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-rw-r--r--target-arm/translate-a64.c24
1 files changed, 23 insertions, 1 deletions
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index d17ca19f03..8ae68148ef 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -3017,7 +3017,28 @@ static void disas_bitfield(DisasContext *s, uint32_t insn)
tcg_rd = cpu_reg(s, rd);
tcg_tmp = read_cpu_reg(s, rn, sf);
- /* OPTME: probably worth recognizing common cases of ext{8,16,32}{u,s} */
+ /* Recognize the common aliases. */
+ if (opc == 0) { /* SBFM */
+ if (ri == 0) {
+ if (si == 7) { /* SXTB */
+ tcg_gen_ext8s_i64(tcg_rd, tcg_tmp);
+ goto done;
+ } else if (si == 15) { /* SXTH */
+ tcg_gen_ext16s_i64(tcg_rd, tcg_tmp);
+ goto done;
+ } else if (si == 31) { /* SXTW */
+ tcg_gen_ext32s_i64(tcg_rd, tcg_tmp);
+ goto done;
+ }
+ }
+ if (si == 63 || (si == 31 && ri <= si)) { /* ASR */
+ if (si == 31) {
+ tcg_gen_ext32s_i64(tcg_tmp, tcg_tmp);
+ }
+ tcg_gen_sari_i64(tcg_rd, tcg_tmp, ri);
+ goto done;
+ }
+ }
if (opc != 1) { /* SBFM or UBFM */
tcg_gen_movi_i64(tcg_rd, 0);
@@ -3042,6 +3063,7 @@ static void disas_bitfield(DisasContext *s, uint32_t insn)
tcg_gen_sari_i64(tcg_rd, tcg_rd, 64 - (pos + len));
}
+ done:
if (!sf) { /* zero extend final result */
tcg_gen_ext32u_i64(tcg_rd, tcg_rd);
}