[PATCH] Improve VRP assert creation for loops
Richard Biener
rguenther@suse.de
Thu Nov 7 11:41:00 GMT 2013
On Thu, 7 Nov 2013, Jakub Jelinek wrote:
> On Thu, Nov 07, 2013 at 10:32:10AM +0100, Richard Biener wrote:
> > I'm looking for adjusting of live compute - either by adjusting the
> > algorithm or by special casing the latches. Like for example
> > with the following (untested, needs cleanup - the PHI processing
> > can be factored out from find_assert_locations_1 and re-used):
> >
> > @@ -5904,6 +5898,27 @@ find_assert_locations (void)
> > for (i = 0; i < rpo_cnt; ++i)
> > bb_rpo[rpo[i]] = i;
> >
> > + /* Pre-seed loop latch liveness from loop header PHI nodes. Due to
> > + the order we compute liveness and insert asserts we otherwise
> > + fail to insert asserts into the loop latch. */
> > + loop_p loop;
> > + loop_iterator li;
> > + FOR_EACH_LOOP (li, loop, 0)
> > + {
> > + i = loop->latch->index;
> > + live[i] = sbitmap_alloc (num_ssa_names);
> > + bitmap_clear (live[i]);
> > + for (gimple_stmt_iterator gsi = gsi_start_phis (loop->header);
> > + !gsi_end_p (gsi); gsi_next (&gsi))
> > + {
> > + gimple phi = gsi_stmt (gsi);
> > + if (virtual_operand_p (gimple_phi_result (phi)))
> > + continue;
> > + for (unsigned j = 0; j < gimple_phi_num_args (phi); ++j)
> > + if (TREE_CODE (gimple_phi_arg_def (phi, j)) == SSA_NAME)
> > + bitmap_set_bit (live[i], SSA_NAME_VERSION
> > (gimple_phi_arg_def (phi, j)));
> > + }
> > + }
>
> LGTM, except that I think we should only care about phi args from the
> latch -> header edge, not others and IMHO it is memory waste to allocate
> sbitmap even when we wouldn't add anything. So, I'm going to
> rebootstrap/regtest the following (including new testcase Jeff asked for):
>
> 2013-11-07 Richard Biener <rguenther@suse.de>
> Jakub Jelinek <jakub@redhat.com>
>
> * tree-vrp.c (find_assert_locations): Pre-seed live bitmaps for loop
> latches from header PHI arguments from the latch edge.
>
> * gcc.dg/unroll_1.c: Add -fno-tree-vrp to dg-options.
> * gcc.dg/unroll_2.c: Likewise.
> * gcc.dg/unroll_3.c: Likewise.
> * gcc.dg/unroll_4.c: Likewise.
> * gcc.dg/vrp90.c: New test.
>
> --- gcc/tree-vrp.c.jj 2013-11-06 16:58:04.675678567 +0100
> +++ gcc/tree-vrp.c 2013-11-07 10:59:38.841283931 +0100
> @@ -5906,6 +5906,34 @@ find_assert_locations (void)
> for (i = 0; i < rpo_cnt; ++i)
> bb_rpo[rpo[i]] = i;
>
> + /* Pre-seed loop latch liveness from loop header PHI nodes. Due to
> + the order we compute liveness and insert asserts we otherwise
> + fail to insert asserts into the loop latch. */
> + loop_p loop;
> + loop_iterator li;
> + FOR_EACH_LOOP (li, loop, 0)
> + {
> + i = loop->latch->index;
> + unsigned int j = find_edge (loop->latch, loop->header)->dest_idx;
Actually there is only one edge from latch to header by definition,
so single_succ_edge (loop->latch) would be better?
Otherwise ok.
Thanks,
Richard.
