I am testing the following patch fixing a python miscompile with FDO
(requires -ftracer to trigger). A previous fix to SCCVN made resetting
of flow-sensitive SSA info from tail-merging ineffective by eventually
restoring the original info.
Fixed by splitting that part out of free_scc_vn and calling it before
tail-merging.
Bootstrap & regtest running on x86_64-unknown-linux-gnu, will apply
to trunk and branch if it succeeds.
Richard.
2016-04-19 Richard Biener <rguent...@suse.de>
PR tree-optimization/70724
* tree-ssa-sccvn.c (scc_vn_restore_ssa_info): Split SSA info
restoring out from ...
(free_scc_vn): ... here.
* tree-ssa-sccvn.h (scc_vn_restore_ssa_info): Declare.
* tres-ssa-pre.c (pass_pre::execute): Restore SSA info before
tail merging.
(pass_fre::execute): Restore SSA info.
* gcc.dg/torture/pr70724.c: New testcase.
Index: gcc/tree-ssa-sccvn.c
===================================================================
*** gcc/tree-ssa-sccvn.c (revision 235188)
--- gcc/tree-ssa-sccvn.c (working copy)
*************** init_scc_vn (void)
*** 4300,4325 ****
}
}
void
! free_scc_vn (void)
{
! size_t i;
!
! delete constant_to_value_id;
! constant_to_value_id = NULL;
! BITMAP_FREE (constant_value_ids);
! shared_lookup_phiargs.release ();
! shared_lookup_references.release ();
! XDELETEVEC (rpo_numbers);
!
! for (i = 0; i < num_ssa_names; i++)
{
tree name = ssa_name (i);
if (name
&& has_VN_INFO (name))
{
if (VN_INFO (name)->needs_insertion)
! release_ssa_name (name);
else if (POINTER_TYPE_P (TREE_TYPE (name))
&& VN_INFO (name)->info.ptr_info)
SSA_NAME_PTR_INFO (name) = VN_INFO (name)->info.ptr_info;
--- 4300,4318 ----
}
}
+ /* Restore SSA info that has been reset on value leaders. */
+
void
! scc_vn_restore_ssa_info (void)
{
! for (unsigned i = 0; i < num_ssa_names; i++)
{
tree name = ssa_name (i);
if (name
&& has_VN_INFO (name))
{
if (VN_INFO (name)->needs_insertion)
! ;
else if (POINTER_TYPE_P (TREE_TYPE (name))
&& VN_INFO (name)->info.ptr_info)
SSA_NAME_PTR_INFO (name) = VN_INFO (name)->info.ptr_info;
*************** free_scc_vn (void)
*** 4332,4337 ****
--- 4325,4352 ----
}
}
}
+ }
+
+ void
+ free_scc_vn (void)
+ {
+ size_t i;
+
+ delete constant_to_value_id;
+ constant_to_value_id = NULL;
+ BITMAP_FREE (constant_value_ids);
+ shared_lookup_phiargs.release ();
+ shared_lookup_references.release ();
+ XDELETEVEC (rpo_numbers);
+
+ for (i = 0; i < num_ssa_names; i++)
+ {
+ tree name = ssa_name (i);
+ if (name
+ && has_VN_INFO (name)
+ && VN_INFO (name)->needs_insertion)
+ release_ssa_name (name);
+ }
obstack_free (&vn_ssa_aux_obstack, NULL);
vn_ssa_aux_table.release ();
Index: gcc/tree-ssa-sccvn.h
===================================================================
*** gcc/tree-ssa-sccvn.h (revision 235188)
--- gcc/tree-ssa-sccvn.h (working copy)
*************** extern vn_ssa_aux_t VN_INFO_GET (tree);
*** 204,209 ****
--- 204,210 ----
tree vn_get_expr_for (tree);
bool run_scc_vn (vn_lookup_kind);
void free_scc_vn (void);
+ void scc_vn_restore_ssa_info (void);
tree vn_nary_op_lookup (tree, vn_nary_op_t *);
tree vn_nary_op_lookup_stmt (gimple *, vn_nary_op_t *);
tree vn_nary_op_lookup_pieces (unsigned int, enum tree_code,
Index: gcc/tree-ssa-pre.c
===================================================================
*** gcc/tree-ssa-pre.c (revision 235188)
--- gcc/tree-ssa-pre.c (working copy)
*************** pass_pre::execute (function *fun)
*** 4828,4833 ****
--- 4828,4836 ----
todo |= fini_eliminate ();
loop_optimizer_finalize ();
+ /* Restore SSA info before tail-merging as that resets it as well. */
+ scc_vn_restore_ssa_info ();
+
/* TODO: tail_merge_optimize may merge all predecessors of a block, in which
case we can merge the block with the remaining predecessor of the block.
It should either:
*************** pass_fre::execute (function *fun)
*** 4901,4906 ****
--- 4904,4910 ----
todo |= fini_eliminate ();
+ scc_vn_restore_ssa_info ();
free_scc_vn ();
statistics_counter_event (fun, "Insertions", pre_stats.insertions);
Index: gcc/testsuite/gcc.dg/torture/pr70724.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr70724.c (revision 0)
--- gcc/testsuite/gcc.dg/torture/pr70724.c (working copy)
***************
*** 0 ****
--- 1,39 ----
+ /* { dg-do run } */
+ /* { dg-additional-options "-ftracer" } */
+
+ extern void abort (void);
+
+ typedef long int _PyTime_t;
+ typedef enum { _PyTime_ROUND_FLOOR = 0, _PyTime_ROUND_CEILING = 1 }
+ _PyTime_round_t;
+
+ static _PyTime_t
+ _PyTime_Divide(const _PyTime_t t, const _PyTime_t k,
+ const _PyTime_round_t round)
+ {
+ if (round == _PyTime_ROUND_CEILING) {
+ if (t >= 0)
+ return (t + k - 1) / k;
+ else
+ return t / k;
+ }
+ else {
+ if (t >= 0)
+ return t / k;
+ else
+ return (t - (k - 1)) / k;
+ }
+ }
+
+ _PyTime_t __attribute__((noinline,noclone))
+ _PyTime_AsMicroseconds(_PyTime_t t, _PyTime_round_t round)
+ {
+ return _PyTime_Divide(t, 1000, round);
+ }
+
+ int main()
+ {
+ if (_PyTime_AsMicroseconds (10000, _PyTime_ROUND_FLOOR) != 10)
+ abort ();
+ return 0;
+ }
