diff options
Diffstat (limited to 'gcc/flow.c')
| -rw-r--r-- | gcc/flow.c | 53 |
1 files changed, 23 insertions, 30 deletions
@@ -378,8 +378,6 @@ find_basic_blocks (f, nonlocal_label_list) /* List of label_refs to all labels whose addresses are taken and used as data. */ rtx label_value_list; - /* List of label_refs from REG_LABEL notes. */ - rtx reg_label_list; rtx x, note, eh_note; enum rtx_code prev_code, code; int depth, pass; @@ -389,7 +387,6 @@ find_basic_blocks (f, nonlocal_label_list) restart: label_value_list = 0; - reg_label_list = 0; block_live_static = block_live; bzero (block_live, n_basic_blocks); bzero (block_marked, n_basic_blocks); @@ -553,14 +550,26 @@ find_basic_blocks (f, nonlocal_label_list) if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') { - /* We have no idea where the label referenced by this - insn will actually be used. - - To create an accurate cfg we mark the target blocks - as live and create a list of all the labels - mentioned in REG_LABEL notes. After we're done - marking blocks, we go back and create an edge from - every live block to labels on the list. */ + /* References to labels in non-jumping insns have + REG_LABEL notes attached to them. + + This can happen for computed gotos; we don't care + about them here since the values are also on the + label_value_list and will be marked live if we find + a live computed goto. + + This can also happen when we take the address of + a label to pass as an argument to __throw. Note + throw only uses the value to determine what handler + should be called -- ie the label is not used as + a jump target, it just marks regions in the code. + + In theory we should be able to ignore the REG_LABEL + notes, but we have to make sure that the label and + associated insns aren't marked dead, so we make + the block in question live and create an edge from + this insn to the label. This is not strictly + correct, but it is close enough for now. */ for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) @@ -569,9 +578,9 @@ find_basic_blocks (f, nonlocal_label_list) { x = XEXP (note, 0); block_live[BLOCK_NUM (x)] = 1; - reg_label_list - = gen_rtx (EXPR_LIST, VOIDmode, x, - reg_label_list); + mark_label_ref (gen_rtx (LABEL_REF, + VOIDmode, x), + insn, 0); } } @@ -632,22 +641,6 @@ find_basic_blocks (f, nonlocal_label_list) } } - /* We couldn't determine what edges are needed for labels on the - reg_label_list above. So make an edge from every live block to - to every label on the reg_label_list. */ - if (reg_label_list) - { - for (i = 1; i < n_basic_blocks; i++) - if (block_live[i]) - { - rtx x; - - for (x = reg_label_list; x; x = XEXP (x, 1)) - mark_label_ref (gen_rtx (LABEL_REF, VOIDmode, XEXP (x, 0)), - basic_block_end[i], 0); - } - } - /* This should never happen. If it does that means we've computed an incorrect flow graph, which can lead to aborts/crashes later in the compiler or incorrect code generation. |