WIP runtime: lock output in print/println

This ensures that calls to print/println happening in different threads
are not interleaved.

TODO: this lock might need to be recursive, so that signal handlers
(such as SIGSEGV) can print things when a segmentation fault happens
while the lock is held.

Author: aykevl

compiler/compiler.go

@@ -1686,6 +1686,7 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 		b.createRuntimeInvoke("_panic", argValues, "")
 		return llvm.Value{}, nil
 	case "print", "println":
+		b.createRuntimeCall("printlock", nil, "")
 		for i, value := range argValues {
 			if i >= 1 && callName == "println" {
 				b.createRuntimeCall("printspace", nil, "")
@@ -1746,6 +1747,7 @@ func (b *builder) createBuiltin(argTypes []types.Type, argValues []llvm.Value, c
 		if callName == "println" {
 			b.createRuntimeCall("printnl", nil, "")
 		}
+		b.createRuntimeCall("printunlock", nil, "")
 		return llvm.Value{}, nil // print() or println() returns void
 	case "real":
 		cplx := argValues[0]

compiler/testdata/defer-cortex-m-qemu.ll

@@ -122,12 +122,18 @@ declare void @runtime.destroyDeferFrame(ptr dereferenceable_or_null(24), ptr) #2
 ; Function Attrs: nounwind
 define internal void @"main.deferSimple$1"(ptr %context) unnamed_addr #1 {
 entry:
+  call void @runtime.printlock(ptr undef) #4
   call void @runtime.printint32(i32 3, ptr undef) #4
+  call void @runtime.printunlock(ptr undef) #4
   ret void
 }
 
+declare void @runtime.printlock(ptr) #2
+
 declare void @runtime.printint32(i32, ptr) #2
 
+declare void @runtime.printunlock(ptr) #2
+
 ; Function Attrs: nounwind
 define hidden void @main.deferMultiple(ptr %context) unnamed_addr #1 {
 entry:
@@ -250,14 +256,18 @@ rundefers.end7:                                   ; preds = %rundefers.loophead1
 ; Function Attrs: nounwind
 define internal void @"main.deferMultiple$1"(ptr %context) unnamed_addr #1 {
 entry:
+  call void @runtime.printlock(ptr undef) #4
   call void @runtime.printint32(i32 3, ptr undef) #4
+  call void @runtime.printunlock(ptr undef) #4
   ret void
 }
 
 ; Function Attrs: nounwind
 define internal void @"main.deferMultiple$2"(ptr %context) unnamed_addr #1 {
 entry:
+  call void @runtime.printlock(ptr undef) #4
   call void @runtime.printint32(i32 5, ptr undef) #4
+  call void @runtime.printunlock(ptr undef) #4
   ret void
 }
 

compiler/testdata/goroutine-cortex-m-qemu-tasks.ll

@@ -70,7 +70,9 @@ entry:
   %stacksize = call i32 @"internal/task.getGoroutineStackSize"(i32 ptrtoint (ptr @"main.closureFunctionGoroutine$1$gowrapper" to i32), ptr undef) #9
   call void @"internal/task.start"(i32 ptrtoint (ptr @"main.closureFunctionGoroutine$1$gowrapper" to i32), ptr nonnull %0, i32 %stacksize, ptr undef) #9
   %2 = load i32, ptr %n, align 4
+  call void @runtime.printlock(ptr undef) #9
   call void @runtime.printint32(i32 %2, ptr undef) #9
+  call void @runtime.printunlock(ptr undef) #9
   ret void
 }
 
@@ -91,8 +93,12 @@ entry:
   ret void
 }
 
+declare void @runtime.printlock(ptr) #2
+
 declare void @runtime.printint32(i32, ptr) #2
 
+declare void @runtime.printunlock(ptr) #2
+
 ; Function Attrs: nounwind
 define hidden void @main.funcGoroutine(ptr %fn.context, ptr %fn.funcptr, ptr %context) unnamed_addr #1 {
 entry:

compiler/testdata/goroutine-wasm-asyncify.ll

@@ -76,7 +76,9 @@ entry:
   store ptr %n, ptr %1, align 4
   call void @"internal/task.start"(i32 ptrtoint (ptr @"main.closureFunctionGoroutine$1$gowrapper" to i32), ptr nonnull %0, i32 65536, ptr undef) #9
   %2 = load i32, ptr %n, align 4
+  call void @runtime.printlock(ptr undef) #9
   call void @runtime.printint32(i32 %2, ptr undef) #9
+  call void @runtime.printunlock(ptr undef) #9
   ret void
 }
 
@@ -98,8 +100,12 @@ entry:
   unreachable
 }
 
+declare void @runtime.printlock(ptr) #1
+
 declare void @runtime.printint32(i32, ptr) #1
 
+declare void @runtime.printunlock(ptr) #1
+
 ; Function Attrs: nounwind
 define hidden void @main.funcGoroutine(ptr %fn.context, ptr %fn.funcptr, ptr %context) unnamed_addr #2 {
 entry:

src/runtime/print.go

@@ -1,13 +1,24 @@
 package runtime
 
 import (
+	"internal/task"
 	"unsafe"
 )
 
 type stringer interface {
 	String() string
 }
 
+var printLock task.PMutex
+
+func printlock() {
+	printLock.Lock()
+}
+
+func printunlock() {
+	printLock.Unlock()
+}
+
 //go:nobounds
 func printstring(s string) {
 	for i := 0; i < len(s); i++ {
@@ -336,24 +347,31 @@ func printitf(msg interface{}) {
 		putchar('(')
 		printuintptr(uintptr(itf.typecode))
 		putchar(':')
-		print(itf.value)
+		printptr(uintptr(itf.value))
 		putchar(')')
 	}
 }
 
 func printmap(m *hashmap) {
-	print("map[")
+	printstring("map[")
 	if m == nil {
-		print("nil")
+		printstring("nil")
 	} else {
-		print(uint(m.count))
+		switch TargetBits {
+		case 64:
+			printuint64(uint64(m.count))
+		case 32:
+			printuint32(uint32(m.count))
+		case 16:
+			printuint16(uint16(m.count))
+		}
 	}
 	putchar(']')
 }
 
 func printptr(ptr uintptr) {
 	if ptr == 0 {
-		print("nil")
+		printstring("nil")
 		return
 	}
 	putchar('0')