Gregory Stark wrote:
"Zdenek Kotala" <Zdenek.Kotala@xxxxxxx> writes:
By my opinion -fipa-struct-reorg GCC option could break structure. And maybe
there are more compiler magic switches and optimization on different platforms
which can modify structure alignment or member order. It probably does not
happen often but footprint should protect people to shot himself.
My version of GCC doesn't have that option, what does it do?
From gcc man page:
-fipa-struct-reorg
Perform structure reorganization optimization, that change C-like
structures layout in order to better utilize spatial locality.
This transformation is affective for programs containing arrays of
structures. Available in two compilation modes: profile-based
(enabled with -fprofile-generate) or static (which uses built-in
heuristics). Require -fipa-type-escape to provide the safety of
this transformation. It works only in whole program mode, so it
requires -fwhole-program and -combine to be enabled. Structures
considered cold by this transformation are not affected (see
--param struct-reorg-cold-struct-ratio=value).
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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