runtime: add MemStats.Mallocs and Frees

src/runtime/gc_conservative.go

@@ -55,7 +55,9 @@ var (
 	metadataStart unsafe.Pointer // pointer to the start of the heap metadata
 	nextAlloc     gcBlock        // the next block that should be tried by the allocator
 	endBlock      gcBlock        // the block just past the end of the available space
-	gcTotalAlloc  uint64         // for runtime.MemStats
+	gcTotalAlloc  uint64         // total number of bytes allocated
+	gcMallocs     uint64         // total number of allocations
+	gcFrees       uint64         // total number of objects freed
 )
 
 // zeroSizedAlloc is just a sentinel that gets returned when allocating 0 bytes.
@@ -268,6 +270,7 @@ func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
 	}
 
 	gcTotalAlloc += uint64(size)
+	gcMallocs++
 
 	neededBlocks := (size + (bytesPerBlock - 1)) / bytesPerBlock
 
@@ -573,6 +576,7 @@ func sweep() {
 			// Unmarked head. Free it, including all tail blocks following it.
 			block.markFree()
 			freeCurrentObject = true
+			gcFrees++
 		case blockStateTail:
 			if freeCurrentObject {
 				// This is a tail object following an unmarked head.

src/runtime/gc_leaking.go

@@ -19,6 +19,12 @@ var heapptr = heapStart
 // Total amount allocated for runtime.MemStats
 var gcTotalAlloc uint64
 
+// Total number of calls to alloc()
+var gcMallocs uint64
+
+// Total number of objected freed; for leaking collector this stays 0
+const gcFrees = 0
+
 // Inlining alloc() speeds things up slightly but bloats the executable by 50%,
 // see https://github.com/tinygo-org/tinygo/issues/2674.  So don't.
 //
@@ -30,6 +36,7 @@ func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
 	size = align(size)
 	addr := heapptr
 	gcTotalAlloc += uint64(size)
+	gcMallocs++
 	heapptr += size
 	for heapptr >= heapEnd {
 		// Try to increase the heap and check again.

src/runtime/gc_none.go

@@ -14,6 +14,8 @@ import (
 const gcAsserts = false // perform sanity checks
 
 var gcTotalAlloc uint64 // for runtime.MemStats
+var gcMallocs uint64
+var gcFrees uint64
 
 func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer
 

src/runtime/mstats.go

@@ -42,6 +42,13 @@ type MemStats struct {
 	// objects are freed.
 	TotalAlloc uint64
 
+	// Mallocs is the cumulative count of heap objects allocated.
+	// The number of live objects is Mallocs - Frees.
+	Mallocs uint64
+
+	// Frees is the cumulative count of heap objects freed.
+	Frees uint64
+
 	// Off-heap memory statistics.
 	//
 	// The following statistics measure runtime-internal

src/runtime/mstats_conservative.go

@@ -22,5 +22,7 @@ func ReadMemStats(m *MemStats) {
 	m.HeapSys = m.HeapInuse + m.HeapIdle
 	m.GCSys = uint64(heapEnd - uintptr(metadataStart))
 	m.TotalAlloc = gcTotalAlloc
+	m.Mallocs = gcMallocs
+	m.Frees = gcFrees
 	m.Sys = uint64(heapEnd - heapStart)
 }

src/runtime/mstats_leaking.go

@@ -15,5 +15,7 @@ func ReadMemStats(m *MemStats) {
 	m.HeapSys = m.HeapInuse + m.HeapIdle
 	m.GCSys = 0
 	m.TotalAlloc = gcTotalAlloc
+	m.Mallocs = gcMallocs
+	m.Frees = gcFrees
 	m.Sys = uint64(heapEnd - heapStart)
 }