runtime: require explicit GC layouts

builder/testdata/binary-size.txt

@@ -1,4 +1,4 @@
 target      package               code rodata data  bss
 hifive1b    examples/echo         4321    323    0 2268
 microbit    examples/serial       2842    382    8 2264
-wioterminal examples/pininterrupt 8039   1665  132 7496
+wioterminal examples/pininterrupt 8039   1669  132 7496

compiler/channel.go

@@ -14,8 +14,10 @@ import (
 )
 
 func (b *builder) createMakeChan(expr *ssa.MakeChan) llvm.Value {
-	elementSize := b.targetData.TypeAllocSize(b.getLLVMType(expr.Type().Underlying().(*types.Chan).Elem()))
+	elementType := b.getLLVMType(expr.Type().Underlying().(*types.Chan).Elem())
+	elementSize := b.targetData.TypeAllocSize(elementType)
 	elementSizeValue := llvm.ConstInt(b.uintptrType, elementSize, false)
+	elementLayout := b.createObjectLayout(elementType, expr.Pos())
 	bufSize := b.getValue(expr.Size, getPos(expr))
 	b.createChanBoundsCheck(elementSize, bufSize, expr.Size.Type().Underlying().(*types.Basic), expr.Pos())
 	if bufSize.Type().IntTypeWidth() < b.uintptrType.IntTypeWidth() {
@@ -23,7 +25,7 @@ func (b *builder) createMakeChan(expr *ssa.MakeChan) llvm.Value {
 	} else if bufSize.Type().IntTypeWidth() > b.uintptrType.IntTypeWidth() {
 		bufSize = b.CreateTrunc(bufSize, b.uintptrType, "")
 	}
-	return b.createRuntimeCall("chanMake", []llvm.Value{elementSizeValue, bufSize}, "")
+	return b.createRuntimeCall("chanMake", []llvm.Value{elementSizeValue, bufSize, elementLayout}, "")
 }
 
 // createChanSend emits a pseudo chan send operation. It is lowered to the

compiler/interface.go

@@ -284,6 +284,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				types.NewVar(token.NoPos, nil, "elementType", types.Typ[types.UnsafePointer]),
 				types.NewVar(token.NoPos, nil, "length", types.Typ[types.Uintptr]),
 				types.NewVar(token.NoPos, nil, "sliceOf", types.Typ[types.UnsafePointer]),
+				types.NewVar(token.NoPos, nil, "layout", types.Typ[types.UnsafePointer]),
 			)
 		case *types.Map:
 			typeFieldTypes = append(typeFieldTypes,
@@ -291,6 +292,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				types.NewVar(token.NoPos, nil, "ptrTo", types.Typ[types.UnsafePointer]),
 				types.NewVar(token.NoPos, nil, "elementType", types.Typ[types.UnsafePointer]),
 				types.NewVar(token.NoPos, nil, "keyType", types.Typ[types.UnsafePointer]),
+				types.NewVar(token.NoPos, nil, "hashmapTypeInfo", types.Typ[types.UnsafePointer]),
 			)
 		case *types.Struct:
 			typeFieldTypes = append(typeFieldTypes,
@@ -299,6 +301,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				types.NewVar(token.NoPos, nil, "pkgpath", types.Typ[types.UnsafePointer]),
 				types.NewVar(token.NoPos, nil, "size", types.Typ[types.Uint32]),
 				types.NewVar(token.NoPos, nil, "numFields", types.Typ[types.Uint16]),
+				types.NewVar(token.NoPos, nil, "layout", types.Typ[types.UnsafePointer]),
 				types.NewVar(token.NoPos, nil, "fields", types.NewArray(c.getRuntimeType("structField"), int64(typ.NumFields()))),
 			)
 			if len(methods) > 0 {
@@ -418,6 +421,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				c.getTypeCode(typ.Elem()),                              // elementType
 				llvm.ConstInt(c.uintptrType, uint64(typ.Len()), false), // length
 				c.getTypeCode(types.NewSlice(typ.Elem())),              // slicePtr
+				c.createObjectLayout(c.getLLVMType(typ), token.NoPos),  // layout
 			}
 		case *types.Map:
 			typeFields = []llvm.Value{
@@ -425,6 +429,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				c.getTypeCode(types.NewPointer(typ)),       // ptrTo
 				c.getTypeCode(typ.Elem()),                  // elem
 				c.getTypeCode(typ.Key()),                   // key
+				c.getHashmapTypeInfo(typ, token.NoPos),     // hashmapTypeInfo
 			}
 		case *types.Struct:
 			var pkgpath string
@@ -450,6 +455,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 				pkgPathPtr,
 				llvm.ConstInt(c.ctx.Int32Type(), uint64(size), false),            // size
 				llvm.ConstInt(c.ctx.Int16Type(), uint64(typ.NumFields()), false), // numFields
+				c.createObjectLayout(llvmStructType, token.NoPos),                // layout
 			}
 			structFieldType := c.getLLVMRuntimeType("structField")
 
@@ -510,7 +516,7 @@ func (c *compilerContext) getTypeCode(typ types.Type) llvm.Value {
 			typeFields = []llvm.Value{c.getTypeCode(types.NewPointer(typ))}
 			// TODO: params, return values, etc
 		}
-		// Prepend metadata byte.
+		// Prepend the common RawType field.
 		typeFields = append([]llvm.Value{
 			llvm.ConstInt(c.ctx.Int8Type(), uint64(metabyte), false),
 		}, typeFields...)

compiler/map.go

@@ -13,6 +13,12 @@ import (
 
 const hashArrayUnrollLimit = 4
 
+const (
+	hashmapBucketSlots  = 8
+	hashmapMaxKeySize   = 128
+	hashmapMaxValueSize = 128
+)
+
 // createMakeMap creates a new map object (runtime.hashmap) by allocating and
 // initializing an appropriately sized object.
 func (b *builder) createMakeMap(expr *ssa.MakeMap) (llvm.Value, error) {
@@ -25,6 +31,8 @@ func (b *builder) createMakeMap(expr *ssa.MakeMap) (llvm.Value, error) {
 	valueSize := b.targetData.TypeAllocSize(llvmValueType)
 	llvmKeySize := llvm.ConstInt(b.uintptrType, keySize, false)
 	llvmValueSize := llvm.ConstInt(b.uintptrType, valueSize, false)
+	mapLayout := b.getHashmapTypeInfo(mapType, expr.Pos())
+
 	sizeHint := llvm.ConstInt(b.uintptrType, 8, false)
 	if expr.Reserve != nil {
 		sizeHint = b.getValue(expr.Reserve, getPos(expr))
@@ -54,11 +62,72 @@ func (b *builder) createMakeMap(expr *ssa.MakeMap) (llvm.Value, error) {
 
 	hashmap := b.createRuntimeCall("hashmapMakeGeneric", []llvm.Value{
 		llvmKeySize, llvmValueSize, sizeHint,
+		mapLayout,
 		hashFn, equalFn,
 	}, "")
 	return hashmap, nil
 }
 
