Some changes on documentation.
Feng
----
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 37aab79..4fdc5c8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2019-06-04 Feng Xue <f...@os.amperecomputing.com>
+
+ PR tree-optimization/89713
+ * doc/invoke.texi (-ffinite-loop): Document new option.
+ * common.opt (-ffinite-loop): 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): 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-loop at -O2+.
+
2019-06-04 Alan Modra <amo...@gmail.com>
PR target/90689
diff --git a/gcc/common.opt b/gcc/common.opt
index 0e72fd0..f570815 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-loop
+Common Report Var(flag_finite_loop) 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..2cb0b9a 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-loop @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-loop @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-loop
+@opindex ffinite-loop
+@opindex fno-finite-loop
+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..369122f 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..0db9dda 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_loop, 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..e374155
--- /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-loop" } */
+
+#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..13e3451 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-loop" } */
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..b294b9c 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-loop"
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..735eeef 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-loop" } */
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..3710eef 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-loop" } */
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..6ac372b 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-loop" } */
/* { 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..e4d331e 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-loop" } */
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..ffca49c
--- /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-loop" } */
+
+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..c605005 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-loop" } */
/* { 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..7c47906 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-loop" } */
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..b7a3d77 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-loop" } */
/* { 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..179605e 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..c25cb1d 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_loop)
+ {
+ unsigned i;
+ vec<edge> exits = get_loop_exit_edges (loop);
+ edge ex;
+
+ /* If the loop has any non-EH exit, we can assume it will terminate. */
+ FOR_EACH_VEC_ELT (exits, i, ex)
+ if (!(ex->flags & EDGE_EH))
+ {
+ exits.release ();
+ if (dump_file)
+ fprintf (dump_file, "Assume loop %i to be finite: it has an exit "
+ "and -ffinite-loop 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..845268b
--- /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-loop" } */
+
+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"} } */
