From: Alexander Graf <ag...@suse.de>
This patch adds emulation for the compare and branch insns,
CBZ and CBNZ.
Signed-off-by: Alexander Graf <ag...@suse.de>
[claudio: adapted to new decoder,
compare with immediate 0,
introduce read_cpu_reg to get the 0 extension on (!sf)]
Signed-off-by: Claudio Fontana <claudio.font...@linaro.org>
Signed-off-by: Peter Maydell <peter.mayd...@linaro.org>
Reviewed-by: Richard Henderson <r...@twiddle.net>
---
target-arm/translate-a64.c | 46 ++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 44 insertions(+), 2 deletions(-)
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 1d04303..5ae3a85 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -202,6 +202,25 @@ static TCGv_i64 cpu_reg(DisasContext *s, int reg)
}
}
+/* read a cpu register in 32bit/64bit mode. Returns a TCGv_i64
+ * representing the register contents. This TCGv is an auto-freed
+ * temporary so it need not be explicitly freed, and may be modified.
+ */
+static TCGv_i64 read_cpu_reg(DisasContext *s, int reg, int sf)
+{
+ TCGv_i64 v = new_tmp_a64(s);
+ if (reg != 31) {
+ if (sf) {
+ tcg_gen_mov_i64(v, cpu_X[reg]);
+ } else {
+ tcg_gen_ext32u_i64(v, cpu_X[reg]);
+ }
+ } else {
+ tcg_gen_movi_i64(v, 0);
+ }
+ return v;
+}
+
/*
* the instruction disassembly implemented here matches
* the instruction encoding classifications in chapter 3 (C3)
@@ -227,10 +246,33 @@ static void disas_uncond_b_imm(DisasContext *s, uint32_t
insn)
gen_goto_tb(s, 0, addr);
}
-/* Compare & branch (immediate) */
+/* C3.2.1 Compare & branch (immediate)
+ * 31 30 25 24 23 5 4 0
+ * +----+-------------+----+---------------------+--------+
+ * | sf | 0 1 1 0 1 0 | op | imm19 | Rt |
+ * +----+-------------+----+---------------------+--------+
+ */
static void disas_comp_b_imm(DisasContext *s, uint32_t insn)
{
- unsupported_encoding(s, insn);
+ unsigned int sf, op, rt;
+ uint64_t addr;
+ int label_match;
+ TCGv_i64 tcg_cmp;
+
+ sf = extract32(insn, 31, 1);
+ op = extract32(insn, 24, 1); /* 0: CBZ; 1: CBNZ */
+ rt = extract32(insn, 0, 5);
+ addr = s->pc + sextract32(insn, 5, 19) * 4 - 4;
+
+ tcg_cmp = read_cpu_reg(s, rt, sf);
+ label_match = gen_new_label();
+
+ tcg_gen_brcondi_i64(op ? TCG_COND_NE : TCG_COND_EQ,
+ tcg_cmp, 0, label_match);
+
+ gen_goto_tb(s, 0, s->pc);
+ gen_set_label(label_match);
+ gen_goto_tb(s, 1, addr);
}
/* C3.2.5 Test & branch (immediate)
--
1.8.5
