Re: [PATCH] [gdb/testsuite] Fix gdb.tui/tailcall-msym.exp on ppc64-linux

[Tom de Vries <tdevries@suse.de>]

On 8/1/26 12:15 PM, Tom de Vries wrote:
> On ppc64-linux, with test-case gdb.tui/tailcall-msym.exp I ran into:
> ...
> FAIL: $exp: status bar says main
> ...
> 
> The test-case:
> - compiles the source to executable tailcall-msym
> - gets some information about addresses
> - recompiles the source to assembly
> - adds some extra text to the assembly
> - compiles the updated assembly into tailcall-msym-updated
> 
> The test-case source contains three functions: main, caller and callee.
> 
> The idea is that the updated executable has the same instructions, but an
> additional function dumy_func at the location of the instructions of caller
> after the call to callee.
> 
> On x86_64-linux, that looks like this:
> ...
> 000000000040111d <caller>:
>    40111d:	55                   	push   %rbp
>    40111e:	48 89 e5             	mov    %rsp,%rbp
>    401121:	e8 f0 ff ff ff       	call   401116 <callee>
> 
> 0000000000401126 <dummy_func>:
>    401126:	8b 05 e8 2e 00 00    	mov    0x2ee8(%rip),%eax
>    40112c:	83 c0 01             	add    $0x1,%eax
>    40112f:	89 05 df 2e 00 00    	mov    %eax,0x2edf(%rip)
>    401135:	8b 05 d9 2e 00 00    	mov    0x2ed9(%rip),%eax
>    40113b:	83 c0 01             	add    $0x1,%eax
>    40113e:	89 05 d0 2e 00 00    	mov    %eax,0x2ed0(%rip)
>    401144:	90                   	nop
>    401145:	5d                   	pop    %rbp
>    401146:	c3                   	ret
> ...
> 
> On ppc64-linux using the v1 ABI that doesn't work out (because of the complex
> way functions are laid out in assembly), and instead caller stays the same,
> but main is renamed to dummy_func:
> ...
> (gdb) p dummy_func
> $3 = {<text variable, no debug info>} 0x9b0 <dummy_func>
> (gdb) p main
> $4 = {<text variable, no debug info>} 0x9b0 <dummy_func>
> (gdb)
> ...
> 
> There's a note in the test-case:
> ...
>   # Emit a new size for function 'caller', the assembler seems happy
>   # enough to just use this new length instead of the original length
>   # the compiler emitted.
>   #
>   # If this is ever a problem then we'll need to parse through the
>   # assembler file and remove the original .size directive.
> ...
> and I tried that out manually, but it didn't help either.
> 
> Fix this by bailing out if not all four functions exist:
> ...
> UNSUPPORTED: $exp: couldn't find function main
> ...
> 
> Likewise in gdb.base/tailcall-msym.exp.
> 

I've pushed this.

Thanks,
- Tom

> Tested on ppc64-linux and x86_64-linux.
> ---
>   gdb/testsuite/gdb.base/tailcall-msym.exp | 19 +++++++++++++++++
>   gdb/testsuite/gdb.tui/tailcall-msym.exp  | 27 +++++++++++++++++++++---
>   2 files changed, 43 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.base/tailcall-msym.exp b/gdb/testsuite/gdb.base/tailcall-msym.exp
> index d6cd06f88cd..9ffaa7f17c1 100644
> --- a/gdb/testsuite/gdb.base/tailcall-msym.exp
> +++ b/gdb/testsuite/gdb.base/tailcall-msym.exp
> @@ -132,6 +132,25 @@ if { [prepare_for_testing "prepare" ${testfile}-updated $asm_file {nodebug}] } {
>       return
>   }
>   
> +foreach func {caller callee main dummy_func} {
> +    set re_found \
> +	"^$valnum_re = {<text variable, no debug info>} $hex <$func>"
> +
> +    set found 0
> +    gdb_test_multiple "p $func" "" {
> +       -re -wrap $re_found {
> +	   set found 1
> +       }
> +       -re -wrap "" {
> +       }
> +    }
> +
> +    if {!$found} {
> +       unsupported "couldn't find function $func"
> +       return
> +    }
> +}
> +
>   if {![runto callee]} {
>       return
>   }
> diff --git a/gdb/testsuite/gdb.tui/tailcall-msym.exp b/gdb/testsuite/gdb.tui/tailcall-msym.exp
> index 81b52355c01..1e13414f760 100644
> --- a/gdb/testsuite/gdb.tui/tailcall-msym.exp
> +++ b/gdb/testsuite/gdb.tui/tailcall-msym.exp
> @@ -136,15 +136,36 @@ if { [build_executable "build" $real_testfile $asm_file {nodebug}] } {
>   
>   Term::clean_restart 24 80 $real_testfile
>   
> -if {![runto callee]} {
> +if {![Term::prepare_for_tui]} {
> +    unsupported "TUI not supported"
>       return
>   }
>   
> -if {![Term::enter_tui]} {
> -    unsupported "TUI not supported"
> +foreach func {caller callee main dummy_func} {
> +    set re_found \
> +	"^$valnum_re = {<text variable, no debug info>} $hex <$func>"
> +
> +    set found 0
> +    gdb_test_multiple "p $func" "" {
> +       -re -wrap $re_found {
> +	   set found 1
> +       }
> +       -re -wrap "" {
> +       }
> +    }
> +
> +    if {!$found} {
> +       unsupported "couldn't find function $func"
> +       return
> +    }
> +}
> +
> +if {![runto callee]} {
>       return
>   }
>   
> +Term::command_no_prompt_prefix "tui enable"
> +
>   # Check the function name on display in the status bar.  The interesting
>   # case here is 'caller', which is a tailcall function in an objfile with
>   # no debug information.
> 
> base-commit: 5b805c95e9399e35f7bc895ec5b67aabdbc6ce41