Launchpad has imported 9 comments from the remote bug at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59744.
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Read more about Launchpad's inter-bugtracker facilities at https://help.launchpad.net/InterBugTracking. ------------------------------------------------------------------------ On 2014-01-10T00:30:27+00:00 Michael Hudson-Doyle wrote: Hi, This slightly strangely written program (it's distilled down from frame_offset_overflow in the gcc source itself) should print "bigger" if the first argument is bigger than 10 (or negative, but let's ignore that please): #include <stdlib.h> #include <stdio.h> int a[2] = { 10, 20 }; int is_bigger (long offset, int index) { unsigned long size = -offset; if (size > a[index]) { printf("bigger\n"); return 1; } return 0; } int main (int argc, char** argv) { long v; v = atol(argv[1]); is_bigger(-v, 0); return 0; } When compiled at -O1 or above (and with inlining disabled at -O2 and above), though, it bungles the 0 case: (t-doko)mwhudson@arm64:~$ gcc-4.9 -O3 test.c -o test -fno-inline -Wall (t-doko)mwhudson@arm64:~$ ./test 1 (t-doko)mwhudson@arm64:~$ ./test 11 bigger (t-doko)mwhudson@arm64:~$ ./test 0 bigger (t-doko)mwhudson@arm64:~$ gcc-4.9 -O0 test.c -o test -Wall (t-doko)mwhudson@arm64:~$ ./test 1 (t-doko)mwhudson@arm64:~$ ./test 11 bigger (t-doko)mwhudson@arm64:~$ ./test 0 (t-doko)mwhudson@arm64:~$ What's going on? Here's the disassembly of is_bigger (at O3): 0000000000400608 <is_bigger>: 400608: b0000082 adrp x2, 411000 <_GLOBAL_OFFSET_TABLE_+0x28> 40060c: 91010042 add x2, x2, #0x40 400610: a9bf7bfd stp x29, x30, [sp,#-16]! 400614: 52800003 mov w3, #0x0 // #0 400618: 910003fd mov x29, sp 40061c: b8a1d841 ldrsw x1, [x2,w1,sxtw #2] 400620: ab00003f cmn x1, x0 400624: 540000a2 b.cs 400638 <is_bigger+0x30> 400628: 90000000 adrp x0, 400000 <_init-0x3f8> 40062c: 911b6000 add x0, x0, #0x6d8 400630: 97ffff90 bl 400470 <puts@plt> 400634: 52800023 mov w3, #0x1 // #1 400638: 2a0303e0 mov w0, w3 40063c: a8c17bfd ldp x29, x30, [sp],#16 400640: d65f03c0 ret Basically it seems that the condition "-offset > val" is being compiled as "val + offset does not overflow", which is not valid for offset == 0. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/2 ------------------------------------------------------------------------ On 2014-01-10T01:00:19+00:00 Pinskia wrote: (insn 14 13 15 2 (set (reg:CC_SWP 66 cc) (compare:CC_SWP (neg:DI (reg:DI 0 x0 [ offset ])) (reg:DI 1 x1 [orig:85 D.3895 ] [85]))) t7.c:11 114 {*compare_negdi} (expr_list:REG_DEAD (reg:DI 1 x1 [orig:85 D.3895 ] [85]) (expr_list:REG_DEAD (reg:DI 0 x0 [ offset ]) (nil)))) --- CUT --- Here is a testcase that fails at -O1 and above without any arguments. int a[2] = { 10, 20 }; int is_bigger (long, int) __attribute__((noinline,noclone)); int is_bigger (long offset, int index) { unsigned long size = -offset; if (size > a[index]) return 1; return 0; } int main (int argc, char** argv) { long v; if (is_bigger(0, 0)) __builtin_abort (); if (!is_bigger(1, 0)) __builtin_abort (); if (is_bigger(-10, 0)) __builtin_abort (); if (!is_bigger(10, 0)) __builtin_abort (); return 0; } Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/4 ------------------------------------------------------------------------ On 2014-01-10T15:21:53+00:00 Rearnsha wrote: Author: rearnsha Date: Fri Jan 10 15:21:21 2014 New Revision: 206530 URL: http://gcc.gnu.org/viewcvs?rev=206530&root=gcc&view=rev Log: PR target/59744 Fix ChangeLog typos in previous commit (r206529). Modified: trunk/gcc/ChangeLog Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/5 ------------------------------------------------------------------------ On 2014-01-10T15:23:36+00:00 Rearnsha wrote: Fixed on trunk Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/6 ------------------------------------------------------------------------ On 2014-01-13T01:00:43+00:00 Michael Hudson-Doyle wrote: Hi, thanks for the super fast fix. Could it be backported to 4.8? git cherry-pick gives a conflict in aarch64.md which is probably easy to fix if you know how this code works: (define_insn "*compare_neg<mode>" <<<<<<< HEAD [(set (reg:CC