542135c357
This scheduler is intended to live along the (stackless) coroutine based scheduler which is needed for WebAssembly and unsupported platforms. The stack based scheduler is somewhat simpler in implementation as it does not require full program transform passes and supports things like function pointers and interface methods out of the box with no changes. Code size is reduced in most cases, even in the case where no scheduler scheduler is used at all. I'm not exactly sure why but these changes likely allowed some further optimizations somewhere. Even RAM is slightly reduced, perhaps some global was elminated in the process as well.
83 строки
3,1 КиБ
Go
83 строки
3,1 КиБ
Go
package compiler
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// This file implements the 'go' keyword to start a new goroutine. See
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// goroutine-lowering.go for more details.
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import "tinygo.org/x/go-llvm"
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// emitStartGoroutine starts a new goroutine with the provided function pointer
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// and parameters.
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//
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// Because a go statement doesn't return anything, return undef.
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func (c *Compiler) emitStartGoroutine(funcPtr llvm.Value, params []llvm.Value) llvm.Value {
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switch c.selectScheduler() {
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case "tasks":
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paramBundle := c.emitPointerPack(params)
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paramBundle = c.builder.CreatePtrToInt(paramBundle, c.uintptrType, "")
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calleeValue := c.createGoroutineStartWrapper(funcPtr)
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c.createRuntimeCall("startGoroutine", []llvm.Value{calleeValue, paramBundle}, "")
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case "coroutines":
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// Mark this function as a 'go' invocation and break invalid
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// interprocedural optimizations. For example, heap-to-stack
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// transformations are not sound as goroutines can outlive their parent.
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calleeType := funcPtr.Type()
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calleeValue := c.builder.CreatePtrToInt(funcPtr, c.uintptrType, "")
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calleeValue = c.createRuntimeCall("makeGoroutine", []llvm.Value{calleeValue}, "")
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calleeValue = c.builder.CreateIntToPtr(calleeValue, calleeType, "")
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c.createCall(calleeValue, params, "")
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default:
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panic("unreachable")
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}
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return llvm.Undef(funcPtr.Type().ElementType().ReturnType())
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}
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// createGoroutineStartWrapper creates a wrapper for the task-based
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// implementation of goroutines. For example, to call a function like this:
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//
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// func add(x, y int) int { ... }
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//
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// It creates a wrapper like this:
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//
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// func add$gowrapper(ptr *unsafe.Pointer) {
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// args := (*struct{
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// x, y int
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// })(ptr)
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// add(args.x, args.y)
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// }
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//
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// This is useful because the task-based goroutine start implementation only
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// allows a single (pointer) argument to the newly started goroutine. Also, it
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// ignores the return value because newly started goroutines do not have a
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// return value.
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func (c *Compiler) createGoroutineStartWrapper(fn llvm.Value) llvm.Value {
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if fn.IsAFunction().IsNil() {
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panic("todo: goroutine start wrapper for func value")
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}
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// See whether this wrapper has already been created. If so, return it.
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name := fn.Name()
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wrapper := c.mod.NamedFunction(name + "$gowrapper")
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if !wrapper.IsNil() {
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return c.builder.CreateIntToPtr(wrapper, c.uintptrType, "")
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}
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// Save the current position in the IR builder.
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currentBlock := c.builder.GetInsertBlock()
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defer c.builder.SetInsertPointAtEnd(currentBlock)
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// Create the wrapper.
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wrapperType := llvm.FunctionType(c.ctx.VoidType(), []llvm.Type{c.i8ptrType}, false)
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wrapper = llvm.AddFunction(c.mod, name+"$gowrapper", wrapperType)
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wrapper.SetLinkage(llvm.PrivateLinkage)
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wrapper.SetUnnamedAddr(true)
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entry := llvm.AddBasicBlock(wrapper, "entry")
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c.builder.SetInsertPointAtEnd(entry)
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paramTypes := fn.Type().ElementType().ParamTypes()
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params := c.emitPointerUnpack(wrapper.Param(0), paramTypes[:len(paramTypes)-2])
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params = append(params, llvm.Undef(c.i8ptrType), llvm.ConstPointerNull(c.i8ptrType))
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c.builder.CreateCall(fn, params, "")
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c.builder.CreateRetVoid()
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return c.builder.CreatePtrToInt(wrapper, c.uintptrType, "")
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}
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