From ef93001ab82bfad9165dc7fd359ae2f40b153fa6 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Sat, 17 Nov 2018 15:02:18 +0100
Subject: [PATCH] runtime: add "none" garbage collector

This collector does not implement runtime.alloc, so it is a
quick-and-dirty way to check where in a program memory is allocated.
---
 main.go                |  2 +-
 src/runtime/gc_none.go | 29 +++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 src/runtime/gc_none.go

diff --git a/main.go b/main.go
index 3858b213..28455319 100644
--- a/main.go
+++ b/main.go
@@ -435,7 +435,7 @@ func handleCompilerError(err error) {
 func main() {
 	outpath := flag.String("o", "", "output filename")
 	opt := flag.String("opt", "z", "optimization level: 0, 1, 2, s, z")
-	gc := flag.String("gc", "dumb", "garbage collector to use (dumb)")
+	gc := flag.String("gc", "dumb", "garbage collector to use (none, dumb)")
 	printIR := flag.Bool("printir", false, "print LLVM IR")
 	dumpSSA := flag.Bool("dumpssa", false, "dump internal Go SSA")
 	target := flag.String("target", "", "LLVM target")
diff --git a/src/runtime/gc_none.go b/src/runtime/gc_none.go
new file mode 100644
index 00000000..b7fc628d
--- /dev/null
+++ b/src/runtime/gc_none.go
@@ -0,0 +1,29 @@
+// +build gc.none
+
+package runtime
+
+// This GC strategy provides no memory allocation at all. It can be useful to
+// detect where in a program memory is allocated, or to combine this runtime
+// with a separate (external) garbage collector.
+
+import (
+	"unsafe"
+)
+
+func alloc(size uintptr) unsafe.Pointer
+
+func free(ptr unsafe.Pointer) {
+	// Nothing to free when nothing gets allocated.
+}
+
+func GC() {
+	// Unimplemented.
+}
+
+func KeepAlive(x interface{}) {
+	// Unimplemented. Only required with SetFinalizer().
+}
+
+func SetFinalizer(obj interface{}, finalizer interface{}) {
+	// Unimplemented.
+}