target-arm: A64: Avoid duplicate exit_tb(0) in non-linked goto_tb
If gen_goto_tb() decides not to link the two TBs, then the
fallback path generates unnecessary code:
* if singlestep is enabled then we generate unreachable code
after the gen_exception_internal(EXCP_DEBUG)
* if singlestep is disabled then we will generate exit_tb(0)
twice, once in gen_goto_tb() and once coming out of the
main loop with is_jmp set to DISAS_JUMP
Correct these deficiencies by only emitting exit_tb() in the
non-singlestep case, in which case we can use DISAS_TB_JUMP
to suppress the main-loop exit_tb().
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index 2e21948..21a997f 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -234,9 +234,10 @@
gen_a64_set_pc_im(dest);
if (s->singlestep_enabled) {
gen_exception_internal(EXCP_DEBUG);
+ } else {
+ tcg_gen_exit_tb(0);
+ s->is_jmp = DISAS_TB_JUMP;
}
- tcg_gen_exit_tb(0);
- s->is_jmp = DISAS_JUMP;
}
}
