[pypy-svn] r65361 - pypy/branch/pyjitpl5-experiments/pypy/jit/metainterp/doc

fijal at codespeak.net fijal at codespeak.net
Fri May 22 21:18:48 CEST 2009

Author: fijal
Date: Fri May 22 21:18:45 2009
New Revision: 65361

   pypy/branch/pyjitpl5-experiments/pypy/jit/metainterp/doc/simple_virtualizables.txt   (contents, props changed)
start a document explaining simplified approach to virtualizables

Added: pypy/branch/pyjitpl5-experiments/pypy/jit/metainterp/doc/simple_virtualizables.txt
--- (empty file)
+++ pypy/branch/pyjitpl5-experiments/pypy/jit/metainterp/doc/simple_virtualizables.txt	Fri May 22 21:18:45 2009
@@ -0,0 +1,24 @@
+Simplified virtualizables
+As a first step for speeding up code, we plan to implement simplified version
+of virtualizables. Simplified in a sense that it won't support virtuals stored
+on virtualizables.
+For those unaware:
+* Virtuals are objects which are known not to escape from jit code, hence
+  they're not allocated at all and their fields are stored in registers and or
+  on the stack.
+* Virtualizables are objects that are known to escape (for example the frame
+  object), but they're stored anyway on the stack with a way to access and
+  modify from outside the jit code. So the jit knows where they're and have
+  a way to reconstruct them if necessary.
+The way to implement virtualizables would be as follows:
+* During translation, all field accesses to virtualizables are replace by
+  calls to helpers that read/write fields via the jit.

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