diff options
Diffstat (limited to 'gcc/gimple-low.c')
-rw-r--r-- | gcc/gimple-low.c | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/gcc/gimple-low.c b/gcc/gimple-low.c index c6f6f7611e2..ee57d9beda0 100644 --- a/gcc/gimple-low.c +++ b/gcc/gimple-low.c @@ -540,3 +540,87 @@ struct tree_opt_pass pass_remove_useless_vars = TODO_dump_func, /* todo_flags_finish */ 0 /* letter */ }; + +/* Mark BLOCK used if it has a used variable in it, then recurse over it's + subblocks. */ + +static void +mark_blocks_with_used_vars (tree block) +{ + tree var; + tree subblock; + + if (!TREE_USED (block)) + { + for (var = BLOCK_VARS (block); + var; + var = TREE_CHAIN (var)) + { + if (TREE_USED (var)) + { + TREE_USED (block) = true; + break; + } + } + } + for (subblock = BLOCK_SUBBLOCKS (block); + subblock; + subblock = BLOCK_CHAIN (subblock)) + mark_blocks_with_used_vars (subblock); +} + +/* Mark BLOCK used if any of it's subblocks have the USED bit set, or it's + abstract origin is used. */ + +static bool +mark_blocks_with_used_subblocks (tree block) +{ + tree subblock; + + /* The block may have no variables, but still be used, if it's abstract + origin is used. This occurs when we inline functions with no parameters + that call functions with no parameters or local vars (such as + dwarf2/dwarf-die7.c). You end up with a block that has an abstract + origin, no variables, and nothing in the subblocks is used. However, the + block is really used, because it's abstract origin was used. */ + + if (BLOCK_ABSTRACT_ORIGIN (block)) + { + if (TREE_USED (BLOCK_ABSTRACT_ORIGIN (block))) + TREE_USED (block) = true; + } + + for (subblock = BLOCK_SUBBLOCKS (block); + subblock; + subblock = BLOCK_CHAIN (subblock)) + TREE_USED (block) |= mark_blocks_with_used_subblocks (subblock); + return TREE_USED (block); +} + +/* Mark the used attribute on blocks correctly. */ + +static void +mark_used_blocks (void) +{ + + mark_blocks_with_used_vars (DECL_INITIAL (current_function_decl)); + mark_blocks_with_used_subblocks (DECL_INITIAL (current_function_decl)); +} + + +struct tree_opt_pass pass_mark_used_blocks = +{ + "blocks", /* name */ + NULL, /* gate */ + mark_used_blocks, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + 0, /* tv_id */ + 0, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func, /* todo_flags_finish */ + 0 /* letter */ +}; |