[squeak-dev] Failing Decompiler tests - how to fix?
Frank Shearar
frank.shearar at angband.za.org
Tue Dec 21 11:07:31 UTC 2010
One of the failing Decompiler tests is when we check
MethodPragmaTest>>testCompileCharacter:
testCompileCharacter
self assertPragma: 'foo: $a' givesKeyword: #foo: arguments: #( $a ).
self assertPragma: 'foo: $ ' givesKeyword: #foo: arguments: #( $ ).
As bytecodes, this method looks like this:
37 <70> self
38 <21> pushConstant: 'foo: $a'
39 <22> pushConstant: #foo:
40 <23> pushConstant: #($a)
41 <83 60> send: assertPragma:givesKeyword:arguments:
43 <87> pop
44 <70> self
45 <24> pushConstant: 'foo: $ '
46 <22> pushConstant: #foo:
47 <25> pushConstant: {Character space}
48 <83 60> send: assertPragma:givesKeyword:arguments:
50 <87> pop
51 <78> returnSelf
And when decompiled, we have:
testCompileCharacter
self
assertPragma: 'foo: $a'
givesKeyword: #foo:
arguments: #($a ).
self
assertPragma: 'foo: $ '
givesKeyword: #foo:
arguments: ((Array new: 1) at: 1 put: Character space; yourself)
Notice that the literal #( $ ) has expanded into an Array declaration etc.
When we compile this decompiled string, we end up with the rather different
self
pushConstant: ''foo: $a''
pushConstant: #foo:
pushConstant: #($a)
send: #assertPragma:givesKeyword:arguments: (3 args)
pop
self
pushConstant: ''foo: $ ''
pushConstant: #foo:
pushLit: Array
pushConstant: 1
send: #new: (1 arg)
dup
pushConstant: 1
pushLit: Character
send: #space (0 args)
send: #at:put: (2 args)
pop
send: #yourself (0 args)
send: #assertPragma:givesKeyword:arguments: (3 args)
pop
returnSelf
The decompiler turns that pushConstant: into a whole bunch of stuff
because it interprets #( $ ) as (Array new: 1) at: 1 put: Character
space; yourself.
(The same thing happens for SyntaxMorph>>replaceSel:menuItem: and
SyntaxMorph>>replaceKeyWord:menuItem. It looks like $ is being
interpreted as Character space, and then decompiled to pushLit:
Character send: #space.)
That's all fine, but what happens is that when you compile the
decompiled method (and then decompile _that_ method), you can't have the
newly-decompiled method match the original decompiled method. The parse
tree are different: where the original has a LiteralNode, the new
version has a CascadeNode.
frank
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