Hello Richard,
the case INDEX_op_dup_vec in optimize.c:tcg_optimize is doing a break
when the input arg is not constant instead of jumping to do_default.
The issue can be reproduced by compiling the following SVE code:
.global main
.section .text
main:
mov z2.d, #0
decp z1.d, p0
ret
When run with SVE vector length set to 128-bit, we get this before TCG opt:
---- 0000000000400524 0000000000000000 0000000000000000
dupi_vec v128,e64,tmp2,$0x0
st_vec v128,e8,tmp2,env,$0xb00
---- 0000000000400528 0000000000000000 0000000000000000
ld_i64 tmp3,env,$0x2900
movi_i64 tmp4,$0x101
and_i64 tmp3,tmp3,tmp4
ctpop_i64 tmp3,tmp3
dup_vec v128,e64,tmp2,tmp3
ld_vec v128,e8,tmp5,env,$0xa00
sub_vec v128,e64,tmp6,tmp5,tmp2
st_vec v128,e8,tmp6,env,$0xa00
After the optimization pass:
---- 0000000000400524 0000000000000000 0000000000000000
dupi_vec v128,e64,tmp2,$0x0
st_vec v128,e8,tmp2,env,$0xb00 dead: 0
---- 0000000000400528 0000000000000000 0000000000000000
ld_vec v128,e8,tmp5,env,$0xa00
mov_vec v128,e64,tmp6,tmp5 dead: 1
st_vec v128,e8,tmp6,env,$0xa00 dead: 0
The dupi_vec TCG op correctly flags tmp2 as a 0 constant. This is then
wrongly propagated down to the sub_vec TCG op despite tmp2 being
overwritten by a dup_vec TCG op.
Thanks,
Laurent
