Inlining of code that corresponds to source code lines, can make it hard to distinguish later between code which is only reachable from except handlers, and that which is reachable in normal control flow. This caused problems with the debugger's jump feature.
This PR turns off the inlining optimisation for code which has line numbers. We still inline things like the implicit "return None".
Break up COMPARE_OP into four logically distinct opcodes:
* COMPARE_OP for rich comparisons
* IS_OP for 'is' and 'is not' tests
* CONTAINS_OP for 'in' and 'is not' tests
* JUMP_IF_NOT_EXC_MATCH for checking exceptions in 'try-except' statements.
Document that lnotab can contain invalid bytecode offsets (because of
terrible reasons that are difficult to fix). Make dis.findlinestarts()
ignore invalid offsets in lnotab. All other uses of lnotab in CPython
(various reimplementations of addr2line or line2addr in Python, C and gdb)
already ignore this, because they take an address to look for, instead.
Add tests for the result of dis.findlinestarts() on wacky constructs in
test_peepholer.py, because it's the easiest place to add them.
Fix a regression introduced by af8646c805 that was causing code of the form:
if True and False:
do_something()
to be optimized incorrectly, eliminating the block.
The peephole optimizer was not optimizing correctly bytecode after negative deltas were introduced. This is due to the fact that some special values (255) were being searched for in both instruction pointer delta and line number deltas.
It no longer spends much time doing complex calculations and no
longer consumes much memory for creating large constants that will
be dropped later.
This fixes also bpo-21074.
* Constant statements will be ignored and the compiler will emit a
SyntaxWarning.
* Replace constant statement (ex: "1") with an expression statement
(ex: "x=1").
* test_traceback: use context manager on the file.
Issue #26204.
I have compared output between pre- and post-patch runs of these tests
to make sure there's nothing missing and nothing broken, on both
Windows and Linux. The only differences I found were actually tests
that were previously *not* run.
where the right hand operand is a set of constants, by turning the set into
a frozenset and pre-building it as a constant. The comparison operation
is made against the constant instead of building a new set each time it is
executed (a similar optimization already existed which turned a list of
constants into a pre-built tuple). Patch and additional tests by Dave
Malcolm.
This patch by Antoine Pitrou optimizes the bytecode for conditional branches by
merging the following "POP_TOP" instruction into the conditional jump. For
example, the list comprehension "[x for x in l if not x]" produced the
following bytecode:
1 0 BUILD_LIST 0
3 LOAD_FAST 0 (.0)
>> 6 FOR_ITER 23 (to 32)
9 STORE_FAST 1 (x)
12 LOAD_FAST 1 (x)
15 JUMP_IF_TRUE 10 (to 28)
18 POP_TOP
19 LOAD_FAST 1 (x)
22 LIST_APPEND 2
25 JUMP_ABSOLUTE 6
>> 28 POP_TOP
29 JUMP_ABSOLUTE 6
>> 32 RETURN_VALUE
but after the patch it produces the following bytecode:
1 0 BUILD_LIST 0
3 LOAD_FAST 0 (.0)
>> 6 FOR_ITER 18 (to 27)
9 STORE_FAST 1 (x)
12 LOAD_FAST 1 (x)
15 POP_JUMP_IF_TRUE 6
18 LOAD_FAST 1 (x)
21 LIST_APPEND 2
24 JUMP_ABSOLUTE 6
>> 27 RETURN_VALUE
Notice that not only the code is shorter, but the conditional jump
(POP_JUMP_IF_TRUE) jumps right to the start of the loop instead of going through
the JUMP_ABSOLUTE at the end. "continue" statements are helped
similarly.
Furthermore, the old jump opcodes (JUMP_IF_FALSE, JUMP_IF_TRUE) have been
replaced by two new opcodes:
- JUMP_IF_TRUE_OR_POP, which jumps if true and pops otherwise
- JUMP_IF_FALSE_OR_POP, which jumps if false and pops otherwise
Completely get rid of StringIO.py and cStringIO.c.
I had to fix a few tests and modules beyond what Christian did, and
invent a few conventions. E.g. in elementtree, I chose to
write/return Unicode strings whe no encoding is given, but bytes when
an explicit encoding is given. Also mimetools was made to always
assume binary files.
Irit Katriel
Dennis Sweeney
Brandt Bucher
Serhiy Storchaka
Mark Shannon
T. Wouters
Joannah Nanjekye
Victor Stinner
Pablo Galindo
Victor Stinner
Zachary Ware
Nick Coghlan
Ezio Melotti
Martin v. Löwis
Mark Dickinson
Raymond Hettinger
Antoine Pitrou
Benjamin Peterson
Georg Brandl
Jeffrey Yasskin
Guido van Rossum