Re: [PATCH v2] gdb/record: avoid rax usage in i386-avx-record.exp

[Guinevere Larsen <guinevere@redhat.com>]

On 8/13/26 11:51 AM, Simon Marchi wrote:
> On 8/13/26 9:10 AM, Guinevere Larsen wrote:
>> My recent commit, 1c04308f0958cbac83bad22703758139ea6969b6:
>>
>>      Author: Guinevere Larsen <guinevere@redhat.com>
>>      Date:   Tue Jun 16 16:03:43 2026 -0300
>>      gdb/record: add support for BMI2 instructions
>>
>> Introduced a few tests that rely on the rax register being set before
>> entering the function. This isn't reliable, as programs compiled with
>> gcc-14 and earlier will have the register. To avoid compiler versions
> This sentence ends abruptly.
>
> It's not clear to me what the problem is, could you explain it in simple
> words :)?
>
> Simon
>
oops, sorry, need to do more proofreading I guess. The sentence should 
be "will have the registered clobbered, saving 0 on it"

I haven't looked at the disassembly to know why, but something about how 
GCC 14 encodes the function calls makes EAX be 0 every time, and the 
test expects eax to be something else. Moving to a different register 
sidesteps this

-- 
Cheers,
Guinevere Larsen
it/its
she/her (deprecated)