Re: [RFA] New GDB target iq2000

[Corinna Vinschen <vinschen@redhat.com>]

On Mar  4 10:06, Daniel Jacobowitz wrote:
> On Fri, Mar 04, 2005 at 04:01:29PM +0100, Corinna Vinschen wrote:
> > All three cases don't look like simple coincidence.  In all three cases
> > we suffer from either optimized code or unavailable debug information.
> > The target specific "knowledge", which is represented by the call to
> > iq2000_scan_prologue helps to master this situation.
> 
> Would you mind posting disassembly, line table (readelf -wl), and GDB
> transcript for these failures?

Sure.  First the both break.exp fails, which are interlocked:

FAIL: gdb.base/break.exp: breakpoint small function, optimized file
FAIL: gdb.base/break.exp: run until breakpoint set at small function, optimized file

- Disassembly of function marker4:

  80000368 <marker4>:
  80000368:       27 bd ff f0     addiu r29,r29,0xfff0

  8000036c <$LCFI9>:
  8000036c:       af bb 00 08     sw r27,0x8(r29)

  80000370 <$LCFI10>:
  80000370:       00 1d d8 25     or r27,r0,r29

  80000374 <$LCFI11>:
  80000374:       af 64 00 00     sw r4,0x0(r27)

  80000378 <$LM8>:
  80000378:       00 1b e8 25     or r29,r0,r27
  8000037c:       8f bb 00 08     lw r27,0x8(r29)
  80000380:       00 00 00 00     nop
  80000384:       27 bd 00 10     addiu r29,r29,0x10
  80000388:       03 e0 00 08     jr r31
  8000038c:       00 00 00 00     nop

- Line table for file break1.c:

  Line Number Statements:
    Extended opcode 2: set Address to 0x800002e8
    Special opcode 49: advance Address by 0 to 0x800002e8 and Line by 39 to 40
    Extended opcode 2: set Address to 0x800002f4
    Copy
    Extended opcode 2: set Address to 0x80000310
    Special opcode 11: advance Address by 0 to 0x80000310 and Line by 1 to 41
    Extended opcode 2: set Address to 0x80000320
    Copy
    Extended opcode 2: set Address to 0x8000033c
    Special opcode 11: advance Address by 0 to 0x8000033c and Line by 1 to 42
    Extended opcode 2: set Address to 0x80000350
    Copy
    Extended opcode 2: set Address to 0x80000368
    Special opcode 11: advance Address by 0 to 0x80000368 and Line by 1 to 43
    Extended opcode 2: set Address to 0x80000378
    Copy
    Extended opcode 2: set Address to 0x80000390
    Extended opcode 1: End of Sequence

- GDB testsuite result with iq2000_skip_prologue:

  break marker4^M 
  Breakpoint 2 at 0x800001f0: file testsuite/gdb.base/break1.c, line 43.^M
  (gdb) PASS: gdb.base/break.exp: breakpoint small function, optimized file
  run^M 
  Starting program: testsuite/gdb.base/breako2 ^M
  ^M
  Breakpoint 1, main (argc=0, argv=0x0, envp=0x0) at testsuite/gdb.base/break.c:85^M
  85      {^M
  (gdb) PASS: gdb.base/break.exp: run until function breakpoint, optimized file (code motion) 
  continue^M
  Continuing.^M
  720^M
  ^M
  Breakpoint 2, marker4 (d=177601976) at testsuite/gdb.base/break1.c:43^M
  43      void marker4 (d) long d; {}             /* set breakpoint 13 here */^M
  PASS: gdb.base/break.exp: run until breakpoint set at small function, optimized file

- GDB testsuite result with skip_prologue_using_sal:

  break marker4^M
  Breakpoint 2 at 0x800001f8^M
  (gdb) FAIL: gdb.base/break.exp: breakpoint small function, optimized file
  run^M
  Starting program: testsuite/gdb.base/breako2 ^M
  ^M
  Breakpoint 1, main (argc=0, argv=0x0, envp=0x0) at testsuite/gdb.base/break.c:85^M
  85      {^M 
  (gdb) PASS: gdb.base/break.exp: run until function breakpoint, optimized file (code motion)
  continue^M
  Continuing.^M
  720^M
  ^M
  Breakpoint 2, 0x800001f8 in write_int ()^M
  (gdb) FAIL: gdb.base/break.exp: run until breakpoint set at small function, optimized file


Now the nodebug.exp case:

FAIL: gdb.base/nodebug.exp: running to inner in runto

- Disassembly of function inner:

