support WASI target (#1373)

* initial commit for WASI support

* merge "time" package with wasi build tag
* override syscall package with wasi build tag
* create runtime_wasm_{js,wasi}.go files
* create syscall_wasi.go file
* create time/zoneinfo_wasi.go file as the replacement of zoneinfo_js.go
* add targets/wasi.json target

* set visbility hidden for runtime extern variables

Accodring to the WASI docs (https://github.com/WebAssembly/WASI/blob/master/design/application-abi.md#current-unstable-abi),
none of exports of WASI executable(Command) should no be accessed.

v0.19.0 of bytecodealliance/wasmetime, which is often refered to as the reference implementation of WASI,
does not accept any exports except functions and the only limited variables like "table", "memory".

* merge syscall_{baremetal,wasi}.go

* fix js target build

* mv wasi functions to syscall/wasi && implement sleepTicks

* WASI: set visibility hidden for globals variables

* mv back syscall/wasi/* to runtime package

* WASI: add test

* unexport wasi types

* WASI test: fix wasmtime path

* stop changing visibility of runtime.alloc

* use GOOS=linux, GOARCH=arm for wasi target

Signed-off-by: mathetake <takeshi@tetrate.io>

* WASI: fix build tags for os/runtime packages

Signed-off-by: mathetake <takeshi@tetrate.io>

* run WASI test only on Linux

Signed-off-by: mathetake <takeshi@tetrate.io>

* set InternalLinkage instead of changing visibility

Signed-off-by: mathetake <takeshi@tetrate.io>

.circleci/config.yml

@@ -44,6 +44,13 @@ commands:
           command: |
             wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
             sudo apt install ./google-chrome-stable_current_amd64.deb
+  install-wasmtime:
+    steps:
+      - run:
+          name: "Install wasmtime"
+          command: |
+            curl https://wasmtime.dev/install.sh -sSf | bash
+            sudo ln -s ~/.wasmtime/bin/wasmtime /usr/local/bin/wasmtime
   install-xtensa-toolchain:
     parameters:
       variant:
@@ -91,6 +98,7 @@ commands:
           llvm: "<<parameters.llvm>>"
       - install-node
       - install-chrome
+      - install-wasmtime
       - restore_cache:
           keys:
             - go-cache-v2-{{ checksum "go.mod" }}-{{ .Environment.CIRCLE_PREVIOUS_BUILD_NUM }}
@@ -134,6 +142,7 @@ commands:
                 gcc-avr \
                 avr-libc
       - install-node
+      - install-wasmtime
       - install-xtensa-toolchain:
           variant: "linux-amd64"
       - restore_cache:
@@ -194,6 +203,7 @@ commands:
                 gcc-avr \
                 avr-libc
       - install-node
+      - install-wasmtime
       - install-xtensa-toolchain:
           variant: "linux-amd64"
       - restore_cache:

loader/goroot.go

@@ -189,7 +189,7 @@ func mergeDirectory(goroot, tinygoroot, tmpgoroot, importPath string, overrides
 // with the TinyGo version. This is the case on some targets.
 func needsSyscallPackage(buildTags []string) bool {
 	for _, tag := range buildTags {
-		if tag == "baremetal" || tag == "darwin" || tag == "nintendoswitch" {
+		if tag == "baremetal" || tag == "darwin" || tag == "nintendoswitch" || tag == "wasi" {
 			return true
 		}
 	}

main_test.go

@@ -98,6 +98,10 @@ func TestCompiler(t *testing.T) {
 				runPlatTests("wasm", matches, t)
 			})
 		}
+
+		t.Run("WASI", func(t *testing.T) {
+			runPlatTests("wasi", matches, t)
+		})
 	}
 }
 
@@ -109,7 +113,6 @@ func runPlatTests(target string, matches []string, t *testing.T) {
 
 		t.Run(filepath.Base(path), func(t *testing.T) {
 			t.Parallel()
-
 			runTest(path, target, t)
 		})
 	}
@@ -161,6 +164,11 @@ func runTest(path, target string, t *testing.T) {
 		PrintSizes: "",
 		WasmAbi:    "js",
 	}
+
+	if target == "wasi" {
+		config.WasmAbi = "generic"
+	}
+
 	binary := filepath.Join(tmpdir, "test")
 	err = runBuild("./"+path, binary, config)
 	if err != nil {

src/os/file_unix.go

@@ -1,4 +1,4 @@
-// +build darwin linux,!baremetal freebsd,!baremetal
+// +build darwin linux,!baremetal,!wasi freebsd,!baremetal
 
 package os
 

src/runtime/arch_arm.go

@@ -1,4 +1,4 @@
-// +build arm,!baremetal arm,arm7tdmi
+// +build arm,!baremetal,!wasm arm,arm7tdmi
 
 package runtime
 

src/runtime/runtime_unix.go

@@ -1,4 +1,4 @@
-// +build darwin linux,!baremetal freebsd,!baremetal
+// +build darwin linux,!baremetal,!wasi freebsd,!baremetal
 // +build !nintendoswitch
 
 package runtime

src/runtime/runtime_unix_heap.go

@@ -1,4 +1,4 @@
-// +build darwin linux,!baremetal freebsd,!baremetal
+// +build darwin linux,!baremetal,!wasi freebsd,!baremetal
 // +build !nintendoswitch
 
