https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71977
Bug ID: 71977
Summary: powerpc64: Use VSR when operating on float and integer
Product: gcc
Version: 6.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: tuliom at linux dot vnet.ibm.com
Target Milestone: ---
The following code is common on libm:
#include <stdint.h>
typedef union
{
float value;
uint32_t word;
} ieee_float_shape_type;
float
mask_float (float f, uint32_t mask)
{
ieee_float_shape_type u;
u.value = f;
u.word &= mask;
return u.value;
}
GCC 6.1.1 is executing the operation in the GPR:
mask_float:
xscvdpspn 12,1
mfvsrd 9,12
srdi 9,9,32
and 4,4,9
sldi 9,4,32
mtvsrd 1,9
xscvspdpn 1,1
blr
However, operating in the VSR reduces the amount of instructions and improves
GPR pressure, e.g.:
mask_float2:
sldi 4,4,32
mtvsrd 0,4
xvcvdpsp 1, 1
xxland 1, 1, 0
xvcvspdp 1, 1
blr
