> gcc/ChangeLog:
>
> * config/i386/i386-expand.cc (emit_reduc_half): Use shuffles to
> generate reduc half for V4SI, similar modes.
> * config/i386/i386.h (TARGET_SSE_REDUCTION_PREFER_PSHUF): New Macro.
> * config/i386/x86-tune.def (X86_TUNE_SSE_REDUCTION_PREFER_PSHUF):
> New tuning.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/reduc-pshuf.c: New test.
> ---
> gcc/config/i386/i386-expand.cc | 28 ++++++++++++++++++---
> gcc/config/i386/i386.h | 2 ++
> gcc/config/i386/x86-tune.def | 5 ++++
> gcc/testsuite/gcc.target/i386/reduc-pshuf.c | 14 +++++++++++
> 4 files changed, 46 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/reduc-pshuf.c
>
> diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
> index 7fd03c88630..c7aec716a55 100644
> --- a/gcc/config/i386/i386-expand.cc
> +++ b/gcc/config/i386/i386-expand.cc
> @@ -18724,9 +18724,31 @@ emit_reduc_half (rtx dest, rtx src, int i)
> case E_V8HFmode:
> case E_V4SImode:
> case E_V2DImode:
> - d = gen_reg_rtx (V1TImode);
> - tem = gen_sse2_lshrv1ti3 (d, gen_lowpart (V1TImode, src),
> - GEN_INT (i / 2));
> + if (TARGET_SSE_REDUCTION_PREFER_PSHUF) {
> + if (i == 128) {
> + d = gen_reg_rtx(V4SImode);
> + tem = gen_sse2_pshufd_1(
> + d, force_reg(V4SImode, gen_lowpart(V4SImode, src)), GEN_INT(2),
> + GEN_INT(3), GEN_INT(2), GEN_INT(3));
> + } else if (i == 64) {
> + d = gen_reg_rtx(V4SImode);
> + tem = gen_sse2_pshufd_1(
> + d, force_reg(V4SImode, gen_lowpart(V4SImode, src)), GEN_INT(1),
> + GEN_INT(1), GEN_INT(1), GEN_INT(1));
> + } else if (i == 32) {
> + d = gen_reg_rtx(V8HImode);
> + tem = gen_sse2_pshuflw_1(
> + d, force_reg(V8HImode, gen_lowpart(V8HImode, src)), GEN_INT(1),
> + GEN_INT(1), GEN_INT(1), GEN_INT(1));
> + } else {
> + d = gen_reg_rtx(V1TImode);
> + tem =
> + gen_sse2_lshrv1ti3(d, gen_lowpart(V1TImode, src), GEN_INT(i /
> 2));
> + }
> + } else {
> + d = gen_reg_rtx(V1TImode);
> + tem = gen_sse2_lshrv1ti3(d, gen_lowpart(V1TImode, src), GEN_INT(i /
> 2));
Instead of duplicating gen_sse2_lshrv1ti3 it is probably cleaner to
simply break after each gen_sse_pshuw call and remove else.
OK with that change
Honza
