On Mon, 13 Jun 2016, Jakub Jelinek wrote:
> Hi!
>
> Cross-jumping at GIMPLE level gives up e.g. because there are any labels
> at the beginning of the block (which is always the case for bbs referenced
> from switches). While labels for non-local goto as well as computed goto
> are hard to handle, after all the edges are then EDGE_ABNORMAL that can't be
> redirected anyway, other labels can be handled very easily.
>
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk?
Ok.
> In the PR, beyond this I'm also talking about switchconv pass not being able
> to know that some cases could be cross-jumped and thus use better conversion
> sequences. Wonder if we shouldn't schedule either a full, or a limited
> version of tailmerging before switchconv, perhaps just use the
> infrastructure from tree-ssa-tail-merge.c to handle the easiest cases
> where the cross-jumping in the end would end up simplifying some of the
> switches. Thoughts on this?
I'd like to postpone this until tail-merging got rid of its SCCVN
dependency (the proposed merge with the ICF machinery).
I also think that switch-conversion is a bit early in the pipeline,
I'd put it not before at least one VRP pass. I know Martin put it
in early opts because it can reduce code-size and thus trigger
inlining but that can be said about most of the scalar opts we have
in the late pipeline as well.
Richard.
> 2016-06-13 Jakub Jelinek <ja...@redhat.com>
>
> PR tree-optimization/71520
> * tree-ssa-tail-merge.c (find_duplicate): Handle labels.
> (replace_block_by): Move user labels from bb1 to bb2.
>
> * gcc.dg/tree-ssa/pr71520.c: New test.
>
> --- gcc/tree-ssa-tail-merge.c.jj 2016-06-10 20:23:55.196164390 +0200
> +++ gcc/tree-ssa-tail-merge.c 2016-06-13 12:08:34.691985005 +0200
> @@ -1265,6 +1265,10 @@ find_duplicate (same_succ *same_succ, ba
> gimple *stmt1 = gsi_stmt (gsi1);
> gimple *stmt2 = gsi_stmt (gsi2);
>
> + if (gimple_code (stmt1) == GIMPLE_LABEL
> + && gimple_code (stmt2) == GIMPLE_LABEL)
> + break;
> +
> if (!gimple_equal_p (same_succ, stmt1, stmt2))
> return;
>
> @@ -1277,6 +1281,20 @@ find_duplicate (same_succ *same_succ, ba
> gsi_advance_bw_nondebug_nonlocal (&gsi2, &vuse2, &vuse_escaped);
> }
>
> + while (!gsi_end_p (gsi1) && gimple_code (gsi_stmt (gsi1)) == GIMPLE_LABEL)
> + {
> + tree label = gimple_label_label (as_a <glabel *> (gsi_stmt (gsi1)));
> + if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
> + return;
> + gsi_prev (&gsi1);
> + }
> + while (!gsi_end_p (gsi2) && gimple_code (gsi_stmt (gsi2)) == GIMPLE_LABEL)
> + {
> + tree label = gimple_label_label (as_a <glabel *> (gsi_stmt (gsi2)));
> + if (DECL_NONLOCAL (label) || FORCED_LABEL (label))
> + return;
> + gsi_prev (&gsi2);
> + }
> if (!(gsi_end_p (gsi1) && gsi_end_p (gsi2)))
> return;
>
> @@ -1555,6 +1573,23 @@ replace_block_by (basic_block bb1, basic
> e2->probability = GCOV_COMPUTE_SCALE (e2->count, out_sum);
> }
>
> + /* Move over any user labels from bb1 after the bb2 labels. */
> + gimple_stmt_iterator gsi1 = gsi_start_bb (bb1);
> + if (!gsi_end_p (gsi1) && gimple_code (gsi_stmt (gsi1)) == GIMPLE_LABEL)
> + {
> + gimple_stmt_iterator gsi2 = gsi_after_labels (bb2);
> + while (!gsi_end_p (gsi1)
> + && gimple_code (gsi_stmt (gsi1)) == GIMPLE_LABEL)
> + {
> + tree label = gimple_label_label (as_a <glabel *> (gsi_stmt (gsi1)));
> + gcc_assert (!DECL_NONLOCAL (label) && !FORCED_LABEL (label));
> + if (DECL_ARTIFICIAL (label))
> + gsi_next (&gsi1);
> + else
> + gsi_move_before (&gsi1, &gsi2);
> + }
> + }
> +
> /* Clear range info from all stmts in BB2 -- this transformation
> could make them out of date. */
> reset_flow_sensitive_info_in_bb (bb2);
> --- gcc/testsuite/gcc.dg/tree-ssa/pr71520.c.jj 2016-06-13
> 12:26:55.251630020 +0200
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr71520.c 2016-06-13 12:26:31.000000000
> +0200
> @@ -0,0 +1,90 @@
> +/* PR tree-optimization/71520 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +void bar (int);
> +
> +void
> +foo (int x)
> +{
> + switch (x)
> + {
> + case 1:
> + case 12:
> + case 28:
> + case 174:
> + bar (1);
> + bar (2);
> + break;
> + case 3:
> + case 7:
> + case 78:
> + case 96:
> + case 121:
> + default:
> + bar (3);
> + bar (4);
> + bar (5);
> + bar (6);
> + break;
> + case 8:
> + case 13:
> + case 27:
> + case 19:
> + case 118:
> + bar (3);
> + bar (4);
> + bar (5);
> + bar (6);
> + break;
> + case 4:
> + bar (7);
> + break;
> + }
> +}
> +
> +void
> +baz (int x)
> +{
> + switch (x)
> + {
> + case 1:
> + case 12:
> + case 28:
> + case 174:
> + bar (8);
> + bar (9);
> + break;
> + case 3:
> + case 7:
> + case 78:
> + case 96:
> + case 121:
> + default:
> + lab1:
> + lab2:
> + bar (10);
> + bar (11);
> + bar (12);
> + bar (13);
> + break;
> + case 8:
> + case 13:
> + case 27:
> + case 19:
> + case 118:
> + lab3:
> + lab4:
> + bar (10);
> + bar (11);
> + bar (12);
> + bar (13);
> + break;
> + case 4:
> + bar (14);
> + break;
> + }
> +}
> +
> +/* { dg-final { scan-tree-dump-times "bar \\\(3\\\);" 1 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "bar \\\(10\\\);" 1 "optimized" } } */
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