CC_REGNUM) (compare:CC (match_operand:GPI 0 "register_operand" "r") (neg:GPI (match_operand:GPI 1 "register_operand" "r"))))] ||||||| parent of 46b590a... PR target/9744 [(set (reg:CC_SWP CC_REGNUM) (compare:CC_SWP (neg:GPI (match_operand:GPI 0 "register_operand" "r")) (match_operand:GPI 1 "register_operand" "r")))] ======= [(set (reg:CC_Z CC_REGNUM) (compare:CC_Z (neg:GPI (match_operand:GPI 0 "register_operand" "r")) (match_operand:GPI 1 "register_operand" "r")))] >>>>>>> 46b590a... PR target/9744 "" "cmn\\t%<w>0, %<w>1" [(set_attr "v8type" "alus") (set_attr "mode" "<MODE>")] ) Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/7 ------------------------------------------------------------------------ On 2014-01-13T09:34:19+00:00 Rearnsha wrote: I don't expect that pattern to match on 4.8 (the pattern is not canonical form), which is why this wasn't seen before. If you can find a test-case that triggers on that branch, I'll do a back-port; otherwise, there's no point. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/8 ------------------------------------------------------------------------ On 2014-01-13T09:35:41+00:00 Ktkachov wrote: I couldn't reproduce the failure using 4.8. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/9 ------------------------------------------------------------------------ On 2014-01-14T00:30:04+00:00 Michael Hudson-Doyle wrote: I saw the problem with Linaro GCC 4.8, but haven't tried the vanilla 4.8 branch. If the committed test case doesn't fail, I'll believe that it is not a problem. Sorry for the noise. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/10 ------------------------------------------------------------------------ On 2014-08-11T22:08:36+00:00 Yroux wrote: Author: yroux Date: Mon Aug 11 22:08:03 2014 New Revision: 213842 URL: https://gcc.gnu.org/viewcvs?rev=213842&root=gcc&view=rev Log: gcc/ 2014-08-11 Michael Collison <michael.colli...@linaro.org> Backport from trunk r206529, r206530 2014-01-10 Richard Earnshaw <rearn...@arm.com> PR target/59744 * aarch64-modes.def (CC_Zmode): New flags mode. * aarch64.c (aarch64_select_cc_mode): Only allow NEG when the condition represents an equality. (aarch64_get_condition_code): Handle CC_Zmode. * aarch64.md (compare_neg<mode>): Restrict to equality operations. gcc/testsuite/ 2014-08-11 Michael Collison <michael.colli...@linaro.org> Backport from trunk r206529 2014-01-10 Richard Earnshaw <rearn...@arm.com> PR target/59744 * gcc.target/aarch64/cmn-neg.c: Use equality comparisons. * gcc.target/aarch64/cmn-neg2.c: New test. Added: branches/linaro/gcc-4_8-branch/gcc/testsuite/gcc.target/aarch64/cmn-neg2.c Modified: branches/linaro/gcc-4_8-branch/gcc/ChangeLog.linaro branches/linaro/gcc-4_8-branch/gcc/config/aarch64/aarch64-modes.def branches/linaro/gcc-4_8-branch/gcc/config/aarch64/aarch64.c branches/linaro/gcc-4_8-branch/gcc/config/aarch64/aarch64.md branches/linaro/gcc-4_8-branch/gcc/testsuite/ChangeLog.linaro branches/linaro/gcc-4_8-branch/gcc/testsuite/gcc.target/aarch64/cmn-neg.c Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.8/+bug/1263806/comments/12 ** Changed in: gcc Status: Unknown => Fix Released ** Changed in: gcc Importance: Unknown => Medium -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to gcc-4.8 in Ubuntu. https://bugs.launchpad.net/bugs/1263806 Title: gccgo fails to compile tomb.go on arm64 Status in The GNU Compiler Collection: Fix Released Status in “gcc-4.8” package in Ubuntu: Fix Released Bug description: Hi, on am2: ubuntu@arm64:~/gopath/src/launchpad.net/tomb$ gccgo -g -c -o tomb.o tomb.go tomb.go: In function 'tomb.Wait.pN12_go.tomb.Tomb': tomb.go:108:1: error: total size of local objects too large func (t *Tomb) Wait() error { ^ tomb.go: In function 'tomb.Kill.pN12_go.tomb.Tomb': tomb.go:134:1: error: total size of local objects too large func (t *Tomb) Kill(reason error) { ^ This is the first error line: http://bazaar.launchpad.net/~niemeyer/tomb/trunk/view/head:/tomb.go#L108 which seems pretty innocuous. Will dig (and probably kick upstream) in January. To manage notifications about this bug go to: https://bugs.launchpad.net/gcc/+bug/1263806/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp