http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59578
Bug ID: 59578
Summary: Overuse of v prefix for SSE instructions
Product: gcc
Version: 4.8.2
Status: UNCONFIRMED
Severity: minor
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: msharov at users dot sourceforge.net
typedef float v16sf __attribute__((vector_size(16)));
v16sf f (v16sf x)
{ return (__builtin_ia32_shufps (x, x, 0xff)); }
Compiled on a Haswell 4770 with -march=native -O emits:
vshufps $255, %xmm0, %xmm0, %xmm0
Even though all registers are the same and
shufps $255, %xmm0, %xmm0
would have worked just as well without the extra byte for the v prefix.
This happens with other __builtin instructions as well. For example:
typedef long long v16so __attribute__((vector_size(16)));
v16so k (v16so x)
{ return (__builtin_ia32_aeskeygenassist128 (x, 1)); }
Emits vaeskeygenassist even though no memory accesses are present.
