https://gcc.gnu.org/bugzilla/show_bug.cgi?id=45274
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot
gnu.org
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
The alias-set issue doesn't occur since quite some time (it's using alias-set 1
for me). Also restrict is working.
GCC 6 optimizes this on x86_64 to
foo:
.LFB0:
.cfi_startproc
movzbl (%rdi), %edx
movzbl (%rsi), %eax
movl %edx, %r8d
movl %edx, %ecx
andl $-4, %eax
andl $1, %r8d
andl $2, %ecx
orl %r8d, %eax
orl %ecx, %eax
movl %edx, %ecx
andl $8, %edx
andl $4, %ecx
andl $-13, %eax
orl %ecx, %eax
orl %edx, %eax
movb %al, (%rsi)
movl (%rdi), %eax
andl $-16, %eax
movl %eax, %edx
movl (%rsi), %eax
andl $15, %eax
orl %edx, %eax
movl %eax, (%rsi)
ret
thus it is doing a good job in piecewise copying of the struct. It doesn't
detect that it can simply use a 32bit load/store. But there are duplicates
in bugzilla for that issue.
Interestingly with some bitfield lowering work plus some match.pd hackery
I get that:
foo:
.LFB0:
.cfi_startproc
movl (%rdi), %eax
movl %eax, (%rsi)
ret
whee.
