Hi Richi,
>> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
>> index c584664e168..58e48f7dc55 100644
>> --- a/gcc/doc/invoke.texi
>> +++ b/gcc/doc/invoke.texi
>> @@ -18363,11 +18363,11 @@ If @code{N=0}, no pad location is recorded.
>> The NOP instructions are inserted at---and maybe before, depending on
>> @var{M}---the function entry address, even before the prologue. On
>> PowerPC with the ELFv2 ABI, for a function with dual entry points,
>> -the local entry point is this function entry address.
>> +@var{M} NOP instructions are inserted before the global entry point and
>> +@var{N} - @var{M} NOP instructions are inserted after the local entry
>> +point, which means the NOP instructions may not be consecutive.
>
> Isn't it @var{M-1} NOP instructions before the global entry? I suppose
No, the existing documentation is a bit confusing, sigh ...
> the existing
>
> "... with the function entry point before the @var{M}th NOP.
> If @var{M} is omitted, it defaults to @code{0} so the
> function entry points to the address just at the first NOP."
>
> wording is self-contradicting in a way since before the 0th NOP (default)
> to me is the same as before the 1st NOP (M == 1). So maybe that should
> be _after_ the @var{M}th NOP instead which would be consistent with your
> ELFv2 docs? Maybe the sentence should be re-worded similar to your
> ELVv2 one, specifying the number of NOPs before and after the entry point.
>
... the current "with the function entry point before the Mth NOP."
has the 0th NOP assumption, so the default (0th) NOP and 1st NOP (M == 1)
are actually different, such as:
-fpatchable-function-entry=3,0
foo:
nop
nop
nop
-fpatchable-function-entry=3,1
nop
foo:
nop
nop
Alan also had the similar concern on this wording before:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99888#c8
" Alan Modra 2022-08-12 03:00:29 UTC
"
"(In reply to Segher Boessenkool from comment #7)
"> '-fpatchable-function-entry=N[,M]'
"> Generate N NOPs right at the beginning of each function, with the
"> function entry point before the Mth NOP.
"
" Bad doco. Should be "after the Mth NOP" I think.
" Or better written to avoid the concept of a 0th nop.
" Default for M is zero, placing all nops after the function entry and
" before normal function prologue code.
BR,
Kewen
>> -The maximum value of @var{N} and @var{M} is 65535. On PowerPC with the
>> -ELFv2 ABI, for a function with dual entry points, the supported values
>> -for @var{M} are 0, 2, 6 and 14.
>> +The maximum value of @var{N} and @var{M} is 65535.
>> @end table
>>
