diff --git a/core/fmt/fmt.odin b/core/fmt/fmt.odin
index 2047aaf75..ce79aab9f 100644
--- a/core/fmt/fmt.odin
+++ b/core/fmt/fmt.odin
@@ -2072,6 +2072,7 @@ fmt_value :: proc(fi: ^Info, v: any, verb: rune) {
 			if info.generated_struct == nil {
 				return
 			}
+			/*
 			entries    := &m.entries
 			gs         := runtime.type_info_base(info.generated_struct).variant.(runtime.Type_Info_Struct)
 			ed         := runtime.type_info_base(gs.types[1]).variant.(runtime.Type_Info_Dynamic_Array)
@@ -2106,6 +2107,7 @@ fmt_value :: proc(fi: ^Info, v: any, verb: rune) {
 				value := data + entry_type.offsets[3] // value: Value
 				fmt_arg(fi, any{rawptr(value), info.value.id}, 'v')
 			}
+			*/
 		}
 
 	case runtime.Type_Info_Struct:
diff --git a/core/mem/alloc.odin b/core/mem/alloc.odin
index 551906bed..2d11b523f 100644
--- a/core/mem/alloc.odin
+++ b/core/mem/alloc.odin
@@ -112,22 +112,21 @@ query_info :: proc(pointer: rawptr, allocator: Allocator, loc := #caller_locatio
 
 
 
-delete_string :: proc(str: string, allocator := context.allocator, loc := #caller_location) {
-	free(raw_data(str), allocator, loc)
+delete_string :: proc(str: string, allocator := context.allocator, loc := #caller_location) -> Allocator_Error {
+	return free(raw_data(str), allocator, loc)
 }
-delete_cstring :: proc(str: cstring, allocator := context.allocator, loc := #caller_location) {
-	free((^byte)(str), allocator, loc)
+delete_cstring :: proc(str: cstring, allocator := context.allocator, loc := #caller_location) -> Allocator_Error {
+	return free((^byte)(str), allocator, loc)
 }
-delete_dynamic_array :: proc(array: $T/[dynamic]$E, loc := #caller_location) {
-	free(raw_data(array), array.allocator, loc)
+delete_dynamic_array :: proc(array: $T/[dynamic]$E, loc := #caller_location) -> Allocator_Error {
+	return free(raw_data(array), array.allocator, loc)
 }
-delete_slice :: proc(array: $T/[]$E, allocator := context.allocator, loc := #caller_location) {
-	free(raw_data(array), allocator, loc)
+delete_slice :: proc(array: $T/[]$E, allocator := context.allocator, loc := #caller_location) -> Allocator_Error {
+	return free(raw_data(array), allocator, loc)
 }
-delete_map :: proc(m: $T/map[$K]$V, loc := #caller_location) {
+delete_map :: proc(m: $T/map[$K]$V, loc := #caller_location) -> Allocator_Error {
 	raw := transmute(Raw_Map)m
-	delete_slice(raw.hashes, raw.entries.allocator, loc)
-	free(raw.entries.data, raw.entries.allocator, loc)
+	return runtime.map_free(raw, loc)
 }
 
 
diff --git a/core/reflect/reflect.odin b/core/reflect/reflect.odin
index 896fc4473..8aab77399 100644
--- a/core/reflect/reflect.odin
+++ b/core/reflect/reflect.odin
@@ -273,7 +273,7 @@ length :: proc(val: any) -> int {
 		return (^runtime.Raw_Dynamic_Array)(val.data).len
 
 	case Type_Info_Map:
-		return (^runtime.Raw_Map)(val.data).entries.len
+		return runtime.map_len((^runtime.Raw_Map)(val.data)^)
 
 	case Type_Info_String:
 		if a.is_cstring {
@@ -305,7 +305,7 @@ capacity :: proc(val: any) -> int {
 		return (^runtime.Raw_Dynamic_Array)(val.data).cap
 
 	case Type_Info_Map:
-		return (^runtime.Raw_Map)(val.data).entries.cap
+		return runtime.map_cap((^runtime.Raw_Map)(val.data)^)
 	}
 	return 0
 }
diff --git a/core/runtime/core.odin b/core/runtime/core.odin
index 385a03b71..ce3aa239b 100644
--- a/core/runtime/core.odin
+++ b/core/runtime/core.odin
@@ -394,9 +394,32 @@ Raw_Dynamic_Array :: struct {
 	allocator: Allocator,
 }
 
+// The raw, type-erased representation of a map.
+//
+// 32-bytes on 64-bit
+// 16-bytes on 32-bit
 Raw_Map :: struct {
-	hashes:  []Map_Index,
-	entries: Raw_Dynamic_Array,
+	// A single allocation spanning all keys, values, and hashes.
+	// {
+	//   k: Map_Cell(K) * (capacity / ks_per_cell)
+	//   v: Map_Cell(V) * (capacity / vs_per_cell)
+	//   h: Map_Cell(H) * (capacity / hs_per_cell)
+	// }
+	//
+	// The data is allocated assuming 64-byte alignment, meaning the address is
+	// always a multiple of 64. This means we have 6 bits of zeros in the pointer
+	// to store the capacity. We can store a value as large as 2^6-1 or 63 in
+	// there. This conveniently is the maximum log2 capacity we can have for a map
+	// as Odin uses signed integers to represent capacity.
+	//
+	// Since the hashes are backed by Map_Hash, which is just a 64-bit unsigned
+	// integer, the cell structure for hashes is unnecessary because 64/8 is 8 and
+	// requires no padding, meaning it can be indexed as a regular array of
+	// Map_Hash directly, though for consistency sake it's written as if it were
+	// an array of Map_Cell(Map_Hash).
+	data:      uintptr,   // 8-bytes on 64-bits, 4-bytes on 32-bits
+	len:       uintptr,   // 8-bytes on 64-bits, 4-bytes on 32-bits
+	allocator: Allocator, // 16-bytes on 64-bits, 8-bytes on 32-bits
 }
 
 Raw_Any :: struct {
diff --git a/core/runtime/core_builtin.odin b/core/runtime/core_builtin.odin
index b0f4cb25c..80a9f2944 100644
--- a/core/runtime/core_builtin.odin
+++ b/core/runtime/core_builtin.odin
@@ -159,20 +159,7 @@ delete_slice :: proc(array: $T/[]$E, allocator := context.allocator, loc := #cal
 }
 @builtin
 delete_map :: proc(m: $T/map[$K]$V, loc := #caller_location) -> Allocator_Error {
-	Entry :: struct {
-		hash:  uintptr,
-		next:  int,
-		key:   K,
-		value: V,
-	}
-
-	raw := transmute(Raw_Map)m
-	err := delete_slice(raw.hashes, raw.entries.allocator, loc)
-	err1 := mem_free_with_size(raw.entries.data, raw.entries.cap*size_of(Entry), raw.entries.allocator, loc)
-	if err == nil {
-		err = err1
-	}
-	return err
+	return map_free(transmute(Raw_Map)m, loc)
 }
 
 
@@ -285,19 +272,13 @@ clear_map :: proc "contextless" (m: ^$T/map[$K]$V) {
 	if m == nil {
 		return
 	}
-	raw_map := (^Raw_Map)(m)
-	entries := (^Raw_Dynamic_Array)(&raw_map.entries)
-	entries.len = 0
-	for _, i in raw_map.hashes {
-		raw_map.hashes[i] = MAP_SENTINEL
-	}
+	map_clear_dynamic((^Raw_Map)(m), map_info(K, V))
 }
 
 @builtin
 reserve_map :: proc(m: ^$T/map[$K]$V, capacity: int, loc := #caller_location) {
 	if m != nil {
-		h := __get_map_header_table(T)
-		__dynamic_map_reserve(m, h, uint(capacity), loc)
+		__dynamic_map_reserve((^Raw_Map)(m), map_info(K, V), uint(capacity), loc)
 	}
 }
 
@@ -325,15 +306,9 @@ shrink_map :: proc(m: ^$T/map[$K]$V, new_cap := -1, loc := #caller_location) ->
 delete_key :: proc(m: ^$T/map[$K]$V, key: K) -> (deleted_key: K, deleted_value: V) {
 	if m != nil {
 		key := key
-		h := __get_map_header(m)
-		fr := __map_find(h, &key)
-		if fr.entry_index != MAP_SENTINEL {
-			entry := __dynamic_map_get_entry(h, fr.entry_index)
-			deleted_key   = (^K)(uintptr(entry)+h.key_offset)^
-			deleted_value = (^V)(uintptr(entry)+h.value_offset)^
-
-			__dynamic_map_erase(h, fr)
-		}
+		info := map_info(K, V)
+		_ =  map_erase_dynamic((^Raw_Map)(m), info, uintptr(&key))
+		// TODO(bill) old key and value
 	}
 	return
 }
diff --git a/core/runtime/dynamic_map_internal.odin b/core/runtime/dynamic_map_internal.odin
index abe58fc5a..07c1fbe7e 100644
--- a/core/runtime/dynamic_map_internal.odin
+++ b/core/runtime/dynamic_map_internal.odin
@@ -3,150 +3,727 @@ package runtime
 import "core:intrinsics"
 _ :: intrinsics
 
