diff options
Diffstat (limited to 'gcc/tree-tailcall.c')
| -rw-r--r-- | gcc/tree-tailcall.c | 29 |
1 files changed, 26 insertions, 3 deletions
diff --git a/gcc/tree-tailcall.c b/gcc/tree-tailcall.c index 2ecca4a..e0d3f48 100644 --- a/gcc/tree-tailcall.c +++ b/gcc/tree-tailcall.c @@ -136,11 +136,23 @@ suitable_for_tail_opt_p (void) if (cfun->stdarg) return false; - /* No local variable nor structure field should be call-used. */ + /* No local variable nor structure field should escape to callees. */ FOR_EACH_REFERENCED_VAR (var, rvi) { if (!is_global_var (var) - && is_call_used (var)) + /* ??? We do not have a suitable predicate for escaping to + callees. With IPA-PTA the following might be incorrect. + We want to catch + foo { + int i; + bar (&i); + foo (); + } + where bar might store &i somewhere and in the next + recursion should not be able to tell if it got the + same (with tail-recursion applied) or a different + address. */ + && is_call_clobbered (var)) return false; } @@ -430,7 +442,9 @@ find_tail_calls (basic_block bb, struct tailcall **ret) func = gimple_call_fndecl (call); if (func == current_function_decl) { - tree arg; + tree arg, var; + referenced_var_iterator rvi; + for (param = DECL_ARGUMENTS (func), idx = 0; param && idx < gimple_call_num_args (call); param = TREE_CHAIN (param), idx ++) @@ -460,6 +474,15 @@ find_tail_calls (basic_block bb, struct tailcall **ret) } if (idx == gimple_call_num_args (call) && !param) tail_recursion = true; + + /* Make sure the tail invocation of this function does not refer + to local variables. */ + FOR_EACH_REFERENCED_VAR (var, rvi) + { + if (!is_global_var (var) + && ref_maybe_used_by_stmt_p (call, var)) + return; + } } /* Now check the statements after the call. None of them has virtual |