[issue2197] Further simplify dict literal bytecode

2008-04-08 Thread Alexander Belopolsky 

Alexander Belopolsky [EMAIL PROTECTED] added the comment:

Python-3000 discussion http://mail.python.org/pipermail/python-
3000/2008-March/012753.html did not reveal any opposition to the idea 
of batch processing of dict displays.  However, a compromise suggestion 
was made to  limit batches to 256 items 
http://mail.python.org/pipermail/python-3000/2008-March/012829.html.   
I don't think this type of micro-optimization belongs to the core.  A 
rare application that would benefit from limited size batch processing 
can do so explicitly using dict.update.

See also relevant discussion at issue2292 (starting at msg65111).

I believe this issue can be reopen.  I will submit documentation patch 
if the change is accepted in principle.

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[issue2197] Further simplify dict literal bytecode

2008-04-08 Thread Raymond Hettinger 

Raymond Hettinger [EMAIL PROTECTED] added the comment:

-1   I don't think this is worth the semantic change.  The current 
approach doesn't require special cases for different dict sizes. The 
code/time savings is very small (seven bytes of opcodes per item get 
condensed by only one byte and the cost of one time around the eval-
loop is tiny in comparison to the cost of inserting a new dict entry).  
Besides, dict literals almost never occur in the inner-loops of time 
critical code. 

I recommend that this stay closed.  Better to aim for meaningful 
optimizations using the AST and avoid micro-optimizations that subtly 
change semantics.

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[issue2197] Further simplify dict literal bytecode

2008-03-19 Thread Sean Reifschneider 

Sean Reifschneider [EMAIL PROTECTED] added the comment:

As addition thought is required by Alexander, I'm going to close this as
postponed and you can re-open it if after further consideration you
think it needs to be applied.  Probably would be good to discuss on
python-dev if you think it still needs to go forward though.

--
assignee:  - rhettinger
nosy: +jafo
priority:  - normal
resolution:  - postponed
status: open - closed

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[issue2197] Further simplify dict literal bytecode

2008-02-26 Thread Alexander Belopolsky 

New submission from Alexander Belopolsky:

I am attaching a proof-of-concept patch that changes the bytecode 
generated from {1:1,2:2,3:3,4:4} from 

BUILD_MAP4  
LOAD_CONST   2 (1)  
LOAD_CONST   2 (1)  
STORE_MAP 
LOAD_CONST   1 (2)  
LOAD_CONST   1 (2)  
STORE_MAP 
LOAD_CONST   4 (3)  
LOAD_CONST   4 (3)  
STORE_MAP 
LOAD_CONST   3 (4)  
LOAD_CONST   3 (4)  
STORE_MAP 

to

LOAD_CONST   1 (4)  
LOAD_CONST   1 (4)  
LOAD_CONST   2 (3)   
LOAD_CONST   2 (3)  
  
LOAD_CONST   3 (2)
LOAD_CONST   3 (2) 
LOAD_CONST   4 (1)  
LOAD_CONST   4 (1)  
BUILD_MAP4  
 
and changes BUILD_MAP to behave similarly to BUILD_(SET|LIST|TUPLE) and 
consume 2*n items from the stack.

The advantage is more compact and faster bytecode and uniform treatment 
of BUILD_* instructions.

--
components: Interpreter Core
files: dict-literal.diff
keywords: patch
messages: 63063
nosy: belopolsky
severity: normal
status: open
title: Further simplify dict literal bytecode
versions: Python 3.0
Added file: http://bugs.python.org/file9564/dict-literal.diff

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