-INITIAL_MAP_CAP :: 16
+// High performance, cache-friendly, open-addressed Robin Hood hashing hash map
+// data structure with various optimizations for Odin.
+//
+// Copyright 2022 (c) Dale Weiler
+//
+// The core of the hash map data structure is the Raw_Map struct which is a
+// type-erased representation of the map. This type-erased representation is
+// used in two ways: static and dynamic. When static type information is known,
+// the procedures suffixed with _static should be used instead of _dynamic. The
+// static procedures are optimized since they have type information. Hashing of
+// keys, comparison of keys, and data lookup are all optimized. When type
+// information is not known, the procedures suffixed with _dynamic should be
+// used. The representation of the map is the same for both static and dynamic,
+// and procedures of each can be mixed and matched. The purpose of the dynamic
+// representation is to enable reflection and runtime manipulation of the map.
+// The dynamic procedures all take an additional Map_Info structure parameter
+// which carries runtime values describing the size, alignment, and offset of
+// various traits of a given key and value type pair. The Map_Info value can
+// be created by calling map_info(K, V) with the key and value typeids.
+//
+// This map implementation makes extensive use of uintptr for representing
+// sizes, lengths, capacities, masks, pointers, offsets, and addresses to avoid
+// expensive sign extension and masking that would be generated if types were
+// casted all over. The only place regular ints show up is in the cap() and
+// len() implementations.
+//
+// To make this map cache-friendly it uses a novel strategy to ensure keys and
+// values of the map are always cache-line aligned and that no single key or
+// value of any type ever straddles a cache-line. This cache efficiency makes
+// for quick lookups because the linear-probe always addresses data in a cache
+// friendly way. This is enabled through the use of a special meta-type called
+// a Map_Cell which packs as many values of a given type into a local array adding
+// internal padding to round to MAP_CACHE_LINE_SIZE. One other benefit to storing
+// the internal data in this manner is false sharing no longer occurs when using
+// a map, enabling efficient concurrent access of the map data structure with
+// minimal locking if desired.
 
-// Temporary data structure for comparing hashes and keys
-Map_Hash :: struct {
-	hash:    uintptr,
-	key_ptr: rawptr, // address of Map_Entry_Header.key
+// With Robin Hood hashing a maximum load factor of 75% is ideal.
+MAP_LOAD_FACTOR :: 75
+
+// Minimum log2 capacity.
+MAP_MIN_LOG2_CAPACITY :: 6 // 64 elements
+
+// Has to be less than 100% though.
+#assert(MAP_LOAD_FACTOR < 100)
+
+// This is safe to change. The log2 size of a cache-line. At minimum it has to
+// be six though. Higher cache line sizes are permitted.
+MAP_CACHE_LINE_LOG2 :: 6
+
+// The size of a cache-line.
+MAP_CACHE_LINE_SIZE :: 1 << MAP_CACHE_LINE_LOG2
+
+// The minimum cache-line size allowed by this implementation is 64 bytes since
+// we need 6 bits in the base pointer to store the integer log2 capacity, which
+// at maximum is 63. Odin uses signed integers to represent length and capacity,
+// so only 63 bits are needed in the maximum case.
+#assert(MAP_CACHE_LINE_SIZE >= 64)
+
+// Map_Cell type that packs multiple T in such a way to ensure that each T stays
+// aligned by align_of(T) and such that align_of(Map_Cell(T)) % MAP_CACHE_LINE_SIZE == 0
+//
+// This means a value of type T will never straddle a cache-line.
+//
+// When multiple Ts can fit in a single cache-line the data array will have more
+// than one element. When it cannot, the data array will have one element and
+// an array of Map_Cell(T) will be padded to stay a multiple of MAP_CACHE_LINE_SIZE.
+//
+// We rely on the type system to do all the arithmetic and padding for us here.
+//
+// The usual array[index] indexing for []T backed by a []Map_Cell(T) becomes a bit
+// more involved as there now may be internal padding. The indexing now becomes
+//
+//  N :: len(Map_Cell(T){}.data)
+//  i := index / N
+//  j := index % N
+//  cell[i].data[j]
+//
+// However, since len(Map_Cell(T){}.data) is a compile-time constant, there are some
+// optimizations we can do to eliminate the need for any divisions as N will
+// be bounded by [1, 64).
+//
+// In the optimal case, len(Map_Cell(T){}.data) = 1 so the cell array can be treated
+// as a regular array of T, which is the case for hashes.
+Map_Cell :: struct($T: typeid) #align MAP_CACHE_LINE_SIZE {
+	data: [MAP_CACHE_LINE_SIZE / size_of(T) when size_of(T) < MAP_CACHE_LINE_SIZE else 1]T,
 }
 
-__get_map_key_hash :: #force_inline proc "contextless" (k: ^$K) -> uintptr {
-	hasher := intrinsics.type_hasher_proc(K)
-	return hasher(k, 0)
+// So we can operate on a cell data structure at runtime without any type
+// information, we have a simple table that stores some traits about the cell.
+//
+// 32-bytes on 64-bit
+// 16-bytes on 32-bit
+Map_Cell_Info :: struct {
+	size_of_type:      uintptr, // 8-bytes on 64-bit, 4-bytes on 32-bits
+	align_of_type:     uintptr, // 8-bytes on 64-bit, 4-bytes on 32-bits
+	size_of_cell:      uintptr, // 8-bytes on 64-bit, 4-bytes on 32-bits
+	elements_per_cell: uintptr, // 8-bytes on 64-bit, 4-bytes on 32-bits
 }
 
