diff options
Diffstat (limited to 'gcc/cfgrtl.c')
| -rw-r--r-- | gcc/cfgrtl.c | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/gcc/cfgrtl.c b/gcc/cfgrtl.c index e78f5ba..9031886 100644 --- a/gcc/cfgrtl.c +++ b/gcc/cfgrtl.c @@ -30,6 +30,8 @@ along with GCC; see the file COPYING3. If not see insert_insn_on_edge, commit_edge_insertions - CFG updating after insn simplification purge_dead_edges, purge_all_dead_edges + - CFG fixing after coarse manipulation + fixup_abnormal_edges Functions not supposed for generic use: - Infrastructure to determine quickly basic block for insn @@ -2471,6 +2473,95 @@ purge_all_dead_edges (void) return purged; } +/* This is used by a few passes that emit some instructions after abnormal + calls, moving the basic block's end, while they in fact do want to emit + them on the fallthru edge. Look for abnormal call edges, find backward + the call in the block and insert the instructions on the edge instead. + + Similarly, handle instructions throwing exceptions internally. + + Return true when instructions have been found and inserted on edges. */ + +bool +fixup_abnormal_edges (void) +{ + bool inserted = false; + basic_block bb; + + FOR_EACH_BB (bb) + { + edge e; + edge_iterator ei; + + /* Look for cases we are interested in - calls or instructions causing + exceptions. */ + FOR_EACH_EDGE (e, ei, bb->succs) + if ((e->flags & EDGE_ABNORMAL_CALL) + || ((e->flags & (EDGE_ABNORMAL | EDGE_EH)) + == (EDGE_ABNORMAL | EDGE_EH))) + break; + + if (e && !CALL_P (BB_END (bb)) && !can_throw_internal (BB_END (bb))) + { + rtx insn; + + /* Get past the new insns generated. Allow notes, as the insns + may be already deleted. */ + insn = BB_END (bb); + while ((NONJUMP_INSN_P (insn) || NOTE_P (insn)) + && !can_throw_internal (insn) + && insn != BB_HEAD (bb)) + insn = PREV_INSN (insn); + + if (CALL_P (insn) || can_throw_internal (insn)) + { + rtx stop, next; + + e = find_fallthru_edge (bb->succs); + + stop = NEXT_INSN (BB_END (bb)); + BB_END (bb) = insn; + + for (insn = NEXT_INSN (insn); insn != stop; insn = next) + { + next = NEXT_INSN (insn); + if (INSN_P (insn)) + { + delete_insn (insn); + + /* Sometimes there's still the return value USE. + If it's placed after a trapping call (i.e. that + call is the last insn anyway), we have no fallthru + edge. Simply delete this use and don't try to insert + on the non-existent edge. */ + if (GET_CODE (PATTERN (insn)) != USE) + { + /* We're not deleting it, we're moving it. */ + INSN_DELETED_P (insn) = 0; + PREV_INSN (insn) = NULL_RTX; + NEXT_INSN (insn) = NULL_RTX; + + insert_insn_on_edge (insn, e); + inserted = true; + } + } + else if (!BARRIER_P (insn)) + set_block_for_insn (insn, NULL); + } + } + + /* It may be that we don't find any trapping insn. In this + case we discovered quite late that the insn that had been + marked as can_throw_internal in fact couldn't trap at all. + So we should in fact delete the EH edges out of the block. */ + else + purge_dead_edges (bb); + } + } + + return inserted; +} + /* Same as split_block but update cfg_layout structures. */ static basic_block |