Hi All,
This is based upon gcc version 4.5.3 (20110221 pre-release)
Any help appreciated
This shows a bug in the Linaro gcc compiler with the Arm NEON
vset_lane intrinsic
Note in the objdump that the vmov.8 instruction that places the
value in the vector for the non-q version uses 1 where it should use
2 and 3:
18: ee410bb0 vmov.8 d17[1], r0
1c: ee420bb0 vmov.8 d18[1], r0
20: ee400b90 vmov.8 d16[0], r0
3c: ee440bb0 vmov.8 d20[1], r0
For the q version the vmov.8 instructions are correct:
40: ee420bf0 vmov.8 d18[3], r0
54: ee420bd0 vmov.8 d18[2], r0
64: ee400b90 vmov.8 d16[0], r0
70: ee420bb0 vmov.8 d18[1], r0
/* Source code */
#include <arm_neon.h>
static uint8x8_t vec[5]
static uint8x16_t qvec[5];
void set(uint8_t value)
{
vec[1] = vset_lane_u8(value, vec[0], 3);
vec[2] = vset_lane_u8(value, vec[0], 2);
vec[3] = vset_lane_u8(value, vec[0], 1);
vec[4] = vset_lane_u8(value, vec[0], 0);
qvec[1] = vsetq_lane_u8(value, qvec[0], 3);
qvec[2] = vsetq_lane_u8(value, qvec[0], 2);
qvec[3] = vsetq_lane_u8(value, qvec[0], 1);
qvec[4] = vsetq_lane_u8(value, qvec[0], 0);
}
Thx
Lee
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