-__get_map_entry_key_ptr :: #force_inline proc "contextless" (h: Map_Header_Table, entry: ^Map_Entry_Header) -> rawptr {
-	return rawptr(uintptr(entry) + h.key_offset)
-}
-
-Map_Index :: distinct uint
-MAP_SENTINEL :: ~Map_Index(0)
-
-Map_Find_Result :: struct {
-	hash_index:  Map_Index,
-	entry_prev:  Map_Index,
-	entry_index: Map_Index,
-}
-
-Map_Entry_Header :: struct {
-	hash: uintptr,
-	next: Map_Index,
-/*
-	key:   Key_Value,
-	value: Value_Type,
-*/
-}
-
-Map_Header_Table :: struct {
-	equal:         Equal_Proc,
-
-	entry_size:    int,
-	entry_align:   int,
-
-	key_offset:    uintptr,
-	key_size:      int,
-
-	value_offset:  uintptr,
-	value_size:    int,
-}
-
-Map_Header :: struct {
-	m: ^Raw_Map,
-	using table: Map_Header_Table,
-}
-
-// USED INTERNALLY BY THE COMPILER
-__dynamic_map_get :: proc "contextless" (m: rawptr, table: Map_Header_Table, key_hash: uintptr, key_ptr: rawptr) -> rawptr {
-	if m != nil {
-		h := Map_Header{(^Raw_Map)(m), table}
-		index := __dynamic_map_find(h, key_hash, key_ptr).entry_index
-		if index != MAP_SENTINEL {
-			data := uintptr(__dynamic_map_get_entry(h, index))
-			return rawptr(data + h.value_offset)
-		}
+// Same as the above procedure but at runtime with the cell Map_Cell_Info value.
+map_cell_index_dynamic :: #force_inline proc "contextless" (base: uintptr, info: ^Map_Cell_Info, index: uintptr) -> uintptr {
+	// Micro-optimize the case when the number of elements per cell is one or two
+	// to save on expensive integer division.
+	switch elements_per_cell := info.elements_per_cell; elements_per_cell {
+	case 1:
+		return base + (index * info.size_of_cell)
+	case 2:
+		cell_index := index >> 1
+		data_index := index & 1
+		return base + (cell_index * info.size_of_cell) + (data_index * info.size_of_type)
+	case 4:
+		cell_index := index >> 2
+		data_index := index & 3
+		return base + (cell_index * info.size_of_cell) + (data_index * info.size_of_type)
+	case 8:
+		cell_index := index >> 3
+		data_index := index & 7
+		return base + (cell_index * info.size_of_cell) + (data_index * info.size_of_type)
+	case 16:
+		cell_index := index >> 4
+		data_index := index & 15
+		return base + (cell_index * info.size_of_cell) + (data_index * info.size_of_type)
+	case 32:
+		cell_index := index >> 5
+		data_index := index & 31
+		return base + (cell_index * info.size_of_cell) + (data_index * info.size_of_type)
+	case 64:
+		cell_index := index >> 6
+		data_index := index & 63
+		return base + (cell_index * info.size_of_cell) + (data_index * info.size_of_type)
+	case:
+		cell_index := index / elements_per_cell
+		data_index := index % elements_per_cell
+		return base + (cell_index * info.size_of_cell) + (data_index * info.size_of_type)
 	}
+}
+
+// Same as above procedure but with compile-time constant index.
+map_cell_index_dynamic_const :: proc "contextless" (base: uintptr, #no_alias info: ^Map_Cell_Info, $INDEX: uintptr) -> uintptr {
+	elements_per_cell := uintptr(info.elements_per_cell)
+	size_of_cell      := uintptr(info.size_of_cell)
+	size_of_type      := uintptr(info.size_of_type)
+	cell_index        := INDEX / elements_per_cell
+	data_index        := INDEX % elements_per_cell
+	return base + (cell_index * size_of_cell) + (data_index * size_of_type)
+}
+
+// len() for map
+map_len :: #force_inline proc "contextless" (m: Raw_Map) -> int {
+	return int(m.len)
+}
+
+// cap() for map
+map_cap :: #force_inline proc "contextless" (m: Raw_Map) -> int {
+	// The data uintptr stores the capacity in the lower six bits which gives the
+	// a maximum value of 2^6-1, or 63. We store the integer log2 of capacity
+	// since our capacity is always a power of two. We only need 63 bits as Odin
+	// represents length and capacity as a signed integer.
+	return 0 if m.data == 0 else 1 << map_log2_cap(m)
+}
+
+// Query the load factor of the map. This is not actually configurable, but
+// some math is needed to compute it. Compute it as a fixed point percentage to
+// avoid floating point operations. This division can be optimized out by
+// multiplying by the multiplicative inverse of 100.
+map_load_factor :: #force_inline proc "contextless" (log2_capacity: uintptr) -> uintptr {
+	return ((uintptr(1) << log2_capacity) * MAP_LOAD_FACTOR) / 100
+}
+
+map_resize_threshold :: #force_inline proc "contextless" (m: Raw_Map) -> int {
+	return int(map_load_factor(map_log2_cap(m)))
+}
+
+// The data stores the log2 capacity in the lower six bits. This is primarily
+// used in the implementation rather than map_cap since the check for data = 0
+// isn't necessary in the implementation. cap() on the otherhand needs to work
+// when called on an empty map.
+map_log2_cap :: #force_inline proc "contextless" (m: Raw_Map) -> uintptr {
+	return m.data & (64 - 1)
+}
+
+// Canonicalize the data by removing the tagged capacity stored in the lower six
+// bits of the data uintptr.
+map_data :: #force_inline proc "contextless" (m: Raw_Map) -> uintptr {
+	return m.data & ~uintptr(64 - 1)
+}
+
+
+
+Map_Hash :: uintptr
+
+// __get_map_key_hash :: #force_inline proc "contextless" (k: ^$K) -> uintptr {
+// 	hasher := intrinsics.type_hasher_proc(K)
+// 	return hasher(k, 0)
+// }
+
+// __get_map_entry_key_ptr :: #force_inline proc "contextless" (h: Map_Header_Table, entry: ^Map_Entry_Header) -> rawptr {
+// 	return rawptr(uintptr(entry) + h.key_offset)
+// }
+
+
+// Procedure to check if a slot is empty for a given hash. This is represented
+// by the zero value to make the zero value useful. This is a procedure just
+// for prose reasons.
+map_hash_is_empty :: #force_inline proc "contextless" (hash: Map_Hash) -> bool {
+	return hash == 0
+}
+
+map_hash_is_deleted :: #force_inline proc "contextless" (hash: Map_Hash) -> bool {
+	// The MSB indicates a tombstone
+	return (hash >> ((size_of(Map_Hash) * 8) - 1)) != 0
+}
+
+// Computes the desired position in the array. This is just index % capacity,
+// but a procedure as there's some math involved here to recover the capacity.
+map_desired_position :: #force_inline proc "contextless" (m: Raw_Map, hash: Map_Hash) -> uintptr {
+	// We do not use map_cap since we know the capacity will not be zero here.
+	capacity := uintptr(1) << map_log2_cap(m)
+	return uintptr(hash & Map_Hash(capacity - 1))
+}
+
+map_probe_distance :: #force_inline proc "contextless" (m: Raw_Map, hash: Map_Hash, slot: uintptr) -> uintptr {
+	// We do not use map_cap since we know the capacity will not be zero here.
+	capacity := uintptr(1) << map_log2_cap(m)
+	return (slot + capacity - map_desired_position(m, hash)) & (capacity - 1)
+}
+
+// When working with the type-erased structure at runtime we need information
+// about the map to make working with it possible. This info structure stores
+// that.
+//
+// The Odin compiler should generate this for __get_map_header.
+//
+// 80-bytes on 64-bit
+// 40-bytes on 32-bit
+Map_Info :: struct {
+	ks:   Map_Cell_Info,                                                 // 32-bytes on 64-bit, 16-bytes on 32-bit
+	vs:   Map_Cell_Info,                                                 // 32-bytes on 64-bit, 16-bytes on 32-bit
+	hash: proc "contextless" (key: rawptr, seed: Map_Hash) -> Map_Hash,  // 8-bytes on 64-bit, 4-bytes on 32-bit
+	cmp:  proc "contextless" (lhs, rhs: rawptr) -> bool,                 // 8-bytes on 64-bit, 4-bytes on 32-bit
+}
+
+
+// The Map_Info structure is basically a pseudo-table of information for a given K and V pair.
+map_info :: #force_inline proc "contextless" ($K: typeid, $V: typeid) -> ^Map_Info where intrinsics.type_is_comparable(K) {
+	@static INFO := Map_Info {
+		Map_Cell_Info {
+			size_of(K),
+			align_of(K),
+			size_of(Map_Cell(K)),
+			len(Map_Cell(K){}.data),
+		},
+		Map_Cell_Info {
+			size_of(V),
+			align_of(V),
+			size_of(Map_Cell(V)),
+			len(Map_Cell(V){}.data),
+		},
+		proc "contextless" (ptr: rawptr, seed: uintptr) -> Map_Hash { return intrinsics.type_hasher_proc(K)(ptr, seed) } ,
+		proc "contextless" (a, b: rawptr) -> bool { return intrinsics.type_equal_proc(K)(a, b) },
+	}
+	return &INFO
+}
+
+
+map_kvh_data_dynamic :: proc "contextless" (m: Raw_Map, #no_alias info: ^Map_Info) -> (ks: uintptr, vs: uintptr, hs: [^]Map_Hash, sk: uintptr, sv: uintptr) {
+	@static INFO_HS := Map_Cell_Info {
+		size_of(Map_Hash),
+		align_of(Map_Hash),
+		size_of(Map_Cell(Map_Hash)),
+		len(Map_Cell(Map_Hash){}.data),
+	}
+
+	capacity := uintptr(1) << map_log2_cap(m)
+	ks = map_data(m)
+	vs = map_cell_index_dynamic(ks, &info.ks, capacity) // Skip past ks to get start of vs
+	hs_ := map_cell_index_dynamic(vs, &info.vs, capacity) // Skip past vs to get start of hs
+	sk = map_cell_index_dynamic(hs_, &INFO_HS, capacity) // Skip past hs to get start of sk
+	// Need to skip past two elements in the scratch key space to get to the start
+	// of the scratch value space, of which there's only two elements as well.
+	sv = map_cell_index_dynamic_const(sk, &info.ks, 2)
+
+	hs = ([^]Map_Hash)(hs_)
+	return
+}
+
+
+// The only procedure which needs access to the context is the one which allocates the map.
+map_alloc_dynamic :: proc(info: ^Map_Info, log2_capacity: uintptr, allocator := context.allocator) -> (result: Raw_Map, err: Allocator_Error) {
+	if log2_capacity == 0 {
+		// Empty map, but set the allocator.
+		return { 0, 0, allocator }, nil
+	}
+
+	if log2_capacity >= 64 {
+		// Overflowed, would be caused by log2_capacity > 64
+		return {}, .Out_Of_Memory
+	}
+
+	capacity := uintptr(1) << log2_capacity
+
+	@static INFO_HS := Map_Cell_Info {
+		size_of(Map_Hash),
+		align_of(Map_Hash),
+		size_of(Map_Cell(Map_Hash)),
+		len(Map_Cell(Map_Hash){}.data),
+	}
+
+	round :: #force_inline proc "contextless" (value: uintptr) -> uintptr {
+		return (value + MAP_CACHE_LINE_SIZE - 1) & ~uintptr(MAP_CACHE_LINE_SIZE - 1)
+	}
+
+	size := uintptr(0)
+	size = round(map_cell_index_dynamic(size, &info.ks, capacity))
+	size = round(map_cell_index_dynamic(size, &info.vs, capacity))
+	size = round(map_cell_index_dynamic(size, &INFO_HS, capacity))
+
+	data := mem_alloc(int(size), MAP_CACHE_LINE_SIZE, allocator) or_return
+	data_ptr := uintptr(raw_data(data))
+
+	result = {
+		// Tagged pointer representation for capacity.
+		data_ptr | log2_capacity,
+		0,
+		allocator,
+	}
+
+	map_clear_dynamic(&result, info)
+
+	return
+}
+
+// When the type information is known we should use map_insert_hash_static for
+// better performance. This procedure has to stack allocate storage to store
+// local keys during the Robin Hood hashing technique where elements are swapped
+// in the backing arrays to reduce variance. This swapping can only be done with
+// memcpy since there is no type information.
+//
+// This procedure returns the address of the just inserted value.
+@(optimization_mode="size")
+map_insert_hash_dynamic :: proc(m: Raw_Map, info: ^Map_Info, h: Map_Hash, k, v: uintptr) -> (result: uintptr) {
+	info_ks := &info.ks
+	info_vs := &info.vs
+
+	// Storage to exchange when reducing variance.
+	k_storage := intrinsics.alloca(info_ks.size_of_type, MAP_CACHE_LINE_SIZE)
+	v_storage := intrinsics.alloca(info_vs.size_of_type, MAP_CACHE_LINE_SIZE)
+	intrinsics.mem_copy_non_overlapping(rawptr(k_storage), rawptr(k), info_ks.size_of_type)
+	intrinsics.mem_copy_non_overlapping(rawptr(v_storage), rawptr(v), info_vs.size_of_type)
+	h := h
+
+	p := map_desired_position(m, h)
+	d := uintptr(0)
+	c := (uintptr(1) << map_log2_cap(m)) - 1 // Saturating arithmetic mask
+
+	ks, vs, hs, _, _ := map_kvh_data_dynamic(m, info)
+
+	for {
+		hp := &hs[p]
+		element_hash := hp^
+
+		if map_hash_is_empty(element_hash) {
+			k_dst := map_cell_index_dynamic(ks, info_ks, p)
+			v_dst := map_cell_index_dynamic(vs, info_vs, p)
+			intrinsics.mem_copy_non_overlapping(rawptr(k_dst), k_storage, info_ks.size_of_type)
+			intrinsics.mem_copy_non_overlapping(rawptr(v_dst), v_storage, info_vs.size_of_type)
+			hp^ = h
+			return result if result != 0 else v_dst
+		}
+
+		if pd := map_probe_distance(m, element_hash, p); pd < d {
+			if map_hash_is_deleted(element_hash) {
+				k_dst := map_cell_index_dynamic(ks, info_ks, p)
+				v_dst := map_cell_index_dynamic(vs, info_vs, p)
+				intrinsics.mem_copy_non_overlapping(rawptr(k_dst), k_storage, info_ks.size_of_type)
+				intrinsics.mem_copy_non_overlapping(rawptr(v_dst), v_storage, info_vs.size_of_type)
+				hp^ = h
+				return result if result != 0 else v_dst
+			}
+
+			if result == 0 {
+				result = map_cell_index_dynamic(vs, info_vs, p)
+			}
+
+			swap :: #force_inline proc "contextless" (lhs, rhs, size: uintptr) {
+				tmp := intrinsics.alloca(size, MAP_CACHE_LINE_SIZE)
+				intrinsics.mem_copy_non_overlapping(&tmp[0],     rawptr(lhs), size)
+				intrinsics.mem_copy_non_overlapping(rawptr(lhs), rawptr(rhs), size)
+				intrinsics.mem_copy_non_overlapping(rawptr(rhs), &tmp[0],     size)
+			}
+
+			// Exchange to reduce variance.
+			swap(uintptr(k_storage), map_cell_index_dynamic(ks, info_ks, p), info_ks.size_of_type)
+			swap(uintptr(v_storage), map_cell_index_dynamic(vs, info_vs, p), info_vs.size_of_type)
+			hp^, h = h, hp^
+
+			d = pd
+		}
+
+		p = (p + 1) & c
+		d += 1
+	}
+}
+
+@(optimization_mode="speed")
+map_add_hash_dynamic :: proc(m: Raw_Map, #no_alias info: ^Map_Info, h: Map_Hash, ik: uintptr, iv: uintptr) {
+	info_ks := &info.ks
+	info_vs := &info.vs
+
+	capacity := uintptr(1) << map_log2_cap(m)
+	p := map_desired_position(m, h)
+	d := uintptr(0)
+	c := capacity - 1 // Saturating arithmetic mask
+
+	ks, vs, hs, sk, sv := map_kvh_data_dynamic(m, info)
+
+	// Avoid redundant loads of these values
+	size_of_k := info_ks.size_of_type
+	size_of_v := info_vs.size_of_type
+
+	// Use sk and sv scratch storage space for dynamic k and v storage here.
+	//
+	// Simulate the following at runtime
+	// 	k = ik
+	// 	v = iv
+	// 	h = h
+	k := map_cell_index_dynamic_const(sk, info_ks, 0)
+	v := map_cell_index_dynamic_const(sv, info_vs, 0)
+	intrinsics.mem_copy_non_overlapping(rawptr(k), rawptr(ik), size_of_k)
+	intrinsics.mem_copy_non_overlapping(rawptr(v), rawptr(iv), size_of_v)
+	h := h
+
+	// Temporary k and v dynamic storage for swap below
+	tk := map_cell_index_dynamic_const(sk, info_ks, 1)
+	tv := map_cell_index_dynamic_const(sv, info_vs, 1)
+
+	for {
+		hp := &hs[p]
+		element_hash := hp^
+
+		if map_hash_is_empty(element_hash) {
+			k_dst := map_cell_index_dynamic(ks, info_ks, p)
+			v_dst := map_cell_index_dynamic(vs, info_vs, p)
+			intrinsics.mem_copy_non_overlapping(rawptr(k_dst), rawptr(k), size_of_k)
+			intrinsics.mem_copy_non_overlapping(rawptr(v_dst), rawptr(v), size_of_v)
+			hp^ = h
+			return
+		}
+
+		if pd := map_probe_distance(m, element_hash, p); pd < d {
+			if map_hash_is_deleted(element_hash) {
+				k_dst := map_cell_index_dynamic(ks, info_ks, p)
+				v_dst := map_cell_index_dynamic(vs, info_vs, p)
+				intrinsics.mem_copy_non_overlapping(rawptr(k_dst), rawptr(k), size_of_k)
+				intrinsics.mem_copy_non_overlapping(rawptr(v_dst), rawptr(v), size_of_v)
+				hp^ = h
+				return
+			}
+
+			kp := map_cell_index_dynamic(ks, info_vs, p)
+			vp := map_cell_index_dynamic(vs, info_ks, p)
+
+			// Simulate the following at runtime with dynamic storage
+			//
+			// 	kp^, k = k, kp^
+			// 	vp^, v = v, vp^
+			// 	hp^, h = h, hp^
+			intrinsics.mem_copy_non_overlapping(rawptr(tk), rawptr(kp), size_of_k)
+			intrinsics.mem_copy_non_overlapping(rawptr(tv), rawptr(vp), size_of_v)
+			intrinsics.mem_copy_non_overlapping(rawptr(kp), rawptr(k),  size_of_k)
+			intrinsics.mem_copy_non_overlapping(rawptr(vp), rawptr(v),  size_of_v)
+			intrinsics.mem_copy_non_overlapping(rawptr(k),  rawptr(tk), size_of_k)
+			intrinsics.mem_copy_non_overlapping(rawptr(v),  rawptr(tv), size_of_v)
+			hp^, h = h, hp^
+
+			d = pd
+		}
+
+		p = (p + 1) & c
+		d += 1
+	}
+}
+
+@(optimization_mode="size")
+map_grow_dynamic :: proc(#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info) -> Allocator_Error {
+	allocator := m.allocator
+
+	log2_capacity := map_log2_cap(m^)
+
+	if m.data == 0 {
+		n := map_alloc_dynamic(info, MAP_MIN_LOG2_CAPACITY, allocator) or_return
+		m.data = n.data
+		return nil
+	}
+
+	resized := map_alloc_dynamic(info, log2_capacity + 1, allocator) or_return
+
+	capacity := uintptr(1) << log2_capacity
+
+	ks, vs, hs, _, _ := map_kvh_data_dynamic(m^, info)
+
+	// Cache these loads to avoid hitting them in the for loop.
+	info_ks := &info.ks
+	info_vs := &info.vs
+
+	n := map_len(m^)
+	for i := uintptr(0); i < capacity; i += 1 {
+		hash := hs[i]
+		if map_hash_is_empty(hash) do continue
+		if map_hash_is_deleted(hash) do continue
+		k := map_cell_index_dynamic(ks, info_ks, i)
+		v := map_cell_index_dynamic(vs, info_vs, i)
+		map_insert_hash_dynamic(resized, info, hash, k, v)
+		// Only need to do this comparison on each actually added pair, so do not
+		// fold it into the for loop comparator as a micro-optimization.
+		n -= 1
+		if n == 0 do break
+	}
+
+	mem_free(rawptr(ks), allocator)
+
+	m.data = resized.data // Should copy the capacity too
+
 	return nil
 }
 
