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Ayke van Laethem
ca7c849da3
Previously we used the i386 target, probably with all optional features disabled. However, the Pentium 4 has been released a _long_ time ago and it seems reasonable to me to take that as a minimum requirement. Upstream Go now also seems to move in this direction: https://github.com/golang/go/issues/40255 The main motivation for this is that there were floating point issues when running the tests for the math package: GOARCH=386 tinygo test math I haven't investigated what's the issue, but I strongly suspect it's caused by the weird x87 80-bit floating point format. This could perhaps be fixed in a different way (by setting the FPU precision to 64 bits) but I figured that just setting the minimum requirement to the Pentium 4 would probably be fine. If needed, we can respect the GO386 environment variable to support these very old CPUs. To support this newer CPU, I had to make sure that the stack is aligned to 16 bytes everywhere. This was not yet always the case.
63 lines
1.7 KiB
Go
63 lines
1.7 KiB
Go
// +build scheduler.tasks,386
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package task
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import "unsafe"
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var systemStack uintptr
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// calleeSavedRegs is the list of registers that must be saved and restored when
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// switching between tasks. Also see task_stack_386.S that relies on the exact
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// layout of this struct.
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type calleeSavedRegs struct {
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ebx uintptr
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esi uintptr
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edi uintptr
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ebp uintptr
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pc uintptr
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// Pad this struct so that tasks start on a 16-byte aligned stack.
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_ [3]uintptr
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}
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// archInit runs architecture-specific setup for the goroutine startup.
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func (s *state) archInit(r *calleeSavedRegs, fn uintptr, args unsafe.Pointer) {
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// Store the initial sp for the startTask function (implemented in assembly).
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s.sp = uintptr(unsafe.Pointer(r))
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// Initialize the registers.
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// These will be popped off of the stack on the first resume of the goroutine.
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// Start the function at tinygo_startTask (defined in
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// src/internal/task/task_stack_386.S). This assembly code calls a function
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// (passed in EBX) with a single argument (passed in ESI). After the
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// function returns, it calls Pause().
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r.pc = uintptr(unsafe.Pointer(&startTask))
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// Pass the function to call in EBX.
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// This function is a compiler-generated wrapper which loads arguments out
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// of a struct pointer. See createGoroutineStartWrapper (defined in
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// compiler/goroutine.go) for more information.
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r.ebx = fn
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// Pass the pointer to the arguments struct in ESI.
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r.esi = uintptr(args)
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}
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func (s *state) resume() {
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swapTask(s.sp, &systemStack)
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}
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func (s *state) pause() {
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newStack := systemStack
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systemStack = 0
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swapTask(newStack, &s.sp)
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}
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// SystemStack returns the system stack pointer when called from a task stack.
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// When called from the system stack, it returns 0.
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func SystemStack() uintptr {
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return systemStack
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}
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