| Message ID | 20191021085715.3797-5-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | s390x/tcg: Vector instruction fixes | expand |
On 10/21/19 1:57 AM, David Hildenbrand wrote: > Looks like my idea of what a "borrow" is was wrong. The PoP says: > > "If the resulting subtraction results in a carry out of bit zero, a value > of one is placed in the corresponding element of the first operand; > otherwise, a value of zero is placed in the corresponding element" > > As clarified by Richard, all we have to do is invert the result. > > Fixes: 1ee2d7ba72f6 ("s390x/tcg: Implement VECTOR SUBTRACT COMPUTE BORROW INDICATION") > Signed-off-by: David Hildenbrand <david@redhat.com> > --- > target/s390x/translate_vx.inc.c | 7 ++++--- > target/s390x/vec_int_helper.c | 2 +- > 2 files changed, 5 insertions(+), 4 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/target/s390x/translate_vx.inc.c b/target/s390x/translate_vx.inc.c index 5ce7bfb0af..6032021d82 100644 --- a/target/s390x/translate_vx.inc.c +++ b/target/s390x/translate_vx.inc.c @@ -2132,12 +2132,12 @@ static DisasJumpType op_vs(DisasContext *s, DisasOps *o) static void gen_scbi_i32(TCGv_i32 d, TCGv_i32 a, TCGv_i32 b) { - tcg_gen_setcond_i32(TCG_COND_LTU, d, a, b); + tcg_gen_setcond_i32(TCG_COND_GEU, d, a, b); } static void gen_scbi_i64(TCGv_i64 d, TCGv_i64 a, TCGv_i64 b) { - tcg_gen_setcond_i64(TCG_COND_LTU, d, a, b); + tcg_gen_setcond_i64(TCG_COND_GEU, d, a, b); } static void gen_scbi2_i64(TCGv_i64 dl, TCGv_i64 dh, TCGv_i64 al, @@ -2151,7 +2151,8 @@ static void gen_scbi2_i64(TCGv_i64 dl, TCGv_i64 dh, TCGv_i64 al, tcg_gen_andi_i64(th, th, 1); tcg_gen_sub2_i64(tl, th, ah, zero, th, zero); tcg_gen_sub2_i64(tl, th, tl, th, bh, zero); - tcg_gen_andi_i64(dl, th, 1); + /* "invert" the result: -1 -> 0; 0 -> 1 */ + tcg_gen_addi_i64(dl, th, 1); tcg_gen_mov_i64(dh, zero); tcg_temp_free_i64(th); diff --git a/target/s390x/vec_int_helper.c b/target/s390x/vec_int_helper.c index d38405848f..0d6bc13dd6 100644 --- a/target/s390x/vec_int_helper.c +++ b/target/s390x/vec_int_helper.c @@ -593,7 +593,7 @@ void HELPER(gvec_vscbi##BITS)(void *v1, const void *v2, const void *v3, \ const uint##BITS##_t a = s390_vec_read_element##BITS(v2, i); \ const uint##BITS##_t b = s390_vec_read_element##BITS(v3, i); \ \ - s390_vec_write_element##BITS(v1, i, a < b); \ + s390_vec_write_element##BITS(v1, i, a >= b); \ } \ } DEF_VSCBI(8)
Looks like my idea of what a "borrow" is was wrong. The PoP says: "If the resulting subtraction results in a carry out of bit zero, a value of one is placed in the corresponding element of the first operand; otherwise, a value of zero is placed in the corresponding element" As clarified by Richard, all we have to do is invert the result. Fixes: 1ee2d7ba72f6 ("s390x/tcg: Implement VECTOR SUBTRACT COMPUTE BORROW INDICATION") Signed-off-by: David Hildenbrand <david@redhat.com> --- target/s390x/translate_vx.inc.c | 7 ++++--- target/s390x/vec_int_helper.c | 2 +- 2 files changed, 5 insertions(+), 4 deletions(-)