vm: ensure consistent trace output between gcc and clang compiled ucode

Clang emits code which evaluates function call argument expressions in a
different order, causing `uc_dump_insn()` to receive the instruction pointer
address after decoding the instruction, not before.

Avoid that problem by explicitly caching the pre-decode address in a
temporary variable which is then passed to `uc_dump_insn()`.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

1 files changed, 8 insertions, 3 deletions

diff --git a/vm.c b/vm.c
index 93ac704..3e027bf 100644
--- a/vm.c
+++ b/vm.c
@@ -2294,12 +2294,17 @@ uc_vm_execute_chunk(uc_vm_t *vm)
 	uc_chunk_t *chunk = uc_vm_frame_chunk(frame);
 	uc_value_t *retval;
 	uc_vm_insn_t insn;
+	uint8_t *ip;
 
 	while (chunk) {
-		if (vm->trace)
-			uc_dump_insn(vm, frame->ip, (insn = uc_vm_decode_insn(vm, frame, chunk)));
-		else
+		if (vm->trace) {
+			ip = frame->ip;
+			insn = uc_vm_decode_insn(vm, frame, chunk);
+			uc_dump_insn(vm, ip, insn);
+		}
+		else {
 			insn = uc_vm_decode_insn(vm, frame, chunk);
+		}
 
 		switch (insn) {
 		case I_LOAD: