http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55701
Bug #: 55701
Summary: Inline some instances of memset for ARM
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: target
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: josh.m.con...@gmail.com
memset() is almost never inlined on ARM, even at -O3. If the target is known
to be 4-byte aligned or greater, it will be inlined for 1, 2, or 4 byte
lengths. If the target alignment is unknown, it will be inlined only for a
single byte.
I don't see this problem with similar builtins (memcpy, memmove, and memclear
(memset with a target value of zero)) - they all inline small cases.
It probably makes sense for memset to be inlined up to at least 16 bytes or so
in all cases.
When aligned, memcpy and memmove use a ldmia/stmia (load multiple/store
multiple) sequence to create fairly compact inline code. We could consider
doing the same sort of optimization with memset, using stmia only.
