Re: [PATCH 2/6] target/ppc: add vmulld instruction

[Lijun Pan]

On Jun 18, 2020, at 6:27 PM, Richard Henderson <richard.henderson@linaro.org> wrote:

On 6/12/20 9:20 PM, Lijun Pan wrote:

vmulld: Vector Multiply Low Doubleword.

Signed-off-by: Lijun Pan <ljp@linux.ibm.com>
---
target/ppc/helper.h                 | 1 +
target/ppc/int_helper.c             | 1 +
target/ppc/translate/vmx-impl.inc.c | 1 +
target/ppc/translate/vmx-ops.inc.c  | 1 +
4 files changed, 4 insertions(+)

diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index 2dfa1c6942..c3f087ccb3 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -185,6 +185,7 @@ DEF_HELPER_3(vmuloub, void, avr, avr, avr)
DEF_HELPER_3(vmulouh, void, avr, avr, avr)
DEF_HELPER_3(vmulouw, void, avr, avr, avr)
DEF_HELPER_3(vmuluwm, void, avr, avr, avr)
+DEF_HELPER_3(vmulld, void, avr, avr, avr)
DEF_HELPER_3(vslo, void, avr, avr, avr)
DEF_HELPER_3(vsro, void, avr, avr, avr)
DEF_HELPER_3(vsrv, void, avr, avr, avr)
diff --git a/target/ppc/int_helper.c b/target/ppc/int_helper.c
index be53cd6f68..afbcdd05b4 100644
--- a/target/ppc/int_helper.c
+++ b/target/ppc/int_helper.c
@@ -533,6 +533,7 @@ void helper_vprtybq(ppc_avr_t *r, ppc_avr_t *b)
        }                                                               \
    }
VARITH_DO(muluwm, *, u32)
+VARITH_DO(mulld, *, s64)

From this implementation, I would say that both vmuluwm and vmulld can be

implemented with tcg_gen_gvec_mul().

I guess vmuluwm was missed when many of the other vmx operations were converted
to gvec.

Please first convert vmuluwm to tcg_gen_gvec_mul, then implement vmulld in the
same manner.

I did a grep in git repo, and found out only arm use this tcg_gen_gvec_mul.

The original implementation is very straightforward, and being adopted at many places

all over target/ppc/int_helper.c. Why do we need to convert

to tcg_gen_gvec_mul, which seems to me very convoluted?

Thanks,

Lijun