Launchpad has imported 7 comments from the remote bug at http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54974.
If you reply to an imported comment from within Launchpad, your comment will be sent to the remote bug automatically. Read more about Launchpad's inter-bugtracker facilities at https://help.launchpad.net/InterBugTracking. ------------------------------------------------------------------------ On 2012-10-18T12:58:24+00:00 Mans Rullgard wrote: Created attachment 28483 Test case If the following conditions are true, a constant pool is placed too far from an LDR instruction accessing it: - Compiling to Thumb2. - There is no unconditional branch within 4k of the LDR instruction. - At least one of: * The LDR instruction is not at a 4-byte aligned address. * There is an instruction boundary 4094 bytes from the value of PC at the LDR. The problem here is twofold: 1. The base address of a PC-relative LDR in Thumb2 is the address of the instruction plus 4, rounded down to a multiple of 4. The calculation for the valid range fails to take this rounding into account. 2. The constant pool is (rightly) 4-byte aligned. When scanning the instructions for a suitable location, the possible need for padding is not considered. The problem can be seen by compiling the attached preprocessed source using flags "-mthumb -march=armv7-a -mfpu=vfpv3-d16 -mfloat-abi=hard -O0 -fPIC". Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.7/+bug/1049614/comments/14 ------------------------------------------------------------------------ On 2012-10-18T13:00:48+00:00 Mans Rullgard wrote: Created attachment 28484 Hack patch This hack patch validates the analysis. A proper fix probably looks different. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.7/+bug/1049614/comments/15 ------------------------------------------------------------------------ On 2012-10-18T13:20:19+00:00 Doko-v wrote: works with 4.7, fails with trunk Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.7/+bug/1049614/comments/16 ------------------------------------------------------------------------ On 2012-10-18T13:23:13+00:00 Mikpe wrote: Also works with gcc-4.6. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.7/+bug/1049614/comments/17 ------------------------------------------------------------------------ On 2012-10-18T19:43:02+00:00 Mikpe wrote: The test case started failing with r189790: http://gcc.gnu.org/ml/gcc-cvs/2012-07/msg00695.html That patch merely enabled insn splitting at -O0, so I suspect it exposed a latent problem in the back-end, consistent with Måns' analysis. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.7/+bug/1049614/comments/18 ------------------------------------------------------------------------ On 2012-10-19T12:23:57+00:00 Doko-v wrote: this patch is now on the 4.7 branch too. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.7/+bug/1049614/comments/19 ------------------------------------------------------------------------ On 2012-11-28T03:03:50+00:00 Ramana-gcc wrote: http://gcc.gnu.org/ml/gcc-patches/2012-11/msg01825.html Patch posted here. Reply at: https://bugs.launchpad.net/ubuntu/+source/gcc-4.7/+bug/1049614/comments/21 ** Changed in: gcc Status: New => In Progress -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1049614 Title: Assembler messages with -O0: Error: offset out of range To manage notifications about this bug go to: https://bugs.launchpad.net/gcc/+bug/1049614/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
