LLVM ComputeValueVTs recursively expands arrays and structs into one
value type per scalar leaf. SelectionDAG call lowering allocates data
structures proportional to this count, which makes very large values
exhaust memory or crash LLVM.
Count scalar leaves and use pointers for internal parameters and results
when the count exceeds 1024. A result pointer is the first parameter,
and aggregate parameters point to read-only memory. Exported function
types are unchanged.
Keep these SSA values in memory and copy them with memcpy when needed.
Handle calls, interfaces, maps, channels, selects, defers, goroutines,
phis, and multiple results. Update the expected compiler IR and re-enable
the native compress/flate tests.
getFunction and getLLVMFunctionType duplicate the construction of LLVM
result types for functions with zero, one, or multiple results.
Move this code to getLLVMResultType. Also split the existing parameter
expansion code into expandDirectFormalParamType so callers can request
the current flattened parameter types directly.
This is a big change: apart from removing LLVM 14 it also removes typed
pointer support (which was only fully supported in LLVM up to version
14). This removes about 200 lines of code, but more importantly removes
a ton of special cases for LLVM 14.
It is possible to create function-local named types:
func foo() any {
type named int
return named(0)
}
This patch makes sure they don't alias with named types declared at the
package scope.
Bug originally found by Damian Gryski while working on reflect support.
This removes the parentHandle argument from the internal calling convention.
It was formerly used to implment coroutines.
Now that coroutines have been removed, it is no longer necessary.
Instead of doing everything in the interrupt lowering pass, generate
some more code in gen-device to declare interrupt handler functions and
do some work in the compiler so that interrupt lowering becomes a lot
simpler.
This has several benefits:
- Overall code is smaller, in particular the interrupt lowering pass.
- The code should be a bit less "magical" and instead a bit easier to
read. In particular, instead of having a magic
runtime.callInterruptHandler (that is fully written by the interrupt
lowering pass), the runtime calls a generated function like
device/sifive.InterruptHandler where this switch already exists in
code.
- Debug information is improved. This can be helpful during actual
debugging but is also useful for other uses of DWARF debug
information.
For an example on debug information improvement, this is what a
backtrace might look like before this commit:
Breakpoint 1, 0x00000b46 in UART0_IRQHandler ()
(gdb) bt
#0 0x00000b46 in UART0_IRQHandler ()
#1 <signal handler called>
[..etc]
Notice that the debugger doesn't see the source code location where it
has stopped.
After this commit, breaking at the same line might look like this:
Breakpoint 1, (*machine.UART).handleInterrupt (arg1=..., uart=<optimized out>) at /home/ayke/src/github.com/tinygo-org/tinygo/src/machine/machine_nrf.go:200
200 uart.Receive(byte(nrf.UART0.RXD.Get()))
(gdb) bt
#0 (*machine.UART).handleInterrupt (arg1=..., uart=<optimized out>) at /home/ayke/src/github.com/tinygo-org/tinygo/src/machine/machine_nrf.go:200
#1 UART0_IRQHandler () at /home/ayke/src/github.com/tinygo-org/tinygo/src/device/nrf/nrf51.go:176
#2 <signal handler called>
[..etc]
By now, the debugger sees an actual source location for UART0_IRQHandler
(in the generated file) and an inlined function.
This adds support for a construct like this:
type foo func(fn foo)
Unfortunately, LLVM cannot create function pointers that look like this.
LLVM only supports named types for structs (not for pointers) and thus
can't add a pointer to a function type of the same type to a parameter
of that function type.
The fix is simple: cast all function pointers to a void function, in
LLVM IR:
void ()*
Raw function pointers are cast to this type before storing, and cast
back to the regular function type before calling. This means that
function parameters will never refer to its own type because raw
function types are fixed at that one type.
Somehow, this does have an effect on binary size in some cases. The
effect is small and goes both ways. On top of that, there is work
underway in LLVM which would make all pointer types opaque (without a
pointee type). This would make this whole commit useless and therefore
should fix any size increases that might happen.
https://llvm.org/docs/OpaquePointers.html
There is no good reason for func values to refer to interface type
codes. The only thing they need is a stable identifier for function
signatures, which is easily created as a new kind of globals. Decoupling
makes it easier to change interface related code.
This commit switches from the previous behavior of compiling the whole
program at once, to compiling every package in parallel and linking the
LLVM bitcode files together for further whole-program optimization.
This is a small performance win, but it has several advantages in the
future:
- There are many more things that can be done per package in parallel,
avoiding the bottleneck at the end of the compiler phase. This
should speed up the compiler futher.
- This change is a necessary step towards a non-LTO build mode for
fast incremental builds that only rebuild the changed package, when
compiler speed is more important than binary size.
- This change refactors the compiler in such a way that it will be
easier to inspect the IR for one package only. Inspecting this IR
will be very helpful for compiler developers.
