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[PR42782] preserve nonaddressable MEMs at calls in VTA
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Tue, 19 Jan 2010 13:09:34 -0200
- Subject: [PR42782] preserve nonaddressable MEMs at calls in VTA
When processing call insns, VTA drops all MEMs from location lists, save
for those that claim to *be* the variable, in their MEM_EXPRs.
This is a bit excessive. MEMs referencing variables that are not
call-clobbered could also be retained. This patch implements this.
I had to include tree-flow.h for the static inline definition of
is_call_clobbered() that it brings in from tree-flow-inline.h, and then
dump_variable in var-tracking conflicted with the declaration in the
header file, that refers to an incompatible definition in another file.
So I renamed the conflicting definition.
Regstrapping on x86_64-linux-gnu. Ok if it succeeds?
for gcc/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>
PR debug/42782
* var-tracking.c: Include tree-flow.h.
(mem_dies_at_call): New.
(dataflow_set_preserve_mem_locs): Use it.
(dataflow_set_remove_mem_locs): Likewise.
(dump_var): Renamed from dump_variable. Adjust all callers.
(dump_var_slot): Renamed from dump_variable_slot. Likewise.
* Makefile.in (var-tracking.o): Adjust deps.
for gcc/testsuite/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>
PR debug/42782
* gcc.dg/guality/pr42782.c: New.
Index: gcc/var-tracking.c
===================================================================
--- gcc/var-tracking.c.orig 2010-01-19 12:53:58.000000000 -0200
+++ gcc/var-tracking.c 2010-01-19 12:57:12.000000000 -0200
@@ -106,6 +106,7 @@
#include "expr.h"
#include "timevar.h"
#include "tree-pass.h"
+#include "tree-flow.h"
#include "cselib.h"
#include "target.h"
#include "toplev.h"
@@ -448,8 +449,8 @@ static bool compute_bb_dataflow (basic_b
static bool vt_find_locations (void);
static void dump_attrs_list (attrs);
-static int dump_variable_slot (void **, void *);
-static void dump_variable (variable);
+static int dump_var_slot (void **, void *);
+static void dump_var (variable);
static void dump_vars (htab_t);
static void dump_dataflow_set (dataflow_set *);
static void dump_dataflow_sets (void);
@@ -3718,13 +3719,33 @@ find_mem_expr_in_1pdv (tree expr, rtx va
return where;
}
+/* Return TRUE if the value of MEM may vary across a call. */
+
+static bool
+mem_dies_at_call (rtx mem)
+{
+ tree expr = MEM_EXPR (mem);
+ tree decl;
+
+ if (!expr)
+ return true;
+
+ decl = get_base_address (expr);
+
+ if (!decl)
+ return true;
+
+ if (!DECL_P (decl))
+ return true;
+
+ /* ??? Should we use callee-specific information, like
+ tree-ssa-alias's call_may_clobber_ref_p()? */
+ return is_call_clobbered (decl);
+}
+
/* Remove all MEMs from the location list of a hash table entry for a
one-part variable, except those whose MEM attributes map back to
- the variable itself, directly or within a VALUE.
-
- ??? We could also preserve MEMs that reference stack slots that are
- annotated as not addressable. This is arguably even more reliable
- than the current heuristic. */
+ the variable itself, directly or within a VALUE. */
static int
dataflow_set_preserve_mem_locs (void **slot, void *data)
@@ -3746,16 +3767,18 @@ dataflow_set_preserve_mem_locs (void **s
{
for (loc = var->var_part[0].loc_chain; loc; loc = loc->next)
{
- /* We want to remove a MEM that doesn't refer to DECL. */
+ /* We want to remove dying MEMs that doesn't refer to
+ DECL. */
if (GET_CODE (loc->loc) == MEM
&& (MEM_EXPR (loc->loc) != decl
- || MEM_OFFSET (loc->loc)))
+ || MEM_OFFSET (loc->loc))
+ && !mem_dies_at_call (loc->loc))
break;
- /* We want to move here a MEM that does refer to DECL. */
+ /* We want to move here MEMs that do refer to DECL. */
