target-arm: A64: add support for conditional branches
This patch adds emulation for the conditional branch (b.cond) instruction.
Signed-off-by: Alexander Graf <agraf@suse.de>
[claudio: adapted to new decoder structure,
reused arm infrastructure for checking the flags]
Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 48281ff..3c0748d 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -221,10 +221,35 @@
unsupported_encoding(s, insn);
}
-/* Conditional branch (immediate) */
+/* C3.2.2 / C5.6.19 Conditional branch (immediate)
+ * 31 25 24 23 5 4 3 0
+ * +---------------+----+---------------------+----+------+
+ * | 0 1 0 1 0 1 0 | o1 | imm19 | o0 | cond |
+ * +---------------+----+---------------------+----+------+
+ */
static void disas_cond_b_imm(DisasContext *s, uint32_t insn)
{
- unsupported_encoding(s, insn);
+ unsigned int cond;
+ uint64_t addr;
+
+ if ((insn & (1 << 4)) || (insn & (1 << 24))) {
+ unallocated_encoding(s);
+ return;
+ }
+ addr = s->pc + sextract32(insn, 5, 19) * 4 - 4;
+ cond = extract32(insn, 0, 4);
+
+ if (cond < 0x0e) {
+ /* genuinely conditional branches */
+ int label_nomatch = gen_new_label();
+ arm_gen_test_cc(cond ^ 1, label_nomatch);
+ gen_goto_tb(s, 0, addr);
+ gen_set_label(label_nomatch);
+ gen_goto_tb(s, 1, s->pc);
+ } else {
+ /* 0xe and 0xf are both "always" conditions */
+ gen_goto_tb(s, 0, addr);
+ }
}
/* C5.6.68 HINT */