Moving settings to a separate config struct has two benefits:
- It decouples the compiler a bit from other packages, most
importantly the compileopts package. Decoupling is generally a good
thing.
- Perhaps more importantly, it precisely specifies which settings are
used while compiling and affect the resulting LLVM module. This will
be necessary for caching the LLVM module.
While it would have been possible to cache without this refactor, it
would have been very easy to miss a setting and thus let the
compiler work with invalid/stale data.
This package was long making the design of the compiler more complicated
than it needs to be. Previously this package implemented several
optimization passes, but those passes have since moved to work directly
with LLVM IR instead of Go SSA. The only remaining pass is the SimpleDCE
pass.
This commit removes the *ir.Function type that permeated the whole
compiler and instead switches to use *ssa.Function directly. The
SimpleDCE pass is kept but is far less tightly coupled to the rest of
the compiler so that it can easily be removed once the switch to
building and caching packages individually happens.
This makes viewing the IR easier because parameters have readable names.
This also makes it easier to write compiler tests (still a work in
progress), that work in LLVM 9 and LLVM 10, as LLVM 10 started printing
value names for unnamed parameters.
This gives a hint to the compiler that such parameters are either NULL
or point to a valid object that can be dereferenced. This is not
directly very useful, but is very useful when combined with
https://reviews.llvm.org/D60047 to remove the runtime.isnil hack without
regressing escape analysis.
This is a fairly big commit, but it actually changes very little.
getValue should really be a property of the builder (or frame), where
the previously created instructions are kept.
This commit unfortunately introduces a significant amount of code
duplication. However, all that duplicate code should be removed once
this refactor is done.
This is the first commit in a series to refactor the compiler. The
intention is to make sure every function to be compiled eventually has
its own IR builder. This will make it much easier to do other
refactorings in the future:
* Most code won't depend (directly) on the central Compiler object,
perhaps making it possible to eliminate it in the future. Right now
it's embedded in the `builder` struct but individual fields from the
`Compiler` can easily be moved into the `builder` object.
* Some functions are not directly exposed in Go SSA, they are wrapper
functions for something. At the moment they are included in the list
of functions to be compiled with the reachability analysis
(SimpleDCE) in the ir package, but eventually this reachability
analys will be removed. At that point, it would be very convenient
to be able to simply build a function with a new IR builder.
The `compilerContext` struct makes sure that it is not possible for
`builder` methods to accidentally use global state such as the global IR
builder. It is a transitional mechanism and may be removed when
finished.
This allows packages other than the compiler to know (from a single
source of truth) which implemenation is used for Go func values.
This refactor is necessary to be able to move the Optimize function to
the transform package.
Move most of the logic of determining which compiler configuration to
use (such as GOOS/GOARCH, build tags, whether to include debug symbols,
panic strategy, etc.) into the compileopts package. This makes it a
single source of truth for anything related to compiler configuration.
It has a few advantages:
* The compile configuration is independent of the compiler package.
This makes it possible to move optimization passes out of the
compiler, as they don't rely on compiler.Config anymore.
* There is only one place to look if an incorrect compile option is
used.
* The compileopts provides some resistance against unintentionally
picking the wrong option, such as with c.selectGC() vs c.GC() in the
compiler.
* It is now a lot easier to change compile options, as most options
are getters now.
This commit allows starting a new goroutine directly from a func value,
not just when the static callee is known.
This is necessary to support the whole time package, not just the
commonly used subset that was compiled with the SimpleDCE pass enabled.
This commit fixes the following issue:
https://github.com/tinygo-org/tinygo/issues/309
Also, it prepares for some other reflect-related changes that should
make it easier to add support for named types (etc.) in the future.
This commit adds getValue which gets a const, global, or result of a
local SSA expression and replaces (almost) all uses of parseExpr with
getValue. The only remaining use is in parseInstr, which makes sure an
instruction is only evaluated once.
This commit replaces "unknown type" errors in getLLVMType with panics.
The main reason this is done is that it simplifies the code *a lot*.
Many `if err != nil` lines were there just because of type information.
Additionally, simply panicking is probably a better approach as the only
way this error can be produced is either with big new language features
or a serious compiler bug. Panicking is probably a better way to handle
this error anyway.
This has several advantages, among them:
- Many passes (heap-to-stack, dead arg elimination, inlining) do not
work with function pointer calls. Making them normal function calls
improves their effectiveness.
- Goroutine lowering to LLVM coroutines does not currently support
function pointers. By eliminating function pointers, coroutine
lowering gets support for them for free.
This is especially useful for WebAssembly.
Because of the second point, this work is currently only enabled for the
WebAssembly target.
Jake Bailey
Nia Waldvogel
Ayke van Laethem
Jaden Weiss