Re: [PATCH][gdb/testsuite] Fix gdb.dwarf2/dw2-dir-file-name.exp

[Luis Machado via Gdb-patches <gdb-patches@sourceware.org>]

On 8/11/22 12:58, Tom de Vries wrote:
> Hi,
> 
> When running test-case gdb.dwarf2/dw2-dir-file-name.exp on x86_64-linux, we
> have:
> ...
> (gdb) break compdir_missing__ldir_missing__file_basename^M
> Breakpoint 2 at 0x4004c4: file tmp-dw2-dir-file-name.c, line 999.^M
> (gdb) continue^M
> Continuing.^M
> ^M
> Breakpoint 2, 0x00000000004004c4 in \
>    compdir_missing__ldir_missing__file_basename () \
>    at tmp-dw2-dir-file-name.c:999^M
> (gdb) PASS: gdb.dwarf2/dw2-dir-file-name.exp: \
>    compdir_missing__ldir_missing__file_basename: continue to breakpoint: \
>    compdir_missing__ldir_missing__file_basename
> ...
> 
> When trying to set a breakpoint on
> compdir_missing__ldir_missing__file_basename, the architecture-specific
> prologue skipper starts at 0x4004c0 and skips past two insns, to 0x4004c4:
> ...
> 00000000004004c0 <compdir_missing__ldir_missing__file_basename>:
>    4004c0: 55                      push   %rbp
>    4004c1: 48 89 e5                mov    %rsp,%rbp
>    4004c4: 8b 05 72 1b 20 00       mov    0x201b72(%rip),%eax        # 60203c <v>
>    4004ca: 83 c0 01                add    $0x1,%eax
>    4004cd: 89 05 69 1b 20 00       mov    %eax,0x201b69(%rip)        # 60203c <v>
>    4004d3: 90                      nop
>    4004d4: 5d                      pop    %rbp
>    4004d5: c3                      ret
> ...
> 
> And because the line table info is rudamentary:
> ...
> CU: tmp-dw2-dir-file-name.c:
> File name                    Line number    Starting address    View    Stmt
> tmp-dw2-dir-file-name.c              999            0x4004c0               x
> tmp-dw2-dir-file-name.c             1000            0x4004d6               x
> tmp-dw2-dir-file-name.c                -            0x4004d6
> ...
> the address does not fall at an actual line, so the breakpoint is shown with
> address, both when setting it and hitting it.
> 
> when running the test-case with aarch64-linux, we have similarly:
> ...
> (gdb) break compdir_missing__ldir_missing__file_basename^M
> Breakpoint 2 at 0x400618: file tmp-dw2-dir-file-name.c, line 999.^M
> ...
> due to the architecture-specific prologue skipper starting at 0x400610 and
> skipping past two insns, to 0x400618:
> ...
> 0000000000400610 <compdir_missing__ldir_missing__file_basename>:
>    400610:       90000100        adrp    x0, 420000 <__libc_start_main@GLIBC_2.17>
>    400614:       9100b000        add     x0, x0, #0x2c
>    400618:       b9400000        ldr     w0, [x0]
>    40061c:       11000401        add     w1, w0, #0x1
>    400620:       90000100        adrp    x0, 420000 <__libc_start_main@GLIBC_2.17>
>    400624:       9100b000        add     x0, x0, #0x2c
>    400628:       b9000001        str     w1, [x0]
>    40062c:       d503201f        nop
>    400630:       d65f03c0        ret
> ...
> 
> But interestingly, the aarch64 architecture-specific prologue skipper is
> wrong.  There is no prologue, and the breakpoint should be set at 0x400610.
> 
> By using "break *compdir_missing__ldir_missing__file_basename"
> we can get the breakpoint set at 0x400610:
> ...
> (gdb) break *compdir_missing__ldir_missing__file_basename^M
> Breakpoint 2 at 0x400610: file tmp-dw2-dir-file-name.c, line 999.^M
> ...
> and make the test-case independent of prologue analysis.
> 
> This requires us to update the expected patterns.
> 
> The fix ensures that once the aarch64 architecture-specific prologue skipper
> will be fixed, this test-case won't start failing.
> 
> Tested on x86_64-linux.
> 
> Any comments?
> 
> Thanks,
> - Tom
> 
> [gdb/testsuite] Fix gdb.dwarf2/dw2-dir-file-name.exp
> 
> ---
>   gdb/testsuite/gdb.dwarf2/dw2-dir-file-name.exp | 8 ++++----
>   gdb/testsuite/lib/gdb.exp                      | 7 ++++++-
>   2 files changed, 10 insertions(+), 5 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.dwarf2/dw2-dir-file-name.exp b/gdb/testsuite/gdb.dwarf2/dw2-dir-file-name.exp
> index 4d3f767f597..4c4c1ff07af 100644
> --- a/gdb/testsuite/gdb.dwarf2/dw2-dir-file-name.exp
> +++ b/gdb/testsuite/gdb.dwarf2/dw2-dir-file-name.exp
> @@ -396,20 +396,20 @@ proc test { func compdir filename } {
>   	    error "not absolute"
>   	}
>   
> -	gdb_breakpoint $func
> +	gdb_breakpoint *$func
>   	gdb_continue_to_breakpoint $func "$func \\(\\) at .*"
>   
>   	gdb_test_no_output "set filename-display absolute"
>   	verbose -log "expect: ${absolute}"
> -	gdb_test "frame" " in $func \\(\\) at [string_to_regexp ${absolute}]:999" "absolute"
> +	gdb_test "frame" "#0  $func \\(\\) at [string_to_regexp ${absolute}]:999" "absolute"
>   
>   	gdb_test_no_output "set filename-display basename"
>   	verbose -log "expect: [file tail $filename]"
> -	gdb_test "frame" " in $func \\(\\) at [string_to_regexp [file tail $filename]]:999" "basename"
> +	gdb_test "frame" "#0  $func \\(\\) at [string_to_regexp [file tail $filename]]:999" "basename"
>   
>   	gdb_test_no_output "set filename-display relative"
>   	verbose -log "expect: $filename"
> -	gdb_test "frame" " in $func \\(\\) at [string_to_regexp $filename]:999" "relative"
> +	gdb_test "frame" "#0  $func \\(\\) at [string_to_regexp $filename]:999" "relative"
>       }
>   }
>   
> diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
> index a8f25b5f0dd..70fc019eeb9 100644
> --- a/gdb/testsuite/lib/gdb.exp
> +++ b/gdb/testsuite/lib/gdb.exp
> @@ -787,9 +787,14 @@ proc gdb_continue_to_breakpoint {name {location_pattern .*}} {
>       global gdb_prompt
>       set full_name "continue to breakpoint: $name"
>   
> +    set re_at_in " (at|in) "
> +    if { [regexp $re_at_in $location_pattern] } {
> +	set re_at_in " "
> +    }
> +
>       set kfail_pattern "Process record does not support instruction 0xfae64 at.*"
>       gdb_test_multiple "continue" $full_name {
> -	-re "(?:Breakpoint|Temporary breakpoint) .* (at|in) $location_pattern\r\n$gdb_prompt $" {
> +	-re "(?:Breakpoint|Temporary breakpoint) .*$re_at_in$location_pattern\r\n$gdb_prompt $" {
>   	    pass $full_name
>   	}
>   	-re "\[\r\n\]*(?:$kfail_pattern)\[\r\n\]+$gdb_prompt $" {

LGTM

I agree that having a test that doesn't rely on prologue analysis is a good move. I'll track the aarch64 prologue analysis
hiccup separate.