+func (c *compilerContext) getHashmapTypeInfo(mapType *types.Map, pos token.Pos) llvm.Value {
+	llvmKeyType := c.getLLVMType(mapType.Key().Underlying())
+	llvmValueType := c.getLLVMType(mapType.Elem().Underlying())
+	keySize := c.targetData.TypeAllocSize(llvmKeyType)
+	valueSize := c.targetData.TypeAllocSize(llvmValueType)
+	keyLayout := c.createObjectLayout(llvmKeyType, pos)
+	valueLayout := c.createObjectLayout(llvmValueType, pos)
+
+	llvmKeySlotType := llvmKeyType
+	if keySize > hashmapMaxKeySize {
+		llvmKeySlotType = c.dataPtrType
+	}
+	llvmValueSlotType := llvmValueType
+	if valueSize > hashmapMaxValueSize {
+		llvmValueSlotType = c.dataPtrType
+	}
+
+	// Keep this in sync with runtime.hashmapBucket and
+	// runtime.hashmapBucketHeaderSize.
+	pointerSize := c.targetData.TypeAllocSize(c.dataPtrType)
+	headerSize := (uint64(8) + pointerSize + 7) &^ 7
+	headerPadding := headerSize - uint64(8) - pointerSize
+	bucketFields := []llvm.Type{
+		llvm.ArrayType(c.ctx.Int8Type(), hashmapBucketSlots),
+		c.dataPtrType,
+	}
+	if headerPadding != 0 {
+		bucketFields = append(bucketFields, llvm.ArrayType(c.ctx.Int8Type(), int(headerPadding)))
+	}
+	bucketFields = append(bucketFields,
+		llvm.ArrayType(llvmKeySlotType, hashmapBucketSlots),
+		llvm.ArrayType(llvmValueSlotType, hashmapBucketSlots),
+	)
+	bucketType := c.ctx.StructType(bucketFields, true)
+	bucketSize := headerSize +
+		c.targetData.TypeAllocSize(llvmKeySlotType)*hashmapBucketSlots +
+		c.targetData.TypeAllocSize(llvmValueSlotType)*hashmapBucketSlots
+	if c.targetData.TypeAllocSize(bucketType) != bucketSize {
+		panic("compiler hashmap bucket layout does not match runtime")
+	}
+	bucketLayout := c.createObjectLayout(bucketType, pos)
+	mapLayoutName := "runtime.hashmapType:" +
+		hashmapCanonicalTypeName(mapType.Key()) + ":" +
+		hashmapCanonicalTypeName(mapType.Elem())
+	mapLayout := c.mod.NamedGlobal(mapLayoutName)
+	if mapLayout.IsNil() {
+		initializer := c.ctx.ConstStruct([]llvm.Value{
+			keyLayout,
+			valueLayout,
+			bucketLayout,
+		}, false)
+		mapLayout = llvm.AddGlobal(c.mod, initializer.Type(), mapLayoutName)
+		mapLayout.SetInitializer(initializer)
+		mapLayout.SetGlobalConstant(true)
+		mapLayout.SetUnnamedAddr(true)
+		mapLayout.SetLinkage(llvm.LinkOnceODRLinkage)
+	}
+	return mapLayout
+}
+
 // getRuntimeFunctionValue returns a TinyGo function value (with nil context)
 // for the named runtime function.
 func (b *builder) getRuntimeFunctionValue(name string, sig *types.Signature) llvm.Value {

compiler/testdata/go1.21.ll

@@ -166,13 +166,13 @@ entry:
 }
 
 ; Function Attrs: nounwind
-define hidden void @main.clearMap(ptr dereferenceable_or_null(48) %m, ptr %context) unnamed_addr #1 {
+define hidden void @main.clearMap(ptr dereferenceable_or_null(52) %m, ptr %context) unnamed_addr #1 {
 entry:
   call void @runtime.hashmapClear(ptr %m, ptr undef) #4
   ret void
 }
 
-declare void @runtime.hashmapClear(ptr dereferenceable_or_null(48), ptr) #0
+declare void @runtime.hashmapClear(ptr dereferenceable_or_null(52), ptr) #0
 
 attributes #0 = { "target-features"="+bulk-memory,+bulk-memory-opt,+call-indirect-overlong,+mutable-globals,+nontrapping-fptoint,+sign-ext,-multivalue,-reference-types" }
 attributes #1 = { nounwind "target-features"="+bulk-memory,+bulk-memory-opt,+call-indirect-overlong,+mutable-globals,+nontrapping-fptoint,+sign-ext,-multivalue,-reference-types" }

compiler/testdata/go1.27.ll

@@ -14,7 +14,7 @@ target triple = "wasm32-unknown-wasi"
 @"main$string" = internal unnamed_addr constant [18 x i8] c"main.genericMethod", align 1
 @"main$string.1" = internal unnamed_addr constant [7 x i8] c"Regular", align 1
 @"pointer:named:main.genericMethod$methodset" = linkonce_odr unnamed_addr constant { i32, [1 x ptr], { ptr } } { i32 1, [1 x ptr] [ptr @"reflect/methods.Regular:func:{basic:int}{basic:int}"], { ptr } { ptr @"(*main.genericMethod).Regular" } }
-@"reflect/types.type:struct:{}" = linkonce_odr constant { i8, i16, ptr, ptr, i32, i16, [0 x %runtime.structField] } { i8 90, i16 0, ptr @"reflect/types.type:pointer:struct:{}", ptr @"reflect/types.type.pkgpath.empty", i32 0, i16 0, [0 x %runtime.structField] zeroinitializer }, align 4
+@"reflect/types.type:struct:{}" = linkonce_odr constant { i8, i16, ptr, ptr, i32, i16, ptr, [0 x %runtime.structField] } { i8 90, i16 0, ptr @"reflect/types.type:pointer:struct:{}", ptr @"reflect/types.type.pkgpath.empty", i32 0, i16 0, ptr inttoptr (i32 3 to ptr), [0 x %runtime.structField] zeroinitializer }, align 4
 @"reflect/types.type.pkgpath.empty" = linkonce_odr unnamed_addr constant [1 x i8] zeroinitializer, align 1
 @"reflect/types.type:pointer:struct:{}" = linkonce_odr constant { i8, i16, ptr } { i8 -43, i16 0, ptr @"reflect/types.type:struct:{}" }, align 4
 @"named:main.genericMethod$methodset" = linkonce_odr unnamed_addr constant { i32, [1 x ptr], { ptr } } { i32 1, [1 x ptr] [ptr @"reflect/methods.Regular:func:{basic:int}{basic:int}"], { ptr } { ptr @"(main.genericMethod).Regular$invoke" } }

compiler/testdata/large.ll

@@ -9,6 +9,7 @@ target triple = "wasm32-unknown-wasi"
 
 @"runtime/gc.layout:258-000000000000000000000000000000000000000000000000000000000000000002" = linkonce_odr unnamed_addr constant { i32, [33 x i8] } { i32 258, [33 x i8] c"\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\02" }
 @"reflect/types.typeid:named:main.largeValue" = external constant i8
+@"runtime.hashmapType:[1025]byte:[1025]byte" = linkonce_odr unnamed_addr constant { ptr, ptr, ptr } { ptr inttoptr (i32 3 to ptr), ptr inttoptr (i32 3 to ptr), ptr inttoptr (i32 67108137 to ptr) }
 @llvm.used = appending global [15 x ptr] [ptr @"(main.largeReceiver).makeLargeValue", ptr @"(main.largeReceiver).readLargeValue", ptr @main.makeLargeValue, ptr @main.makeZeroLargeValue, ptr @main.readLargeValue, ptr @main.deferLargeValue, ptr @main.goLargeValue, ptr @main.makeLargeResults, ptr @main.makeTwoLargeResults, ptr @main.makeMixedLargeResults, ptr @main.chooseLargeValue, ptr @main.makePointerLargeValue, ptr @main.useLargeMap, ptr @main.useLargeChannel, ptr @main.selectLargeChannel]
 @"main$string" = internal unnamed_addr constant [31 x i8] c"blocking select matched no case", align 1
 @"main$pack" = internal unnamed_addr constant { %runtime._string } { %runtime._string { ptr @"main$string", i32 31 } }
@@ -350,7 +351,7 @@ declare void @llvm.memset.p0.i32(ptr nocapture writeonly, i8, i32, i1 immarg) #7
 define hidden i8 @main.useLargeMap(ptr readonly dereferenceable_or_null(1025) %key, ptr readonly dereferenceable_or_null(1025) %value, ptr %context) unnamed_addr #1 {
 entry:
   %stackalloc = alloca i8, align 1
-  %0 = call ptr @runtime.hashmapMakeGeneric(i32 1025, i32 1025, i32 1, ptr null, ptr nonnull @runtime.hash32, ptr null, ptr nonnull @runtime.memequal, ptr undef) #9
+  %0 = call ptr @runtime.hashmapMakeGeneric(i32 1025, i32 1025, i32 1, ptr nonnull @"runtime.hashmapType:[1025]byte:[1025]byte", ptr null, ptr nonnull @runtime.hash32, ptr null, ptr nonnull @runtime.memequal, ptr undef) #9
   call void @runtime.trackPointer(ptr %0, ptr nonnull %stackalloc, ptr undef) #9
   call void @runtime.hashmapBinarySet(ptr %0, ptr %key, ptr %value, ptr undef) #9
   %result = call align 1 dereferenceable(1025) ptr @runtime.alloc(i32 1025, ptr nonnull inttoptr (i32 3 to ptr), ptr undef) #9
@@ -381,11 +382,11 @@ declare i32 @runtime.hash32(ptr, i32, i32, ptr) #0
 
 declare i1 @runtime.memequal(ptr, ptr, i32, ptr) #0
 
-declare ptr @runtime.hashmapMakeGeneric(i32, i32, i32, ptr, ptr, ptr, ptr, ptr) #0
+declare ptr @runtime.hashmapMakeGeneric(i32, i32, i32, ptr, ptr, ptr, ptr, ptr, ptr) #0
 
