target/microblaze: Handle DISAS_EXIT_NEXT in delay slot

It is legal to put an mts instruction into a delay slot.
We should continue to return to the main loop in that
case so that we recognize any pending interrupts.

Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Tested-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 33 insertions, 1 deletions

diff --git a/target/microblaze/translate.c b/target/microblaze/translate.c
index 6bf299a826..608d413c83 100644
--- a/target/microblaze/translate.c
+++ b/target/microblaze/translate.c
@@ -1696,6 +1696,10 @@ static void mb_tr_translate_insn(DisasContextBase *dcb, CPUState *cs)
     dc->base.pc_next += 4;
 
     if (dc->jmp_cond != TCG_COND_NEVER && !(dc->tb_flags & D_FLAG)) {
+        /*
+         * Finish any return-from branch.
+         * TODO: Diagnose rtXd in delay slot of rtYd earlier.
+         */
         if (dc->tb_flags & DRTI_FLAG) {
             do_rti(dc);
         } else if (dc->tb_flags & DRTB_FLAG) {
@@ -1703,7 +1707,35 @@ static void mb_tr_translate_insn(DisasContextBase *dcb, CPUState *cs)
         } else if (dc->tb_flags & DRTE_FLAG) {
             do_rte(dc);
         }
-        dc->base.is_jmp = DISAS_JUMP;
+
+        /* Complete the branch, ending the TB. */
+        switch (dc->base.is_jmp) {
+        case DISAS_NORETURN:
+            /*
+             * E.g. illegal insn in a delay slot.  We've already exited
+             * and will handle D_FLAG in mb_cpu_do_interrupt.
+             */
+            break;
+        case DISAS_EXIT:
+            /*
+             * TODO: diagnose brk/brki in delay slot earlier.
+             * This would then fold into the illegal insn case above.
+             */
+            break;
+        case DISAS_NEXT:
+            /* Normal insn a delay slot.  */
+            dc->base.is_jmp = DISAS_JUMP;
+            break;
+        case DISAS_EXIT_NEXT:
+            /*
+             * E.g. mts insn in a delay slot.  Continue with btarget,
+             * but still return to the main loop.
+             */
+            dc->base.is_jmp = DISAS_EXIT_JUMP;
+            break;
+        default:
+            g_assert_not_reached();
+        }
     }
 }