This implements the copy() built-in function. It may not work in all
cases, but should work in most cases.
This commit gets the following 3 packages to compile, according to
tinygo-site/imports/main.go:
* encoding/base32
* encoding/base64
* encoding/pem (was blocked by encoding/base64)
* Loading from a dirty global must be done at runtime (!). For some
reason this wasn't already the case.
* Global variables somehow had IsConstant() the wrong way round,
returning the inverse from what they should.
* Do binary and logical operations at runtime if necessary, relying on
const propagation in the IR builder.
* Don't try to interpret functions that take a dirty parameter. Call
them at runtime.
This interpreter currently complements the Go SSA level interpreter. It
may stay complementary or may be the only interpreter in the future.
This interpreter is experimental and not yet finished (there are known
bugs!) so it is disabled by default. It can be enabled by passing the
-initinterp flag.
The goal is to be able to run all initializations at compile time except
for the ones having side effects. This mostly works except perhaps for a
few edge cases.
In the future, this interpeter may be used to actually run regular Go
code, perhaps in a shell.
