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target/openrisc: Cache constant 0 in DisasContext

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We are virtually certain to have fetched constant 0 once, at the
beginning of the TB, so we might as well use it elsewhere.

Reviewed-by: Stafford Horne <shorne@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-07-08 14:15:56 -07:00
parent 4d10fa0ff9
commit 118671f02f
1 changed files with 6 additions and 6 deletions
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12
target/openrisc/translate.c
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@ -52,6 +52,8 @@ typedef struct DisasContext {
/* The temporary corresponding to register 0 for this compilation. */
TCGv R0;
/* The constant zero. */
TCGv zero;
} DisasContext;
static inline bool is_user(DisasContext *dc)
@ -536,10 +538,8 @@ static bool trans_l_extbz(DisasContext *dc, arg_da *a)
static bool trans_l_cmov(DisasContext *dc, arg_dab *a)
{
TCGv zero = tcg_constant_tl(0);
check_r0_write(dc, a->d);
tcg_gen_movcond_tl(TCG_COND_NE, cpu_R(dc, a->d), cpu_sr_f, zero,
tcg_gen_movcond_tl(TCG_COND_NE, cpu_R(dc, a->d), cpu_sr_f, dc->zero,
cpu_R(dc, a->a), cpu_R(dc, a->b));
return true;
}
@ -630,9 +630,8 @@ static void do_bf(DisasContext *dc, arg_l_bf *a, TCGCond cond)
target_ulong tmp_pc = dc->base.pc_next + a->n * 4;
TCGv t_next = tcg_constant_tl(dc->base.pc_next + 8);
TCGv t_true = tcg_constant_tl(tmp_pc);
TCGv t_zero = tcg_constant_tl(0);
tcg_gen_movcond_tl(cond, jmp_pc, cpu_sr_f, t_zero, t_true, t_next);
tcg_gen_movcond_tl(cond, jmp_pc, cpu_sr_f, dc->zero, t_true, t_next);
dc->delayed_branch = 2;
}
@ -1594,8 +1593,9 @@ static void openrisc_tr_tb_start(DisasContextBase *db, CPUState *cs)
/* Allow the TCG optimizer to see that R0 == 0,
when it's true, which is the common case. */
dc->zero = tcg_constant_tl(0);
if (dc->tb_flags & TB_FLAGS_R0_0) {
dc->R0 = tcg_constant_tl(0);
dc->R0 = dc->zero;
} else {
dc->R0 = cpu_regs[0];
}