diff options
Diffstat (limited to 'gcc/cfganal.c')
| -rw-r--r-- | gcc/cfganal.c | 179 |
1 files changed, 15 insertions, 164 deletions
diff --git a/gcc/cfganal.c b/gcc/cfganal.c index 00771b47703..1a7d280513f 100644 --- a/gcc/cfganal.c +++ b/gcc/cfganal.c @@ -52,7 +52,6 @@ static void flow_dfs_compute_reverse_add_bb (depth_first_search_ds, static basic_block flow_dfs_compute_reverse_execute (depth_first_search_ds); static void flow_dfs_compute_reverse_finish (depth_first_search_ds); static void remove_fake_successors (basic_block); -static bool need_fake_edge_p (rtx); static bool flow_active_insn_p (rtx); /* Like active_insn_p, except keep the return value clobber around @@ -242,169 +241,6 @@ set_edge_can_fallthru_flag (void) } } -/* Return true if we need to add fake edge to exit. - Helper function for the flow_call_edges_add. */ - -static bool -need_fake_edge_p (rtx insn) -{ - if (!INSN_P (insn)) - return false; - - if ((GET_CODE (insn) == CALL_INSN - && !SIBLING_CALL_P (insn) - && !find_reg_note (insn, REG_NORETURN, NULL) - && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL) - && !CONST_OR_PURE_CALL_P (insn))) - return true; - - return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS - && MEM_VOLATILE_P (PATTERN (insn))) - || (GET_CODE (PATTERN (insn)) == PARALLEL - && asm_noperands (insn) != -1 - && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0))) - || GET_CODE (PATTERN (insn)) == ASM_INPUT); -} - -/* Add fake edges to the function exit for any non constant and non noreturn - calls, volatile inline assembly in the bitmap of blocks specified by - BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks - that were split. - - The goal is to expose cases in which entering a basic block does not imply - that all subsequent instructions must be executed. */ - -int -flow_call_edges_add (sbitmap blocks) -{ - int i; - int blocks_split = 0; - int last_bb = last_basic_block; - bool check_last_block = false; - - if (n_basic_blocks == 0) - return 0; - - if (! blocks) - check_last_block = true; - else - check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index); - - /* In the last basic block, before epilogue generation, there will be - a fallthru edge to EXIT. Special care is required if the last insn - of the last basic block is a call because make_edge folds duplicate - edges, which would result in the fallthru edge also being marked - fake, which would result in the fallthru edge being removed by - remove_fake_edges, which would result in an invalid CFG. - - Moreover, we can't elide the outgoing fake edge, since the block - profiler needs to take this into account in order to solve the minimal - spanning tree in the case that the call doesn't return. - - Handle this by adding a dummy instruction in a new last basic block. */ - if (check_last_block) - { - basic_block bb = EXIT_BLOCK_PTR->prev_bb; - rtx insn = BB_END (bb); - - /* Back up past insns that must be kept in the same block as a call. */ - while (insn != BB_HEAD (bb) - && keep_with_call_p (insn)) - insn = PREV_INSN (insn); - - if (need_fake_edge_p (insn)) - { - edge e; - - for (e = bb->succ; e; e = e->succ_next) - if (e->dest == EXIT_BLOCK_PTR) - { - insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e); - commit_edge_insertions (); - break; - } - } - } - - /* Now add fake edges to the function exit for any non constant - calls since there is no way that we can determine if they will - return or not... */ - - for (i = 0; i < last_bb; i++) - { - basic_block bb = BASIC_BLOCK (i); - rtx libcall_end = NULL_RTX; - rtx insn; - rtx prev_insn; - - if (!bb) - continue; - - if (blocks && !TEST_BIT (blocks, i)) - continue; - - for (insn = BB_END (bb); ; insn = prev_insn) - { - prev_insn = PREV_INSN (insn); - if (need_fake_edge_p (insn)) - { - edge e; - rtx split_at_insn = insn; - - /* Don't split libcalls. */ - if (libcall_end) - split_at_insn = libcall_end; - - /* Don't split the block between a call and an insn that should - remain in the same block as the call. */ - else if (GET_CODE (insn) == CALL_INSN) - while (split_at_insn != BB_END (bb) - && keep_with_call_p (NEXT_INSN (split_at_insn))) - split_at_insn = NEXT_INSN (split_at_insn); - - /* The handling above of the final block before the epilogue - should be enough to verify that there is no edge to the exit - block in CFG already. Calling make_edge in such case would - cause us to mark that edge as fake and remove it later. */ - -#ifdef ENABLE_CHECKING - if (split_at_insn == BB_END (bb)) - for (e = bb->succ; e; e = e->succ_next) - if (e->dest == EXIT_BLOCK_PTR) - abort (); -#endif - - /* Note that the following may create a new basic block - and renumber the existing basic blocks. */ - if (split_at_insn != BB_END (bb)) - { - e = split_block (bb, split_at_insn); - if (e) - blocks_split++; - } - - make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE); - } - - /* Watch out for REG_LIBCALL/REG_RETVAL notes so that we know - whether we are currently in a libcall or not. Remember that - we are scanning backwards! */ - if (find_reg_note (insn, REG_RETVAL, NULL_RTX)) - libcall_end = insn; - if (find_reg_note (insn, REG_LIBCALL, NULL_RTX)) - libcall_end = NULL_RTX; - - if (insn == BB_HEAD (bb)) - break; - } - } - - if (blocks_split) - verify_flow_info (); - - return blocks_split; -} - /* Find unreachable blocks. An unreachable block will have 0 in the reachable bit in block->flags. A nonzero value indicates the block is reachable. */ @@ -603,6 +439,21 @@ verify_edge_list (FILE *f, struct edge_list *elist) } } +/* Given PRED and SUCC blocks, return the edge which connects the blocks. + If no such edge exists, return NULL. */ + +edge +find_edge (basic_block pred, basic_block succ) +{ + edge e; + + for (e = pred->succ; e; e = e->succ_next) + if (e->dest == succ) + return e; + + return NULL; +} + /* This routine will determine what, if any, edge there is between a specified predecessor and successor. */ |