py/emitnative: Ensure load_subscr does not clobber existing REG_ARG_2.

Follow up from a similar fix in 426785a19eeb12aef7383fbda4693575d8c4dddf

Fixes issue #6314.

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/tests/micropython/viper_subscr_multi.py b/tests/micropython/viper_subscr_multi.py
index 1561e5534..a2baba241 100644
--- a/tests/micropython/viper_subscr_multi.py
+++ b/tests/micropython/viper_subscr_multi.py
@@ -6,15 +6,24 @@ def f1(b: ptr8):
     b[0] += b[1]
 
 
+b = bytearray(b"\x01\x02")
+f1(b)
+print(b)
+
+
 @micropython.viper
 def f2(b: ptr8, i: int):
     b[0] += b[i]
 
 
 b = bytearray(b"\x01\x02")
-f1(b)
-print(b)
-
-b = bytearray(b"\x01\x02")
 f2(b, 1)
 print(b)
+
+
+@micropython.viper
+def f3(b: ptr8) -> int:
+    return b[0] << 24 | b[1] << 16 | b[2] << 8 | b[3]
+
+
+print(hex(f3(b"\x01\x02\x03\x04")))