Re: [Qemu-devel] [PATCH 1/8] target/ppc: Optimize emulation of lvsl and lvsr instructions

[Richard Henderson]

On 6/19/19 1:03 PM, Stefan Brankovic wrote:
> Adding simple macro that is calling tcg implementation of appropriate
> instruction if altivec support is active.
> 
> Optimization of altivec instruction lvsl (Load Vector for Shift Left).
> Place bytes sh:sh+15 of value 0x00 || 0x01 || 0x02 || ... || 0x1E || 0x1F
> in destination register. Sh is calculated by adding 2 source registers and
> getting bits 60-63 of result.
> 
> First, the bits [28-31] are placed from EA to variable sh. After that,
> the bytes are created in the following way:
> sh:(sh+7) of X(from description) by multiplying sh with 0x0101010101010101
> followed by addition of the result with 0x0001020304050607. Value obtained
> is placed in higher doubleword element of vD.
> (sh+8):(sh+15) by adding the result of previous multiplication with
> 0x08090a0b0c0d0e0f. Value obtained is placed in lower doubleword element
> of vD.
> 
> Optimization of altivec instruction lvsr (Load Vector for Shift Right).
> Place bytes 16-sh:31-sh of value 0x00 || 0x01 || 0x02 || ... || 0x1E ||
> 0x1F in destination register. Sh is calculated by adding 2 source
> registers and getting bits 60-63 of result.
> 
> First, the bits [28-31] are placed from EA to variable sh. After that,
> the bytes are created in the following way:
> sh:(sh+7) of X(from description) by multiplying sh with 0x0101010101010101
> followed by substraction of the result from 0x1011121314151617. Value
> obtained is placed in higher doubleword element of vD.
> (sh+8):(sh+15) by substracting the result of previous multiplication from
> 0x18191a1b1c1d1e1f. Value obtained is placed in lower doubleword element
> of vD.
> 
> Signed-off-by: Stefan Brankovic <address@hidden>
> ---
>  target/ppc/helper.h                 |   2 -
>  target/ppc/int_helper.c             |  18 ------
>  target/ppc/translate/vmx-impl.inc.c | 120 
> ++++++++++++++++++++++++++----------
>  3 files changed, 88 insertions(+), 52 deletions(-)

Reviewed-by: Richard Henderson <address@hidden>


r~