Hi Richard,
On 25 November 2016 at 11:20, Richard Biener <rguent...@suse.de> wrote:
> On Thu, 24 Nov 2016, Richard Biener wrote:
>
>>
>> I am testing the following patch for an optimization regression where
>> a loop made dead by final value replacement was made used again by
>> DOM 20 passes later. The real issue here is that we do not get rid
>> of dead loops until very late so this patch makes sure to do that.
>> We could schedule it later (but better no later than unrolling
>> as that might expose a pretty inefficient way of removing a dead loop).
>>
>> Bootstrap and regtest running on x86_64-unknown-linux-gnu.
>
> As expected some testcases need adjustment, thus applied as follows.
>
> Richard.
>
> 2016-11-24 Richard Biener <rguent...@suse.de>
>
> PR tree-optimization/78343
> * passes.def: Add CD-DCE pass after loop splitting.
> * tree-ssa-dce.c (find_obviously_necessary_stmts): Move
> SCEV init/finalize ...
> (perform_tree_ssa_dce): ... here. Deal with being
> executed inside the loop pipeline in aggressive mode.
>
> * gcc.dg/tree-ssa/sccp-2.c: New testcase.
> * gcc.dg/autopar/uns-outer-6.c: Adjust.
> * gcc.dg/tree-ssa/20030808-1.c: Likewise.
> * gcc.dg/tree-ssa/20040305-1.c: Likewise.
> * gcc.dg/vect/pr38529.c: Likewise.
>
But now, I am seeing failures on:
gcc.dg/tree-ssa/20030808-1.c scan-tree-dump-times cddce3 "->code" 0
gcc.dg/tree-ssa/20030808-1.c scan-tree-dump-times cddce3 "if " 0
gcc.dg/tree-ssa/20040305-1.c scan-tree-dump-times cddce3 "if " 2
because the dump file does not exist.
(on aarch64 and arm targets)
Christophe
> diff --git a/gcc/passes.def b/gcc/passes.def
> index 2a470a7..2fa682b 100644
> --- a/gcc/passes.def
> +++ b/gcc/passes.def
> @@ -271,6 +271,9 @@ along with GCC; see the file COPYING3. If not see
> NEXT_PASS (pass_tree_unswitch);
> NEXT_PASS (pass_scev_cprop);
> NEXT_PASS (pass_loop_split);
> + /* All unswitching, final value replacement and splitting can expose
> + empty loops. Remove them now. */
> + NEXT_PASS (pass_cd_dce);
> NEXT_PASS (pass_record_bounds);
> NEXT_PASS (pass_loop_distribution);
> NEXT_PASS (pass_copy_prop);
> diff --git a/gcc/testsuite/gcc.dg/autopar/uns-outer-6.c
> b/gcc/testsuite/gcc.dg/autopar/uns-outer-6.c
> index dc2870b..5af60b0 100644
> --- a/gcc/testsuite/gcc.dg/autopar/uns-outer-6.c
> +++ b/gcc/testsuite/gcc.dg/autopar/uns-outer-6.c
> @@ -25,7 +25,7 @@ parloop (int N)
> for (i = 0; i < N; i++)
> {
> for (j = 0; j < N; j++)
> - y[i]=x[i][j];
> + y[i] += x[i][j];
> sum += y[i];
> }
> g_sum = sum;
> @@ -46,6 +46,10 @@ main (void)
>
>
> /* Check that outer loop is parallelized. */
> +/* This fails because we have
> + FAILED: data dependencies exist across iterations
> +
> +
> /* { dg-final { scan-tree-dump-times "parallelizing outer loop" 1
> "parloops2" } } */
> /* { dg-final { scan-tree-dump-times "parallelizing inner loop" 0
> "parloops2" } } */
> /* { dg-final { scan-tree-dump-times "loopfn" 4 "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/20030808-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/20030808-1.c
> index 7cc5404..cda86a7 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/20030808-1.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/20030808-1.c
> @@ -33,8 +33,8 @@ delete_dead_jumptables ()
> /* There should be no loads of ->code. If any exist, then we failed to
> optimize away all the IF statements and the statements feeding
> their conditions. */