 // +build gc.conservative gc.leaking

src/runtime/runtime_unix_noheap.go

@@ -1,4 +1,4 @@
-// +build darwin linux,!baremetal freebsd,!baremetal
+// +build darwin linux,!baremetal,!wasi freebsd,!baremetal
 
 // +build !nintendoswitch
 

src/runtime/runtime_wasm.go

@@ -2,35 +2,26 @@
 
 package runtime
 
-import "unsafe"
-
-type timeUnit float64 // time in milliseconds, just like Date.now() in JavaScript
+import (
+	"unsafe"
+)
 
-// Implements __wasi_ciovec_t and __wasi_iovec_t.
-type wasiIOVec struct {
+// Implements __wasi_iovec_t.
+type __wasi_iovec_t struct {
 	buf    unsafe.Pointer
 	bufLen uint
 }
 
 //go:wasm-module wasi_unstable
 //export fd_write
-func fd_write(id uint32, iovs *wasiIOVec, iovs_len uint, nwritten *uint) (errno uint)
+func fd_write(id uint32, iovs *__wasi_iovec_t, iovs_len uint, nwritten *uint) (errno uint)
 
 func postinit() {}
 
-//export _start
-func _start() {
-	// These need to be initialized early so that the heap can be initialized.
-	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
-	heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
-
-	run()
-}
-
 // Using global variables to avoid heap allocation.
 var (
 	putcharBuf   = byte(0)
-	putcharIOVec = wasiIOVec{
+	putcharIOVec = __wasi_iovec_t{
 		buf:    unsafe.Pointer(&putcharBuf),
 		bufLen: 1,
 	}
@@ -44,49 +35,6 @@ func putchar(c byte) {
 	fd_write(stdout, &putcharIOVec, 1, &nwritten)
 }
 
-var handleEvent func()
-
-//go:linkname setEventHandler syscall/js.setEventHandler
-func setEventHandler(fn func()) {
-	handleEvent = fn
-}
-
-//export resume
-func resume() {
-	go func() {
-		handleEvent()
-	}()
-	scheduler()
-}
-
-//export go_scheduler
-func go_scheduler() {
-	scheduler()
-}
-
-const asyncScheduler = true
-
-func ticksToNanoseconds(ticks timeUnit) int64 {
-	// The JavaScript API works in float64 milliseconds, so convert to
-	// nanoseconds first before converting to a timeUnit (which is a float64),
-	// to avoid precision loss.
-	return int64(ticks * 1e6)
-}
-
-func nanosecondsToTicks(ns int64) timeUnit {
-	// The JavaScript API works in float64 milliseconds, so convert to timeUnit
-	// (which is a float64) first before dividing, to avoid precision loss.
-	return timeUnit(ns) / 1e6
-}
-
-// This function is called by the scheduler.
-// Schedule a call to runtime.scheduler, do not actually sleep.
-//export runtime.sleepTicks
-func sleepTicks(d timeUnit)
-
-//export runtime.ticks
-func ticks() timeUnit
-
 // Abort executes the wasm 'unreachable' instruction.
 func abort() {
 	trap()

src/runtime/runtime_wasm_js.go

@@ -0,0 +1,59 @@
+// +build wasm,!wasi
+
+package runtime
+
+import "unsafe"
+
+type timeUnit float64 // time in milliseconds, just like Date.now() in JavaScript
+
+//export _start
+func _start() {
+	// These need to be initialized early so that the heap can be initialized.
+	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
+	heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
+
+	run()
+}
+
+var handleEvent func()
+
+//go:linkname setEventHandler syscall/js.setEventHandler
+func setEventHandler(fn func()) {
+	handleEvent = fn
+}
+
+//export resume
+func resume() {
+	go func() {
+		handleEvent()
+	}()
+	scheduler()
+}
+
+//export go_scheduler
+func go_scheduler() {
+	scheduler()
+}
+
+const asyncScheduler = true
+
+func ticksToNanoseconds(ticks timeUnit) int64 {
+	// The JavaScript API works in float64 milliseconds, so convert to
+	// nanoseconds first before converting to a timeUnit (which is a float64),
+	// to avoid precision loss.
+	return int64(ticks * 1e6)
+}
+
+func nanosecondsToTicks(ns int64) timeUnit {
+	// The JavaScript API works in float64 milliseconds, so convert to timeUnit
+	// (which is a float64) first before dividing, to avoid precision loss.
+	return timeUnit(ns) / 1e6
+}
+
+// This function is called by the scheduler.
+// Schedule a call to runtime.scheduler, do not actually sleep.
+//export runtime.sleepTicks
+func sleepTicks(d timeUnit)
+
+//export runtime.ticks
+func ticks() timeUnit

