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Re: [Qemu-devel] [PATCH 7/7] tcg: Do constant folding on double-word com
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH 7/7] tcg: Do constant folding on double-word comparisons |
Date: |
Mon, 1 Oct 2012 20:50:35 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Sep 27, 2012 at 10:19:57AM -0700, Richard Henderson wrote:
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> tcg/optimize.c | 134
> ++++++++++++++++++++++++++++++++++++++++-----------------
> 1 file changed, 94 insertions(+), 40 deletions(-)
>
> diff --git a/tcg/optimize.c b/tcg/optimize.c
> index dfac877..f6a16fd 100644
> --- a/tcg/optimize.c
> +++ b/tcg/optimize.c
> @@ -398,6 +398,40 @@ static TCGArg do_constant_folding_cond(TCGOpcode op,
> TCGArg x,
> }
> }
>
> +/* Return 2 if the condition can't be simplified, and the result
> + of the condition (0 or 1) if it can */
> +static TCGArg do_constant_folding_cond2(TCGArg *p1, TCGArg *p2, TCGCond c)
> +{
> + TCGArg al = p1[0], ah = p1[1];
> + TCGArg bl = p2[0], bh = p2[1];
> +
> + if (temps[bl].state == TCG_TEMP_CONST
> + && temps[bh].state == TCG_TEMP_CONST) {
> + uint64_t b = ((uint64_t)temps[bh].val << 32) |
> (uint32_t)temps[bl].val;
> +
> + if (temps[al].state == TCG_TEMP_CONST
> + && temps[ah].state == TCG_TEMP_CONST) {
> + uint64_t a;
> + a = ((uint64_t)temps[ah].val << 32) | (uint32_t)temps[al].val;
> + return do_constant_folding_cond_64(a, b, c);
> + }
> + if (b == 0) {
> + switch (c) {
> + case TCG_COND_LTU:
> + return 0;
> + case TCG_COND_GEU:
> + return 1;
> + default:
> + break;
> + }
> + }
> + }
> + if (temps_are_copies(al, bl) && temps_are_copies(ah, bh)) {
> + return do_constant_folding_cond_eq(c);
> + }
> + return 2;
> +}
> +
> static bool swap_commutative(TCGArg dest, TCGArg *p1, TCGArg *p2)
> {
> TCGArg a1 = *p1, a2 = *p2;
> @@ -816,53 +850,73 @@ static TCGArg *tcg_constant_folding(TCGContext *s,
> uint16_t *tcg_opc_ptr,
> args += 6;
> break;
> case INDEX_op_brcond2_i32:
> - /* Simplify LT/GE comparisons vs zero to a single compare
> - vs the high word of the input. */
> - if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
> - && temps[args[2]].state == TCG_TEMP_CONST
> - && temps[args[3]].state == TCG_TEMP_CONST
> - && temps[args[2]].val == 0
> - && temps[args[2]].val == 0) {
> - gen_opc_buf[op_index] = INDEX_op_brcond_i32;
> - args[0] = args[1];
> - args[1] = args[3];
> - args[2] = args[4];
> - args[3] = args[5];
> - gen_args += 4;
> + tmp = do_constant_folding_cond2(&args[0], &args[2], args[4]);
> + if (tmp != 2) {
> + if (tmp) {
> + gen_opc_buf[op_index] = INDEX_op_br;
> + gen_args[0] = args[5];
> + gen_args += 1;
> + } else {
> + gen_opc_buf[op_index] = INDEX_op_nop;
> + args += 6;
> + break;
> + }
> } else {
> - gen_args[0] = args[0];
> - gen_args[1] = args[1];
> - gen_args[2] = args[2];
> - gen_args[3] = args[3];
> - gen_args[4] = args[4];
> - gen_args[5] = args[5];
> - gen_args += 6;
> + /* Simplify LT/GE comparisons vs zero to a single compare
> + vs the high word of the input. */
> + if ((args[4] == TCG_COND_LT || args[4] == TCG_COND_GE)
> + && temps[args[2]].state == TCG_TEMP_CONST
> + && temps[args[3]].state == TCG_TEMP_CONST
> + && temps[args[2]].val == 0
> + && temps[args[2]].val == 0) {
> + gen_opc_buf[op_index] = INDEX_op_brcond_i32;
> + args[0] = args[1];
> + args[1] = args[3];
> + args[2] = args[4];
> + args[3] = args[5];
> + gen_args += 4;
> + } else {
> + gen_args[0] = args[0];
> + gen_args[1] = args[1];
> + gen_args[2] = args[2];
> + gen_args[3] = args[3];
> + gen_args[4] = args[4];
> + gen_args[5] = args[5];
> + gen_args += 6;
> + }
> }
> memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
> args += 6;
> break;
> case INDEX_op_setcond2_i32:
> - /* Simplify LT/GE comparisons vs zero to a single compare
> - vs the high word of the input. */
> - if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
> - && temps[args[3]].state == TCG_TEMP_CONST
> - && temps[args[4]].state == TCG_TEMP_CONST
> - && temps[args[3]].val == 0
> - && temps[args[4]].val == 0) {
> - gen_opc_buf[op_index] = INDEX_op_setcond_i32;
> - args[1] = args[2];
> - args[2] = args[4];
> - args[3] = args[5];
> - gen_args += 4;
> + tmp = do_constant_folding_cond2(&args[1], &args[3], args[5]);
> + if (tmp != 2) {
> + gen_opc_buf[op_index] = INDEX_op_movi_i32;
> + tcg_opt_gen_movi(gen_args, args[0], tmp);
> + gen_args += 2;
> } else {
> - reset_temp(args[0]);
> - gen_args[0] = args[0];
> - gen_args[1] = args[1];
> - gen_args[2] = args[2];
> - gen_args[3] = args[3];
> - gen_args[4] = args[4];
> - gen_args[5] = args[5];
> - gen_args += 6;
> + /* Simplify LT/GE comparisons vs zero to a single compare
> + vs the high word of the input. */
> + if ((args[5] == TCG_COND_LT || args[5] == TCG_COND_GE)
> + && temps[args[3]].state == TCG_TEMP_CONST
> + && temps[args[4]].state == TCG_TEMP_CONST
> + && temps[args[3]].val == 0
> + && temps[args[4]].val == 0) {
> + gen_opc_buf[op_index] = INDEX_op_setcond_i32;
> + args[1] = args[2];
> + args[2] = args[4];
> + args[3] = args[5];
> + gen_args += 4;
> + } else {
> + reset_temp(args[0]);
> + gen_args[0] = args[0];
> + gen_args[1] = args[1];
> + gen_args[2] = args[2];
> + gen_args[3] = args[3];
> + gen_args[4] = args[4];
> + gen_args[5] = args[5];
> + gen_args += 6;
> + }
> }
> args += 6;
> break;
Reviewed-by: Aurelien Jarno <address@hidden>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
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