From b56baa7aad93b4ead470b4207c45169fcc4c2c40 Mon Sep 17 00:00:00 2001
From: Damian Gryski <damian@gryski.com>
Date: Tue, 9 Aug 2022 14:01:43 -0700
Subject: [PATCH] runtime: make MemStats available to leaking collector

---
 src/runtime/gc_none.go             |  2 ++
 src/runtime/mstats.go              | 24 ------------------------
 src/runtime/mstats_conservative.go | 25 +++++++++++++++++++++++++
 src/runtime/mstats_leaking.go      | 18 ++++++++++++++++++
 4 files changed, 45 insertions(+), 24 deletions(-)
 create mode 100644 src/runtime/mstats_conservative.go
 create mode 100644 src/runtime/mstats_leaking.go

diff --git a/src/runtime/gc_none.go b/src/runtime/gc_none.go
index a27b57a2..789802ed 100644
--- a/src/runtime/gc_none.go
+++ b/src/runtime/gc_none.go
@@ -13,6 +13,8 @@ import (
 
 const gcAsserts = false // perform sanity checks
 
+var gcTotalAlloc uint64 // for runtime.MemStats
+
 func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer
 
 func realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer
diff --git a/src/runtime/mstats.go b/src/runtime/mstats.go
index 38596dce..5f42d6a5 100644
--- a/src/runtime/mstats.go
+++ b/src/runtime/mstats.go
@@ -1,6 +1,3 @@
-//go:build gc.conservative
-// +build gc.conservative
-
 package runtime
 
 // Memory statistics
@@ -47,24 +44,3 @@ type MemStats struct {
 	// GCSys is bytes of memory in garbage collection metadata.
 	GCSys uint64
 }
-
-// ReadMemStats populates m with memory statistics.
-//
-// The returned memory statistics are up to date as of the
-// call to ReadMemStats. This would not do GC implicitly for you.
-func ReadMemStats(m *MemStats) {
-	m.HeapIdle = 0
-	m.HeapInuse = 0
-	for block := gcBlock(0); block < endBlock; block++ {
-		bstate := block.state()
-		if bstate == blockStateFree {
-			m.HeapIdle += uint64(bytesPerBlock)
-		} else {
-			m.HeapInuse += uint64(bytesPerBlock)
-		}
-	}
-	m.HeapReleased = 0 // always 0, we don't currently release memory back to the OS.
-	m.HeapSys = m.HeapInuse + m.HeapIdle
-	m.GCSys = uint64(heapEnd - uintptr(metadataStart))
-	m.Sys = uint64(heapEnd - heapStart)
-}
diff --git a/src/runtime/mstats_conservative.go b/src/runtime/mstats_conservative.go
new file mode 100644
index 00000000..a65c9da5
--- /dev/null
+++ b/src/runtime/mstats_conservative.go
@@ -0,0 +1,25 @@
+//go:build gc.conservative
+// +build gc.conservative
+
+package runtime
+
+// ReadMemStats populates m with memory statistics.
+//
+// The returned memory statistics are up to date as of the
+// call to ReadMemStats. This would not do GC implicitly for you.
+func ReadMemStats(m *MemStats) {
+	m.HeapIdle = 0
+	m.HeapInuse = 0
+	for block := gcBlock(0); block < endBlock; block++ {
+		bstate := block.state()
+		if bstate == blockStateFree {
+			m.HeapIdle += uint64(bytesPerBlock)
+		} else {
+			m.HeapInuse += uint64(bytesPerBlock)
+		}
+	}
+	m.HeapReleased = 0 // always 0, we don't currently release memory back to the OS.
+	m.HeapSys = m.HeapInuse + m.HeapIdle
+	m.GCSys = uint64(heapEnd - uintptr(metadataStart))
+	m.Sys = uint64(heapEnd - heapStart)
+}
diff --git a/src/runtime/mstats_leaking.go b/src/runtime/mstats_leaking.go
new file mode 100644
index 00000000..70e0503e
--- /dev/null
+++ b/src/runtime/mstats_leaking.go
@@ -0,0 +1,18 @@
+//go:build gc.leaking
+// +build gc.leaking
+
+package runtime
+
+// ReadMemStats populates m with memory statistics.
+//
+// The returned memory statistics are up to date as of the
+// call to ReadMemStats. This would not do GC implicitly for you.
+func ReadMemStats(m *MemStats) {
+	m.HeapIdle = 0
+	m.HeapInuse = uint64(heapptr - heapStart)
+	m.HeapReleased = 0 // always 0, we don't currently release memory back to the OS.
+
+	m.HeapSys = m.HeapInuse + m.HeapIdle
+	m.GCSys = 0
+	m.Sys = uint64(heapEnd - heapStart)
+}