From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 4928 invoked by alias); 23 Feb 2012 13:00:46 -0000 Received: (qmail 4918 invoked by uid 22791); 23 Feb 2012 13:00:45 -0000 X-SWARE-Spam-Status: No, hits=-2.8 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Thu, 23 Feb 2012 13:00:32 +0000 From: "rguenth at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/52353] New: -ftrapv -fnon-call-exceptions does not work Date: Thu, 23 Feb 2012 13:05:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Keywords: wrong-code X-Bugzilla-Severity: normal X-Bugzilla-Who: rguenth at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2012-02/txt/msg02308.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52353 Bug #: 52353 Summary: -ftrapv -fnon-call-exceptions does not work Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: middle-end AssignedTo: unassigned@gcc.gnu.org ReportedBy: rguenth@gcc.gnu.org The testcase from PR47086 void foo () { int n = 0; while (1) { int i[n % 1]; n++; } } reveals that while on the tree level n++ has an outgoing EH edge, RTL expansion leaves us with ;; n_5 = n_1 + 1; (insn 12 11 13 (set (reg:DI 67) (sign_extend:DI (reg/v:SI 61 [ n ]))) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (nil)) (insn 13 12 14 (set (reg:DI 4 si) (const_int 1 [0x1])) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (nil)) (insn 14 13 15 (set (reg:DI 5 di) (reg:DI 67)) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (nil)) (call_insn/u 15 14 16 (set (reg:DI 0 ax) (call (mem:QI (symbol_ref:DI ("__addvdi3") [flags 0x41]) [0 S1 A8]) (const_int 0 [0]))) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (expr_list:REG_EH_REGION (const_int -2147483648 [0xffffffff80000000]) (nil)) (expr_list:REG_DEP_TRUE (use (reg:DI 4 si)) (expr_list:REG_DEP_TRUE (use (reg:DI 5 di)) (nil)))) (insn 16 15 17 (set (reg:DI 68) (reg:DI 0 ax)) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (expr_list:REG_EQUAL (plus:DI (reg:DI 67) (const_int 1 [0x1])) (nil))) (insn 17 16 0 (set (reg/v:SI 63 [ n ]) (subreg:SI (reg:DI 68) 0)) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (nil)) note that the call is marked CONST. The EH edge is simply thrown away: ;; Basic block 4 , prev 3, next 5, loop_depth 1, count 0, freq 10000, maybe hot, flags: new reachable rtl modified. ;; Predecessors: 3 [100.0%] (fallthru) 5 [100.0%] (dfs_back) ... (call_insn/u 15 14 16 4 (set (reg:DI 0 ax) (call (mem:QI (symbol_ref:DI ("__addvdi3") [flags 0x41]) [0 S1 A8]) (const_int 0 [0]))) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (expr_list:REG_EH_REGION (const_int -2147483648 [0xffffffff80000000]) (nil)) (expr_list:REG_DEP_TRUE (use (reg:DI 4 si)) (expr_list:REG_DEP_TRUE (use (reg:DI 5 di)) (nil)))) (insn 16 15 17 4 (set (reg:DI 68) (reg:DI 0 ax)) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (expr_list:REG_EQUAL (plus:DI (reg:DI 67) (const_int 1 [0x1])) (nil))) (insn 17 16 18 4 (set (reg/v:SI 63 [ n ]) (subreg:SI (reg:DI 68) 0)) /space/rguenther/src/svn/trunk/gcc/testsuite/gcc.dg/pr47086.c:11 -1 (nil)) ;; Successors: 5 [100.0%] (fallthru) So we seem to leave around the libcall because of the EH side-effect but do not consider that call as possibly throwing (as it is marked nothrow on RTL) in find_many_sub_basic_blocks (at least) and DCE it later, too (sounds similar to PR19020). Currently generated assembly for gcc.dg/pr47086.c on x86_64 is foo: .LFB0: .cfi_startproc .cfi_personality 0x3,__gcc_personality_v0 pushq %rbx .cfi_def_cfa_offset 16 .cfi_offset 3, -16 movl $0, %ebx .L2: addl $1, %ebx jmp .L2 I'm running into this issue when removing unreachable blocks during expansion, then the landing pad unwind info expansion ICEs because the landing pad was removed. We mark the call as not throwing via emit_libcall_block because we pass it (plus (reg) 1) as EQUIV, which may not trap.