  80000048 <inner>:
  80000048:       27 bd ff f0     addiu r29,r29,0xfff0
  8000004c:       af bb 00 08     sw r27,0x8(r29)
  80000050:       00 1d d8 25     or r27,r0,r29
  80000054:       af 64 00 00     sw r4,0x0(r27)
  80000058:       3c 02 00 00     lui r2,0x0
  8000005c:       8f 63 00 00     lw r3,0x0(r27)
  80000060:       8c 42 10 00     lw r2,0x1000(r2)
  80000064:       00 00 00 00     nop
  80000068:       00 62 10 21     addu r2,r3,r2
  8000006c:       3c 03 00 00     lui r3,0x0
  80000070:       8c 63 10 04     lw r3,0x1004(r3)
  80000074:       00 00 00 00     nop
  80000078:       00 43 10 21     addu r2,r2,r3
  8000007c:       3c 03 00 00     lui r3,0x0
  80000080:       8c 63 19 b4     lw r3,0x19b4(r3)
  80000084:       00 00 00 00     nop
  80000088:       00 43 10 21     addu r2,r2,r3
  8000008c:       3c 03 00 00     lui r3,0x0
  80000090:       8c 63 19 74     lw r3,0x1974(r3)
  80000094:       00 00 00 00     nop
  80000098:       00 43 10 21     addu r2,r2,r3
  8000009c:       00 1b e8 25     or r29,r0,r27
  800000a0:       8f bb 00 08     lw r27,0x8(r29)
  800000a4:       00 00 00 00     nop
  800000a8:       27 bd 00 10     addiu r29,r29,0x10
  800000ac:       03 e0 00 08     jr r31

- Line table for file nodebug.c:

  There is none since nodebug.c is compiled without -g

- GDB testsuite result with iq2000_skip_prologue:

  (gdb) file testsuite/gdb.base/nodebug^M
  Reading symbols from testsuite/gdb.base/nodebug...done.^M
  (gdb) target sim ^M
  Connected to the simulator.^M
  (gdb) load^M
  Loading section .text, size 0x3858 lma 0x80000000^M
  Loading section .data, size 0x7e0 lma 0x1000^M
  Loading section .eh_frame, size 0x118 lma 0x17e0^M
  Loading section .rodata, size 0x7c lma 0x18f8^M
  Start address 0x80000000^M
  Transfer rate: 134752 bits in <1 sec.^M
  (gdb) delete breakpoints^M
  (gdb) info breakpoints^M
  No breakpoints or watchpoints.^M
  (gdb) break inner^M
  Breakpoint 1 at 0x80000058^M
  (gdb) target sim ^M
  Connected to the simulator.^M
  (gdb) load^M
  Loading section .text, size 0x3858 lma 0x80000000^M
  Loading section .data, size 0x7e0 lma 0x1000^M
  Loading section .eh_frame, size 0x118 lma 0x17e0^M
  Loading section .rodata, size 0x7c lma 0x18f8^M
  Start address 0x80000000^M
  Transfer rate: 134752 bits in <1 sec.^M
  (gdb) run ^M
  Starting program: testsuite/gdb.base/nodebug ^M
  ^M
  Breakpoint 1, 0x80000058 in inner ()^M

- GDB testsuite result with skip_prologue_using_sal:

  (gdb) file testsuite/gdb.base/nodebug^M
  Reading symbols from testsuite/gdb.base/nodebug...done.^M
  (gdb) target sim ^M 
  Connected to the simulator.^M
  (gdb) load^M
  Loading section .text, size 0x3858 lma 0x80000000^M
  Loading section .data, size 0x7e0 lma 0x1000^M
  Loading section .eh_frame, size 0x118 lma 0x17e0^M 
  Loading section .rodata, size 0x7c lma 0x18f8^M
  Start address 0x80000000^M
  Transfer rate: 134752 bits in <1 sec.^M
  (gdb) delete breakpoints^M
  (gdb) info breakpoints^M
  No breakpoints or watchpoints.^M
  (gdb) break inner^M
  Breakpoint 1 at 0x0^M
  (gdb) target sim ^M
  Connected to the simulator.^M
  (gdb) load^M
  Loading section .text, size 0x3858 lma 0x80000000^M
  Loading section .data, size 0x7e0 lma 0x1000^M
  Loading section .eh_frame, size 0x118 lma 0x17e0^M
  Loading section .rodata, size 0x7c lma 0x18f8^M 
  Start address 0x80000000^M
  Transfer rate: 134752 bits in <1 sec.^M
  (gdb) run ^M
  Starting program: testsuite/gdb.base/nodebug ^M
  ^M
  *** EXIT code 28^M
  ^M
  Program exited with code 034.^M
  (gdb) FAIL: gdb.base/nodebug.exp: running to inner in runto

Note especially the `break inner' which sets a breakpoint to address 0.


Corinna

-- 
Corinna Vinschen
Cygwin Project Co-Leader
Red Hat, Inc.