src/runtime/runtime_wasm_wasi.go

@@ -0,0 +1,117 @@
+// +build wasm,wasi
+
+package runtime
+
+import (
+	"unsafe"
+)
+
+type timeUnit int64
+
+//export _start
+func _start() {
+	// These need to be initialized early so that the heap can be initialized.
+	heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
+	heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
+	run()
+}
+
+func ticksToNanoseconds(ticks timeUnit) int64 {
+	return int64(ticks)
+}
+
+func nanosecondsToTicks(ns int64) timeUnit {
+	return timeUnit(ns)
+}
+
+const (
+	asyncScheduler           = false
+	timePrecisionNanoseconds = 1000 // TODO: how can we determine the appropriate `precision`?
+)
+
+var (
+	sleepTicksSubscription = __wasi_subscription_t{
+		userData: 0,
+		u: __wasi_subscription_u_t{
+			tag: __wasi_eventtype_t_clock,
+			u: __wasi_subscription_clock_t{
+				userData:  0,
+				id:        0,
+				timeout:   0,
+				precision: timePrecisionNanoseconds,
+				flags:     0,
+			},
+		},
+	}
+	sleepTicksResult  = __wasi_event_t{}
+	sleepTicksNEvents uint32
+)
+
+func sleepTicks(d timeUnit) {
+	sleepTicksSubscription.u.u.timeout = int64(d)
+	poll_oneoff(&sleepTicksSubscription, &sleepTicksResult, 1, &sleepTicksNEvents)
+}
+
+func ticks() timeUnit {
+	var nano int64
+	clock_time_get(0, timePrecisionNanoseconds, &nano)
+	return timeUnit(nano)
+}
+
+// Implementations of wasi_unstable APIs
+
+//go:wasm-module wasi_unstable
+//export clock_time_get
+func clock_time_get(clockid uint32, precision uint64, time *int64) (errno uint16)
+
+//go:wasm-module wasi_unstable
+//export poll_oneoff
+func poll_oneoff(in *__wasi_subscription_t, out *__wasi_event_t, nsubscriptions uint32, nevents *uint32) (errno uint16)
+
+type __wasi_eventtype_t = uint8
+
+const (
+	__wasi_eventtype_t_clock __wasi_eventtype_t = 0
+	// TODO: __wasi_eventtype_t_fd_read  __wasi_eventtype_t = 1
+	// TODO: __wasi_eventtype_t_fd_write __wasi_eventtype_t = 2
+)
+
+type (
+	// https://github.com/wasmerio/wasmer/blob/1.0.0-alpha3/lib/wasi/src/syscalls/types.rs#L584-L588
+	__wasi_subscription_t struct {
+		userData uint64
+		u        __wasi_subscription_u_t
+	}
+
+	__wasi_subscription_u_t struct {
+		tag __wasi_eventtype_t
+
+		// TODO: support fd_read/fd_write event
+		u __wasi_subscription_clock_t
+	}
+
+	// https://github.com/wasmerio/wasmer/blob/1.0.0-alpha3/lib/wasi/src/syscalls/types.rs#L711-L718
+	__wasi_subscription_clock_t struct {
+		userData  uint64
+		id        uint32
+		timeout   int64
+		precision int64
+		flags     uint16
+	}
+)
+
+type (
+	// https://github.com/wasmerio/wasmer/blob/1.0.0-alpha3/lib/wasi/src/syscalls/types.rs#L191-L198
+	__wasi_event_t struct {
+		userData  uint64
+		errno     uint16
+		eventType __wasi_eventtype_t
+
+		// only used for fd_read or fd_write events
+		// TODO: support fd_read/fd_write event
+		_ struct {
+			nBytes uint64
+			flags  uint16
+		}
+	}
+)

src/syscall/syscall_baremetal.go

@@ -1,4 +1,4 @@
-// +build baremetal
+// +build baremetal wasi
 
 package syscall
 

src/syscall/tables_baremetal.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build baremetal nintendoswitch
+// +build baremetal nintendoswitch wasi
 
 package syscall