diff options
Diffstat (limited to 'gcc/tree-ssa-dce.c')
| -rw-r--r-- | gcc/tree-ssa-dce.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c index e29f365..f225030 100644 --- a/gcc/tree-ssa-dce.c +++ b/gcc/tree-ssa-dce.c @@ -309,6 +309,8 @@ mark_stmt_if_obviously_necessary (gimple stmt, bool aggressive) case BUILT_IN_CALLOC: case BUILT_IN_ALLOCA: return; + + default:; } /* Most, but not all function calls are required. Function calls that produce no result and have no side effects (i.e. const pure @@ -625,6 +627,25 @@ mark_all_reaching_defs_necessary_1 (ao_ref *ref ATTRIBUTE_UNUSED, return false; } + /* We want to skip statments that do not constitute stores but have + a virtual definition. */ + if (is_gimple_call (def_stmt)) + { + tree callee = gimple_call_fndecl (def_stmt); + if (callee != NULL_TREE + && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL) + switch (DECL_FUNCTION_CODE (callee)) + { + case BUILT_IN_MALLOC: + case BUILT_IN_CALLOC: + case BUILT_IN_ALLOCA: + case BUILT_IN_FREE: + return false; + + default:; + } + } + mark_operand_necessary (vdef); return false; @@ -805,6 +826,25 @@ propagate_necessity (struct edge_list *el) ssa_op_iter iter; tree use; + /* If this is a call to free which is directly fed by an + allocation function do not mark that necessary through + processing the argument. */ + if (gimple_call_builtin_p (stmt, BUILT_IN_FREE)) + { + tree ptr = gimple_call_arg (stmt, 0); + gimple def_stmt; + tree def_callee; + /* If the pointer we free is defined by an allocation + function do not add the call to the worklist. */ + if (TREE_CODE (ptr) == SSA_NAME + && is_gimple_call (def_stmt = SSA_NAME_DEF_STMT (ptr)) + && (def_callee = gimple_call_fndecl (def_stmt)) + && DECL_BUILT_IN_CLASS (def_callee) == BUILT_IN_NORMAL + && (DECL_FUNCTION_CODE (def_callee) == BUILT_IN_MALLOC + || DECL_FUNCTION_CODE (def_callee) == BUILT_IN_CALLOC)) + continue; + } + FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE) mark_operand_necessary (use); @@ -1218,6 +1258,29 @@ eliminate_unnecessary_stmts (void) stats.total++; + /* We can mark a call to free as not necessary if the + defining statement of its argument is an allocation + function and that is not necessary itself. */ + if (gimple_call_builtin_p (stmt, BUILT_IN_FREE)) + { + tree ptr = gimple_call_arg (stmt, 0); + tree callee2; + gimple def_stmt; + if (TREE_CODE (ptr) != SSA_NAME) + continue; + def_stmt = SSA_NAME_DEF_STMT (ptr); + if (!is_gimple_call (def_stmt) + || gimple_plf (def_stmt, STMT_NECESSARY)) + continue; + callee2 = gimple_call_fndecl (def_stmt); + if (callee2 == NULL_TREE + || DECL_BUILT_IN_CLASS (callee2) != BUILT_IN_NORMAL + || (DECL_FUNCTION_CODE (callee2) != BUILT_IN_MALLOC + && DECL_FUNCTION_CODE (callee2) != BUILT_IN_CALLOC)) + continue; + gimple_set_plf (stmt, STMT_NECESSARY, false); + } + /* If GSI is not necessary then remove it. */ if (!gimple_plf (stmt, STMT_NECESSARY)) { |