On Fri, Mar 11, 2011 at 10:09:58AM +0000, Peter Maydell wrote:
> SMUAD and SMLAD are supposed to set the Q bit if the addition of
> the two 16x16 multiply products and optional accumulator overflows
> considered as a signed value. However we were only doing this check
> for the addition of the accumulator, not when adding the products,
> with the effect that we were mishandling the edge case where
> both inputs are 0x80008000.
>
> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
> ---
> target-arm/translate.c | 16 ++++++++++++----
> 1 files changed, 12 insertions(+), 4 deletions(-)
Thanks, applied.
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index 062de5e..8f7c461 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -7038,11 +7038,15 @@ static void disas_arm_insn(CPUState * env,
> DisasContext *s)
> if (insn & (1 << 5))
> gen_swap_half(tmp2);
> gen_smul_dual(tmp, tmp2);
> - /* This addition cannot overflow. */
> if (insn & (1 << 6)) {
> + /* This subtraction cannot overflow. */
> tcg_gen_sub_i32(tmp, tmp, tmp2);
> } else {
> - tcg_gen_add_i32(tmp, tmp, tmp2);
> + /* This addition cannot overflow 32 bits;
> + * however it may overflow considered as a signed
> + * operation, in which case we must set the Q
> flag.
> + */
> + gen_helper_add_setq(tmp, tmp, tmp2);
> }
> tcg_temp_free_i32(tmp2);
> if (insn & (1 << 22)) {
> @@ -7860,11 +7864,15 @@ static int disas_thumb2_insn(CPUState *env,
> DisasContext *s, uint16_t insn_hw1)
> if (op)
> gen_swap_half(tmp2);
> gen_smul_dual(tmp, tmp2);
> - /* This addition cannot overflow. */
> if (insn & (1 << 22)) {
> + /* This subtraction cannot overflow. */
> tcg_gen_sub_i32(tmp, tmp, tmp2);
> } else {
> - tcg_gen_add_i32(tmp, tmp, tmp2);
> + /* This addition cannot overflow 32 bits;
> + * however it may overflow considered as a signed
> + * operation, in which case we must set the Q flag.
> + */
> + gen_helper_add_setq(tmp, tmp, tmp2);
> }
> tcg_temp_free_i32(tmp2);
> if (rs != 15)
> --
> 1.7.1
>
>
>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
aurel...@aurel32.net http://www.aurel32.net
