Hi Nicolai, On Fri, Feb 26, 2016 at 1:50 PM, Nicolai Hess <[email protected]> wrote:
> 17618 > <https://pharo.fogbugz.com/f/cases/17618/Failing-test-ReleaseTest-testInstalledMethodsWithIncorrectTrailerKind> > Failing test: ReleaseTest>>#testInstalledMethodsWithIncorrectTrailerKind > Interesting bug. > someone who can tell me what exactly is this trailer kind and why it is > based > on some "flag" in "method at: method size". > There's a rich class comment in CompiledMethodTrailer which explains a lot, but let me add a little. Back in the day the source pointer in methods (the pointer that says which of the two source files and where in the file a method's source is kept) was stored in three bytes added onto the end of a CompiledMethod after its endPC. Then Dan Ingalls added the ability to not have source files at all but just to have named temporary variables. he added a compressed version of the temp names in bytes tacked on at the end of a method, replacing the source pointer. IIRC the difference between a source pointer, no source pointer, or a compressed version of the temp names was all encoded in the last byte. Round about 2009 Igor Stasenko did a really nice reimplementation of this scheme where he factored out the encoding tricks into CompiledMethodTrailer, allowing one to generalize the scheme and add new encoding types, for a total of 256 different kinds of trailer. (and if you already know all of this, forgive me for trying to teach you to suck eggs) Anyway this trailer is CompiledMethodTrailer >>encodeEmbeddedSourceQCompress "data is string with method's source code, encode it using qCompress method" self encodeUsingQCompress CompiledMethodTrailer >>decodeEmbeddedSourceQCompress "data is string with method's source code, encoded using qCompress method" self qDecompress. HTH And why it seems to be wrong for many GT-methods: > > (CompiledMethod allInstances select:[:m | (m at: m size) = 24]) > collect:[:k | > k -> k trailer kind] "an Array(String > class>>#gtInspectorFourtyTwo->#EmbeddedSourceQCompress > OSEnvironment>>#getEnv:->#EmbeddedSourceQCompress > OSEnvironment>>#getEnv:->#EmbeddedSourceQCompress GlobalVariable > class>>#gtExampleSmalltalk->#EmbeddedSourceQCompress VirtualMachine > class>>#gtExampleBasic->#EmbeddedSourceQCompress GLMBrowser > class>>#gtExampleBasic->#EmbeddedSourceQCompress RPackageTag > class>>#gtExamplePackageTag->#EmbeddedSourceQCompress Object > class>>#gtExampleBasic->#EmbeddedSourceQCompress GLMCompositePresentation > class>>#gtExampleCompositePresentation->#EmbeddedSourceQCompress > LiteralVariable > class>>#gtExampleUniqueLiteralVariable->#EmbeddedSourceQCompress > GTSpotterRecorderEvent > class>>#gtExampleAnySubclass->#EmbeddedSourceQCompress > MetacelloAbstractPackageSpec > class>>#gtExamplePackageSpec->#EmbeddedSourceQCompress > MetacelloProjectReferenceSpec > class>>#gtExampleProjectReferenceSpec->#EmbeddedSourceQCompress > MetacelloProjectSpec > class>>#gtExampleMetacelloSpec->#EmbeddedSourceQCompress MetacelloSpec > class>>#gtExampleMetacelloSpec->#EmbeddedSourceQCompress MetacelloVersion > class>>#gtExampleMetacelloVersion->#EmbeddedSourceQCompress GLMPresentation > class>>#gtExampleBasic->#EmbeddedSourceQCompress Bag > class>>#gtExampleBagWithTenElements->#EmbeddedSourceQCompress Bag > class>>#gtExampleBagWithOneElement->#EmbeddedSourceQCompress > GTDummyExamplesRecursive class>>#h->#EmbeddedSourceQCompress GLMAlertBrick > class>>#gtExample->#EmbeddedSourceQCompress > GTDummyExampleProvider>>#a->#EmbeddedSourceQCompress > GTDummyExampleProvider>>#b->#EmbeddedSourceQCompress > GTDummyExampleWithAssertions>>#a->#EmbeddedSourceQCompress > GTDummyExampleWithAssertions>>#b->#EmbeddedSourceQCompress GTDummyExamples > class>>#l->#EmbeddedSourceQCompress GTDummyExamples > class>>#o->#EmbeddedSourceQCompress GTDummyExamplesInvalid > class>>#a:->#EmbeddedSourceQCompress GTDummyExamplesPragmas > class>>#a->#EmbeddedSourceQCompress GTDummyExamplesPragmas > class>>#c->#EmbeddedSourceQCompress GTDummyExamplesPragmas > class>>#b->#EmbeddedSourceQCompress GLMCollapsableBrick > class>>#gtExample->#EmbeddedSourceQCompress FileReference > class>>#gtExampleText->#EmbeddedSourceQCompress GTSpotterStep > class>>#gtExampleBasic->#EmbeddedSourceQCompress GTEventAnnouncement > class>>#gtExampleEmptyAnnouncement->#EmbeddedSourceQCompress > UndefinedObject>>#DoIt->#EmbeddedSourceQCompress > UndefinedObject>>#DoIt->#EmbeddedSourceQCompress)" > _,,,^..^,,,_ best, Eliot
