Hi Richard,
Does this have to wait for stage 1? Or I will try to work out a full
patch with loop recreating issue fixed.
On Wed, Feb 19, 2014 at 7:57 PM, Richard Biener <rguent...@suse.de> wrote:
>
> This allows cfgcleanup to remove some of the extra CFG that exists
> just for loop analysis passes convenience (those can be and are
> easily re-created by passes doing loop_optimizer_init ()).
>
> It may fix a regression uncovered in private communication.
It's the regression about the code size checks in
gcc.target/arm/ivopts.c and gcc.target/arm/ivopts-2.c
>
> Untested - my original idea how to fix this (tree_forwarder_block_p
> hunk) ran into the issue in remove_forwarder_block which causes
> loops to be removed / re-discovered (losing meta-data).
>
> Richard.
>
> 2014-02-19 Richard Biener <rguent...@suse.de>
>
> * tree-cfgcleanup.c (tree_forwarder_block_p): Protect
> latches and preheaders only if requested.
> (remove_forwarder_block): Update loop structure if we
> removed a forwarder that is a loop latch.
>
> Index: gcc/tree-cfgcleanup.c
> ===================================================================
> *** gcc/tree-cfgcleanup.c (revision 207878)
> --- gcc/tree-cfgcleanup.c (working copy)
> *************** tree_forwarder_block_p (basic_block bb,
> *** 307,321 ****
>
> if (current_loops)
> {
> ! basic_block dest;
> ! /* Protect loop latches, headers and preheaders. */
> if (bb->loop_father->header == bb)
> return false;
> - dest = EDGE_SUCC (bb, 0)->dest;
>
> ! if (dest->loop_father->header == dest)
> return false;
> }
> return true;
> }
>
> --- 307,324 ----
>
> if (current_loops)
> {
> ! /* Protect loop headers. */
> if (bb->loop_father->header == bb)
> return false;
>
> ! /* Protect loop latches and preheaders if requested. */
> ! basic_block dest = EDGE_SUCC (bb, 0)->dest;
> ! if (dest->loop_father->header == dest
> ! && (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)
> ! || loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)))
> return false;
> }
Sorry for being nit-picking here. There is a scenario that bb is
pre-header and loop prop is set to (!LOOPS_HAVE_PREHEADERS &&
LOOPS_HAVE_SIMPLE_LATCHES). Of course, this may not happen anyway.
> +
> return true;
> }
>
> *************** remove_forwarder_block (basic_block bb)
> *** 497,503 ****
> set_immediate_dominator (CDI_DOMINATORS, dest, dom);
> }
>
> ! /* And kill the forwarder block. */
> delete_basic_block (bb);
>
> return true;
> --- 500,511 ----
> set_immediate_dominator (CDI_DOMINATORS, dest, dom);
> }
>
> ! /* And kill the forwarder block, but first adjust its parent loop
> ! latch info as otherwise the cfg hook has a hard time not to
> ! kill the loop. */
> ! if (current_loops
> ! && bb->loop_father->latch == bb)
> ! bb->loop_father->latch = dest;
> delete_basic_block (bb);
By this code, do you mean to prevent cfgcleanup from
removing/rebuilding the loop struct?
>
> return true;
Thanks,
bin
