compiler, runtime: enable go:wasmexport for wasip2 (#4499)

* compiler: prefer go:wasmexport over go:export

* runtime, targets/wasip2: enable -buildmode=c-shared for wasip2

* runtime: rename import from wasi_run to wasiclirun (PR feedback)

Author: ydnar

compiler/symbol.go

@@ -389,6 +389,13 @@ func (c *compilerContext) parsePragmas(info *functionInfo, f *ssa.Function) {
 			}
 		}
 	}
+
+	// If both //go:wasmexport and //go:export or //export are declared,
+	// only honor go:wasmexport.
+	if info.wasmExport != "" {
+		// TODO: log warning?
+		info.exported = false
+	}
 }
 
 // Check whether this function can be used in //go:wasmimport or

src/runtime/runtime_wasm_wasip2.go renamed to src/runtime/runtime_wasip2.go

@@ -6,18 +6,19 @@ import (
 	"unsafe"
 
 	"internal/wasi/cli/v0.2.0/environment"
+	wasiclirun "internal/wasi/cli/v0.2.0/run"
 	monotonicclock "internal/wasi/clocks/v0.2.0/monotonic-clock"
+
+	"internal/cm"
 )
 
 type timeUnit int64
 
-//export wasi:cli/run@0.2.0#run
-func __wasi_cli_run_run() uint32 {
-	// 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()
-	return 0
+func init() {
+	wasiclirun.Exports.Run = func() cm.BoolResult {
+		callMain()
+		return false
+	}
 }
 
 var args []string
@@ -51,3 +52,6 @@ func sleepTicks(d timeUnit) {
 func ticks() timeUnit {
 	return timeUnit(monotonicclock.Now())
 }
+
+func beforeExit() {
+}

src/runtime/runtime_wasmentry.go

@@ -1,4 +1,4 @@
-//go:build tinygo.wasm && !wasip2 && !js
+//go:build tinygo.wasm && !js
 
 package runtime
 

targets/wasip2.json

@@ -3,6 +3,7 @@
 	"cpu":           "generic",
 	"features":      "+bulk-memory,+mutable-globals,+nontrapping-fptoint,+sign-ext",
 	"build-tags":    ["tinygo.wasm", "wasip2"],
+	"buildmode":     "c-shared",
 	"goos":          "linux",
 	"goarch":        "arm",
 	"linker":        "wasm-ld",