-declare void @runtime.hashmapBinarySet(ptr dereferenceable_or_null(48), ptr, ptr, ptr) #0
+declare void @runtime.hashmapBinarySet(ptr dereferenceable_or_null(52), ptr, ptr, ptr) #0
 
-declare i1 @runtime.hashmapBinaryGet(ptr dereferenceable_or_null(48), ptr, ptr, i32, ptr) #0
+declare i1 @runtime.hashmapBinaryGet(ptr dereferenceable_or_null(52), ptr, ptr, i32, ptr) #0
 
 ; Function Attrs: nounwind
 define hidden i8 @main.useLargeChannel(ptr dereferenceable_or_null(36) %ch, ptr readonly dereferenceable_or_null(1025) %value, ptr %context) unnamed_addr #1 {

compiler/testdata/zeromap.ll

@@ -6,6 +6,12 @@ target triple = "wasm32-unknown-wasi"
 %main.hasPadding = type { i1, i32, i1 }
 %runtime._string = type { ptr, i32 }
 
+@"runtime/gc.layout:44-545555550500" = linkonce_odr unnamed_addr constant { i32, [6 x i8] } { i32 44, [6 x i8] c"TUUU\05\00" }
+@"runtime.hashmapType:struct{string; string}:int" = linkonce_odr unnamed_addr constant { ptr, ptr, ptr } { ptr inttoptr (i32 329 to ptr), ptr inttoptr (i32 3 to ptr), ptr @"runtime/gc.layout:44-545555550500" }
+@"runtime.hashmapType:[2]string:int" = linkonce_odr unnamed_addr constant { ptr, ptr, ptr } { ptr inttoptr (i32 69 to ptr), ptr inttoptr (i32 3 to ptr), ptr @"runtime/gc.layout:44-545555550500" }
+@"runtime/gc.layout:92-545555555555555555550500" = linkonce_odr unnamed_addr constant { i32, [12 x i8] } { i32 92, [12 x i8] c"TUUUUUUUUU\05\00" }
+@"runtime.hashmapType:[5]string:int" = linkonce_odr unnamed_addr constant { ptr, ptr, ptr } { ptr inttoptr (i32 69 to ptr), ptr inttoptr (i32 3 to ptr), ptr @"runtime/gc.layout:92-545555555555555555550500" }
+
 declare void @runtime.trackPointer(ptr nocapture readonly, ptr, ptr) #0
 
 ; Function Attrs: nounwind
@@ -15,7 +21,7 @@ entry:
 }
 
 ; Function Attrs: noinline nounwind
-define hidden i32 @main.testZeroGet(ptr dereferenceable_or_null(48) %m, i1 %s.b1, i32 %s.i, i1 %s.b2, ptr %context) unnamed_addr #2 {
+define hidden i32 @main.testZeroGet(ptr dereferenceable_or_null(52) %m, i1 %s.b1, i32 %s.i, i1 %s.b2, ptr %context) unnamed_addr #2 {
 entry:
   %hashmap.key = alloca %main.hasPadding, align 8
   %hashmap.value = alloca i32, align 4
@@ -35,13 +41,13 @@ entry:
 ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 declare void @llvm.lifetime.start.p0(ptr nocapture) #3
 
-declare i1 @runtime.hashmapGenericGet(ptr dereferenceable_or_null(48), ptr nocapture, ptr nocapture, i32, ptr) #0
+declare i1 @runtime.hashmapGenericGet(ptr dereferenceable_or_null(52), ptr nocapture, ptr nocapture, i32, ptr) #0
 
 ; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
 declare void @llvm.lifetime.end.p0(ptr nocapture) #3
 
 ; Function Attrs: noinline nounwind
-define hidden void @main.testZeroSet(ptr dereferenceable_or_null(48) %m, i1 %s.b1, i32 %s.i, i1 %s.b2, ptr %context) unnamed_addr #2 {
+define hidden void @main.testZeroSet(ptr dereferenceable_or_null(52) %m, i1 %s.b1, i32 %s.i, i1 %s.b2, ptr %context) unnamed_addr #2 {
 entry:
   %hashmap.key = alloca %main.hasPadding, align 8
   %hashmap.value = alloca i32, align 4
@@ -58,10 +64,10 @@ entry:
   ret void
 }
 
-declare void @runtime.hashmapGenericSet(ptr dereferenceable_or_null(48), ptr nocapture, ptr nocapture, ptr) #0
+declare void @runtime.hashmapGenericSet(ptr dereferenceable_or_null(52), ptr nocapture, ptr nocapture, ptr) #0
 
 ; Function Attrs: noinline nounwind
-define hidden i32 @main.testZeroArrayGet(ptr dereferenceable_or_null(48) %m, [2 x %main.hasPadding] %s, ptr %context) unnamed_addr #2 {
+define hidden i32 @main.testZeroArrayGet(ptr dereferenceable_or_null(52) %m, [2 x %main.hasPadding] %s, ptr %context) unnamed_addr #2 {
 entry:
   %hashmap.key = alloca [2 x %main.hasPadding], align 8
   %hashmap.value = alloca i32, align 4
@@ -80,7 +86,7 @@ entry:
 }
 
 ; Function Attrs: noinline nounwind
-define hidden void @main.testZeroArraySet(ptr dereferenceable_or_null(48) %m, [2 x %main.hasPadding] %s, ptr %context) unnamed_addr #2 {
+define hidden void @main.testZeroArraySet(ptr dereferenceable_or_null(52) %m, [2 x %main.hasPadding] %s, ptr %context) unnamed_addr #2 {
 entry:
   %hashmap.key = alloca [2 x %main.hasPadding], align 8
   %hashmap.value = alloca i32, align 4
@@ -102,7 +108,7 @@ entry:
 define hidden ptr @main.makeStringStructMap(ptr %context) unnamed_addr #2 {
 entry:
   %stackalloc = alloca i8, align 1
-  %0 = call ptr @runtime.hashmapMakeGeneric(i32 16, i32 4, i32 8, ptr null, ptr nonnull @"hashmapKeyHash.struct{string; string}", ptr null, ptr nonnull @"hashmapKeyEqual.struct{string; string}", ptr undef) #4
+  %0 = call ptr @runtime.hashmapMakeGeneric(i32 16, i32 4, i32 8, ptr nonnull @"runtime.hashmapType:struct{string; string}:int", ptr null, ptr nonnull @"hashmapKeyHash.struct{string; string}", ptr null, ptr nonnull @"hashmapKeyEqual.struct{string; string}", ptr undef) #4
   call void @runtime.trackPointer(ptr %0, ptr nonnull %stackalloc, ptr undef) #4
   ret ptr %0
 }
@@ -145,13 +151,13 @@ entry:
 
 declare i1 @runtime.stringEqual(ptr readonly, i32, ptr readonly, i32, ptr) #0
 
-declare ptr @runtime.hashmapMakeGeneric(i32, i32, i32, ptr, ptr, ptr, ptr, ptr) #0
+declare ptr @runtime.hashmapMakeGeneric(i32, i32, i32, ptr, ptr, ptr, ptr, ptr, ptr) #0
 
