Hi!
On Thu, Nov 13, 2014 at 12:11:08AM +0100, Jan Hubicka wrote:
> Actually I think you want to do this for can_throw, too.
> We probably do not have throwing internal calls, but it is better to be safe.
I'll leave that change to you ;), as I said in my last mail, it isn't
immediately clear to me what exactly you want to do with internal calls
for can_throw (if anything) and for pure_const/looping.
E.g. for pure_const, internal calls can be memory accesses (e.g.
MASK_LOAD/MASK_STORE/LOAD_LANES/STORE_LANES, supposedly even ASAN_CHECK
can be considered a memory access). Though, the first 4 should ATM
appear only post-IPA, and ASAN_CHECK should just accompany some normal
memory access.
> The propagation seems fine, but I wonder if we won't get better memory
> locality doing this
> during the propagation of pure/const?
Done below, though I chose to use a separate w = node; ... w =
w_info->next_cycle;
loop to compute can_free, because trying to do it in the same loop as
pure_const which can stop early etc. would be too ugly. The update of
can_free and setting of nonfreeing_fn flag is done in the same loop as
storing of pure_const/looping results.
> You want to walk aliases,
>
> cgraph_node::get (fndecl)->function_symbol (&availability)
>
> > + if (!n || n->get_availability () <= AVAIL_INTERPOSABLE)
>
> and use availability here.
Done below.
What about the:
> > 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.
question though (maybe it is more on Richard)?
2014-11-13 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_pure_const): Propagate also can_free flag, set
w->nonfreeing_fn if it is false after propagation.
* 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/cgraph.c.jj 2014-11-13 00:07:34.271125586 +0100
+++ gcc/cgraph.c 2014-11-13 09:14:41.217090244 +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/ipa-pure-const.c.jj 2014-11-13 00:08:37.566011221 +0100
+++ gcc/ipa-pure-const.c 2014-11-13 09:25:02.933637928 +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))
{
@@ -760,7 +771,8 @@ check_stmt (gimple_stmt_iterator *gsip,
fprintf (dump_file, " volatile is not const/pure\n");
/* Abandon all hope, ye who enter here. */
local->pure_const_state = IPA_NEITHER;
- local->looping = true;
+ 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");
}
}
@@ -1347,6 +1369,33 @@ propagate_pure_const (void)
pure_const_names [pure_const_state],
looping);
+ /* Find the worst state of can_free for any node in the cycle. */
+ bool can_free = false;
+ 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 pure_const_state which is shared by
all nodes in the region. */
w = node;
@@ -1356,6 +1405,12 @@ propagate_pure_const (void)
enum pure_const_state_e this_state = pure_const_state;
bool this_looping = looping;
+ w_l->can_free = can_free;
+ w->nonfreeing_fn = !can_free;
+ if (!can_free && dump_file)
+ fprintf (dump_file, "Function found not to call free: %s\n",
+ w->name ());
+
if (w_l->state_previously_known != IPA_NEITHER
&& this_state > w_l->state_previously_known)
{
--- gcc/cgraph.h.jj 2014-11-13 00:07:34.278125463 +0100
+++ gcc/cgraph.h 2014-11-13 09:14:41.216090285 +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 2014-11-13 09:14:28.853595937 +0100
+++ gcc/gimple.c 2014-11-13 09:16:08.111606042 +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 +2545,17 @@ 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)
+ return false;
+ enum availability availability;
+ n = n->function_symbol (&availability);
+ if (!n || availability <= AVAIL_INTERPOSABLE)
+ return false;
+ return n->nonfreeing_fn;
}
/* Callback for walk_stmt_load_store_ops.
--- gcc/lto-cgraph.c.jj 2014-11-13 00:07:34.306124970 +0100
+++ gcc/lto-cgraph.c 2014-11-13 09:14:41.227089835 +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