else if (GET_CODE (loc->loc) == VALUE
&& find_mem_expr_in_1pdv (decl, loc->loc,
shared_hash_htab (set->vars)))
- break;
+ break;
}
if (!loc)
@@ -3792,7 +3815,8 @@ dataflow_set_preserve_mem_locs (void **s
if (GET_CODE (loc->loc) != MEM
|| (MEM_EXPR (loc->loc) == decl
- && MEM_OFFSET (loc->loc) == 0))
+ && MEM_OFFSET (loc->loc) == 0)
+ || !mem_dies_at_call (loc->loc))
{
if (old_loc != loc->loc && emit_notes)
{
@@ -3840,7 +3864,8 @@ dataflow_set_remove_mem_locs (void **slo
if (var->refcount > 1 || shared_hash_shared (set->vars))
{
for (loc = var->var_part[0].loc_chain; loc; loc = loc->next)
- if (GET_CODE (loc->loc) == MEM)
+ if (GET_CODE (loc->loc) == MEM
+ && mem_dies_at_call (loc->loc))
break;
if (!loc)
@@ -3854,7 +3879,8 @@ dataflow_set_remove_mem_locs (void **slo
for (locp = &var->var_part[0].loc_chain, loc = *locp;
loc; loc = *locp)
{
- if (GET_CODE (loc->loc) != MEM)
+ if (GET_CODE (loc->loc) != MEM
+ || !mem_dies_at_call (loc->loc))
{
locp = &loc->next;
continue;
@@ -4036,7 +4062,7 @@ dataflow_set_different_1 (void **slot, v
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "dataflow difference found: removal of:\n");
- dump_variable (var1);
+ dump_var (var1);
}
/* Stop traversing the hash table. */
@@ -4050,8 +4076,8 @@ dataflow_set_different_1 (void **slot, v
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file, "dataflow difference found: old and new follow:\n");
- dump_variable (var1);
- dump_variable (var2);
+ dump_var (var1);
+ dump_var (var2);
}
/* Stop traversing the hash table. */
@@ -5733,11 +5759,11 @@ dump_attrs_list (attrs list)
/* Print the information about variable *SLOT to dump file. */
static int
-dump_variable_slot (void **slot, void *data ATTRIBUTE_UNUSED)
+dump_var_slot (void **slot, void *data ATTRIBUTE_UNUSED)
{
variable var = (variable) *slot;
- dump_variable (var);
+ dump_var (var);
/* Continue traversing the hash table. */
return 1;
@@ -5746,7 +5772,7 @@ dump_variable_slot (void **slot, void *d
/* Print the information about variable VAR to dump file. */
static void
-dump_variable (variable var)
+dump_var (variable var)
{
int i;
location_chain node;
@@ -5793,7 +5819,7 @@ dump_vars (htab_t vars)
if (htab_elements (vars) > 0)
{
fprintf (dump_file, "Variables:\n");
- htab_traverse (vars, dump_variable_slot, NULL);
+ htab_traverse (vars, dump_var_slot, NULL);
}
}
Index: gcc/testsuite/gcc.dg/guality/pr42782.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ gcc/testsuite/gcc.dg/guality/pr42782.c 2010-01-19 12:53:59.000000000 -0200
@@ -0,0 +1,24 @@
+/* { dg-options "-g" } */
+
+#include "guality.h"
+
+void __attribute__ ((__noinline__))
+g (void)
+{
+ asm volatile ("");
+}
+
+int
+f (int a)
+{
+ g ();
+ GUALCHKVAL (a);
+ return a;
+}
+
+int
+main (int argc, char *argv[])
+{
+ f (argc + 2);
+ f (argc + 5);
+}
Index: gcc/Makefile.in
===================================================================
--- gcc/Makefile.in.orig 2010-01-19 12:54:14.000000000 -0200
+++ gcc/Makefile.in 2010-01-19 12:54:56.000000000 -0200
@@ -3024,7 +3024,7 @@ regstat.o : regstat.c $(CONFIG_H) $(SYST
var-tracking.o : var-tracking.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
$(RTL_H) $(TREE_H) hard-reg-set.h insn-config.h reload.h $(FLAGS_H) \
$(BASIC_BLOCK_H) output.h sbitmap.h alloc-pool.h $(FIBHEAP_H) $(HASHTAB_H) \
- $(REGS_H) $(EXPR_H) $(TIMEVAR_H) $(TREE_PASS_H) \
+ $(REGS_H) $(EXPR_H) $(TIMEVAR_H) $(TREE_PASS_H) $(TREE_FLOW_H) \
cselib.h $(TARGET_H) $(TOPLEV_H) $(PARAMS_H)
profile.o : profile.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H) \
$(TREE_H) $(FLAGS_H) output.h $(REGS_H) $(EXPR_H) $(FUNCTION_H) \
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist Red Hat Brazil Compiler Engineer