Re: [Qemu-devel] [PATCH 1/6] tcg: Generic support for conditional set and conditional move.

[malc <av1474@comtv.ru>]

On Thu, 17 Dec 2009, Richard Henderson wrote:

> Defines setcond and movcond for implementing conditional moves at
> the tcg opcode level.  64-bit-on-32-bit is expanded via a setcond2
> primitive plus other operations.
> 
> Signed-off-by: Richard Henderson <rth@twiddle.net>
> ---
>  tcg/README    |   26 +++++++++++++++-
>  tcg/tcg-op.h  |   91 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  tcg/tcg-opc.h |    5 +++
>  tcg/tcg.c     |   23 ++++++++++----
>  4 files changed, 138 insertions(+), 7 deletions(-)
> 
> diff --git a/tcg/README b/tcg/README
> index e672258..8617994 100644
> --- a/tcg/README
> +++ b/tcg/README
> @@ -152,6 +152,11 @@ Conditional jump if t0 cond t1 is true. cond can be:
>      TCG_COND_LEU /* unsigned */
>      TCG_COND_GTU /* unsigned */
>  
> +* brcond2_i32 cond, t0_low, t0_high, t1_low, t1_high, label
> +
> +Similar to brcond, except that the 64-bit values T0 and T1
> +are formed from two 32-bit arguments.
> +
>  ********* Arithmetic
>  
>  * add_i32/i64 t0, t1, t2
> @@ -282,6 +287,25 @@ order bytes must be set to zero.
>  Indicate that the value of t0 won't be used later. It is useful to
>  force dead code elimination.
>  
> +********* Conditional moves
> +
> +* setcond_i32/i64 cond, dest, t1, t2
> +
> +dest = (t1 cond t2)
> +
> +Set DEST to 1 if (T1 cond T2) is true, otherwise set to 0.
> +
> +* movcond_i32/i64 cond, dest, c1, c2, vtrue, vfalse
> +
> +dest= (c1 cond c2 ? vtrue : of)

Nitpick: no space before '='

> +
> +Set DEST to VTRUE if (c1 cond c2) is true, otherwise set to VFALSE.

But it reads `? vtrue : of'. Should probably be  `? vtrue : vfalse`

[..snip..]

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