 ; Function Attrs: noinline nounwind
 define hidden ptr @main.makeShortStringArrayMap(ptr %context) unnamed_addr #2 {
 entry:
   %stackalloc = alloca i8, align 1
-  %0 = call ptr @runtime.hashmapMakeGeneric(i32 16, i32 4, i32 8, ptr null, ptr nonnull @"hashmapKeyHash.[2]string", ptr null, ptr nonnull @"hashmapKeyEqual.[2]string", ptr undef) #4
+  %0 = call ptr @runtime.hashmapMakeGeneric(i32 16, i32 4, i32 8, ptr nonnull @"runtime.hashmapType:[2]string:int", ptr null, ptr nonnull @"hashmapKeyHash.[2]string", ptr null, ptr nonnull @"hashmapKeyEqual.[2]string", ptr undef) #4
   call void @runtime.trackPointer(ptr %0, ptr nonnull %stackalloc, ptr undef) #4
   ret ptr %0
 }
@@ -194,7 +200,7 @@ entry:
 define hidden ptr @main.makeLongStringArrayMap(ptr %context) unnamed_addr #2 {
 entry:
   %stackalloc = alloca i8, align 1
-  %0 = call ptr @runtime.hashmapMakeGeneric(i32 40, i32 4, i32 8, ptr null, ptr nonnull @"hashmapKeyHash.[5]string", ptr null, ptr nonnull @"hashmapKeyEqual.[5]string", ptr undef) #4
+  %0 = call ptr @runtime.hashmapMakeGeneric(i32 40, i32 4, i32 8, ptr nonnull @"runtime.hashmapType:[5]string:int", ptr null, ptr nonnull @"hashmapKeyHash.[5]string", ptr null, ptr nonnull @"hashmapKeyEqual.[5]string", ptr undef) #4
   call void @runtime.trackPointer(ptr %0, ptr nonnull %stackalloc, ptr undef) #4
   ret ptr %0
 }

interp/memory.go

@@ -1278,13 +1278,14 @@ func (r *runner) readObjectLayout(layoutValue value) (uint64, *big.Int) {
 	// integer value, or can be nil.
 	ptr, err := layoutValue.asPointer(r)
 	if err == errIntegerAsPointer {
-		// It's an integer, which means it's a small object or unknown.
+		// It's an integer, which means it's a small object.
 		layout := layoutValue.Uint(r)
 		if layout == 0 {
-			// Nil pointer, which means the layout is unknown.
+			panic("runtime.alloc called without a GC layout")
-			return 0, nil
 		}
 		if layout%2 != 1 {
+			// Conservative layouts are reserved for stack storage and cannot
+			// reach interpreted heap allocations.
 			// Sanity check: the least significant bit must be set. This is how
 			// the runtime can separate pointers from integers.
 			panic("unexpected layout")
@@ -1331,11 +1332,6 @@ func (r *runner) readObjectLayout(layoutValue value) (uint64, *big.Int) {
 // have some additional repetition, for example in the buffer of a slice.
 func (r *runner) getLLVMTypeFromLayout(layoutValue value) llvm.Type {
 	objectSizeWords, bitmap := r.readObjectLayout(layoutValue)
-	if bitmap == nil {
-		// No information available.
-		return llvm.Type{}
-	}
-
 	if bitmap.BitLen() == 0 {
 		// There are no pointers in this object, so treat this as a raw byte
 		// buffer. This is important because objects without pointers may have

interp/testdata/alloc.ll

@@ -11,6 +11,7 @@ target triple = "wasm32--wasi"
 @layout3 = global ptr null
 @layout4 = global ptr null
 @bigobj1 = global ptr null
+@pointerFree10 = global ptr null
 
 declare ptr @runtime.alloc(i32, ptr) unnamed_addr
 
@@ -49,5 +50,9 @@ define internal void @main.init() unnamed_addr {
   ; Large object that needs to be stored in a separate global.
   %bigobj1 = call ptr @runtime.alloc(i32 248, ptr @"runtime/gc.layout:62-2000000000000001")
   store ptr %bigobj1, ptr @bigobj1
+
+  ; Another pointer-free object.
+  %pointerFree10 = call ptr @runtime.alloc(i32 10, ptr inttoptr (i32 3 to ptr))
+  store ptr %pointerFree10, ptr @pointerFree10
   ret void
 }

interp/testdata/alloc.out.ll

@@ -10,6 +10,7 @@ target triple = "wasm32--wasi"
 @layout3 = local_unnamed_addr global ptr @"main$alloc.6"
 @layout4 = local_unnamed_addr global ptr @"main$alloc.7"
 @bigobj1 = local_unnamed_addr global ptr @"main$alloc.8"
+@pointerFree10 = local_unnamed_addr global ptr @"main$alloc.9"
 @"main$alloc" = internal global [12 x i8] zeroinitializer, align 4
 @"main$alloc.1" = internal global [7 x i8] zeroinitializer, align 4
 @"main$alloc.2" = internal global [3 x i8] zeroinitializer, align 4
@@ -19,6 +20,7 @@ target triple = "wasm32--wasi"
 @"main$alloc.6" = internal global { ptr, ptr, ptr, i32, i32, ptr, ptr, i32, i32, i32, i32, i32, i32, ptr, ptr, i32, i32, i32, ptr, ptr, i32, i32, ptr, i32, i32, ptr } zeroinitializer, align 4
 @"main$alloc.7" = internal global [3 x { ptr, ptr, ptr, i32, i32, ptr, ptr, i32, i32, i32, i32, i32, i32, ptr, ptr, i32, i32, i32, ptr, ptr, i32, i32, ptr, i32, i32, ptr }] zeroinitializer, align 4
 @"main$alloc.8" = internal global { ptr, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, ptr } zeroinitializer, align 4
+@"main$alloc.9" = internal global [10 x i8] zeroinitializer, align 4
 
 define void @runtime.initAll() unnamed_addr {
   ret void

src/internal/gclayout/gclayout.go

@@ -19,8 +19,13 @@ const (
 
 	NoPtrs      = Layout((0 << sizeShift) | (1 << 1) | 1)
 	Pointer     = Layout((1 << sizeShift) | ((unsafe.Sizeof(unsafe.Pointer(nil)) / ptrAlign) << 1) | 1)
+	PointerPair = Layout((3 << sizeShift) | ((2 * unsafe.Sizeof(unsafe.Pointer(nil)) / ptrAlign) << 1) | 1)
 	String      = Layout((1 << sizeShift) | ((unsafe.Sizeof("") / ptrAlign) << 1) | 1)
 	Slice       = Layout((1 << sizeShift) | ((unsafe.Sizeof([]byte{}) / ptrAlign) << 1) | 1)
+
+	// Conservative is reserved for stack storage, which does not have an
+	// ordinary Go object layout.
+	Conservative = Layout(2)
 )
 
 func (l Layout) AsPtr() unsafe.Pointer { return unsafe.Pointer(l) }

src/internal/reflectlite/type.go

@@ -166,6 +166,11 @@ type RawType struct {
 	meta uint8 // metadata byte, contains kind and flags (see constants above)
 }
 
+type basicType struct {
+	RawType
+	ptrTo *RawType
+}
+
 // All types that have an element type: named, chan, slice, array, map (but not
 // pointer because it doesn't have ptrTo).
 type elemType struct {
@@ -200,6 +205,7 @@ type arrayType struct {
 	elem      *RawType
 	arrayLen  uintptr
 	slicePtr  *RawType
+	layout    unsafe.Pointer
 }
 
 type mapType struct {
@@ -208,6 +214,7 @@ type mapType struct {
 	ptrTo     *RawType
 	elem      *RawType
 	key       *RawType
+	typeInfo  unsafe.Pointer
 }
 
 // namedType is the type descriptor for named types. The numMethod field uses
@@ -243,6 +250,7 @@ type structType struct {
 	pkgpath   *byte
 	size      uint32
 	numField  uint16
+	layout    unsafe.Pointer
 	fields    [1]structField // the remaining fields are all of type structField
 	// methods methodSet follows after fields, only when numMethod & numMethodHasMethodSet != 0
 }
@@ -298,6 +306,8 @@ func pointerTo(t *RawType) *RawType {
 	}
 
 	switch t.Kind() {
+	case Bool, Int, Int8, Int16, Int32, Int64, Uint, Uint8, Uint16, Uint32, Uint64, Uintptr, Complex64, Complex128, Float32, Float64, String, UnsafePointer:
+		return (*basicType)(unsafe.Pointer(t)).ptrTo
 	case Pointer:
 		if tag := t.ptrtag(); tag < 3 {
 			return (*RawType)(unsafe.Add(unsafe.Pointer(t), 1))
@@ -306,6 +316,8 @@ func pointerTo(t *RawType) *RawType {
 		// TODO(dgryski): This is blocking https://github.com/tinygo-org/tinygo/issues/3131
 		// We need to be able to create types that match existing types to prevent typecode equality.
 		panic("reflect: cannot make *****T type")
+	case Interface, Func:
+		return (*interfaceType)(unsafe.Pointer(t)).ptrTo
 	case Struct:
 		return (*structType)(unsafe.Pointer(t)).ptrTo
 	default:
@@ -729,6 +741,7 @@ func (t *RawType) Align() int {
 }
 
 func (r *RawType) gcLayout() unsafe.Pointer {
+	r = r.underlying()
 	kind := r.Kind()
 
 	if kind < String {
@@ -736,16 +749,26 @@ func (r *RawType) gcLayout() unsafe.Pointer {
 	}
 
 	switch kind {
-	case Pointer, UnsafePointer, Chan, Map:
-		return gclayout.Pointer.AsPtr()
 	case String:
 		return gclayout.String.AsPtr()
+	case UnsafePointer, Chan, Pointer, Map:
+		return gclayout.Pointer.AsPtr()
+	case Interface, Func:
+		return gclayout.PointerPair.AsPtr()
 	case Slice:
 		return gclayout.Slice.AsPtr()
+	case Array:
+		return (*arrayType)(unsafe.Pointer(r)).layout
+	case Struct:
+		return (*structType)(unsafe.Pointer(r)).layout
+	default:
+		panic("reflect: invalid GC layout kind")
+	}
 }
 
