tree b631166b29128e07e71b263e145634a6870c47a8
parent d114261608f986b5c797eef4330fbe32041d3eb6
author Jeremy Hylton <jeremy@alum.mit.edu> 1003325849 +0000
committer Jeremy Hylton <jeremy@alum.mit.edu> 1003325849 +0000
HG:extra convert_revision:svn%3A6015fed2-1504-0410-9fe1-9d1591cc4771/python/branches/legacy-trunk%4023759

Vastly improved stacksize calculation.

There are now no known cases where the compiler package computes a
stack depth lower than the one computed by the builtin compiler.  (To
achieve this state, we had to fix bugs in both compilers :-).

The chief change is to do the depth calculations with respect to basic
blocks.  The stack effect of block is calculated.  Then the flow graph
is traversed using breadth-first search to find the max weight path
through the graph.

Had to fix the StackDepthTracker to calculate the right info for
several opcodes: LOAD_ATTR, CALL_FUNCTION (and friends), MAKE_CLOSURE,
and DUP_TOPX.

XXX Still need to handle free variables in MAKE_CLOSURE.

XXX There are still a lot of places where the computed stack depth is
larger than for the builtin compiler.  These won't cause the
interpreter to overflow the frame, but they waste space.