diff options
Diffstat (limited to 'gcc/flow.c')
| -rw-r--r-- | gcc/flow.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/gcc/flow.c b/gcc/flow.c index 0fd58c09f6d..992cac6584b 100644 --- a/gcc/flow.c +++ b/gcc/flow.c @@ -396,7 +396,7 @@ static bool try_optimize_cfg PARAMS ((int)); static bool can_fallthru PARAMS ((basic_block, basic_block)); static bool try_redirect_by_replacing_jump PARAMS ((edge, basic_block)); static bool try_simplify_condjump PARAMS ((basic_block)); -static bool try_forward_edges PARAMS ((basic_block)); +static bool try_forward_edges PARAMS ((int, basic_block)); static void tidy_fallthru_edges PARAMS ((void)); static int verify_wide_reg_1 PARAMS ((rtx *, void *)); static void verify_wide_reg PARAMS ((int, rtx, rtx)); @@ -3182,8 +3182,9 @@ try_simplify_condjump (cbranch_block) Return true if sucessful. */ static bool -try_forward_edges (b) +try_forward_edges (mode, b) basic_block b; + int mode; { bool changed = false; edge e, next; @@ -3216,6 +3217,30 @@ try_forward_edges (b) /* Bypass trivial infinite loops. */ if (target == target->succ->dest) counter = n_basic_blocks; + + /* Avoid killing of loop pre-headers, as it is the place loop + optimizer wants to hoist code to. + + For fallthru forwarders, the LOOP_BEG note must appear between + the header of block and CODE_LABEL of the loop, for non forwarders + it must appear before the JUMP_INSN. */ + if (mode & CLEANUP_PRE_LOOP) + { + rtx insn = (target->succ->flags & EDGE_FALLTHRU + ? target->head : prev_nonnote_insn (target->end)); + + if (GET_CODE (insn) != NOTE) + insn = NEXT_INSN (insn); + + for (;insn && GET_CODE (insn) != CODE_LABEL && !INSN_P (insn); + insn = NEXT_INSN (insn)) + if (GET_CODE (insn) == NOTE + && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) + break; + + if (GET_CODE (insn) == NOTE) + break; + } target = target->succ->dest, counter++; } @@ -3953,7 +3978,7 @@ try_optimize_cfg (mode) changed_here = true; /* Simplify branch to branch. */ - if (try_forward_edges (b)) + if (try_forward_edges (mode, b)) changed_here = true; /* Look for shared code between blocks. */ |
