Powerpc fix for gdb.base/unwind-on-each-insn.exp

  GDB maintainers:

The test gdb.base/unwind-on-each-insn.exp was recently added.  The
patch generates about 575 failures on PowerPC.  The issue is the code
to determine the number of lines in function foo does not work
correctly on PowerPC.  As a result, the test doesn't stop the frame
checks when it reaches the end of the function.  The test keeps going
past the end of the function which results in the errors and warnings.

This patch adds code to skip lines with the .long specifier in the
disassembly output that follow the last instruction in the function. 
With this fix, the test correctly determines the number of lines in
function foo.

Please let me know if the patch is acceptable for mainline.  Thanks.

                   Carl Love

--------------------------------------------
Powerpc fix for gdb.base/unwind-on-each-insn.exp

The test disassembles function foo and searches for the line
"End of assembler dump" to determing the last address in the function.  The
assumption is the last instruction will be given right before the line
"End of assembler dump".  This assumption fails on PowerPC.

The PowerPC disassembly of the function foo looks like:
 Dump of assembler code for function foo:
#  => 0x00000000100006dc <+0>:     std     r31,-8(r1)
#     0x00000000100006e0 <+4>:     stdu    r1,-48(r1)
#     0x00000000100006e4 <+8>:     mr      r31,r1
#     0x00000000100006e8 <+12>:    nop
#     0x00000000100006ec <+16>:    addi    r1,r31,48
#     0x00000000100006f0 <+20>:    ld      r31,-8(r1)
#     0x00000000100006f4 <+24>:    blr
#     0x00000000100006f8 <+28>:    .long 0x0
#     0x00000000100006fc <+32>:    .long 0x0
#     0x0000000010000700 <+36>:    .long 0x1000180
#     End of assembler dump.

The blr instruction is the last instruction in function foo.  The lines
with .long following the blr instruction need to be ignored.

This patch adds a new condition to the gdb_test_multiple "disassemble foo"
test to ignore the lines with the .long.

The patch has been tested on PowerPC and Intel X86-64.
---
 .../gdb.base/unwind-on-each-insn.exp          | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)
  

Carl Love <cel@us.ibm.com> wrote:

>Powerpc fix for gdb.base/unwind-on-each-insn.exp

This is OK.

Thanks,
Ulrich
  

On 02/11/2022 18:03, Carl Love wrote:
> GDB maintainers:
>
> The test gdb.base/unwind-on-each-insn.exp was recently added.  The
> patch generates about 575 failures on PowerPC.  The issue is the code
> to determine the number of lines in function foo does not work
> correctly on PowerPC.  As a result, the test doesn't stop the frame
> checks when it reaches the end of the function.  The test keeps going
> past the end of the function which results in the errors and warnings.
>
> This patch adds code to skip lines with the .long specifier in the
> disassembly output that follow the last instruction in the function.
> With this fix, the test correctly determines the number of lines in
> function foo.
>
> Please let me know if the patch is acceptable for mainline.  Thanks.
>
>                     Carl Love
>
> --------------------------------------------
> Powerpc fix for gdb.base/unwind-on-each-insn.exp
>
> The test disassembles function foo and searches for the line
> "End of assembler dump" to determing the last address in the function.  The
> assumption is the last instruction will be given right before the line
> "End of assembler dump".  This assumption fails on PowerPC.
>
> The PowerPC disassembly of the function foo looks like:
>   Dump of assembler code for function foo:
> #  => 0x00000000100006dc <+0>:     std     r31,-8(r1)
> #     0x00000000100006e0 <+4>:     stdu    r1,-48(r1)
> #     0x00000000100006e4 <+8>:     mr      r31,r1
> #     0x00000000100006e8 <+12>:    nop
> #     0x00000000100006ec <+16>:    addi    r1,r31,48
> #     0x00000000100006f0 <+20>:    ld      r31,-8(r1)
> #     0x00000000100006f4 <+24>:    blr
> #     0x00000000100006f8 <+28>:    .long 0x0
> #     0x00000000100006fc <+32>:    .long 0x0
> #     0x0000000010000700 <+36>:    .long 0x1000180
> #     End of assembler dump.
>
> The blr instruction is the last instruction in function foo.  The lines
> with .long following the blr instruction need to be ignored.
>
> This patch adds a new condition to the gdb_test_multiple "disassemble foo"
> test to ignore the lines with the .long.
>
> The patch has been tested on PowerPC and Intel X86-64.

Thanks, this looks good.

Reviewed-By: Bruno Larsen <blarsen@redhat.com>

Cheers,
Bruno

> ---
>   .../gdb.base/unwind-on-each-insn.exp          | 22 +++++++++++++++++++
>   1 file changed, 22 insertions(+)
>
> diff --git a/gdb/testsuite/gdb.base/unwind-on-each-insn.exp b/gdb/testsuite/gdb.base/unwind-on-each-insn.exp
> index 3b48805cff8..d8863ad2895 100644
> --- a/gdb/testsuite/gdb.base/unwind-on-each-insn.exp
> +++ b/gdb/testsuite/gdb.base/unwind-on-each-insn.exp
> @@ -75,6 +75,24 @@ gdb_continue_to_breakpoint "enter foo"
>   
>   # Figure out the range of addresses covered by this function.
>   set last_addr_in_foo ""
> +
> +# The disassembly of foo on PowerPC looks like:
> +#     Dump of assembler code for function foo:
> +#  => 0x00000000100006dc <+0>:     std     r31,-8(r1)
> +#     0x00000000100006e0 <+4>:     stdu    r1,-48(r1)
> +#     0x00000000100006e4 <+8>:     mr      r31,r1
> +#     0x00000000100006e8 <+12>:    nop
> +#     0x00000000100006ec <+16>:    addi    r1,r31,48
> +#     0x00000000100006f0 <+20>:    ld      r31,-8(r1)
> +#     0x00000000100006f4 <+24>:    blr
> +#     0x00000000100006f8 <+28>:    .long 0x0
> +#     0x00000000100006fc <+32>:    .long 0x0
> +#     0x0000000010000700 <+36>:    .long 0x1000180
> +#     End of assembler dump.
> +#
> +# The last instruction in function foo is blr.  Need to ignore the .long
> +# entries following the blr instruction.
> +
>   gdb_test_multiple "disassemble foo" "" {
>       -re "^disassemble foo\r\n" {
>   	exp_continue
> @@ -84,6 +102,10 @@ gdb_test_multiple "disassemble foo" "" {
>   	exp_continue
>       }
>   
> +    -re "^...($hex) \[<>+0-9:\s\t\]*\.long\[\s\t\]*\[^\r\n\]*\r\n" {
> +	exp_continue
> +    }
> +
>       -re "^...($hex) \[^\r\n\]+\r\n" {
>   	set last_addr_in_foo $expect_out(1,string)
>   	exp_continue