From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12267 invoked by alias); 26 Oct 2005 14:28:04 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 12255 invoked by uid 48); 26 Oct 2005 14:28:01 -0000 Date: Wed, 26 Oct 2005 14:28:00 -0000 Subject: [Bug c/24539] New: inconsistent handling of null-valued language hooks in GCC X-Bugzilla-Reason: CC Message-ID: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "gary at intrepid dot com" X-SW-Source: 2005-10/txt/msg03433.txt.bz2 List-Id: Also posted to the GCC mailing list: http://gcc.gnu.org/ml/gcc/2005-10/msg00932.html http://gcc.gnu.org/ml/gcc/2005-10/msg00938.html While working with GCC's language hooks, we found that certain places in GCC test for a null value of lang_hooks.callgraph.expand_function, but cgraph_expand_function() calls the hook directly: In cgraphunit.c: /* Expand function specified by NODE. */ static void cgraph_expand_function (struct cgraph_node *node) { tree decl = node->decl; /* We ought to not compile any inline clones. */ gcc_assert (!node->global.inlined_to); if (flag_unit_at_a_time) announce_function (decl); cgraph_lower_function (node); /* Generate RTL for the body of DECL. */ lang_hooks.callgraph.expand_function (decl); ------------ In toplev.c: /* Disable unit-at-a-time mode for frontends not supporting callgraph interface. */ if (flag_unit_at_a_time && ! lang_hooks.callgraph.expand_function) flag_unit_at_a_time = 0; ------------ In function.c: /* Possibly warn about unused parameters. When frontend does unit-at-a-time, the warning is already issued at finalization time. */ if (warn_unused_parameter && !lang_hooks.callgraph.expand_function) do_warn_unused_parameter (current_function_decl); ------------ We tried setting lang_hooks.callgraph.expand_function to NULL: /* For now, disable unit-at-a-time by setting expand_function to NULL */ #undef LANG_HOOKS_CALLGRAPH_EXPAND_FUNCTION #define LANG_HOOKS_CALLGRAPH_EXPAND_FUNCTION NULL which has the desired effect of disabling unit-at-a-time, but runs aground in cgraph_expand_function() with a segfault, when it attempts to call lang_hooks.callgraph.expand_function(). It seems that GCC is handling lang_hooks.callgraph.expand_function in an inconsistent fashion. Is a null value for expand_function meaningful? If it is, then what is the fix for cgraph_expand_function()? ---- In a follow-up note on the GCC list, Dueway Qi notes: I have found another similar case. lang_hooks.callgraph.analyze_expr in gcc/gcc/cgraphunit.c 490 if (lang_hooks.callgraph.analyze_expr) 491 return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees, 492 data); but in another part of this file 517 if ((unsigned int) TREE_CODE (t) >= LAST_AND_UNUSED_TREE_CODE) 518 return lang_hooks.callgraph.analyze_expr (tp, walk_subtrees, data); -- Summary: inconsistent handling of null-valued language hooks in GCC Product: gcc Version: 4.0.1 Status: UNCONFIRMED Severity: normal Priority: P2 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: gary at intrepid dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24539