diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc index b1e7a2d5afc..782266bdad8 100644 --- a/gcc/tree-ssa-alias.cc +++ b/gcc/tree-ssa-alias.cc @@ -87,10 +87,11 @@ along with GCC; see the file COPYING3. If not see This function tries to disambiguate two reference trees. - bool ptr_deref_may_alias_global_p (tree) + bool ptr_deref_may_alias_global_p (tree, bool) This function queries if dereferencing a pointer variable may - alias global memory. + alias global memory. If bool argument is true, global memory + is considered to also include function local memory that escaped. More low-level disambiguators are available and documented in this file. Low-level disambiguators dealing with points-to @@ -3333,11 +3334,18 @@ stmt_kills_ref_p (gimple *stmt, ao_ref *ref) && TREE_CODE (gimple_get_lhs (stmt)) != SSA_NAME /* The assignment is not necessarily carried out if it can throw and we can catch it in the current function where we could inspect - the previous value. + the previous value. Similarly if the function can throw externally + and the ref does not die on the function return. ??? We only need to care about the RHS throwing. For aggregate assignments or similar calls and non-call exceptions the LHS - might throw as well. */ - && !stmt_can_throw_internal (cfun, stmt)) + might throw as well. + ??? We also should care about possible longjmp, but since we + do not understand that longjmp is not using global memory we will + not consider a kill here since the function call will be considered + as possibly using REF. */ + && !stmt_can_throw_internal (cfun, stmt) + && (!stmt_can_throw_external (cfun, stmt) + || !ref_may_alias_global_p (ref, false))) { tree lhs = gimple_get_lhs (stmt); /* If LHS is literally a base of the access we are done. */ @@ -3434,8 +3442,12 @@ stmt_kills_ref_p (gimple *stmt, ao_ref *ref) && node->binds_to_current_def_p () && (summary = get_modref_function_summary (node)) != NULL && summary->kills.length () + /* Check that we can not trap while evaulating function + parameters. This check is overly conservative. */ && (!cfun->can_throw_non_call_exceptions - || !stmt_can_throw_internal (cfun, stmt))) + || (!stmt_can_throw_internal (cfun, stmt) + && (!stmt_can_throw_external (cfun, stmt) + || !ref_may_alias_global_p (ref, false))))) { for (auto kill : summary->kills) {