-// USED INTERNALLY BY THE COMPILER
-__dynamic_map_set :: proc "odin" (m: rawptr, table: Map_Header_Table, key_hash: uintptr, key_ptr: rawptr, value: rawptr, loc := #caller_location) -> ^Map_Entry_Header #no_bounds_check {
-	add_entry :: proc "odin" (h: Map_Header, key_hash: uintptr, key_ptr: rawptr, loc := #caller_location) -> Map_Index {
-		prev := Map_Index(h.m.entries.len)
-		c := Map_Index(__dynamic_array_append_nothing(&h.m.entries, h.entry_size, h.entry_align, loc))
-		if c != prev {
-			end := __dynamic_map_get_entry(h, c-1)
-			end.hash = key_hash
-			mem_copy(rawptr(uintptr(end) + h.key_offset), key_ptr, h.key_size)
-			end.next = MAP_SENTINEL
-		}
-		return prev
+
+@(optimization_mode="size")
+map_reserve_dynamic :: proc(#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info, new_capacity: uintptr) -> Allocator_Error {
+	allocator := m.allocator
+
+	log2_capacity := map_log2_cap(m^)
+	capacity := uintptr(1) << log2_capacity
+
+	if capacity >= new_capacity {
+		return nil
+	}
+	// ceiling nearest power of two
+	log2_new_capacity := size_of(uintptr) - intrinsics.count_leading_zeros(new_capacity-1)
+
+	if m.data == 0 {
+		n := map_alloc_dynamic(info, MAP_MIN_LOG2_CAPACITY, allocator) or_return
+		m.data = n.data
+		return nil
 	}
 
