target/i386: document use of DISAS_NORETURN
DISAS_NORETURN suppresses the work normally done by gen_eob(), and therefore
must be used in special cases only. Document them.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/target/i386/tcg/translate.c b/target/i386/tcg/translate.c
index a9c6424..2b6f67b 100644
--- a/target/i386/tcg/translate.c
+++ b/target/i386/tcg/translate.c
@@ -4761,6 +4761,17 @@
switch (dc->base.is_jmp) {
case DISAS_NORETURN:
+ /*
+ * Most instructions should not use DISAS_NORETURN, as that suppresses
+ * the handling of hflags normally done by gen_eob(). We can
+ * get here:
+ * - for exception and interrupts
+ * - for jump optimization (which is disabled by INHIBIT_IRQ/RF/TF)
+ * - for VMRUN because RF/TF handling for the host is done after vmexit,
+ * and INHIBIT_IRQ is loaded from the VMCB
+ * - for HLT/PAUSE/MWAIT to exit the main loop with specific EXCP_* values;
+ * the helpers handle themselves the tasks normally done by gen_eob().
+ */
break;
case DISAS_TOO_MANY:
gen_update_cc_op(dc);
