From 2169b5c6f7a791ef9c43c72412efaafae3245114 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Fri, 12 Feb 2021 10:48:52 -0800 Subject: [PATCH] target/arm: Improve gen_top_byte_ignore Use simple arithmetic instead of a conditional move when tbi0 != tbi1. Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson Message-id: 20210212184902.1251044-22-richard.henderson@linaro.org Signed-off-by: Peter Maydell --- target/arm/translate-a64.c | 25 ++++++++++++++----------- 1 file changed, 14 insertions(+), 11 deletions(-) diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c index 1c4b8d02f3..b23a8975d5 100644 --- a/target/arm/translate-a64.c +++ b/target/arm/translate-a64.c @@ -183,17 +183,20 @@ static void gen_top_byte_ignore(DisasContext *s, TCGv_i64 dst, /* Sign-extend from bit 55. */ tcg_gen_sextract_i64(dst, src, 0, 56); - if (tbi != 3) { - TCGv_i64 tcg_zero = tcg_const_i64(0); - - /* - * The two TBI bits differ. - * If tbi0, then !tbi1: only use the extension if positive. - * if !tbi0, then tbi1: only use the extension if negative. - */ - tcg_gen_movcond_i64(tbi == 1 ? TCG_COND_GE : TCG_COND_LT, - dst, dst, tcg_zero, dst, src); - tcg_temp_free_i64(tcg_zero); + switch (tbi) { + case 1: + /* tbi0 but !tbi1: only use the extension if positive */ + tcg_gen_and_i64(dst, dst, src); + break; + case 2: + /* !tbi0 but tbi1: only use the extension if negative */ + tcg_gen_or_i64(dst, dst, src); + break; + case 3: + /* tbi0 and tbi1: always use the extension */ + break; + default: + g_assert_not_reached(); } } }