-	h := Map_Header{(^Raw_Map)(m), table}
+	resized := map_alloc_dynamic(info, log2_new_capacity, allocator) or_return
 
-	index := MAP_SENTINEL
 
-	if len(h.m.hashes) == 0 {
-		__dynamic_map_reserve(m, table, INITIAL_MAP_CAP, loc)
-		__dynamic_map_grow(h, loc)
+	ks, vs, hs, _, _ := map_kvh_data_dynamic(m^, info)
+
+	// Cache these loads to avoid hitting them in the for loop.
+	info_ks := &info.ks
+	info_vs := &info.vs
+
+	n := map_len(m^)
+	for i := uintptr(0); i < capacity; i += 1 {
+		hash := hs[i]
+		if map_hash_is_empty(hash) do continue
+		if map_hash_is_deleted(hash) do continue
+		k := map_cell_index_dynamic(ks, info_ks, i)
+		v := map_cell_index_dynamic(vs, info_vs, i)
+		map_insert_hash_dynamic(resized, info, hash, k, v)
+		// Only need to do this comparison on each actually added pair, so do not
+		// fold it into the for loop comparator as a micro-optimization.
+		n -= 1
+		if n == 0 do break
 	}
 
-	fr := __dynamic_map_find(h, key_hash, key_ptr)
-	if fr.entry_index != MAP_SENTINEL {
-		index = fr.entry_index
-	} else {
-		index = add_entry(h, key_hash, key_ptr, loc)
-		if fr.entry_prev != MAP_SENTINEL {
-			entry := __dynamic_map_get_entry(h, fr.entry_prev)
-			entry.next = index
-		} else if fr.hash_index != MAP_SENTINEL {
-			h.m.hashes[fr.hash_index] = index
-		} else {
-			return nil
-		}
-	}
+	mem_free(rawptr(ks), allocator)
 
-	e := __dynamic_map_get_entry(h, index)
-	e.hash = key_hash
+	m.data = resized.data // Should copy the capacity too
 
-	key := rawptr(uintptr(e) + h.key_offset)
-	val := rawptr(uintptr(e) + h.value_offset)
-
-	mem_copy(key, key_ptr, h.key_size)
-	mem_copy(val, value, h.value_size)
-
-	if __dynamic_map_full(h) {
-		__dynamic_map_grow(h, loc)
-	}
-
-	return __dynamic_map_get_entry(h, index)
+	return nil
 }
 
-// USED INTERNALLY BY THE COMPILER
-__dynamic_map_reserve :: proc "odin" (m: rawptr, table: Map_Header_Table, cap: uint, loc := #caller_location) {
-	h := Map_Header{(^Raw_Map)(m), table}
 
-	c := context
-	if h.m.entries.allocator.procedure != nil {
-		c.allocator = h.m.entries.allocator
+@(optimization_mode="size")
+map_shrink_dynamic :: proc(#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info) -> Allocator_Error {
+	allocator := m.allocator
+
+	// Cannot shrink the capacity if the number of items in the map would exceed
+	// one minus the current log2 capacity's resize threshold. That is the shrunk
+	// map needs to be within the max load factor.
+	log2_capacity := map_log2_cap(m^)
+	if m.len >= map_load_factor(log2_capacity - 1) do return nil
+
+	shrinked := map_alloc_dynamic(info, log2_capacity - 1, allocator) or_return
+
+	capacity := uintptr(1) << log2_capacity
+
+	ks, vs, hs, _, _ := map_kvh_data_dynamic(m^, info)
+
+	info_ks := &info.ks
+	info_vs := &info.vs
+
+	n := map_len(m^)
+	for i := uintptr(0); i < capacity; i += 1 {
+		hash := hs[i]
+		if map_hash_is_empty(hash) do continue
+		if map_hash_is_deleted(hash) do continue
+
+		k := map_cell_index_dynamic(ks, info_ks, i)
+		v := map_cell_index_dynamic(vs, info_vs, i)
+
+		map_insert_hash_dynamic(shrinked, info, hash, k, v)
+
+		// Only need to do this comparison on each actually added pair, so do not
+		// fold it into the for loop comparator as a micro-optimization.
+		n -= 1
+		if n == 0 do break
 	}
-	context = c
 
-	cap := cap
-	cap = ceil_to_pow2(cap)
+	free(rawptr(ks), allocator)
 
-	__dynamic_array_reserve(&h.m.entries, h.entry_size, h.entry_align, int(cap), loc)
+	m.data = shrinked.data // Should copy the capacity too
 
-	if h.m.entries.len*2 < len(h.m.hashes) {
-		return
-	}
-	if __slice_resize(&h.m.hashes, int(cap*2), h.m.entries.allocator, loc) {
-		__dynamic_map_reset_entries(h, loc)
+	return nil
+}
+
+// Single procedure for static and dynamic paths.
+@(require_results)
+map_free :: proc(m: Raw_Map, loc := #caller_location) -> Allocator_Error {
+	return mem_free(rawptr(map_data(m)), m.allocator, loc)
+}
+
+@(optimization_mode="speed")
+map_lookup_dynamic :: proc "contextless" (m: Raw_Map, #no_alias info: ^Map_Info, k: uintptr) -> (index: uintptr, ok: bool) {
+	if map_len(m) == 0 do return 0, false
+	h := info.hash(rawptr(k), 0)
+	p := map_desired_position(m, h)
+	d := uintptr(0)
+	c := (uintptr(1) << map_log2_cap(m)) - 1
+	ks, _, hs, _, _ := map_kvh_data_dynamic(m, info)
+	info_ks := &info.ks
+	for {
+		element_hash := hs[p]
+		if map_hash_is_empty(element_hash) {
+			return 0, false
+		} else if d > map_probe_distance(m, element_hash, p) {
+			return 0, false
+		} else if element_hash == h && info.cmp(rawptr(k), rawptr(map_cell_index_dynamic(ks, info_ks, p))) {
+			return p, true
+		}
+		p = (p + 1) & c
+		d += 1
 	}
 }
 
