public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.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 [thread overview] Message-ID: <bug-52353-4@http.gcc.gnu.org/bugzilla/> (raw) 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.
next reply other threads:[~2012-02-23 13:00 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-02-23 13:05 rguenth at gcc dot gnu.org [this message] 2012-02-23 13:21 ` [Bug middle-end/52353] " rguenth at gcc dot gnu.org 2012-03-05 13:09 ` rguenth at gcc dot gnu.org 2012-03-05 13:10 ` rguenth at gcc dot gnu.org
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=bug-52353-4@http.gcc.gnu.org/bugzilla/ \ --to=gcc-bugzilla@gcc.gnu.org \ --cc=gcc-bugs@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).