Uploaded image for project: 'MariaDB Server'
  1. MariaDB Server
  2. MDEV-23618

InnoDB lacks IA-32 non-PIC CRC-32C acceleration on GCC 4

Details

    Description

      When MDEV-22669 introduced CRC-32C acceleration to IA-32, it worked around a bug of GCC 4 by disabling the acceleration for IA-32. The bug only affects the generating of position independent code (-fPIC):

      /home/buildbot/buildbot/build/storage/innobase/ut/ut0crc32.cc: In function 'void ut_crc32_init()':
      		 
      /home/buildbot/buildbot/build/storage/innobase/ut/ut0crc32.cc:120:50: error: PIC register clobbered by 'ebx' in 'asm'
      		 
         asm("cpuid" : "=c"(i) : "ax"(1) : "ebx", "edx");

      In MDEV-23585 I found a more elegant solution to this problem: implement a CMake check for that the cpuid instruction.
      We can extend this check so that the source code can simply refer to HAVE_CPUID_INSTRUCTION. In that way, only those platforms that are affected by the compiler bug will avoid using any instruction set extensions.

      Clarification: We always generated the CPUID instruction for AMD64. We only unnecessarily disabled it on IA-32 in some cases. I do not know whether and how the code could be compiled without -fPIC.

      Attachments

        Issue Links

          is caused by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-22669 InnoDB lacks CRC-32C acceleration on IA-32

          • Major - Major loss of function.
          • Closed

          Activity

            Ascending order - Click to sort in descending order
            marko Marko Mäkelä created issue -
            marko Marko Mäkelä made changes -
            Field Original Value New Value
            marko Marko Mäkelä made changes -
            Description When MDEV-22669 introduced CRC-32C acceleration to IA-32, it worked around a bug of GCC 4 by disabling the acceleration for AMD64. The bug affects the generating of position independent code ({{-fPIC}}) for IA-32:
            {noformat}
            /home/buildbot/buildbot/build/storage/innobase/ut/ut0crc32.cc: In function 'void ut_crc32_init()':
            /home/buildbot/buildbot/build/storage/innobase/ut/ut0crc32.cc:120:50: error: PIC register clobbered by 'ebx' in 'asm'
               asm("cpuid" : "=c"(i) : "ax"(1) : "ebx", "edx");
            {noformat}
            In MDEV-23585 I found a [more elegant solution to this problem: implement a CMake check for that the {{cpuid}} instruction|https://github.com/MariaDB/server/commit/fe5dbfe723427a3606c41409626dc853f997e679].
            We can extend this check so that the source code can simply refer to {{HAVE_CPUID_INSTRUCTION}}. In that way, only those platforms that are affected by the compiler bug will avoid using any instruction set extensions.             		When MDEV-22669 introduced CRC-32C acceleration to IA-32, it worked around a bug of GCC 4 by disabling the acceleration for IA-32. The bug only affects the generating of position independent code ({{-fPIC}}):
            {noformat}
            /home/buildbot/buildbot/build/storage/innobase/ut/ut0crc32.cc: In function 'void ut_crc32_init()':
            /home/buildbot/buildbot/build/storage/innobase/ut/ut0crc32.cc:120:50: error: PIC register clobbered by 'ebx' in 'asm'
               asm("cpuid" : "=c"(i) : "ax"(1) : "ebx", "edx");
            {noformat}
            In MDEV-23585 I found a [more elegant solution to this problem: implement a CMake check for that the {{cpuid}} instruction|https://github.com/MariaDB/server/commit/fe5dbfe723427a3606c41409626dc853f997e679].
            We can extend this check so that the source code can simply refer to {{HAVE_CPUID_INSTRUCTION}}. In that way, only those platforms that are affected by the compiler bug will avoid using any instruction set extensions.

            Clarification: We always generated the {{CPUID}} instruction for AMD64. We only unnecessarily disabled it on IA-32 in some cases. I do not know whether and how the code could be compiled without {{-fPIC}}.
            Environment GCC 4.8.2, AMD64 GCC 4, IA-32, non-PIC
            Labels performance portability regression performance portability
            Summary InnoDB lacks CRC-32C acceleration on GCC 4 InnoDB lacks IA-32 non-PIC CRC-32C acceleration on GCC 4
            marko Marko Mäkelä made changes -
            issue.field.resolutiondate 2020-08-28 11:46:58.0 2020-08-28 11:46:58.999
            marko Marko Mäkelä made changes -
            Fix Version/s 10.5.6 [ 24508 ]
            Fix Version/s 10.5 [ 23123 ]
            Resolution Fixed [ 1 ]
            Status Open [ 1 ] Closed [ 6 ]
            ralf.gebhardt Ralf Gebhardt made changes -
            Fix Version/s 10.5.7 [ 25019 ]
            ralf.gebhardt Ralf Gebhardt made changes -
            Fix Version/s 10.5.6 [ 24508 ]
            serg Sergei Golubchik made changes -
            Workflow MariaDB v3 [ 113046 ] MariaDB v4 [ 158319 ]

            People

              marko Marko Mäkelä
              marko Marko Mäkelä
              Votes:
              0 Vote for this issue
              Watchers:
              1 Start watching this issue

              Dates

                Created:
                Updated:
                Resolved:

                Git Integration

                  Error rendering 'com.xiplink.jira.git.jira_git_plugin:git-issue-webpanel'. Please contact your Jira administrators.