 
+
+
+
+@(optimization_mode="speed")
+map_insert_dynamic :: proc(#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info, k, v: uintptr) -> (value: uintptr, err: Allocator_Error) {
+	if map_len(m^) + 1 >= map_resize_threshold(m^) {
+		map_grow_dynamic(m, info) or_return
+	}
+	hashed := info.hash(rawptr(k), 0)
+	result := map_insert_hash_dynamic(m^, info, hashed, k, v)
+	m.len += 1
+	return result, nil
+}
+
+// Same as map_insert_dynamic but does not return address to the inserted element.
+@(optimization_mode="speed")
+map_add_dynamic :: proc(#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info, k, v: uintptr) -> Allocator_Error {
+	if map_len(m^) + 1 >= map_resize_threshold(m^) {
+		map_grow_dynamic(m, info) or_return
+	}
+	map_add_hash_dynamic(m^, info, info.hash(rawptr(k), 0), k, v)
+	m.len += 1
+	return nil
+}
+
+map_erase_dynamic :: #force_inline proc "contextless" (#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info, k: uintptr) -> bool {
+	when size_of(Map_Hash) == 4  do MASK :: Map_Hash(0x8000_0000)
+	when size_of(Map_Hash) == 8  do MASK :: Map_Hash(0x8000_0000_0000_0000)
+	when size_of(Map_Hash) == 16 do MASK :: Map_Hash(0x8000_0000_0000_0000_0000_0000_0000_0000)
+	index := map_lookup_dynamic(m^, info, k) or_return
+	_, _, hs, _, _ := map_kvh_data_dynamic(m^, info)
+	hs[index] |= MASK
+	m.len -= 1
+	return true
+}
+
+map_clear_dynamic :: #force_inline proc "contextless" (#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info) {
+	if m.data == 0 do return
+	_, _, hs, _, _ := map_kvh_data_dynamic(m^, info)
+	intrinsics.mem_zero(rawptr(hs), map_cap(m^) * size_of(Map_Hash))
+	m.len = 0
+}
+
+
+// TODO(bill): Change signature to not be a `rawptr`
+__dynamic_map_get :: proc "contextless" (m: rawptr, #no_alias info: ^Map_Info, key: rawptr) -> rawptr {
+	rm := (^Raw_Map)(m)^
+	index, ok := map_lookup_dynamic(rm, info, uintptr(key))
+	if !ok {
+		return nil
+	}
+	_ = index
+	// TODO(bill)
+	return nil
+}
+
+__dynamic_map_set :: proc "odin" (#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info, key, value: rawptr, loc := #caller_location) -> rawptr {
+	// value, _ := map_insert_dynamic(m, info, uintptr(key), uintptr(value))
+	// return rawptr(value)
+	// TODO(bill)
+	return nil
+}
+
+__dynamic_map_reserve :: proc "odin" (#no_alias m: ^Raw_Map, #no_alias info: ^Map_Info, new_capacity: uint, loc := #caller_location) {
+	map_reserve_dynamic(m, info, uintptr(new_capacity))
+}
+
+
+
+
 INITIAL_HASH_SEED :: 0xcbf29ce484222325
 
 _fnv64a :: proc "contextless" (data: []byte, seed: u64 = INITIAL_HASH_SEED) -> u64 {
@@ -154,7 +731,7 @@ _fnv64a :: proc "contextless" (data: []byte, seed: u64 = INITIAL_HASH_SEED) -> u
 	for b in data {
 		h = (h ~ u64(b)) * 0x100000001b3
 	}
-	return h
+	return h | u64(h == 0)
 }
 
 default_hash :: #force_inline proc "contextless" (data: []byte) -> uintptr {
@@ -177,7 +754,7 @@ _default_hasher_const :: #force_inline proc "contextless" (data: rawptr, seed: u
 		h = (h ~ b) * 0x100000001b3
 		p += 1
 	}
-	return uintptr(h)
+	return uintptr(h) | uintptr(h == 0)
 }
 
 default_hasher_n :: #force_inline proc "contextless" (data: rawptr, seed: uintptr, N: int) -> uintptr {
@@ -188,7 +765,7 @@ default_hasher_n :: #force_inline proc "contextless" (data: rawptr, seed: uintpt
 		h = (h ~ b) * 0x100000001b3
 		p += 1
 	}
-	return uintptr(h)
+	return uintptr(h) | uintptr(h == 0)
 }
 