> + for (gimple_stmt_iterator gsi = gsi_start_phis (loop->header);
> + !gsi_end_p (gsi); gsi_next (&gsi))
> + {
> + gimple phi = gsi_stmt (gsi);
> + if (virtual_operand_p (gimple_phi_result (phi)))
> + continue;
> + tree arg = gimple_phi_arg_def (phi, j);
> + if (TREE_CODE (arg) == SSA_NAME)
> + {
> + if (live[i] == NULL)
> + {
> + live[i] = sbitmap_alloc (num_ssa_names);
> + bitmap_clear (live[i]);
> + }
> + bitmap_set_bit (live[i], SSA_NAME_VERSION (arg));
> + }
> + }
> + }
> +
> need_asserts = false;
> for (i = rpo_cnt - 1; i >= 0; --i)
> {
> --- gcc/testsuite/gcc.dg/unroll_1.c.jj 2013-09-09 11:32:36.000000000 +0200
> +++ gcc/testsuite/gcc.dg/unroll_1.c 2013-11-06 17:10:52.900722932 +0100
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-rtl-loop2_unroll=stderr -fno-peel-loops -fdisable-tree-cunroll -fdisable-tree-cunrolli -fenable-rtl-loop2_unroll" } */
> +/* { dg-options "-O2 -fdump-rtl-loop2_unroll=stderr -fno-peel-loops -fno-tree-vrp -fdisable-tree-cunroll -fdisable-tree-cunrolli -fenable-rtl-loop2_unroll" } */
>
> unsigned a[100], b[100];
> inline void bar()
> --- gcc/testsuite/gcc.dg/unroll_2.c.jj 2013-08-30 14:38:39.000000000 +0200
> +++ gcc/testsuite/gcc.dg/unroll_2.c 2013-11-06 17:10:30.751845504 +0100
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-rtl-loop2_unroll -fno-peel-loops -fdisable-tree-cunroll=foo -fdisable-tree-cunrolli=foo -fenable-rtl-loop2_unroll" } */
> +/* { dg-options "-O2 -fdump-rtl-loop2_unroll -fno-peel-loops -fno-tree-vrp -fdisable-tree-cunroll=foo -fdisable-tree-cunrolli=foo -fenable-rtl-loop2_unroll" } */
>
> unsigned a[100], b[100];
> inline void bar()
> --- gcc/testsuite/gcc.dg/unroll_3.c.jj 2013-08-30 14:38:39.000000000 +0200
> +++ gcc/testsuite/gcc.dg/unroll_3.c 2013-11-06 17:10:38.864800338 +0100
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-rtl-loop2_unroll -fno-peel-loops -fdisable-tree-cunroll -fdisable-tree-cunrolli -fenable-rtl-loop2_unroll=foo" } */
> +/* { dg-options "-O2 -fdump-rtl-loop2_unroll -fno-peel-loops -fno-tree-vrp -fdisable-tree-cunroll -fdisable-tree-cunrolli -fenable-rtl-loop2_unroll=foo" } */
>
> unsigned a[100], b[100];
> inline void bar()
> --- gcc/testsuite/gcc.dg/unroll_4.c.jj 2013-08-30 14:38:40.000000000 +0200
> +++ gcc/testsuite/gcc.dg/unroll_4.c 2013-11-06 17:11:03.816665603 +0100
> @@ -1,5 +1,5 @@
> /* { dg-do compile } */
> -/* { dg-options "-O2 -fdump-rtl-loop2_unroll -fno-peel-loops -fdisable-tree-cunroll -fdisable-tree-cunrolli -fenable-rtl-loop2_unroll=foo2" } */
> +/* { dg-options "-O2 -fdump-rtl-loop2_unroll -fno-peel-loops -fno-tree-vrp -fdisable-tree-cunroll -fdisable-tree-cunrolli -fenable-rtl-loop2_unroll=foo2" } */
>
> unsigned a[100], b[100];
> inline void bar()
> --- gcc/testsuite/gcc.dg/tree-ssa/vrp90.c.jj 2013-11-07 11:01:55.137535477 +0100
> +++ gcc/testsuite/gcc.dg/tree-ssa/vrp90.c 2013-11-07 11:02:35.189335924 +0100
> @@ -0,0 +1,36 @@
> +/* { dg-do link } */
> +/* { dg-options "-O2 -fdump-tree-vrp1" } */
> +/* { dg-final { scan-tree-dump-not "link_error" "vrp1"} } */
> +/* { dg-final { cleanup-tree-dump "vrp1" } } */
> +
> +extern void link_error (void);
> +
> +__attribute__((noinline, noclone)) int
> +foo (unsigned int n, int r)
> +{
> + int i;
> + if (n > 0)
> + {
> + asm ("");
> + if (n < 10)
> + {
> + asm ("");
> + do
> + {
> + --n;
> + r *= 2;
> + if (n >= 9)
> + link_error ();
> + }
> + while (n > 0);
> + }
> + }
> + return r + n;
> +}
> +
> +int
> +main ()
> +{
> + foo (7, 2);
> + return 0;
> +}
>
>
> Jakub
>
>
--
Richard Biener <rguenther@suse.de>
SUSE / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746
GF: Jeff Hawn, Jennifer Guild, Felix Imend
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