-	// Unknown (for now); let the conservative pointer scanning handle it
+func (r *RawType) hashmapTypeInfo() unsafe.Pointer {
-	return nil
+	r = r.underlying()
+	return (*mapType)(unsafe.Pointer(r)).typeInfo
 }
 
 // FieldAlign returns the alignment if this type is used in a struct field. It

src/internal/reflectlite/value.go

@@ -1,6 +1,7 @@
 package reflectlite
 
 import (
+	"internal/gclayout"
 	"math"
 	"unsafe"
 )
@@ -1644,7 +1645,7 @@ func makeInt(flags valueFlags, bits uint64, t *RawType) Value {
 
 	ptr := unsafe.Pointer(&v.value)
 	if size > unsafe.Sizeof(uintptr(0)) {
-		ptr = alloc(size, nil)
+		ptr = alloc(size, gclayout.NoPtrs.AsPtr())
 		v.value = ptr
 	}
 
@@ -1671,7 +1672,7 @@ func makeFloat(flags valueFlags, f float64, t *RawType) Value {
 
 	ptr := unsafe.Pointer(&v.value)
 	if size > unsafe.Sizeof(uintptr(0)) {
-		ptr = alloc(size, nil)
+		ptr = alloc(size, gclayout.NoPtrs.AsPtr())
 		v.value = ptr
 	}
 
@@ -1703,7 +1704,7 @@ func makeComplex(flags valueFlags, f complex128, t *RawType) Value {
 
 	ptr := unsafe.Pointer(&v.value)
 	if size > unsafe.Sizeof(uintptr(0)) {
-		ptr = alloc(size, nil)
+		ptr = alloc(size, gclayout.NoPtrs.AsPtr())
 		v.value = ptr
 	}
 
@@ -1834,7 +1835,7 @@ func Zero(typ Type) Value {
 
 	return Value{
 		typecode: typ.(*RawType),
-		value:    alloc(size, nil),
+		value:    alloc(size, typ.(*RawType).gcLayout()),
 		flags:    valueFlagExported | valueFlagRO,
 	}
 }
@@ -1844,7 +1845,7 @@ func Zero(typ Type) Value {
 func New(typ Type) Value {
 	return Value{
 		typecode: pointerTo(typ.(*RawType)),
-		value:    alloc(typ.Size(), nil),
+		value:    alloc(typ.Size(), typ.(*RawType).gcLayout()),
 		flags:    valueFlagExported,
 	}
 }
@@ -2203,13 +2204,13 @@ func (v Value) FieldByNameFunc(match func(string) bool) Value {
 }
 
 //go:linkname hashmapMake runtime.hashmapMake
-func hashmapMake(keySize, valueSize uintptr, sizeHint uintptr, alg uint8) unsafe.Pointer
+func hashmapMake(keySize, valueSize uintptr, sizeHint uintptr, typeInfo unsafe.Pointer, alg uint8) unsafe.Pointer
 
 //go:linkname hashmapMakeReflect runtime.hashmapMakeReflect
-func hashmapMakeReflect(keySize, valueSize, sizeHint uintptr, keyType unsafe.Pointer) unsafe.Pointer
+func hashmapMakeReflect(keySize, valueSize, sizeHint uintptr, typeInfo, keyType unsafe.Pointer) unsafe.Pointer
 
 //go:linkname chanMake runtime.chanMake
-func chanMake(elementSize uintptr, bufSize uintptr) unsafe.Pointer
+func chanMake(elementSize uintptr, bufSize uintptr, elementLayout unsafe.Pointer) unsafe.Pointer
 
 // MakeMapWithSize creates a new map with the specified type and initial space
 // for approximately n elements.
@@ -2231,18 +2232,19 @@ func MakeMapWithSize(typ Type, n int) Value {
 
 	key := typ.Key().(*RawType)
 	val := typ.Elem().(*RawType)
+	typeInfo := typ.(*RawType).hashmapTypeInfo()
 
 	var m unsafe.Pointer
 
 	if key.Kind() == String {
-		m = hashmapMake(key.Size(), val.Size(), uintptr(n), hashmapAlgorithmString)
+		m = hashmapMake(key.Size(), val.Size(), uintptr(n), typeInfo, hashmapAlgorithmString)
 	} else if key.isBinary() {
-		m = hashmapMake(key.Size(), val.Size(), uintptr(n), hashmapAlgorithmBinary)
+		m = hashmapMake(key.Size(), val.Size(), uintptr(n), typeInfo, hashmapAlgorithmBinary)
 	} else {
 		// Composite key type (struct with strings, floats, etc.).
 		// Use runtime-generated hash/equal closures that walk the
 		// type structure, matching the compiler-generated functions.
-		m = hashmapMakeReflect(key.Size(), val.Size(), uintptr(n), unsafe.Pointer(key))
+		m = hashmapMakeReflect(key.Size(), val.Size(), uintptr(n), typeInfo, unsafe.Pointer(key))
 	}
 
 	return Value{
@@ -2269,7 +2271,7 @@ func MakeChan(typ Type, size int) Value {
 		panic("reflect.MakeChan: unidirectional channel type")
 	}
 	elem := typ.Elem().(*RawType)
-	ch := chanMake(elem.Size(), uintptr(size))
+	ch := chanMake(elem.Size(), uintptr(size), elem.gcLayout())
 	return Value{
 		typecode: typ.(*RawType),
 		value:    ch,

src/internal/task/task_asyncify.go

@@ -3,6 +3,7 @@
 package task
 
 import (
+	"internal/gclayout"
 	"unsafe"
 )
 
@@ -73,7 +74,7 @@ func (s *state) initialize(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	s.args = args
 
 	// Create a stack.
-	stack := runtime_alloc(stackSize, nil)
+	stack := runtime_alloc(stackSize, gclayout.Conservative.AsPtr())
 
 	// Set up the stack canary, a random number that should be checked when
 	// switching from the task back to the scheduler. The stack canary pointer

src/internal/task/task_stack.go

@@ -3,6 +3,7 @@
 package task
 
 import (
+	"internal/gclayout"
 	"unsafe"
 )
 
@@ -36,7 +37,7 @@ func taskExit() {
 // initialize the state and prepare to call the specified function with the specified argument bundle.
 func (s *state) initialize(fn uintptr, args unsafe.Pointer, stackSize uintptr) {
 	// Create a stack.
-	stack := runtime_alloc(stackSize, nil)
+	stack := runtime_alloc(stackSize, gclayout.Conservative.AsPtr())
 
 	// Set up the stack canary, a random number that should be checked when
 	// switching from the task back to the scheduler. The stack canary pointer

src/reflect/value_test.go

@@ -994,6 +994,20 @@ func TestTypeAssertPanic(t *testing.T) {
 	})
 }
 
+type tinyMakeChanElement struct {
+	ptr  *int
+	text string
+}
+
+var tinyMakeChanChurn []*int
+
+//go:noinline
+func fillTinyMakeChan(ch chan tinyMakeChanElement) {
+	value := new(int)
+	*value = 42
+	ch <- tinyMakeChanElement{ptr: value, text: "hello"}
+}
+
 func TestTinyMakeChan(t *testing.T) {
 	// Value.Send and Value.Recv are not implemented yet, so the channel is
 	// exercised through Interface(): that proves MakeChan returns a working
@@ -1027,6 +1041,22 @@ func TestTinyMakeChan(t *testing.T) {
 		}
 	})
 
