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GCC 4.2.2 can't handle large case statements with -fPIC

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Information:
Type :: BUG
Status :: CLOSED
Assigned to :: Jeremy, Bennett

Description:

OpenRISC GCC 4.2.2 has a problem with large case statements when targeting position independent code. Here is a code fragment that demos the problem

int
bug_demo(char  arg)
{
  /* There is a bug in GCC for OR1K, which can't handle two many cases
     with position independent code (PIC). Get rid of 1 case and it
     all works OK. */
  switch (arg)
    {
    case 'c':
      return 0;

    case 'i':
      return 1;

    case 'd':
      return 2;

    case 'o':
      return 3;

    case 'x':
      return 4;

    }

  return -1;

}	/* bug_demo () */

Compile this with:

or32-elf-gcc -fPIC -c bug-demo.c

The resulting output is:

or32-elf-gcc -fPIC -c bug-demo.c
/tmp/ccqWzGPc.s: Assembler messages:
/tmp/ccqWzGPc.s:45: Error: can't resolve `.text' {.text section} - `.L8' {.rodata section}
/tmp/ccqWzGPc.s:46: Error: can't resolve `.text' {.text section} - `.L8' {.rodata section}
...
/tmp/ccqWzGPc.s:65: Error: can't resolve `.text' {.text section} - `.L8' {.rodata section}
/tmp/ccqWzGPc.s:66: Error: can't resolve `.text' {.text section} - `.L8' {.rodata section}

Analysis of the assembler code shows the compiler attempting to construct a jump-table by subtracting labels in the read only data section from labels in the text section.

Jeremy

p> --
Tel: +44 (1590) 610184
Cell: +44 (7970) 676050
SkypeID: jeremybennett
Email: jeremy.bennett@embecosm.com
Web: www.embecosm.com

Comments:

Bennett, Jeremy	Jul 1, 2011
Transferred to OpenRISC bugzilla (Bug 13). Marking closed in this bugtracker.

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