On Wed, Nov 12, 2014 at 02:49:30PM +0400, Maxim Ostapenko wrote:
> We used this code for IPA propagation of nonfreeing_call_p. It implemented
> with a separate pass, but it probably could be propagated in some existing
> one. This analysis doesn't seem to be costly thought, we didn't see any
> significant slowdown compiling big files.
Here it is rewritten using ipa-pure-const which is where Richard/Honza
suggested it should be done in.
I wonder if the nonfreeing_call_p function shouldn't be moved elsewhere
though (suggestion where), so that gimple.c doesn't need the cgraph
includes.
In any case, bootstrapped/regtested on x86_64-linux and i686-linux.
2014-11-12 Jakub Jelinek <ja...@redhat.com>
* ipa-pure-const.c (struct funct_state_d): Add can_free field.
(varying_state): Add true for can_free.
(check_call): For builtin or internal !nonfreeing_call_p set
local->can_free.
(check_stmt): For asm volatile and asm with "memory" set
local->can_free.
(analyze_function): Clear local->can_free initially, continue
calling check_stmt until all flags are computed, dump can_free
flag.
(pure_const_write_summary): Write can_free flag.
(pure_const_read_summary): Read it back.
(propagate_can_free): New function.
(pass_ipa_pure_const::execute): Call it.
* cgraph.h (cgraph_node): Add nonfreeing_fn member.
* gimple.c: Include ipa-ref.h, lto-streamer.h and cgraph.h.
(nonfreeing_call_p): Return cgraph nonfreeing_fn flag if set.
* cgraph.c (cgraph_node::dump): Dump nonfreeing_fn flag.
* lto-cgraph.c (lto_output_node): Write nonfreeing_fn flag.
(input_overwrite_node): Read it back.
--- gcc/ipa-pure-const.c.jj 2014-11-12 18:32:56.351139726 +0100
+++ gcc/ipa-pure-const.c 2014-11-12 21:11:08.574354600 +0100
@@ -112,11 +112,15 @@ struct funct_state_d
bool looping;
bool can_throw;
+
+ /* If function can call free, munmap or otherwise make previously
+ non-trapping memory accesses trapping. */
+ bool can_free;
};
/* State used when we know nothing about function. */
static struct funct_state_d varying_state
- = { IPA_NEITHER, IPA_NEITHER, true, true, true };
+ = { IPA_NEITHER, IPA_NEITHER, true, true, true, true };
typedef struct funct_state_d * funct_state;
@@ -559,6 +563,10 @@ check_call (funct_state local, gimple ca
enum pure_const_state_e call_state;
bool call_looping;
+ if (gimple_call_builtin_p (call, BUILT_IN_NORMAL)
+ && !nonfreeing_call_p (call))
+ local->can_free = true;
+
if (special_builtin_state (&call_state, &call_looping, callee_t))
{
worse_state (&local->pure_const_state, &local->looping,
@@ -589,6 +597,8 @@ check_call (funct_state local, gimple ca
break;
}
}
+ else if (gimple_call_internal_p (call) && !nonfreeing_call_p (call))
+ local->can_free = true;
/* When not in IPA mode, we can still handle self recursion. */
if (!ipa && callee_t
@@ -753,6 +763,7 @@ check_stmt (gimple_stmt_iterator *gsip,
fprintf (dump_file, " memory asm clobber is not const/pure\n");
/* Abandon all hope, ye who enter here. */
local->pure_const_state = IPA_NEITHER;
+ local->can_free = true;
}
if (gimple_asm_volatile_p (stmt))
{
@@ -761,6 +772,7 @@ check_stmt (gimple_stmt_iterator *gsip,
/* Abandon all hope, ye who enter here. */
local->pure_const_state = IPA_NEITHER;
local->looping = true;
+ local->can_free = true;
}
return;
default:
