[PATCH] Add a ValueMap type, whose keys act like WeakVHs

ValueMap<Value*, T> is safe to use even when keys get RAUWed and deleted during its lifetime. By default the keys act like WeakVHs, but users can pass a third template parameter to configure how updates work and whether to do anything beyond updating the map on each action.

This type should make http://codereview.appspot.com/133043/diff/1/2 quite a bit simpler, but I haven't yet updated it so I could have missed something.

[Jeffrey Yasskin, 2009-10-17 07:42:54]

This breaks check-lit with the following error:

********************
UNRESOLVED: LLVM-Unit::ADT/Debug/ADTTests/ValueMapTest/1.NoFollowRAUW (103 of
4819)
******************** TEST
'LLVM-Unit::ADT/Debug/ADTTests/ValueMapTest/1.NoFollowRAUW' FAILED
********************
Exception during script execution:
Traceback (most recent call last):
  File "/Users/jyasskin/src/llvm/jit_del/src/utils/lit/lit.py", line 118, in
runTest
    self.litConfig)
  File "/Users/jyasskin/src/llvm/jit_del/src/utils/lit/TestFormats.py", line 58,
in execute
    out, err, exitCode = TestRunner.executeCommand(cmd)
  File "/Users/jyasskin/src/llvm/jit_del/src/utils/lit/TestRunner.py", line 23,
in executeCommand
    env=env)
  File
"/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py",
line 595, in __init__
    errread, errwrite)
  File
"/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py",
line 1092, in _execute_child
    raise child_exception
OSError: [Errno 20] Not a directory



I guess I'll have to figure out how to fix it before submitting.