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Re: [Qemu-devel] [PATCH 5/5] tcg: Optimize two-address commutative opera
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 5/5] tcg: Optimize two-address commutative operations |
Date: |
Tue, 18 Sep 2012 23:11:50 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Tue, Sep 18, 2012 at 07:24:00AM -0700, Richard Henderson wrote:
> While swapping constants to the second operand, swap
> sources matching destinations to the first operand.
>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> tcg/optimize.c | 22 +++++++++++++++++++---
> 1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index 5b0a8ce..becc408 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -337,6 +337,8 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
> const TCGOpDef *def;
> TCGArg *gen_args;
> TCGArg tmp;
> + TCGCond cond;
> +
> /* Array VALS has an element for each temp.
> If this temp holds a constant then its value is kept in VALS' element.
> If this temp is a copy of other ones then this equivalence class'
> @@ -363,7 +365,8 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
> }
> }
>
> - /* For commutative operations make constant second argument */
> + /* For commutative operations make constant second argument, or
> + if the destination is an input, make it the first argument. */
> switch (op) {
> CASE_OP_32_64(add):
> CASE_OP_32_64(mul):
> @@ -373,7 +376,9 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
> CASE_OP_32_64(eqv):
> CASE_OP_32_64(nand):
> CASE_OP_32_64(nor):
> - if (temps[args[1]].state == TCG_TEMP_CONST) {
> + if (temps[args[1]].state == TCG_TEMP_CONST
> + || (args[0] == args[2]
> + && temps[args[1]].state != TCG_TEMP_CONST)) {
> tmp = args[1];
Not directly related to movcond, and I also got that in my tree, but I
guess it's fine.
> args[1] = args[2];
> args[2] = tmp;
> @@ -398,13 +403,24 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
> }
> break;
> CASE_OP_32_64(movcond):
> + cond = args[5];
> if (temps[args[1]].state == TCG_TEMP_CONST
> && temps[args[2]].state != TCG_TEMP_CONST) {
> tmp = args[1];
> args[1] = args[2];
> args[2] = tmp;
> - args[5] = tcg_swap_cond(args[5]);
> + cond = tcg_swap_cond(cond);
> + }
> + /* For movcond, we canonicalize the "false" input reg to match
> + the destination reg so that the tcg backend can implement
> + a "move if true" operation. */
> + if (args[0] == args[3]) {
> + tmp = args[3];
> + args[3] = args[4];
> + args[4] = tmp;
> + cond = tcg_invert_cond(cond);
> }
> + args[5] = cond;
> default:
> break;
> }
> --
> 1.7.11.4
>
Reviewed-by: Aurelien Jarno <address@hidden>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
[Qemu-devel] [PATCH 3/5] tcg-i386: Implement movcond, Richard Henderson, 2012/09/18
[Qemu-devel] [PATCH 2/5] target-alpha: Use movcond, Richard Henderson, 2012/09/18
[Qemu-devel] [PATCH 1/5] tcg: Introduce movcond, Richard Henderson, 2012/09/18