On 27/11/11 23:59, Eric Botcazou wrote: >> No, DELETED_LABEL notes still work just fine. It depends on how you >> remove the label and replace it with a note, and Tom isn't showing >> what he did, so... > > I agree that there is no obvious reason why just calling delete_insn would > not > work, so this should be investigated first. >
The reason it didn't work, is because after turning a label into a NOTE_INSN_DELETED_LABEL, one needs to move it to after the NOTE_INSN_BASIC_BLOCK as in cfgcleanup.c:try_optimize_cfg(): ... delete_insn_chain (label, label, false); /* If the case label is undeletable, move it after the BASIC_BLOCK note. */ if (NOTE_KIND (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL) { rtx bb_note = NEXT_INSN (BB_HEAD (b)); reorder_insns_nobb (label, label, bb_note); BB_HEAD (b) = bb_note; if (BB_END (b) == bb_note) BB_END (b) = label; } ... Attached patch factors out this piece of code and reuses it in fixup_reorder_chain. Bootstrapped and reg-tested on x86_64. OK for next stage1? Thanks, - Tom 2011-12-01 Tom de Vries <t...@codesourcery.com> * cfgcleanup.c (fixup_deleted_label): New function, factored out of ... (try_optimize_cfg): Use fixup_deleted_label. * cfglayout.c (fixup_reorder_chain): Delete unused label, and fixup using fixup_deleted_label. * gcc.dg/superblock.c: New test.
Index: gcc/cfgcleanup.c =================================================================== --- gcc/cfgcleanup.c (revision 181652) +++ gcc/cfgcleanup.c (working copy) @@ -2518,6 +2518,27 @@ trivially_empty_bb_p (basic_block bb) } } +/* Move a DELETED_LABEL note after the BASIC_BLOCK note of BB. */ + +void +fixup_deleted_label (basic_block bb) +{ + rtx deleted_label = BB_HEAD (bb), bb_note; + + if (deleted_label == NULL_RTX + || !NOTE_P (deleted_label) + || NOTE_KIND (deleted_label) != NOTE_INSN_DELETED_LABEL) + return; + + bb_note = NEXT_INSN (deleted_label); + gcc_assert (bb_note != NULL_RTX && NOTE_INSN_BASIC_BLOCK_P (bb_note)); + + reorder_insns_nobb (deleted_label, deleted_label, bb_note); + BB_HEAD (bb) = bb_note; + if (BB_END (bb) == bb_note) + BB_END (bb) = deleted_label; +} + /* Do simple CFG optimizations - basic block merging, simplifying of jump instructions etc. Return nonzero if changes were made. */ @@ -2637,15 +2658,7 @@ try_optimize_cfg (int mode) delete_insn_chain (label, label, false); /* If the case label is undeletable, move it after the BASIC_BLOCK note. */ - if (NOTE_KIND (BB_HEAD (b)) == NOTE_INSN_DELETED_LABEL) - { - rtx bb_note = NEXT_INSN (BB_HEAD (b)); - - reorder_insns_nobb (label, label, bb_note); - BB_HEAD (b) = bb_note; - if (BB_END (b) == bb_note) - BB_END (b) = label; - } + fixup_deleted_label (b); if (dump_file) fprintf (dump_file, "Deleted label in block %i.\n", b->index); Index: gcc/cfglayout.c =================================================================== --- gcc/cfglayout.c (revision 181652) +++ gcc/cfglayout.c (working copy) @@ -857,6 +857,12 @@ fixup_reorder_chain (void) (e_taken->src, e_taken->dest)); e_taken->flags |= EDGE_FALLTHRU; update_br_prob_note (bb); + if (LABEL_NUSES (ret_label) == 0 + && single_pred_p (e_taken->dest)) + { + delete_insn (ret_label); + fixup_deleted_label (e_taken->dest); + } continue; } } Index: gcc/basic-block.h =================================================================== --- gcc/basic-block.h (revision 181652) +++ gcc/basic-block.h (working copy) @@ -813,6 +813,7 @@ extern void rtl_make_eh_edge (sbitmap, b enum replace_direction { dir_none, dir_forward, dir_backward, dir_both }; /* In cfgcleanup.c. */ +extern void fixup_deleted_label (basic_block); extern bool cleanup_cfg (int); extern int flow_find_cross_jump (basic_block, basic_block, rtx *, rtx *, enum replace_direction*); Index: gcc/testsuite/gcc.dg/superblock.c =================================================================== --- /dev/null (new file) +++ gcc/testsuite/gcc.dg/superblock.c (revision 0) @@ -0,0 +1,23 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-asynchronous-unwind-tables -fsched2-use-superblocks -fdump-rtl-sched2 -fdump-rtl-bbro" } */ + +typedef int aligned __attribute__ ((aligned (64))); +extern void abort (void); + +int bar (void *p); + +void +foo (void) +{ + char *p = __builtin_alloca (13); + aligned i; + + if (bar (p) || bar (&i)) + abort (); +} + +/* { dg-final { scan-rtl-dump-times "0 uses" 0 "bbro"} } */ +/* { dg-final { scan-rtl-dump-times "ADVANCING TO" 2 "sched2"} } */ +/* { dg-final { cleanup-rtl-dump "bbro" } } */ +/* { dg-final { cleanup-rtl-dump "sched2" } } */ +