+	t.Run("buffered pointers survive GC", func(t *testing.T) {
+		v := MakeChan(TypeOf(make(chan tinyMakeChanElement)), 1)
+		ch := v.Interface().(chan tinyMakeChanElement)
+		fillTinyMakeChan(ch)
+		runtime.GC()
+		tinyMakeChanChurn = make([]*int, 128)
+		for i := range tinyMakeChanChurn {
+			tinyMakeChanChurn[i] = new(int)
+		}
+
+		got := <-ch
+		if *got.ptr != 42 || got.text != "hello" {
+			t.Errorf("<-ch=%v, want {42 hello}", got)
+		}
+	})
+
 	t.Run("unbuffered", func(t *testing.T) {
 		v := MakeChan(TypeOf(make(chan string)), 0)
 		if got, want := v.Cap(), 0; got != want {

src/runtime/arch_tinygowasm_malloc.go

@@ -2,7 +2,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/gclayout"
+	"unsafe"
+)
 
 // The below functions override the default allocator of wasi-libc. This ensures
 // code linked from other languages can allocate memory without colliding with
@@ -21,7 +24,7 @@ func libc_malloc(size uintptr) unsafe.Pointer {
 	if size == 0 {
 		return nil
 	}
-	ptr := alloc(size, nil)
+	ptr := alloc(size, gclayout.NoPtrs.AsPtr())
 	allocs[(*byte)(ptr)] = size
 	return ptr
 }
@@ -54,7 +57,7 @@ func libc_realloc(oldPtr unsafe.Pointer, size uintptr) unsafe.Pointer {
 	// It's hard to optimize this to expand the current buffer with our GC, but
 	// it is theoretically possible. For now, just always allocate fresh.
 	// TODO: we could skip this if the new allocation is smaller than the old.
-	ptr := alloc(size, nil)
+	ptr := alloc(size, gclayout.NoPtrs.AsPtr())
 
 	if oldPtr != nil {
 		if oldSize, ok := allocs[(*byte)(oldPtr)]; ok {

src/runtime/baremetal.go

@@ -3,6 +3,7 @@
 package runtime
 
 import (
+	"internal/gclayout"
 	"sync/atomic"
 	"unsafe"
 )
@@ -11,7 +12,7 @@ import (
 func libc_malloc(size uintptr) unsafe.Pointer {
 	// Note: this zeroes the returned buffer which is not necessary.
 	// The same goes for bytealg.MakeNoZero.
-	return alloc(size, nil)
+	return alloc(size, gclayout.NoPtrs.AsPtr())
 }
 
 //export calloc

src/runtime/chan.go

@@ -137,11 +137,11 @@ type chanSelectState struct {
 	value unsafe.Pointer
 }
 
-func chanMake(elementSize uintptr, bufSize uintptr) *channel {
+func chanMake(elementSize uintptr, bufSize uintptr, elementLayout unsafe.Pointer) *channel {
 	return &channel{
 		elementSize: elementSize,
 		bufCap:      bufSize,
-		buf:         alloc(elementSize*bufSize, nil),
+		buf:         alloc(elementSize*bufSize, elementLayout),
 	}
 }
 

src/runtime/gc_blocks.go

@@ -31,6 +31,7 @@ package runtime
 // Moss.
 
 import (
+	"internal/gclayout"
 	"internal/reflectlite"
 	"internal/task"
 	"runtime/interrupt"
@@ -501,7 +502,7 @@ func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
 
 func realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
 	if ptr == nil {
-		return alloc(size, nil)
+		return alloc(size, gclayout.NoPtrs.AsPtr())
 	}
 
 	// Find the first block of the original allocation.
@@ -526,7 +527,7 @@ func realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
 	}
 
 	// Create a new allocation and copy the old data.
-	newAlloc := alloc(size, nil)
+	newAlloc := alloc(size, gclayout.NoPtrs.AsPtr())
 	memcpy(newAlloc, ptr, oldSize)
 	free(ptr)
 

src/runtime/gc_leaking.go

@@ -7,6 +7,7 @@ package runtime
 // may be the only memory allocator possible.
 
 import (
+	"internal/gclayout"
 	"internal/task"
 	"sync/atomic"
 	"unsafe"
@@ -69,7 +70,7 @@ func alloc(size uintptr, layout unsafe.Pointer) unsafe.Pointer {
 }
 
 func realloc(ptr unsafe.Pointer, size uintptr) unsafe.Pointer {
-	newAlloc := alloc(size, nil)
+	newAlloc := alloc(size, gclayout.NoPtrs.AsPtr())
 	if ptr == nil {
 		return newAlloc
 	}

src/runtime/gc_precise.go

@@ -55,7 +55,10 @@
 
 package runtime
 
-import "unsafe"
+import (
+	"internal/gclayout"
+	"unsafe"
+)
 
 const sizeFieldBits = 4 + (unsafe.Sizeof(uintptr(0)) / 4)
 
@@ -76,9 +79,7 @@ func (layout gcLayout) pointerFree() bool {
 // The length is rounded down to a multiple of the element size.
 func (layout gcLayout) scan(start, len uintptr) {
 	switch {
-	case layout == 0:
+	case layout == gcLayout(gclayout.Conservative):
-		// This is an unknown layout.
-		// Scan conservatively.
 		// NOTE: This is *NOT* equivalent to a slice of pointers on AVR.
 		scanConservative(start, len)
 

src/runtime/hashmap.go

@@ -14,6 +14,7 @@ import (
 // The underlying hashmap structure for Go.
 type hashmap struct {
 	buckets       unsafe.Pointer // pointer to array of buckets
+	typeInfo      *hashmapTypeInfo
 	seed          uintptr
 	count         uintptr
 	keySize       uintptr
@@ -26,6 +27,17 @@ type hashmap struct {
 	keyHash       func(key unsafe.Pointer, size, seed uintptr) uint32
 }
 
+type hashmapTypeInfo struct {
+	keyLayout    unsafe.Pointer
+	valueLayout  unsafe.Pointer
+	bucketLayout unsafe.Pointer
+}
+
+//go:inline
+func hashmapType(m *hashmap) *hashmapTypeInfo {
+	return m.typeInfo
+}
+
 const (
 	hashmapMaxKeySize   = 128
 	hashmapMaxValueSize = 128
@@ -113,7 +125,7 @@ func hashmapTopHash(hash uint32) uint8 {
 }
 
 // Create a new hashmap with the given keySize and valueSize.
-func hashmapMake(keySize, valueSize uintptr, sizeHint uintptr, alg uint8) *hashmap {
+func hashmapMake(keySize, valueSize uintptr, sizeHint uintptr, typeInfo unsafe.Pointer, alg uint8) *hashmap {
 	bucketBits := uint8(0)
 	for hashmapHasSpaceToGrow(bucketBits) && hashmapOverLoadFactor(sizeHint, bucketBits) {
 		bucketBits++
@@ -132,13 +144,14 @@ func hashmapMake(keySize, valueSize uintptr, sizeHint uintptr, alg uint8) *hashm
 	}
 
 	bucketBufSize := hashmapBucketHeaderSize + keySlotSize*8 + valueSlotSize*8
-	buckets := alloc(bucketBufSize*(1<<bucketBits), nil)
+	buckets := alloc(bucketBufSize*(1<<bucketBits), (*hashmapTypeInfo)(typeInfo).bucketLayout)
 
 	keyHash := hashmapKeyHashAlg(tinygo.HashmapAlgorithm(alg))
 	keyEqual := hashmapKeyEqualAlg(tinygo.HashmapAlgorithm(alg))
 
 	return &hashmap{
 		buckets:       buckets,
+		typeInfo:      (*hashmapTypeInfo)(typeInfo),
 		seed:          uintptr(fastrand()),
 		keySize:       keySize,
 		valueSize:     valueSize,
@@ -325,7 +338,7 @@ func hashmapSet(m *hashmap, key unsafe.Pointer, value unsafe.Pointer, hash uint3
 //go:inline
 func hashmapStoreKey(m *hashmap, slotKey, key unsafe.Pointer) {
 	if m.flags&hashmapFlagIndirectKey != 0 {
-		p := alloc(m.keySize, nil)
+		p := alloc(m.keySize, hashmapType(m).keyLayout)
 		memcpy(p, key, m.keySize)
 		*(*unsafe.Pointer)(slotKey) = p
 	} else {
@@ -343,7 +356,7 @@ func hashmapStoreValue(m *hashmap, slotValue, value unsafe.Pointer) {
 		p := *(*unsafe.Pointer)(slotValue)
 		if p == nil {
 			// First insert: allocate backing storage.
-			p = alloc(m.valueSize, nil)
+			p = alloc(m.valueSize, hashmapType(m).valueLayout)
 			*(*unsafe.Pointer)(slotValue) = p
 		}
 		memcpy(p, value, m.valueSize)
@@ -356,7 +369,7 @@ func hashmapStoreValue(m *hashmap, slotValue, value unsafe.Pointer) {
 // value into the bucket, and returns a pointer to this bucket.
 func hashmapInsertIntoNewBucket(m *hashmap, key, value unsafe.Pointer, tophash uint8) *hashmapBucket {
 	bucketBufSize := hashmapBucketSize(m)
-	bucketBuf := alloc(bucketBufSize, nil)
+	bucketBuf := alloc(bucketBufSize, hashmapType(m).bucketLayout)
 	bucket := (*hashmapBucket)(bucketBuf)
 
