This commit changes many things:
* Most interface-related operations are moved into an optimization
pass for more modularity. IR construction creates pseudo-calls which
are lowered in this pass.
* Type codes are assigned in this interface lowering pass, after DCE.
* Type codes are sorted by usage: types more often used in type
asserts are assigned lower numbers to ease jump table construction
during machine code generation.
* Interface assertions are optimized: they are replaced by constant
false, comparison against a constant, or a typeswitch with only
concrete types in the general case.
* Interface calls are replaced with unreachable, direct calls, or a
concrete type switch with direct calls depending on the number of
implementing types. This hopefully makes some interface patterns
zero-cost.
These changes lead to a ~0.5K reduction in code size on Cortex-M for
testdata/interface.go. It appears that a major cause for this is the
replacement of function pointers with direct calls, which are far more
susceptible to optimization. Also, not having a fixed global array of
function pointers greatly helps dead code elimination.
This change also makes future optimizations easier, like optimizations
on interface value comparisons.
This avoids a ton of duplication and makes it easier to change a generic
target (for example, the "cortex-m" target) for all boards that use it.
Also, by making it possible to inherit properties from a parent target
specification, it is easier to support out-of-tree boards that don't
have to be updated so often. A target specification for a
special-purpose board can simply inherit the specification of a
supported chip and override the properites it needs to override (like
the programming interface).
This can be used in the future to trigger garbage collection. For now,
it provides a more useful error message in case the heap is completely
filled up.
Make sure every to-be-implemented GC can use the same interface. As a
result, a 1MB chunk of RAM is allocated on Unix systems on init instead
of allocating on demand.
Move attaching debug info to where the function is defined. As LLVM does
not allow setting debug info on declarations, this makes more sense and
is less error-prone.
This commit fixes debug info when using CGo.
* Use 64-bit integers on 64-bit platforms, just like gc and gccgo:
https://golang.org/doc/go1.1#int
* Do not use a separate length type. Instead, use uintptr everywhere a
length is expected.
To support the WebAssembly<->JS barrier, return values also have to be
passed in memory. i64 return values are used by syscall/js, so must be
supported across this ABI barrier.
* 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.
Cast operations will still be evaluated at compile time in all cases
they did before because of the built-in constant propagation of the
IRBuilder, but when one of the parameters is not a constant it will
transparently be evaluated at runtime.
This avoids some errors in the partial evaluator. It is not yet complete
as all binops will need a similar treatment.
This makes it easier to get an overview of everything interface related,
because interfaces are quite complicated and were scattered through the
(huge!) compiler.go file.
Let the standard library think that it is compiling for js/wasm.
The most correct way of supporting bare metal Cortex-M targets would be
using the 'arm' build tag and specifying no OS or an 'undefined' OS
(perhaps GOOS=noos?). However, there is no build tag for specifying no
OS at all, the closest possible is GOOS=js which makes very few
assumptions.
Sadly GOOS=js also makes some assumptions: it assumes to be running with
GOARCH=wasm. This would not be such a problem, just add js, wasm and arm
as build tags. However, having two GOARCH build tags leads to an error
in internal/cpu: it defines variables for both architectures which then
conflict.
To work around these problems, the 'arm' target has been renamed to
'tinygo.arm', which should work around these problems. In the future, a
GOOS=noos (or similar) should be added which can work with any
architecture and doesn't implement OS-specific stuff.
Ayke van Laethem
Ron Evans
Denys Smirnov
Marc-Antoine Ruel