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garble/testdata
Daniel Martí 79c775e218
obfuscate unexported names like exported ones (#227)
In 90fa325da7, the obfuscation logic was changed to use hashes for
exported names, but incremental names starting at just one letter for
unexported names. Presumably, this was done for the sake of binary size.

I argue that this is not a good idea for the default mode for a number
of reasons:

1) It makes reversing of stack traces nearly impossible for unexported
   names, since replacing an obfuscated name "c" with "originalName"
   would trigger too many false positives by matching single characters.

2) Exported and unexported names aren't different. We need to know how
   names were obfuscated at a later time in both cases, thanks to use
   cases like -ldflags=-X. Using short names for one but not the other
   doesn't make a lot of sense, and makes the logic inconsistent.

3) Shaving off three bytes for unexported names doesn't seem like a huge
   deal for the default mode, when we already have -tiny to optimize for
   size.

This saves us a bit of work, but most importantly, simplifies the
obfuscation state as we no longer need to carry privateNameMap between
the compile and link stages.

	name     old time/op       new time/op       delta
	Build-8        153ms ± 2%        150ms ± 2%    ~     (p=0.065 n=6+6)

	name     old bin-B         new bin-B         delta
	Build-8        7.09M ± 0%        7.08M ± 0%  -0.24%  (p=0.002 n=6+6)

	name     old sys-time/op   new sys-time/op   delta
	Build-8        296ms ± 5%        277ms ± 6%  -6.50%  (p=0.026 n=6+6)

	name     old user-time/op  new user-time/op  delta
	Build-8        562ms ± 1%        558ms ± 3%    ~     (p=0.329 n=5+6)

Note that I do not oppose using short names for both exported and
unexported names in the future for -tiny, since reversing of stack
traces will by design not work there. The code can be resurrected from
the git history if we want to improve -tiny that way in the future, as
we'd need to store state in header files again.

Another major cleanup we can do here is to no longer use the
garbledImports map. From a look at obfuscateImports, we hash a package's
import path with its action ID, much like exported names, so we can
simply re-do that hashing for the linker's -X flag.

garbledImports does have some logic to handle duplicate package names,
but it's worth noting that should not affect package paths, as they are
always unique. That area of code could probably do with some
simplification in the future, too.

While at it, make hashWith panic if either parameter is empty.
obfuscateImports was hashing the main package path without a salt due to
a bug, so we want to catch those in the future.

Finally, make some tiny spacing and typo tweaks to the README.
4 years ago
..
bench set up an AUTHORS file to attribute copyright 5 years ago
mod support building modules which require other modules 5 years ago
scripts obfuscate unexported names like exported ones (#227) 4 years ago