 	// Insert into the first slot, which is empty as it has just been allocated.
@@ -392,13 +405,13 @@ func hashmapCopy(m *hashmap, sizeBits uint8) hashmap {
 	n.bucketBits = sizeBits
 	numBuckets := uintptr(1) << n.bucketBits
 	bucketBufSize := hashmapBucketSize(m)
-	n.buckets = alloc(bucketBufSize*numBuckets, nil)
+	n.buckets = alloc(bucketBufSize*numBuckets, hashmapType(m).bucketLayout)
 
 	// use a hashmap iterator to go through the old map
 	var it hashmapIterator
 
-	var key = alloc(m.keySize, nil)
+	var key = alloc(m.keySize, hashmapType(m).keyLayout)
-	var value = alloc(m.valueSize, nil)
+	var value = alloc(m.valueSize, hashmapType(m).valueLayout)
 
 	for hashmapNext(m, &it, key, value) {
 		h := n.keyHash(key, uintptr(n.keySize), n.seed)
@@ -624,6 +637,7 @@ func hashmapGenericDelete(m *hashmap, key unsafe.Pointer) {
 // equal functions. This avoids the interface/reflection path for composite
 // key types like structs containing strings.
 func hashmapMakeGeneric(keySize, valueSize uintptr, sizeHint uintptr,
+	typeInfo unsafe.Pointer,
 	keyHash func(key unsafe.Pointer, size, seed uintptr) uint32,
 	keyEqual func(x, y unsafe.Pointer, n uintptr) bool) *hashmap {
 	bucketBits := uint8(0)
@@ -644,10 +658,11 @@ func hashmapMakeGeneric(keySize, valueSize uintptr, sizeHint uintptr,
 	}
 
 	bucketBufSize := hashmapBucketHeaderSize + keySlotSize*8 + valueSlotSize*8
-	buckets := alloc(bucketBufSize*(1<<bucketBits), nil)
+	buckets := alloc(bucketBufSize*(1<<bucketBits), (*hashmapTypeInfo)(typeInfo).bucketLayout)
 
 	return &hashmap{
 		buckets:       buckets,
+		typeInfo:      (*hashmapTypeInfo)(typeInfo),
 		seed:          uintptr(fastrand()),
 		keySize:       keySize,
 		valueSize:     valueSize,
@@ -663,12 +678,12 @@ func hashmapMakeGeneric(keySize, valueSize uintptr, sizeHint uintptr,
 // hashmapMakeReflect creates a hashmap for reflect.MakeMapWithSize using
 // closures that reconstruct interface{} values from raw key bytes,
 // delegating to hashmapInterfaceHash for hashing and == for equality.
-func hashmapMakeReflect(keySize, valueSize, sizeHint uintptr, keyType unsafe.Pointer) *hashmap {
+func hashmapMakeReflect(keySize, valueSize, sizeHint uintptr, typeInfo, keyType unsafe.Pointer) *hashmap {
 	t := (*reflectlite.RawType)(keyType)
 	if t.Kind() == reflectlite.Interface {
 		// Interface keys are already stored as interface values in the
 		// bucket; use the existing interface hash/equal directly.
-		return hashmapMakeGeneric(keySize, valueSize, sizeHint,
+		return hashmapMakeGeneric(keySize, valueSize, sizeHint, typeInfo,
 			hashmapInterfacePtrHash, hashmapInterfaceEqual)
 	}
 	keyHash := func(key unsafe.Pointer, size, seed uintptr) uint32 {
@@ -677,7 +692,7 @@ func hashmapMakeReflect(keySize, valueSize, sizeHint uintptr, keyType unsafe.Poi
 	keyEqual := func(x, y unsafe.Pointer, n uintptr) bool {
 		return rawToInterface(t, x) == rawToInterface(t, y)
 	}
-	return hashmapMakeGeneric(keySize, valueSize, sizeHint, keyHash, keyEqual)
+	return hashmapMakeGeneric(keySize, valueSize, sizeHint, typeInfo, keyHash, keyEqual)
 }
 
 // rawToInterface reconstructs an interface{} from raw bytes at ptr.

transform/testdata/allocs.ll

@@ -7,7 +7,7 @@ declare nonnull ptr @runtime.alloc(i32, ptr)
 
 ; Test allocating a single int (i32) that should be allocated on the stack.
 define void @testInt() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   store i32 5, ptr %alloc
   ret void
 }
@@ -15,7 +15,7 @@ define void @testInt() {
 ; Test allocating an array of 3 i16 values that should be allocated on the
 ; stack.
 define i16 @testArray() {
-  %alloc = call align 2 ptr @runtime.alloc(i32 6, ptr null)
+  %alloc = call align 2 ptr @runtime.alloc(i32 6, ptr inttoptr (i32 3 to ptr))
   %alloc.1 = getelementptr i16, ptr %alloc, i32 1
   store i16 5, ptr %alloc.1
   %alloc.2 = getelementptr i16, ptr %alloc, i32 2
@@ -25,15 +25,15 @@ define i16 @testArray() {
 
 ; Test allocating objects with an unknown alignment.
 define void @testUnknownAlign() {
-  %alloc32 = call ptr @runtime.alloc(i32 32, ptr null)
+  %alloc32 = call ptr @runtime.alloc(i32 32, ptr inttoptr (i32 3 to ptr))
   store i8 5, ptr %alloc32
-  %alloc24 = call ptr @runtime.alloc(i32 24, ptr null)
+  %alloc24 = call ptr @runtime.alloc(i32 24, ptr inttoptr (i32 3 to ptr))
   store i16 5, ptr %alloc24
-  %alloc12 = call ptr @runtime.alloc(i32 12, ptr null)
+  %alloc12 = call ptr @runtime.alloc(i32 12, ptr inttoptr (i32 3 to ptr))
   store i16 5, ptr %alloc12
-  %alloc6 = call ptr @runtime.alloc(i32 6, ptr null)
+  %alloc6 = call ptr @runtime.alloc(i32 6, ptr inttoptr (i32 3 to ptr))
   store i16 5, ptr %alloc6
-  %alloc3 = call ptr @runtime.alloc(i32 3, ptr null)
+  %alloc3 = call ptr @runtime.alloc(i32 3, ptr inttoptr (i32 3 to ptr))
   store i16 5, ptr %alloc3
   ret void
 }
@@ -41,27 +41,27 @@ define void @testUnknownAlign() {
 ; Call a function that will let the pointer escape, so the heap-to-stack
 ; transform shouldn't be applied.
 define void @testEscapingCall() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %val = call ptr @escapeIntPtr(ptr %alloc)
   ret void
 }
 
 define void @testEscapingCall2() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %val = call ptr @escapeIntPtrSometimes(ptr %alloc, ptr %alloc)
   ret void
 }
 
 ; Call a function that doesn't let the pointer escape.
 define void @testNonEscapingCall() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %val = call ptr @noescapeIntPtr(ptr %alloc)
   ret void
 }
 
 ; Return the allocated value, which lets it escape.
 define ptr @testEscapingReturn() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   ret ptr %alloc
 }
 
@@ -70,7 +70,7 @@ define void @testNonEscapingLoop() {
 entry:
   br label %loop
 loop:
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %ptr = call ptr @noescapeIntPtr(ptr %alloc)
   %result = icmp eq ptr null, %ptr
   br i1 %result, label %loop, label %end
@@ -80,7 +80,7 @@ end:
 
