diff options
Diffstat (limited to 'gcc/cfglayout.c')
| -rw-r--r-- | gcc/cfglayout.c | 42 |
1 files changed, 41 insertions, 1 deletions
diff --git a/gcc/cfglayout.c b/gcc/cfglayout.c index 3214e808886..ca5f4751a41 100644 --- a/gcc/cfglayout.c +++ b/gcc/cfglayout.c @@ -460,11 +460,44 @@ fixup_reorder_chain () && e_fall->dest == EXIT_BLOCK_PTR)) continue; + if (!e_taken) + e_taken = e_fall; + + /* The degenerated case of conditional jump jumping to the next + instruction can happen on target having jumps with side + effects. + + Create temporarily the duplicated edge representing branch. + It will get unidentified by force_nonfallthru_and_redirect + that would otherwise get confused by fallthru edge not pointing + to the next basic block. */ + if (!e_taken) + { + rtx note; + edge e_fake; + + e_fake = unchecked_make_edge (bb, e_fall->dest, 0); + + note = find_reg_note (bb->end, REG_BR_PROB, NULL_RTX); + if (note) + { + int prob = INTVAL (XEXP (note, 0)); + + e_fake->probability = prob; + e_fake->count = e_fall->count * prob / REG_BR_PROB_BASE; + e_fall->probability -= e_fall->probability; + e_fall->count -= e_fake->count; + if (e_fall->probability < 0) + e_fall->probability = 0; + if (e_fall->count < 0) + e_fall->count = 0; + } + } /* There is one special case: if *neither* block is next, such as happens at the very end of a function, then we'll need to add a new unconditional jump. Choose the taken edge based on known or assumed probability. */ - if (RBI (bb)->next != e_taken->dest) + else if (RBI (bb)->next != e_taken->dest) { rtx note = find_reg_note (bb_end_insn, REG_BR_PROB, 0); @@ -836,6 +869,13 @@ cfg_layout_redirect_edge (e, dest) src->next_bb = NULL; if (e->flags & EDGE_FALLTHRU) { + /* Redirect any branch edges unified with the fallthru one. */ + if (GET_CODE (src->end) == JUMP_INSN + && JUMP_LABEL (src->end) == e->dest->head) + { + if (!redirect_jump (src->end, block_label (dest), 0)) + abort (); + } /* In case we are redirecting fallthru edge to the branch edge of conditional jump, remove it. */ if (src->succ->succ_next |