On 12/18/18 6:51 AM, Mark Cave-Ayland wrote:
> On 18/12/2018 09:49, Mark Cave-Ayland wrote:
>
>> A quick bisection suggests that there could be 2 separate issues related to
>> the
>> implementation of splat:
>>
>> Patch "target/ppc: convert vspltis[bhw] to use vector operations" causes a
>> black
>> border to appear around the OS X splash screen
>> (https://www.ilande.co.uk/tmp/qemu/badapple1.png) which may suggest an
>> overflow/alignment issue.
>
> This one appears to be a sign extension issue - if I make use of the same
> technique
> used by the previous helper then this problem goes away. Below is my
> experimental
> diff to be squashed into "target/ppc: convert vspltis[bhw] to use vector
> operations":
>
> diff --git a/target/ppc/translate/vmx-impl.inc.c
> b/target/ppc/translate/vmx-impl.inc.c
> index be638cdb1a..6cd25c8dc6 100644
> --- a/target/ppc/translate/vmx-impl.inc.c
> +++ b/target/ppc/translate/vmx-impl.inc.c
> @@ -723,12 +723,12 @@ GEN_VXRFORM_DUAL(vcmpgtfp, PPC_ALTIVEC, PPC_NONE, \
> #define GEN_VXFORM_DUPI(name, tcg_op, opc2, opc3) \
> static void glue(gen_, name)(DisasContext *ctx) \
> { \
> - int simm; \
> + int8_t simm;
This shouldn't matter.
\
> if (unlikely(!ctx->altivec_enabled)) { \
> gen_exception(ctx, POWERPC_EXCP_VPU); \
> return; \
> } \
> - simm = SIMM5(ctx->opcode); \
> + simm = (int8_t)(SIMM5(ctx->opcode) << 3) >> 3; \
This suggests that SIMM5 should be using sextract32.
r~