 ; Test a zero-sized allocation.
 define void @testZeroSizedAlloc() {
-  %alloc = call align 1 ptr @runtime.alloc(i32 0, ptr null)
+  %alloc = call align 1 ptr @runtime.alloc(i32 0, ptr inttoptr (i32 3 to ptr))
   %ptr = call ptr @noescapeIntPtr(ptr %alloc)
   ret void
 }

transform/testdata/allocs.out.ll

@@ -42,13 +42,13 @@ define void @testUnknownAlign() {
 }
 
 define void @testEscapingCall() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %val = call ptr @escapeIntPtr(ptr %alloc)
   ret void
 }
 
 define void @testEscapingCall2() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %val = call ptr @escapeIntPtrSometimes(ptr %alloc, ptr %alloc)
   ret void
 }
@@ -61,7 +61,7 @@ define void @testNonEscapingCall() {
 }
 
 define ptr @testEscapingReturn() {
-  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr null)
+  %alloc = call align 4 ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   ret ptr %alloc
 }
 

transform/testdata/gc-stackslots.ll

@@ -18,7 +18,7 @@ define ptr @getPointer() {
 define ptr @needsStackSlots() {
   ; Tracked pointer. Although, in this case the value is immediately returned
   ; so tracking it is not really necessary.
-  %ptr = call ptr @runtime.alloc(i32 4, ptr null)
+  %ptr = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %ptr)
   call void @someArbitraryFunction()
   %val = load i8, ptr @someGlobal
@@ -39,7 +39,7 @@ define ptr @needsStackSlots2() {
   call void @runtime.trackPointer(ptr %ptr2)
 
   ; Here is finally the point where an allocation happens.
-  %unused = call ptr @runtime.alloc(i32 4, ptr null)
+  %unused = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %unused)
 
   ret ptr %ptr1
@@ -57,7 +57,7 @@ define ptr @fibNext(ptr %x, ptr %y) {
   %x.val = load i8, ptr %x
   %y.val = load i8, ptr %y
   %out.val = add i8 %x.val, %y.val
-  %out.alloc = call ptr @runtime.alloc(i32 1, ptr null)
+  %out.alloc = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %out.alloc)
   store i8 %out.val, ptr %out.alloc
   ret ptr %out.alloc
@@ -65,9 +65,9 @@ define ptr @fibNext(ptr %x, ptr %y) {
 
 define ptr @allocLoop() {
 entry:
-  %entry.x = call ptr @runtime.alloc(i32 1, ptr null)
+  %entry.x = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %entry.x)
-  %entry.y = call ptr @runtime.alloc(i32 1, ptr null)
+  %entry.y = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %entry.y)
   store i8 1, ptr %entry.y
   br label %loop
@@ -93,7 +93,7 @@ define void @testGEPBitcast() {
   %arr = call ptr @arrayAlloc()
   %arr.bitcast = getelementptr [32 x i8], ptr %arr, i32 0, i32 0
   call void @runtime.trackPointer(ptr %arr.bitcast)
-  %other = call ptr @runtime.alloc(i32 1, ptr null)
+  %other = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %other)
   ret void
 }
@@ -103,7 +103,7 @@ define void @someArbitraryFunction() {
 }
 
 define void @earlyPopRegression() {
-  %x.alloc = call ptr @runtime.alloc(i32 4, ptr null)
+  %x.alloc = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %x.alloc)
   ; At this point the pass used to pop the stack chain, resulting in a potential use-after-free during allocAndSave.
   musttail call void @allocAndSave(ptr %x.alloc)
@@ -111,7 +111,7 @@ define void @earlyPopRegression() {
 }
 
 define void @allocAndSave(ptr %x) {
-  %y = call ptr @runtime.alloc(i32 4, ptr null)
+  %y = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   call void @runtime.trackPointer(ptr %y)
   store ptr %y, ptr %x
   store ptr %x, ptr @ptrGlobal

transform/testdata/gc-stackslots.out.ll

@@ -21,7 +21,7 @@ define ptr @needsStackSlots() {
   %2 = getelementptr { ptr, i32, ptr }, ptr %gc.stackobject, i32 0, i32 0
   store ptr %1, ptr %2, align 4
   store ptr %gc.stackobject, ptr @runtime.stackChainStart, align 4
-  %ptr = call ptr @runtime.alloc(i32 4, ptr null)
+  %ptr = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %3 = getelementptr { ptr, i32, ptr }, ptr %gc.stackobject, i32 0, i32 2
   store ptr %ptr, ptr %3, align 4
   call void @someArbitraryFunction()
@@ -47,7 +47,7 @@ define ptr @needsStackSlots2() {
   %ptr2 = getelementptr i8, ptr @someGlobal, i32 0
   %6 = getelementptr { ptr, i32, ptr, ptr, ptr, ptr, ptr }, ptr %gc.stackobject, i32 0, i32 5
   store ptr %ptr2, ptr %6, align 4
-  %unused = call ptr @runtime.alloc(i32 4, ptr null)
+  %unused = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %7 = getelementptr { ptr, i32, ptr, ptr, ptr, ptr, ptr }, ptr %gc.stackobject, i32 0, i32 6
   store ptr %unused, ptr %7, align 4
   store ptr %1, ptr @runtime.stackChainStart, align 4
@@ -69,7 +69,7 @@ define ptr @fibNext(ptr %x, ptr %y) {
   %x.val = load i8, ptr %x, align 1
   %y.val = load i8, ptr %y, align 1
   %out.val = add i8 %x.val, %y.val
-  %out.alloc = call ptr @runtime.alloc(i32 1, ptr null)
+  %out.alloc = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   %3 = getelementptr { ptr, i32, ptr }, ptr %gc.stackobject, i32 0, i32 2
   store ptr %out.alloc, ptr %3, align 4
   store i8 %out.val, ptr %out.alloc, align 1
@@ -85,10 +85,10 @@ entry:
   %1 = getelementptr { ptr, i32, ptr, ptr, ptr, ptr, ptr }, ptr %gc.stackobject, i32 0, i32 0
   store ptr %0, ptr %1, align 4
   store ptr %gc.stackobject, ptr @runtime.stackChainStart, align 4
-  %entry.x = call ptr @runtime.alloc(i32 1, ptr null)
+  %entry.x = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   %2 = getelementptr { ptr, i32, ptr, ptr, ptr, ptr, ptr }, ptr %gc.stackobject, i32 0, i32 2
   store ptr %entry.x, ptr %2, align 4
-  %entry.y = call ptr @runtime.alloc(i32 1, ptr null)
+  %entry.y = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   %3 = getelementptr { ptr, i32, ptr, ptr, ptr, ptr, ptr }, ptr %gc.stackobject, i32 0, i32 3
   store ptr %entry.y, ptr %3, align 4
   store i8 1, ptr %entry.y, align 1
@@ -126,7 +126,7 @@ define void @testGEPBitcast() {
   %arr.bitcast = getelementptr [32 x i8], ptr %arr, i32 0, i32 0
   %3 = getelementptr { ptr, i32, ptr, ptr }, ptr %gc.stackobject, i32 0, i32 2
   store ptr %arr.bitcast, ptr %3, align 4
-  %other = call ptr @runtime.alloc(i32 1, ptr null)
+  %other = call ptr @runtime.alloc(i32 1, ptr inttoptr (i32 3 to ptr))
   %4 = getelementptr { ptr, i32, ptr, ptr }, ptr %gc.stackobject, i32 0, i32 3
   store ptr %other, ptr %4, align 4
   store ptr %1, ptr @runtime.stackChainStart, align 4
@@ -144,7 +144,7 @@ define void @earlyPopRegression() {
   %2 = getelementptr { ptr, i32, ptr }, ptr %gc.stackobject, i32 0, i32 0
   store ptr %1, ptr %2, align 4
   store ptr %gc.stackobject, ptr @runtime.stackChainStart, align 4
-  %x.alloc = call ptr @runtime.alloc(i32 4, ptr null)
+  %x.alloc = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %3 = getelementptr { ptr, i32, ptr }, ptr %gc.stackobject, i32 0, i32 2
   store ptr %x.alloc, ptr %3, align 4
   call void @allocAndSave(ptr %x.alloc)
@@ -159,7 +159,7 @@ define void @allocAndSave(ptr %x) {
   %2 = getelementptr { ptr, i32, ptr }, ptr %gc.stackobject, i32 0, i32 0
   store ptr %1, ptr %2, align 4
   store ptr %gc.stackobject, ptr @runtime.stackChainStart, align 4
-  %y = call ptr @runtime.alloc(i32 4, ptr null)
+  %y = call ptr @runtime.alloc(i32 4, ptr inttoptr (i32 3 to ptr))
   %3 = getelementptr { ptr, i32, ptr }, ptr %gc.stackobject, i32 0, i32 2
   store ptr %y, ptr %3, align 4
   store ptr %y, ptr %x, align 4