On Tue, 11 Mar 2014, Jakub Jelinek wrote:
> Hi!
>
> As described in the PR, the r208165 change regressed following test.
> The problem is that VRP inserts a useless ASSERT_EXPR right before
> __builtin_unreachable () (obviously, the uses of the ASSERT_EXPR
> lhs aren't and can't be used by anything), which then prevents
> assert_unreachable_fallthru_edge_p from detecting it properly
> (but, even ignoring ASSERT_EXPRs there still would fail, because
> the ASSERT_EXPR adds another user of the SSA_NAME we check imm uses for).
>
> Perhaps FOUND_IN_SUBGRAPH (4.3 and earlier era) would be always true
> here, but live_on_edge provably isn't always true, so it makes sense to test
> it, something that isn't live on the edge is useless.
>
> The tree-cfg.c change is just small improvement discovered when looking into
> it, clobber stmts before __builtin_unreachable can be certainly ignored,
> they don't do anything.
>
> The patch regresses ssa-ifcombine-10.c testcase, I'll post a fix for that
> momentarily.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Ok.
Thanks,
Richard.
> 2014-03-11 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/60482
> * tree-vrp.c (register_edge_assert_for_1): Don't add assert
> if there are multiple uses, but op doesn't live on E edge.
> * tree-cfg.c (assert_unreachable_fallthru_edge_p): Also ignore
> clobber stmts before __builtin_unreachable.
>
> * gcc.dg/vect/pr60482.c: New test.
>
> --- gcc/tree-vrp.c.jj 2014-01-25 00:11:37.000000000 +0100
> +++ gcc/tree-vrp.c 2014-03-10 14:59:03.748267354 +0100
> @@ -5423,12 +5423,9 @@ register_edge_assert_for_1 (tree op, enu
> return false;
>
> /* We know that OP will have a zero or nonzero value. If OP is used
> - more than once go ahead and register an assert for OP.
> -
> - The FOUND_IN_SUBGRAPH support is not helpful in this situation as
> - it will always be set for OP (because OP is used in a COND_EXPR in
> - the subgraph). */
> - if (!has_single_use (op))
> + more than once go ahead and register an assert for OP. */
> + if (live_on_edge (e, op)
> + && !has_single_use (op))
> {
> val = build_int_cst (TREE_TYPE (op), 0);
> register_new_assert_for (op, op, code, val, NULL, e, bsi);
> --- gcc/tree-cfg.c.jj 2014-02-20 21:38:42.000000000 +0100
> +++ gcc/tree-cfg.c 2014-03-10 14:59:52.058957446 +0100
> @@ -410,9 +410,9 @@ assert_unreachable_fallthru_edge_p (edge
> if (gsi_end_p (gsi))
> return false;
> stmt = gsi_stmt (gsi);
> - if (is_gimple_debug (stmt))
> + while (is_gimple_debug (stmt) || gimple_clobber_p (stmt))
> {
> - gsi_next_nondebug (&gsi);
> + gsi_next (&gsi);
> if (gsi_end_p (gsi))
> return false;
> stmt = gsi_stmt (gsi);
> --- gcc/testsuite/gcc.dg/vect/pr60482.c.jj 2014-03-10 15:08:16.700085976
> +0100
> +++ gcc/testsuite/gcc.dg/vect/pr60482.c 2014-03-10 15:15:09.609738455
> +0100
> @@ -0,0 +1,20 @@
> +/* PR middle-end/60482 */
> +/* { dg-do compile } */
> +/* { dg-additional-options "-Ofast" } */
> +/* { dg-require-effective-target vect_int } */
> +
> +double
> +foo (double *x, int n)
> +{
> + double p = 0.0;
> + int i;
> + x = __builtin_assume_aligned (x, 128);
> + if (n % 128)
> + __builtin_unreachable ();
> + for (i = 0; i < n; i++)
> + p += x[i];
> + return p;
> +}
> +
> +/* { dg-final { scan-tree-dump-not "epilog loop required" "vect" } } */
> +/* { dg-final { cleanup-tree-dump "vect" } } */
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend"orffer
