | 1 + gcc/testsuite/ChangeLog | 15 ++++++++ gcc/testsuite/g++.dg/tree-ssa/empty-loop.C | 33 +++++++++++++++++ gcc/testsuite/gcc.dg/const-1.c | 2 +- gcc/testsuite/gcc.dg/graphite/graphite.exp | 2 +- gcc/testsuite/gcc.dg/loop-unswitch-1.c | 2 +- gcc/testsuite/gcc.dg/predict-9.c | 2 +- gcc/testsuite/gcc.dg/pure-2.c | 2 +- gcc/testsuite/gcc.dg/tree-ssa/20040211-1.c | 2 +- gcc/testsuite/gcc.dg/tree-ssa/dce-2.c | 37 +++++++++++++++++++ gcc/testsuite/gcc.dg/tree-ssa/loop-10.c | 2 +- gcc/testsuite/gcc.dg/tree-ssa/split-path-6.c | 2 +- gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-12.c | 2 +- gcc/tree-ssa-dce.c | 11 ++++++ gcc/tree-ssa-loop-niter.c | 21 +++++++++++ libgomp/ChangeLog | 5 +++ .../libgomp.oacc-c-c++-common/pr84955-1.c | 31 ++++++++++++++++ 21 files changed, 201 insertions(+), 10 deletions(-) create mode 100644 gcc/testsuite/g++.dg/tree-ssa/empty-loop.C create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/dce-2.c create mode 100644 libgomp/testsuite/libgomp.oacc-c-c++-common/pr84955-1.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 079379e45dc..efb3b7361f2 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,16 @@ +2019-06-13 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+. + 2019-06-13 Kugan Vivekanandarajah PR target/88838 diff --git a/gcc/common.opt b/gcc/common.opt index e1404165feb..a1544d06824 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 090d606b3ba..bf9da0f0a6e 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -413,6 +413,7 @@ 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 @@ -8303,6 +8304,7 @@ 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 @@ -9524,6 +9526,15 @@ 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 97ae47b3135..c8a281c6d28 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 64f94ac8ffd..b38bfb15a56 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/ChangeLog b/gcc/testsuite/ChangeLog index 7212c6be525..f82dc9e09ed 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,18 @@ +2019-06-13 Feng Xue + + PR tree-optimization/89713 + * g++.dg/tree-ssa/empty-loop.C: New test. + * gcc.dg/tree-ssa/dce-2.c: New test. + * gcc.dg/const-1.c: Add -fno-finite-loops option. + * gcc.dg/graphite/graphite.exp: Likewise. + * gcc.dg/loop-unswitch-1.c: Likewise. + * gcc.dg/predict-9.c: Likewise. + * gcc.dg/pure-2.c: Likewise. + * gcc.dg/tree-ssa/20040211-1.c: Likewise. + * gcc.dg/tree-ssa/loop-10.c: Likewise. + * gcc.dg/tree-ssa/split-path-6.c: Likewise. + * gcc.dg/tree-ssa/ssa-thread-12.c: Likewise. + 2019-06-13 Kugan Vivekanandarajah PR target/88838 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 00000000000..6b1e879e6a9 --- /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 a5b2b167728..2e95bd8e2ea 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 ea6144607e2..523a955e82d 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 f6fc41d6bcc..de2fb2c0e4b 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 7e5ba085ece..f491c511bd9 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 fe6e2bce695..318cfd18630 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 d289e5d0f55..a9bdf26931a 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 00000000000..18c1ddb819e --- /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 a29c9fb2501..3d05ad2d073 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 e9b4f2628d5..187c08407d5 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 d829b04d177..67526762f2c 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 2478219d873..a38899edd6c 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 84e6e313c85..f51385900ed 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -2830,6 +2830,27 @@ 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/ChangeLog b/libgomp/ChangeLog index 34878806786..35fe54851f9 100644 --- a/libgomp/ChangeLog +++ b/libgomp/ChangeLog @@ -1,3 +1,8 @@ +2019-06-13 Feng Xue + + PR tree-optimization/89713 + * testsuite/libgomp.oacc-c-c++-common/pr84955-1.c: New test. + 2019-06-11 Jakub Jelinek PR target/90811 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 00000000000..44767cd27c3 --- /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"} } */ -- 2.30.2