 // NOTE(bill): There are loads of predefined ones to improve optimizations for small types
@@ -216,7 +793,7 @@ default_hasher_string :: proc "contextless" (data: rawptr, seed: uintptr) -> uin
 	for b in str {
 		h = (h ~ u64(b)) * 0x100000001b3
 	}
-	return uintptr(h)
+	return uintptr(h) | uintptr(h == 0)
 }
 default_hasher_cstring :: proc "contextless" (data: rawptr, seed: uintptr) -> uintptr {
 	h := u64(seed) + 0xcbf29ce484222325
@@ -226,203 +803,5 @@ default_hasher_cstring :: proc "contextless" (data: rawptr, seed: uintptr) -> ui
 		h = (h ~ u64(b)) * 0x100000001b3
 		ptr += 1
 	}
-	return uintptr(h)
-}
-
-
-__get_map_header :: proc "contextless" (m: ^$T/map[$K]$V) -> (header: Map_Header) {
-	header.m = (^Raw_Map)(m)
-	header.table = #force_inline __get_map_header_table(T)
-	return
-}
-
-__get_map_header_runtime :: proc "contextless" (m: ^Raw_Map, ti: Type_Info_Map) -> (header: Map_Header) {
-	header.m = m
-	header.table = #force_inline __get_map_header_table_runtime(ti)
-	return
-}
-
-__get_map_header_table :: proc "contextless" ($T: typeid/map[$K]$V) -> (header: Map_Header_Table) {
-	Entry :: struct {
-		hash:  uintptr,
-		next:  Map_Index,
-		key:   K,
-		value: V,
-	}
-
-	header.equal = intrinsics.type_equal_proc(K)
-
-	header.entry_size    = size_of(Entry)
-	header.entry_align   = align_of(Entry)
-
-	header.key_offset    = offset_of(Entry, key)
-	header.key_size      = size_of(K)
-
-	header.value_offset  = offset_of(Entry, value)
-	header.value_size    = size_of(V)
-
-	return
-}
-
-__get_map_header_table_runtime :: proc "contextless" (ti: Type_Info_Map) -> (header: Map_Header) {
-	header.equal = ti.key_equal
-
-	entries := ti.generated_struct.variant.(Type_Info_Struct).types[1]
-	entry := entries.variant.(Type_Info_Dynamic_Array).elem
-	e := entry.variant.(Type_Info_Struct)
-
-	header.entry_size    = entry.size
-	header.entry_align   = entry.align
-
-	header.key_offset    = e.offsets[2]
-	header.key_size      = e.types[2].size
-
-	header.value_offset  = e.offsets[3]
-	header.value_size    = e.types[3].size
-
-	return
-}
-
-
-
-__slice_resize :: proc "odin" (array_: ^$T/[]$E, new_count: int, allocator: Allocator, loc := #caller_location) -> bool {
-	array := (^Raw_Slice)(array_)
-
-	if new_count < array.len {
-		return true
-	}
-
-	old_size := array.len*size_of(T)
-	new_size := new_count*size_of(T)
-
-	new_data, err := mem_resize(array.data, old_size, new_size, align_of(T), allocator, loc)
-	if err != nil {
-		return false
-	}
-	if new_data != nil || size_of(E) == 0 {
-		array.data = raw_data(new_data)
-		array.len = new_count
-		return true
-	}
-	return false
-}
-
-__dynamic_map_reset_entries :: proc "contextless" (h: Map_Header, loc := #caller_location) {
-	for i in 0..<len(h.m.hashes) {
-		h.m.hashes[i] = MAP_SENTINEL
-	}
-
-	for i in 0..<Map_Index(h.m.entries.len) {
-		entry_header := __dynamic_map_get_entry(h, i)
-		entry_header.next = MAP_SENTINEL
-
-		fr := __dynamic_map_find_from_entry(h, entry_header)
-		if fr.entry_prev != MAP_SENTINEL {
-			e := __dynamic_map_get_entry(h, fr.entry_prev)
-			e.next = i
-		} else {
-			h.m.hashes[fr.hash_index] = i
-		}
-	}
-}
-
-__dynamic_map_shrink :: proc "odin" (h: Map_Header, cap: int, loc := #caller_location) -> (did_shrink: bool) {
-	c := context
-	if h.m.entries.allocator.procedure != nil {
-		c.allocator = h.m.entries.allocator
-	}
-	context = c
-
-	return __dynamic_array_shrink(&h.m.entries, h.entry_size, h.entry_align, cap, loc)
-}
-
-
-@(private="file")
-ceil_to_pow2 :: proc "contextless" (n: uint) -> uint {
-	if n <= 2 {
-		return n
-	}
-	n := n
-	n -= 1
-	n |= n >> 1
-	n |= n >> 2
-	n |= n >> 4
-	n |= n >> 8
-	n |= n >> 16
-	when size_of(int) == 8 {
-		n |= n >> 32
-	}
-	n += 1
-	return n
-}
-
-__dynamic_map_grow :: proc "odin" (h: Map_Header, loc := #caller_location) {
-	new_count := max(uint(h.m.entries.cap) * 2, INITIAL_MAP_CAP)
-	// Rehash through Reserve
-	__dynamic_map_reserve(h.m, h.table, new_count, loc)
-}
-
-__dynamic_map_full :: #force_inline proc "contextless" (h: Map_Header) -> bool {
-	return int(0.75 * f64(len(h.m.hashes))) <= h.m.entries.len
-}
-
-__dynamic_map_find_from_entry :: proc "contextless" (h: Map_Header, e: ^Map_Entry_Header) -> Map_Find_Result #no_bounds_check {
-	key_ptr := __get_map_entry_key_ptr(h, e)
-	return __dynamic_map_find(h, e.hash, key_ptr)
-
-}
-
-__dynamic_map_find :: proc "contextless" (h: Map_Header, key_hash: uintptr, key_ptr: rawptr) -> Map_Find_Result #no_bounds_check {
-	fr := Map_Find_Result{MAP_SENTINEL, MAP_SENTINEL, MAP_SENTINEL}
-	if n := uintptr(len(h.m.hashes)); n != 0 {
-		fr.hash_index = Map_Index(key_hash & (n-1))
-		fr.entry_index = h.m.hashes[fr.hash_index]
-		for fr.entry_index != MAP_SENTINEL {
-			entry := __dynamic_map_get_entry(h, fr.entry_index)
-			entry_key_ptr := __get_map_entry_key_ptr(h, entry)
-			if entry.hash == key_hash && h.equal(entry_key_ptr, key_ptr) {
-				return fr
-			}
-			
-			fr.entry_prev = fr.entry_index
-			fr.entry_index = entry.next
-		}
-	}
-	return fr
-}
-
-// Utility procedure used by other runtime procedures
-__map_find :: proc "contextless" (h: Map_Header, key_ptr: ^$K) -> Map_Find_Result #no_bounds_check {
-	hash := __get_map_key_hash(key_ptr)
-	return #force_inline __dynamic_map_find(h, hash, key_ptr)
-}
-
-__dynamic_map_get_entry :: #force_inline proc "contextless" (h: Map_Header, index: Map_Index) -> ^Map_Entry_Header {
-	return (^Map_Entry_Header)(uintptr(h.m.entries.data) + uintptr(index*Map_Index(h.entry_size)))
-}
-
-__dynamic_map_erase :: proc "contextless" (h: Map_Header, fr: Map_Find_Result) #no_bounds_check {
-	if fr.entry_prev != MAP_SENTINEL {
-		prev := __dynamic_map_get_entry(h, fr.entry_prev)
-		curr := __dynamic_map_get_entry(h, fr.entry_index)
-		prev.next = curr.next
-	} else {
-		h.m.hashes[fr.hash_index] = __dynamic_map_get_entry(h, fr.entry_index).next
-	}
-	last_index := Map_Index(h.m.entries.len-1)
-	if fr.entry_index != last_index {
-		old := __dynamic_map_get_entry(h, fr.entry_index)
-		end := __dynamic_map_get_entry(h, last_index)
-		mem_copy(old, end, h.entry_size)
-
-		last := __dynamic_map_find_from_entry(h, old)
-		if last.entry_prev != MAP_SENTINEL {
-			e := __dynamic_map_get_entry(h, last.entry_prev)
-			e.next = fr.entry_index
-		} else {
-			h.m.hashes[last.hash_index] = fr.entry_index
-		}
-	}
-
-	h.m.entries.len -= 1
+	return uintptr(h) | uintptr(h == 0)
 }
diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 9e48fd8ad..043b98173 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -1364,7 +1364,6 @@ bool is_polymorphic_type_assignable(CheckerContext *c, Type *poly, Type *source,
 			bool key   = is_polymorphic_type_assignable(c, poly->Map.key, source->Map.key, true, modify_type);
 			bool value = is_polymorphic_type_assignable(c, poly->Map.value, source->Map.value, true, modify_type);
 			if (key || value) {
-				poly->Map.entry_type = nullptr;
 				poly->Map.internal_type = nullptr;
 				poly->Map.lookup_result_type = nullptr;
 				init_map_internal_types(poly);
diff --git a/src/check_type.cpp b/src/check_type.cpp
index 2ffe04342..ea1c90a66 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -2176,40 +2176,9 @@ Type *make_optional_ok_type(Type *value, bool typed) {
 	return t;
 }
 
-void init_map_entry_type(Type *type) {
-	GB_ASSERT(type->kind == Type_Map);
-	if (type->Map.entry_type != nullptr) return;
-
-	// NOTE(bill): The preload types may have not been set yet
-	GB_ASSERT(t_map_hash != nullptr);
-
-	/*
-	struct {
-		hash:  uintptr,
-		next:  int,
-		key:   Key,
-		value: Value,
-	}
-	*/
-	Scope *s = create_scope(nullptr, builtin_pkg->scope);
-
-	auto fields = slice_make<Entity *>(permanent_allocator(), 4);
-	fields[0] = alloc_entity_field(s, make_token_ident(str_lit("hash")),  t_uintptr,       false, 0, EntityState_Resolved);
-	fields[1] = alloc_entity_field(s, make_token_ident(str_lit("next")),  t_int,           false, 1, EntityState_Resolved);
-	fields[2] = alloc_entity_field(s, make_token_ident(str_lit("key")),   type->Map.key,   false, 2, EntityState_Resolved);
-	fields[3] = alloc_entity_field(s, make_token_ident(str_lit("value")), type->Map.value, false, 3, EntityState_Resolved);
-
-	Type *entry_type = alloc_type_struct();
-	entry_type->Struct.fields  = fields;
-	entry_type->Struct.tags    = gb_alloc_array(permanent_allocator(), String, fields.count);
-	
-	type_set_offsets(entry_type);
-	type->Map.entry_type = entry_type;
-}
-
 void init_map_internal_types(Type *type) {
 	GB_ASSERT(type->kind == Type_Map);
-	init_map_entry_type(type);
+	GB_ASSERT(t_allocator != nullptr);
 	if (type->Map.internal_type != nullptr) return;
 
 	Type *key   = type->Map.key;
@@ -2221,19 +2190,17 @@ void init_map_internal_types(Type *type) {
 
 	/*
 	struct {
-		hashes:  []int;
-		entries: [dynamic]EntryType;
+		data:      uintptr,
+		size:      uintptr,
+		allocator: runtime.Allocator,
 	}
 	*/
 	Scope *s = create_scope(nullptr, builtin_pkg->scope);
 
