py: Rework and compress second part of bytecode prelude.

This patch compresses the second part of the bytecode prelude which
contains the source file name, function name, source-line-number mapping
and cell closure information.  This part of the prelude now begins with a
single varible length unsigned integer which encodes 2 numbers, being the
byte-size of the following 2 sections in the header: the "source info
section" and the "closure section".  After decoding this variable unsigned
integer it's possible to skip over one or both of these sections very
easily.

This scheme saves about 2 bytes for most functions compared to the original
format: one in the case that there are no closure cells, and one because
padding was eliminated.

4 files changed, 15 insertions, 15 deletions

diff --git a/tests/cmdline/cmd_parsetree.py.exp b/tests/cmdline/cmd_parsetree.py.exp
index 58d419dc4..18986318a 100644
--- a/tests/cmdline/cmd_parsetree.py.exp
+++ b/tests/cmdline/cmd_parsetree.py.exp
@@ -36,7 +36,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names:
 (N_STATE 5)
 (N_EXC_STACK 0)
-  bc=-1 line=1
+  bc=0 line=1
   bc=0 line=4
   bc=9 line=5
   bc=12 line=6
diff --git a/tests/cmdline/cmd_showbc.py.exp b/tests/cmdline/cmd_showbc.py.exp
index 839034a69..b0a9016c5 100644
--- a/tests/cmdline/cmd_showbc.py.exp
+++ b/tests/cmdline/cmd_showbc.py.exp
@@ -5,7 +5,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names:
 (N_STATE 3)
 (N_EXC_STACK 0)
-  bc=-1 line=1
+  bc=0 line=1
 ########
   bc=\\d\+ line=155
 00 MAKE_FUNCTION \.\+
@@ -38,7 +38,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 (INIT_CELL 14)
 (INIT_CELL 15)
 (INIT_CELL 16)
-  bc=-4 line=1
+  bc=0 line=1
 ########
   bc=\\d\+ line=126
 00 LOAD_CONST_NONE
@@ -318,7 +318,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 \.\+rg names:
 (N_STATE 22)
 (N_EXC_STACK 0)
-  bc=-1 line=1
+  bc=0 line=1
 ########
   bc=\\d\+ line=132
 00 LOAD_CONST_SMALL_INT 1
@@ -392,7 +392,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names:
 (N_STATE 2)
 (N_EXC_STACK 0)
-  bc=-1 line=1
+  bc=0 line=1
   bc=0 line=143
   bc=3 line=144
   bc=6 line=145
@@ -416,7 +416,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names:
 (N_STATE 1)
 (N_EXC_STACK 0)
-  bc=-1 line=1
+  bc=0 line=1
 ########
   bc=13 line=149
 00 LOAD_NAME __name__ (cache=0)
@@ -432,7 +432,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names: self
 (N_STATE 4)
 (N_EXC_STACK 0)
-  bc=-1 line=1
+  bc=0 line=1
   bc=0 line=156
 00 LOAD_GLOBAL super (cache=0)
 \\d\+ LOAD_GLOBAL __class__ (cache=0)
@@ -449,7 +449,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names: * * *
 (N_STATE 9)
 (N_EXC_STACK 0)
-  bc=-\\d\+ line=1
+  bc=0 line=1
   bc=0 line=59
 ########
 00 LOAD_NULL
@@ -473,7 +473,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names: * * *
 (N_STATE 10)
 (N_EXC_STACK 0)
-  bc=-\\d\+ line=1
+  bc=0 line=1
   bc=0 line=60
 ########
 00 BUILD_LIST 0
@@ -494,7 +494,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names: * * *
 (N_STATE 11)
 (N_EXC_STACK 0)
-  bc=-\\d\+ line=1
+  bc=0 line=1
 ########
 00 BUILD_MAP 0
 02 LOAD_FAST 2
@@ -515,7 +515,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names: *
 (N_STATE 4)
 (N_EXC_STACK 0)
-  bc=-\\d\+ line=1
+  bc=0 line=1
 ########
   bc=\\d\+ line=113
 00 LOAD_DEREF 0
@@ -534,7 +534,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names: * b
 (N_STATE 4)
 (N_EXC_STACK 0)
-  bc=-\\d\+ line=1
+  bc=0 line=1
 ########
   bc=\\d\+ line=139
 00 LOAD_FAST 1
diff --git a/tests/cmdline/cmd_verbose.py.exp b/tests/cmdline/cmd_verbose.py.exp
index 60b499c26..a2fdf1f00 100644
--- a/tests/cmdline/cmd_verbose.py.exp
+++ b/tests/cmdline/cmd_verbose.py.exp
@@ -6,7 +6,7 @@ Raw bytecode (code_info_size=\\d\+, bytecode_size=\\d\+):
 arg names:
 (N_STATE 2)
 (N_EXC_STACK 0)
-  bc=-1 line=1
+  bc=0 line=1
   bc=0 line=3
 00 LOAD_NAME print (cache=0)
 04 LOAD_CONST_SMALL_INT 1
diff --git a/tests/import/mpy_native.py b/tests/import/mpy_native.py
index 03abab349..749320dbb 100644
--- a/tests/import/mpy_native.py
+++ b/tests/import/mpy_native.py
@@ -56,8 +56,8 @@ user_files = {
     '/mod1.mpy': (
         b'M\x05\x0b\x1f\x20' # header
 
-        b'\x24' # n bytes, bytecode
-            b'\x00\x05\x00\x00\x00\x00\xff' # prelude
+        b'\x20' # n bytes, bytecode
+            b'\x00\x08\x00\x00\x00\x00' # prelude
             b'\x51' # LOAD_CONST_NONE
             b'\x63' # RETURN_VALUE