@@ -785,6 +797,7 @@ analyze_function (struct cgraph_node *fn
l->looping_previously_known = true;
l->looping = false;
l->can_throw = false;
+ l->can_free = false;
state_from_flags (&l->state_previously_known, &l->looping_previously_known,
flags_from_decl_or_type (fn->decl),
fn->cannot_return_p ());
@@ -815,7 +828,10 @@ analyze_function (struct cgraph_node *fn
gsi_next (&gsi))
{
check_stmt (&gsi, l, ipa);
- if (l->pure_const_state == IPA_NEITHER && l->looping && l->can_throw)
+ if (l->pure_const_state == IPA_NEITHER
+ && l->looping
+ && l->can_throw
+ && l->can_free)
goto end;
}
}
@@ -882,6 +898,8 @@ end:
fprintf (dump_file, "Function is locally const.\n");
if (l->pure_const_state == IPA_PURE)
fprintf (dump_file, "Function is locally pure.\n");
+ if (l->can_free)
+ fprintf (dump_file, "Function can locally free.\n");
}
return l;
}
@@ -1021,6 +1039,7 @@ pure_const_write_summary (void)
bp_pack_value (&bp, fs->looping_previously_known, 1);
bp_pack_value (&bp, fs->looping, 1);
bp_pack_value (&bp, fs->can_throw, 1);
+ bp_pack_value (&bp, fs->can_free, 1);
streamer_write_bitpack (&bp);
}
}
@@ -1080,6 +1099,7 @@ pure_const_read_summary (void)
fs->looping_previously_known = bp_unpack_value (&bp, 1);
fs->looping = bp_unpack_value (&bp, 1);
fs->can_throw = bp_unpack_value (&bp, 1);
+ fs->can_free = bp_unpack_value (&bp, 1);
if (dump_file)
{
int flags = flags_from_decl_or_type (node->decl);
@@ -1102,6 +1122,8 @@ pure_const_read_summary (void)
fprintf (dump_file," function is previously known
looping\n");
if (fs->can_throw)
fprintf (dump_file," function is locally throwing\n");
+ if (fs->can_free)
+ fprintf (dump_file," function can locally free\n");
}
}
@@ -1510,6 +1532,82 @@ propagate_nothrow (void)
free (order);
}
+/* Produce transitive closure over the callgraph and compute can_free
+ attributes. */
+
+static void
+propagate_can_free (void)
+{
+ struct cgraph_node *node;
+ struct cgraph_node *w;
+ struct cgraph_node **order
+ = XCNEWVEC (struct cgraph_node *, symtab->cgraph_count);
+ int order_pos;
+ int i;
+ struct ipa_dfs_info *w_info;
+
+ order_pos = ipa_reduced_postorder (order, true, false, NULL);
+ if (dump_file)
+ {
+ cgraph_node::dump_cgraph (dump_file);
+ ipa_print_order (dump_file, "reduced", order, order_pos);
+ }
+
+ /* Propagate the local information through the call graph to produce
+ the global information. All the nodes within a cycle will have
+ the same info so we collapse cycles first. Then we can do the
+ propagation in one pass from the leaves to the roots. */
+ for (i = 0; i < order_pos; i++ )
+ {
+ bool can_free = false;
+ node = order[i];
+
+ if (node->alias)
+ continue;
+
+ /* Find the worst state for any node in the cycle. */
+ w = node;
+ while (w && !can_free)
+ {
+ struct cgraph_edge *e;
+ funct_state w_l = get_function_state (w);
+
+ if (w_l->can_free
+ || w->get_availability () == AVAIL_INTERPOSABLE
+ || w->indirect_calls)
+ can_free = true;
+
+ for (e = w->callees; e && !can_free; e = e->next_callee)
+ {
+ enum availability avail;
+ struct cgraph_node *y = e->callee->function_symbol (&avail);
+
+ if (avail > AVAIL_INTERPOSABLE)
+ can_free = get_function_state (y)->can_free;
+ else
+ can_free = true;
+ }
+ w_info = (struct ipa_dfs_info *) w->aux;
+ w = w_info->next_cycle;
+ }
+
