http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47759
Summary: _mm_empty() intrinsic fails to serve as a boundary
between MMX and x87 code due to optimizations
Product: gcc
Version: 4.5.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: siarhei.siamas...@gmail.com
Host: i686-pc-linux-gnu
Created attachment 23355
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23355
mm_empty_testcase.c
The attached testcase fails when compiled with -O2 or -O3 optimizations, but
works with -O1.
I'm actually not precisely sure how this code is expected to behave because
intrinsics are x86 architecture specific and C standard can't be used as a
reference. But my guess is that if the optimizer would not be allowed to
arbitrarily move code across _mm_empty() boundary, then the problem would
disappear.