> -/* { dg-final { scan-tree-dump-times "->code" 0 "cddce2"} } */
> +/* { dg-final { scan-tree-dump-times "->code" 0 "cddce3"} } */
>
> /* There should be no IF statements. */
> -/* { dg-final { scan-tree-dump-times "if " 0 "cddce2"} } */
> +/* { dg-final { scan-tree-dump-times "if " 0 "cddce3"} } */
>
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c
> index 501e28c..d1a9af8 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/20040305-1.c
> @@ -27,4 +27,4 @@ void foo(int edx, int eax)
>
> /* After cddce we should have two IF statements remaining as the other
> two tests can be threaded. */
> -/* { dg-final { scan-tree-dump-times "if " 2 "cddce2"} } */
> +/* { dg-final { scan-tree-dump-times "if " 2 "cddce3"} } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/sccp-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/sccp-2.c
> new file mode 100644
> index 0000000..099b281
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/sccp-2.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +unsigned int
> +test(unsigned int quant)
> +{
> + unsigned int sum = 0;
> + for (unsigned int i = 0; i < quant; ++i)
> + sum += quant;
> + return sum;
> +}
> +
> +/* A single basic-block should remain (computing and
> + returning quant * quant). */
> +/* { dg-final { scan-tree-dump-times "bb" 1 "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/vect/pr38529.c
> b/gcc/testsuite/gcc.dg/vect/pr38529.c
> index 171adeb..9b5919d 100644
> --- a/gcc/testsuite/gcc.dg/vect/pr38529.c
> +++ b/gcc/testsuite/gcc.dg/vect/pr38529.c
> @@ -11,7 +11,3 @@ void foo()
> for (j = 0; j < 17; ++j)
> a[i] = 0;
> }
> -
> -/* { dg-final { scan-tree-dump-times "OUTER LOOP VECTORIZED" 1 "vect" } } */
> -
> -
> diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
> index 7b9814e..50b5eef 100644
> --- a/gcc/tree-ssa-dce.c
> +++ b/gcc/tree-ssa-dce.c
> @@ -400,7 +400,6 @@ find_obviously_necessary_stmts (bool aggressive)
> if (aggressive)
> {
> struct loop *loop;
> - scev_initialize ();
> if (mark_irreducible_loops ())
> FOR_EACH_BB_FN (bb, cfun)
> {
> @@ -423,7 +422,6 @@ find_obviously_necessary_stmts (bool aggressive)
> fprintf (dump_file, "can not prove finiteness of loop %i\n",
> loop->num);
> mark_control_dependent_edges_necessary (loop->latch, false);
> }
> - scev_finalize ();
> }
> }
>
> @@ -1567,9 +1565,13 @@ perform_tree_ssa_dce (bool aggressive)
> /* Preheaders are needed for SCEV to work.
> Simple lateches and recorded exits improve chances that loop will
> proved to be finite in testcases such as in loop-15.c and loop-24.c */
> - if (aggressive)
> - loop_optimizer_init (LOOPS_NORMAL
> - | LOOPS_HAVE_RECORDED_EXITS);
> + bool in_loop_pipeline = scev_initialized_p ();
> + if (aggressive && ! in_loop_pipeline)
> + {
> + scev_initialize ();
> + loop_optimizer_init (LOOPS_NORMAL
> + | LOOPS_HAVE_RECORDED_EXITS);
> + }
>
> tree_dce_init (aggressive);
>
> @@ -1588,8 +1590,11 @@ perform_tree_ssa_dce (bool aggressive)
>
> find_obviously_necessary_stmts (aggressive);
>
> - if (aggressive)
> - loop_optimizer_finalize ();
> + if (aggressive && ! in_loop_pipeline)
> + {
> + loop_optimizer_finalize ();
> + scev_finalize ();
> + }
>
> longest_chain = 0;
> total_chain = 0;
> @@ -1623,7 +1628,7 @@ perform_tree_ssa_dce (bool aggressive)
> if (something_changed)
> {
> free_numbers_of_iterations_estimates (cfun);
> - if (scev_initialized_p ())
> + if (in_loop_pipeline)
> scev_reset ();
> return TODO_update_ssa | TODO_cleanup_cfg;
> }
