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tcg/optimize: Canonicalize sub2 with constants to add2

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Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20231026013945.1152174-4-richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2023-10-25 18:39:44 -07:00
parent 6334a968ee
commit f245757701
1 changed files with 19 additions and 2 deletions
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21
tcg/optimize.c
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@ -1044,8 +1044,10 @@ static bool fold_add_vec(OptContext *ctx, TCGOp *op)
static bool fold_addsub2(OptContext *ctx, TCGOp *op, bool add)
{
if (arg_is_const(op->args[2]) && arg_is_const(op->args[3]) &&
arg_is_const(op->args[4]) && arg_is_const(op->args[5])) {
bool a_const = arg_is_const(op->args[2]) && arg_is_const(op->args[3]);
bool b_const = arg_is_const(op->args[4]) && arg_is_const(op->args[5]);
if (a_const && b_const) {
uint64_t al = arg_info(op->args[2])->val;
uint64_t ah = arg_info(op->args[3])->val;
uint64_t bl = arg_info(op->args[4])->val;
@ -1089,6 +1091,21 @@ static bool fold_addsub2(OptContext *ctx, TCGOp *op, bool add)
tcg_opt_gen_movi(ctx, op2, rh, ah);
return true;
}
/* Fold sub2 r,x,i to add2 r,x,-i */
if (!add && b_const) {
uint64_t bl = arg_info(op->args[4])->val;
uint64_t bh = arg_info(op->args[5])->val;
/* Negate the two parts without assembling and disassembling. */
bl = -bl;
bh = ~bh + !bl;
op->opc = (ctx->type == TCG_TYPE_I32
? INDEX_op_add2_i32 : INDEX_op_add2_i64);
op->args[4] = arg_new_constant(ctx, bl);
op->args[5] = arg_new_constant(ctx, bh);
}
return false;
}