Commit 23e79774 authored by David Hildenbrand's avatar David Hildenbrand Committed by Cornelia Huck
Browse files

s390x/tcg: Fix VECTOR SUBTRACT COMPUTE BORROW INDICATION 



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: 1ee2d7ba ("s390x/tcg: Implement VECTOR SUBTRACT COMPUTE BORROW INDICATION")
Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Message-Id: <20191021085715.3797-5-david@redhat.com>
Reviewed-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Signed-off-by: default avatarCornelia Huck <cohuck@redhat.com>
parent b57b3368

target/s390x/translate_vx.inc.c

+4 −3
Original line number Diff line number Diff line
@@ -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);

target/s390x/vec_int_helper.c

+1 −1
Original line number Diff line number Diff line
@@ -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)