+ /* Copy back the region's can_free which is shared by
+ all nodes in the region. */
+ w = node;
+ while (w)
+ {
+ funct_state w_l = get_function_state (w);
+ w_l->can_free = can_free;
+ w->nonfreeing_fn = !can_free;
+ w_info = (struct ipa_dfs_info *) w->aux;
+ w = w_info->next_cycle;
+ }
+ }
+
+ ipa_free_postorder_info ();
+ free (order);
+}
+
/* Produce the global information by preforming a transitive closure
on the local information that was produced by generate_summary. */
@@ -1528,6 +1626,7 @@ execute (function *)
later analysis. */
propagate_nothrow ();
propagate_pure_const ();
+ propagate_can_free ();
/* Cleanup. */
FOR_EACH_FUNCTION (node)
--- gcc/cgraph.h.jj 2014-11-12 18:09:27.784014976 +0100
+++ gcc/cgraph.h 2014-11-12 21:05:53.851895859 +0100
@@ -1260,6 +1260,10 @@ public:
/* True when function is clone created for Pointer Bounds Checker
instrumentation. */
unsigned instrumentation_clone : 1;
+ /* True if call to node can't result in a call to free, munmap or
+ other operation that could make previously non-trapping memory
+ accesses trapping. */
+ unsigned nonfreeing_fn : 1;
};
/* A cgraph node set is a collection of cgraph nodes. A cgraph node
--- gcc/gimple.c.jj 2014-11-12 21:01:52.532940986 +0100
+++ gcc/gimple.c 2014-11-12 21:05:53.849895526 +0100
@@ -58,6 +58,9 @@ along with GCC; see the file COPYING3.
#include "bitmap.h"
#include "stringpool.h"
#include "tree-ssanames.h"
+#include "ipa-ref.h"
+#include "lto-streamer.h"
+#include "cgraph.h"
/* All the tuples have their operand vector (if present) at the very bottom
@@ -2542,7 +2545,13 @@ nonfreeing_call_p (gimple call)
&& gimple_call_flags (call) & ECF_LEAF)
return true;
- return false;
+ tree fndecl = gimple_call_fndecl (call);
+ if (!fndecl)
+ return false;
+ struct cgraph_node *n = cgraph_node::get (fndecl);
+ if (!n || n->get_availability () <= AVAIL_INTERPOSABLE)
+ return false;
+ return n->nonfreeing_fn;
}
/* Callback for walk_stmt_load_store_ops.
--- gcc/cgraph.c.jj 2014-11-11 00:05:42.000000000 +0100
+++ gcc/cgraph.c 2014-11-12 21:05:53.848895354 +0100
@@ -1986,6 +1986,8 @@ cgraph_node::dump (FILE *f)
fprintf (f, " tm_clone");
if (icf_merged)
fprintf (f, " icf_merged");
+ if (nonfreeing_fn)
+ fprintf (f, " nonfreeing_fn");
if (DECL_STATIC_CONSTRUCTOR (decl))
fprintf (f," static_constructor (priority:%i)", get_init_priority ());
if (DECL_STATIC_DESTRUCTOR (decl))
--- gcc/lto-cgraph.c.jj 2014-11-11 00:06:11.000000000 +0100
+++ gcc/lto-cgraph.c 2014-11-12 21:05:53.846895004 +0100
@@ -549,6 +549,7 @@ lto_output_node (struct lto_simple_outpu
bp_pack_value (&bp, node->tm_clone, 1);
bp_pack_value (&bp, node->calls_comdat_local, 1);
bp_pack_value (&bp, node->icf_merged, 1);
+ bp_pack_value (&bp, node->nonfreeing_fn, 1);
bp_pack_value (&bp, node->thunk.thunk_p && !boundary_p, 1);
bp_pack_enum (&bp, ld_plugin_symbol_resolution,
LDPR_NUM_KNOWN, node->resolution);
@@ -1097,6 +1098,7 @@ input_overwrite_node (struct lto_file_de
node->tm_clone = bp_unpack_value (bp, 1);
node->calls_comdat_local = bp_unpack_value (bp, 1);
node->icf_merged = bp_unpack_value (bp, 1);
+ node->nonfreeing_fn = bp_unpack_value (bp, 1);
node->thunk.thunk_p = bp_unpack_value (bp, 1);
node->resolution = bp_unpack_enum (bp, ld_plugin_symbol_resolution,
LDPR_NUM_KNOWN);
Jakub
