Author: Antonio Cuni <[email protected]>
Branch: extradoc
Changeset: r4286:e995aa00abe5
Date: 2012-07-04 11:46 +0200
http://bitbucket.org/pypy/extradoc/changeset/e995aa00abe5/
Log: (arigo, antocuni) progress
diff --git a/talk/ep2012/jit/talk/talk.rst b/talk/ep2012/jit/talk/talk.rst
--- a/talk/ep2012/jit/talk/talk.rst
+++ b/talk/ep2012/jit/talk/talk.rst
@@ -297,67 +297,249 @@
- unroll
-Intbound optimization
+Intbound optimization (1)
+-------------------------
+
+|example<| |small| intbound.py |end_small| |>|
+
+.. sourcecode:: python
+
+ def fn():
+ i = 0
+ while i < 5000:
+ i += 2
+ return i
+
+|end_example|
+
+Intbound optimization (2)
+--------------------------
+
+|scriptsize|
+|column1|
+|example<| |small| unoptimized |end_small| |>|
+
+.. sourcecode:: python
+
+ ...
+ i17 = int_lt(i15, 5000)
+ guard_true(i17)
+ i19 = int_add_ovf(i15, 2)
+ guard_no_overflow()
+ ...
+
+|end_example|
+
+|pause|
+
+|column2|
+|example<| |small| optimized |end_small| |>|
+
+.. sourcecode:: python
+
+ ...
+ i17 = int_lt(i15, 5000)
+ guard_true(i17)
+ i19 = int_add(i15, 2)
+ ...
+
+|end_example|
+|end_columns|
+|end_scriptsize|
+
+|pause|
+
+* It works **often**
+
+* array bound checking
+
+* intbound info propagates all over the trace
+
+
+Virtuals (1)
+-------------
+
+|example<| |small| virtuals.py |end_small| |>|
+
+.. sourcecode:: python
+
+ def fn():
+ i = 0
+ while i < 5000:
+ i += 2
+ return i
+
+|end_example|
+
+
+Virtuals (2)
+------------
+
+|scriptsize|
+|column1|
+|example<| |small| unoptimized |end_small| |>|
+
+.. sourcecode:: python
+
+ ...
+ guard_class(p0, W_IntObject)
+ i1 = getfield_pure(p0, 'intval')
+ i2 = int_add(i1, 2)
+ p3 = new(W_IntObject)
+ setfield_gc(p3, i2, 'intval')
+ ...
+
+|end_example|
+
+|pause|
+
+|column2|
+|example<| |small| optimized |end_small| |>|
+
+.. sourcecode:: python
+
+ ...
+ i2 = int_add(i1, 2)
+ ...
+
+|end_example|
+|end_columns|
+|end_scriptsize|
+
+|pause|
+
+* The most important optimization (TM)
+
+* It works both inside the trace and across the loop
+
+* It works for tons of cases
+
+ - e.g. function frames
+
+
+Constant folding (1)
+---------------------
+
+|example<| |small| constfold.py |end_small| |>|
+
+.. sourcecode:: python
+
+ def fn():
+ i = 0
+ while i < 5000:
+ i += 2
+ return i
+
+|end_example|
+
+
+Constant folding (2)
+--------------------
+
+|scriptsize|
+|column1|
+|example<| |small| unoptimized |end_small| |>|
+
+.. sourcecode:: python
+
+ ...
+ i1 = getfield_pure(p0, 'intval')
+ i2 = getfield_pure(<W_Int(2)>,
+ 'intval')
+ i3 = int_add(i1, i2)
+ ...
+
+|end_example|
+
+|pause|
+
+|column2|
+|example<| |small| optimized |end_small| |>|
+
+.. sourcecode:: python
+
+ ...
+ i1 = getfield_pure(p0, 'intval')
+ i3 = int_add(i1, 2)
+ ...
+
+|end_example|
+|end_columns|
+|end_scriptsize|
+
+|pause|
+
+* It "finishes the job"
+
+* Works well together with other optimizations (e.g. virtuals)
+
+* It also does "normal, boring, static" constant-folding
+
+
+Out of line guards (1)
+-----------------------
+
+|example<| |small| outoflineguards.py |end_small| |>|
+
+.. sourcecode:: python
+
+ N = 2
+ def fn():
+ i = 0
+ while i < 5000:
+ i += N
+ return i
+
+|end_example|
+
+
+Out of line guards (2)
----------------------
|scriptsize|
|column1|
|example<| |small| unoptimized |end_small| |>|
-.. sourcecode:: java
+.. sourcecode:: python
-
-
-jjjjjjj
- class IncrOrDecr {
...
- public DoSomething(I)I
- ILOAD 1
- IFGE LABEL_0
- ILOAD 1
- ICONST_1
- ISUB
- IRETURN
- LABEL_0
- ILOAD 1
- ICONST_1
- IADD
- IRETURN
- }
+ quasiimmut_field(<Cell>, 'val')
+ guard_not_invalidated()
+ p0 = getfield_gc(<Cell>, 'val')
+ ...
+ i2 = getfield_pure(p0, 'intval')
+ i3 = int_add(i1, i2)
|end_example|
|pause|
|column2|
-|example<| |small| Java bytecode |end_small| |>|
+|example<| |small| optimized |end_small| |>|
-.. sourcecode:: java
+.. sourcecode:: python
- class tracing {
...
- public static main(
- [Ljava/lang/String;)V
- ...
- LABEL_0
- ILOAD 2
- ILOAD 1
- IF_ICMPGE LABEL_1
- ALOAD 3
- ILOAD 2
- INVOKEINTERFACE
- Operation.DoSomething (I)I
- ISTORE 2
- GOTO LABEL_0
- LABEL_1
- ...
- }
+ guard_not_invalidated()
+ ...
+ i3 = int_add(i1, 2)
+ ...
|end_example|
|end_columns|
|end_scriptsize|
+|pause|
+* Python is too dynamic, but we don't care :-)
+
+* No overhead in assembler code
+
+* Used a bit "everywhere"
+
+* Credits to Mark Shannon
+
+ - for the name :-)
Guards
-------
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