Re: [PATCH] aarch64: increase alias candidate limit in aarch64-gen

On 21/08/2026 11:45, Muhammad Kamran wrote:
> 
> 
> On 21/08/2026 11:36, Richard Earnshaw (foss) wrote:
>> On 19/08/2026 09:23, Muhammad Kamran wrote:
>>> Increase max_num_aliases from 32 to 64 so that aarch64-gen can
>>> accommodate the additional HINT-space alias added for FEAT_PAuth_LR.
>>>
>>
>> What were the symptoms of the overflow? A build time failure, a run-time assert, or crash, or just garbled output?
>>
> 
> The overflow shows up as a build-time failure while regenerating the
> generated AArch64 opcode files.  The FEAT_PAuth_LR HINT-space alias
> (yet to be posted) increases the number of aliases matching the same
> encoding group, and find_alias_opcode trips:
> 
>   assert (i < max_num_aliases)
> 
> For instance,
> $ aarch64-gen --gen-dis > $(binutils)/opcodes/aarch64-dis-2.c
> aarch64-gen: /work/src/binutils/opcodes/aarch64-gen.c:813: find_alias_opcode: Assertion `i < max_num_aliases' failed.
> Aborted
> 

OK, thanks. Patch pushed.

R.

>>
>>> The generated disassembler alias preference list can otherwise exceed
>>> the old fixed limit.
>>> ---
>>>   opcodes/aarch64-gen.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/opcodes/aarch64-gen.c b/opcodes/aarch64-gen.c
>>> index a387cd4a1e0..abe4147f2c4 100644
>>> --- a/opcodes/aarch64-gen.c
>>> +++ b/opcodes/aarch64-gen.c
>>> @@ -789,8 +789,8 @@ opcode_node *
>>>   find_alias_opcode (const aarch64_opcode *opcode)
>>>   {
>>>     int i;
>>> -  /* Assume maximum of 32 disassemble preference candidates.  */
>>> -  const int max_num_aliases = 32;
>>> +  /* Assume maximum of 64 disassemble preference candidates.  */
>>> +  const int max_num_aliases = 64;
>>>     const aarch64_opcode *ent;
>>>     const aarch64_opcode *preferred[max_num_aliases + 1];
>>>     opcode_node head, **next;
>>
>