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