target/arm: Improve gen_top_byte_ignore
Use simple arithmetic instead of a conditional move when tbi0 != tbi1. Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20210212184902.1251044-22-richard.henderson@linaro.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
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@ -183,17 +183,20 @@ static void gen_top_byte_ignore(DisasContext *s, TCGv_i64 dst,
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/* Sign-extend from bit 55. */
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tcg_gen_sextract_i64(dst, src, 0, 56);
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if (tbi != 3) {
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TCGv_i64 tcg_zero = tcg_const_i64(0);
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/*
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* The two TBI bits differ.
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* If tbi0, then !tbi1: only use the extension if positive.
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* if !tbi0, then tbi1: only use the extension if negative.
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*/
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tcg_gen_movcond_i64(tbi == 1 ? TCG_COND_GE : TCG_COND_LT,
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dst, dst, tcg_zero, dst, src);
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tcg_temp_free_i64(tcg_zero);
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switch (tbi) {
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case 1:
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/* tbi0 but !tbi1: only use the extension if positive */
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tcg_gen_and_i64(dst, dst, src);
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break;
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case 2:
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/* !tbi0 but tbi1: only use the extension if negative */
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tcg_gen_or_i64(dst, dst, src);
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break;
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case 3:
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/* tbi0 and tbi1: always use the extension */
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break;
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default:
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g_assert_not_reached();
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}
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}
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}
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