Perl_more_bodies - figure out sizing from sv_type #23360
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richardleach
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bulk88
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Jun 10, 2025
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I like this patch. It is long overdue. |
`Perl_more_bodies` allocates and sets up a new arena for the likes of
SV body, HE, and HVAUX structs. It has traditionally been called with
three arguments:
* the `svtype`
* the size of the structs that the arena will contain
* the size of the arena to allocate
This commit changes the function definition such that it only takes
a single argument: the `svtype`. From that, and with a bit of
additional logic to account of HE and HVAUX using the indexes
notionally for SVt_NULL and SVt_IV, `Perl_more_bodies` can figure
out the sizing for itself.
The rationale for this is that:
* When an application is starting up, the need to call `Perl_more_bodies`
is the unlikely case in each new SV allocation or upgrade.
* When the application has reached a steady state, the function
may not be called regardless of how many SVs are created or upgraded.
With `Perl_newSV_type` being an inline function, there are a lot of
potential callers to this function though, each of which will have
two `mov` instructions for pushing the two size parameters onto the
stack should the need to call `Perl_more_bodies` arise. Removing two
instructions from each potential call site should help reduce binary
size a little and avoid taking up unnecessary space in the CPU's
instruction buffer.
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Perl_more_bodiesallocates and sets up a new arena for the likes of SV body, HE, and HVAUX structs. It has traditionally been called with three arguments:svtypeThis commit changes the function definition such that it only takes a single argument: the
svtype. From that, and with a bit of additional logic to account of HE and HVAUX using the indexes notionally for SVt_NULL and SVt_IV,Perl_more_bodiescan figure out the sizing for itself.The rationale for this is that:
Perl_more_bodiesis the unlikely case in each new SV allocation or upgrade.With
Perl_newSV_typebeing an inline function, there are a lot of potential callers to this function though, each of which will have twomovinstructions for pushing the two size parameters onto the stack should the need to callPerl_more_bodiesarise. Removing two instructions from each potential call site should help reduce binary size a little and avoid taking up unnecessary space in the CPU's instruction buffer.