support print(int)

hello/hello.go

@@ -3,4 +3,5 @@ package main
 
 func main() {
 	println("Hello world from Go!")
+	println("The answer is:", 42)
 }

runtime/runtime.c

@@ -4,16 +4,35 @@
 #include <stdio.h>
 #include "runtime.h"
 
+#define print(buf, len) write(STDOUT_FILENO, buf, len)
+
 void __go_printstring(string_t *str) {
 	write(STDOUT_FILENO, str->buf, str->len);
 }
 
+void __go_printint(int32_t n) {
+	// Print integer in signed big-endian base-10 notation, for humans to
+	// read.
+	// TODO: don't recurse, but still be compact (and don't divide/mod
+	// more than necessary).
+	if (n < 0) {
+		print("-", 1);
+		n = -n;
+	}
+	int32_t prevdigits = n / 10;
+	if (prevdigits != 0) {
+		__go_printint(prevdigits);
+	}
+	char buf[1] = {(n % 10) + '0'};
+	print(buf, 1);
+}
+
 void __go_printspace() {
-	write(STDOUT_FILENO, " ", 1);
+	print(" ", 1);
 }
 
 void __go_printnl() {
-	write(STDOUT_FILENO, "\n", 1);
+	print("\n", 1);
 }
 
 void go_main() __asm__("main.main");

tgo.go

@@ -30,6 +30,7 @@ type Compiler struct {
 	stringType      llvm.Type
 	stringPtrType   llvm.Type
 	printstringFunc llvm.Value
+	printintFunc    llvm.Value
 	printspaceFunc  llvm.Value
 	printnlFunc     llvm.Value
 }
@@ -53,6 +54,8 @@ func NewCompiler(path, triple string) (*Compiler, error) {
 
 	printstringType := llvm.FunctionType(llvm.VoidType(), []llvm.Type{c.stringPtrType}, false)
 	c.printstringFunc = llvm.AddFunction(c.mod, "__go_printstring", printstringType)
+	printintType := llvm.FunctionType(llvm.VoidType(), []llvm.Type{llvm.Int32Type()}, false)
+	c.printintFunc = llvm.AddFunction(c.mod, "__go_printint", printintType)
 	printspaceType := llvm.FunctionType(llvm.VoidType(), nil, false)
 	c.printspaceFunc = llvm.AddFunction(c.mod, "__go_printspace", printspaceType)
 	printnlType := llvm.FunctionType(llvm.VoidType(), nil, false)
@@ -179,6 +182,10 @@ func (c *Compiler) parseExpr(expr ast.Expr) error {
 					ptr.SetLinkage(llvm.InternalLinkage)
 					ptrCast := llvm.ConstPointerCast(ptr, c.stringPtrType)
 					c.builder.CreateCall(c.printstringFunc, []llvm.Value{ptrCast}, "")
+				case token.INT:
+					n, _ := constant.Int64Val(val) // TODO: do something with the 'exact' return value?
+					val := llvm.ConstInt(llvm.Int32Type(), uint64(n), true)
+					c.builder.CreateCall(c.printintFunc, []llvm.Value{val}, "")
 				default:
 					return errors.New("todo: print anything other than strings")
 				}