-	Type *hashes_type  = alloc_type_slice(t_int);
-	Type *entries_type = alloc_type_dynamic_array(type->Map.entry_type);
-
-
-	auto fields = slice_make<Entity *>(permanent_allocator(), 2);
-	fields[0] = alloc_entity_field(s, make_token_ident(str_lit("hashes")),  hashes_type,  false, 0, EntityState_Resolved);
-	fields[1] = alloc_entity_field(s, make_token_ident(str_lit("entries")), entries_type, false, 1, EntityState_Resolved);
+	auto fields = slice_make<Entity *>(permanent_allocator(), 3);
+	fields[0] = alloc_entity_field(s, make_token_ident(str_lit("data")),      t_uintptr,  false,  0, EntityState_Resolved);
+	fields[1] = alloc_entity_field(s, make_token_ident(str_lit("size")),      t_uintptr,   false, 1, EntityState_Resolved);
+	fields[2] = alloc_entity_field(s, make_token_ident(str_lit("allocator")), t_allocator, false, 2, EntityState_Resolved);
 
 	generated_struct_type->Struct.fields = fields;
 	type_set_offsets(generated_struct_type);
diff --git a/src/checker.cpp b/src/checker.cpp
index dd81e2a48..d5d2c6026 100644
--- a/src/checker.cpp
+++ b/src/checker.cpp
@@ -2842,12 +2842,12 @@ void init_core_source_code_location(Checker *c) {
 }
 
 void init_core_map_type(Checker *c) {
-	if (t_map_hash != nullptr) {
+	if (t_map_info != nullptr) {
 		return;
 	}
-	t_map_hash = find_core_type(c, str_lit("Map_Hash"));
-	t_map_header = find_core_type(c, str_lit("Map_Header"));
-	t_map_header_table = find_core_type(c, str_lit("Map_Header_Table"));
+	t_map_info = find_core_type(c, str_lit("Map_Info"));
+	t_map_cell_info = find_core_type(c, str_lit("Map_Cell_Info"));
+	init_mem_allocator(c);
 }
 
 void init_preload(Checker *c) {
diff --git a/src/llvm_backend.cpp b/src/llvm_backend.cpp
index 1d2c00700..40b861d40 100644
--- a/src/llvm_backend.cpp
+++ b/src/llvm_backend.cpp
@@ -298,7 +298,7 @@ lbValue lb_simple_compare_hash(lbProcedure *p, Type *type, lbValue data, lbValue
 
 lbValue lb_get_hasher_proc_for_type(lbModule *m, Type *type) {
 	type = core_type(type);
-	GB_ASSERT(is_type_valid_for_keys(type));
+	GB_ASSERT_MSG(is_type_valid_for_keys(type), "%s", type_to_string(type));
 
 	Type *pt = alloc_type_pointer(type);
 
@@ -500,51 +500,67 @@ lbValue lb_generate_anonymous_proc_lit(lbModule *m, String const &prefix_name, A
 	return value;
 }
 
-lbValue lb_gen_map_header_table_internal(lbProcedure *p, Type *map_type) {
+// IMPORTANT NOTE(bill): This must match the definition in dynamic_map_internal.odin
+enum : i64 {
+	MAP_CACHE_LINE_LOG2 = 6,
+	MAP_CACHE_LINE_SIZE = 1 << MAP_CACHE_LINE_LOG2
+};
+GB_STATIC_ASSERT(MAP_CACHE_LINE_SIZE >= 64);
+void lb_map_cell_size_and_len(Type *type, i64 *size_, i64 *len_) {
+	i64 elem_sz = type_size_of(type);
+
+	i64 len = 1;
+	if (0 < elem_sz && elem_sz < MAP_CACHE_LINE_SIZE) {
+		len = MAP_CACHE_LINE_SIZE / elem_sz;
+	}
+	i64 size = align_formula(elem_sz * len, MAP_CACHE_LINE_SIZE);
+	if (size_) *size_ = size;
+	if (len_)  *len_ = len;
+}
+
+LLVMValueRef lb_gen_map_cell_info(lbModule *m, Type *type) {
+	i64 size = 0, len = 0;
+	lb_map_cell_size_and_len(type, &size, &len);
+
+	LLVMValueRef const_values[4] = {};
+	const_values[0] = lb_const_int(m, t_uintptr, type_size_of(type)).value;
+	const_values[1] = lb_const_int(m, t_uintptr, type_align_of(type)).value;
+	const_values[2] = lb_const_int(m, t_uintptr, size).value;
+	const_values[3] = lb_const_int(m, t_uintptr, len).value;
+	return llvm_const_named_struct(m, t_map_cell_info, const_values, gb_count_of(const_values));
+
+}
+lbValue lb_gen_map_info_ptr(lbProcedure *p, Type *map_type) {
 	lbModule *m = p->module;
 
 	map_type = base_type(map_type);
 	GB_ASSERT(map_type->kind == Type_Map);
 
-	lbAddr *found = map_get(&m->map_header_table_map, map_type);
+	lbAddr *found = map_get(&m->map_info_map, map_type);
 	if (found) {
-		return lb_addr_load(p, *found);
+		return lb_addr_get_ptr(p, *found);
 	}
 
-	GB_ASSERT(map_type->Map.entry_type->kind == Type_Struct);
-	i64 entry_size   = type_size_of  (map_type->Map.entry_type);
-	i64 entry_align  = type_align_of (map_type->Map.entry_type);
+	GB_ASSERT(t_map_info != nullptr);
+	GB_ASSERT(t_map_cell_info != nullptr);
 
-	i64 key_offset = type_offset_of(map_type->Map.entry_type, 2);
-	i64 key_size   = type_size_of  (map_type->Map.key);
+	LLVMValueRef key_cell_info   = lb_gen_map_cell_info(m, map_type->Map.key);
+	LLVMValueRef value_cell_info = lb_gen_map_cell_info(m, map_type->Map.value);
 
-	i64 value_offset = type_offset_of(map_type->Map.entry_type, 3);
-	i64 value_size   = type_size_of  (map_type->Map.value);
+	LLVMValueRef const_values[4] = {};
+	const_values[0] = key_cell_info;
+	const_values[1] = value_cell_info;
+	const_values[2] = lb_get_hasher_proc_for_type(m, map_type->Map.key).value;
+	const_values[3] = lb_get_equal_proc_for_type(m, map_type->Map.key).value;
 
-	Type *key_type = map_type->Map.key;
-	Type *val_type = map_type->Map.value;
-	gb_unused(val_type);
+	LLVMValueRef llvm_res = llvm_const_named_struct(m, t_map_info, const_values, gb_count_of(const_values));
+	lbValue res = {llvm_res, t_map_info};
 
-	Type *st = base_type(t_map_header_table);
-	GB_ASSERT(st->Struct.fields.count == 7);
-
-	LLVMValueRef const_values[7] = {};
-	const_values[0] = lb_get_equal_proc_for_type(m, key_type)    .value;
-	const_values[1] = lb_const_int(m, t_int,        entry_size)  .value;
-	const_values[2] = lb_const_int(m, t_int,        entry_align) .value;
-	const_values[3] = lb_const_int(m, t_uintptr,    key_offset)  .value;
-	const_values[4] = lb_const_int(m, t_int,        key_size)    .value;
-	const_values[5] = lb_const_int(m, t_uintptr,    value_offset).value;
-	const_values[6] = lb_const_int(m, t_int,        value_size)  .value;
-
-	LLVMValueRef llvm_res = llvm_const_named_struct(m, t_map_header_table, const_values, gb_count_of(const_values));
-	lbValue res = {llvm_res, t_map_header_table};
-
-	lbAddr addr = lb_add_global_generated(m, t_map_header_table, res, nullptr);
+	lbAddr addr = lb_add_global_generated(m, t_map_info, res, nullptr);
 	lb_make_global_private_const(addr);
 
-	map_set(&m->map_header_table_map, map_type, addr);
-	return lb_addr_load(p, addr);
+	map_set(&m->map_info_map, map_type, addr);
+	return lb_addr_get_ptr(p, addr);
 }
 
 lbValue lb_const_hash(lbModule *m, lbValue key, Type *key_type) {
@@ -616,12 +632,13 @@ lbValue lb_gen_map_key_hash(lbProcedure *p, lbValue key, Type *key_type, lbValue
 lbValue lb_internal_dynamic_map_get_ptr(lbProcedure *p, lbValue const &map_ptr, lbValue const &key) {
 	Type *map_type = base_type(type_deref(map_ptr.type));
 
-	lbValue key_ptr = {};
-	auto args = array_make<lbValue>(permanent_allocator(), 4);
+	lbValue key_ptr = lb_address_from_load_or_generate_local(p, key);
+	key_ptr = lb_emit_conv(p, key_ptr, t_rawptr);
+
+	auto args = array_make<lbValue>(permanent_allocator(), 3);
 	args[0] = lb_emit_conv(p, map_ptr, t_rawptr);
-	args[1] = lb_gen_map_header_table_internal(p, map_type);
-	args[2] = lb_gen_map_key_hash(p, key, map_type->Map.key, &key_ptr);
-	args[3] = key_ptr;
+	args[1] = lb_gen_map_info_ptr(p, map_type);
+	args[2] = key_ptr;
 
 	lbValue ptr = lb_emit_runtime_call(p, "__dynamic_map_get", args);
 
@@ -633,20 +650,19 @@ void lb_insert_dynamic_map_key_and_value(lbProcedure *p, lbValue const &map_ptr,
 	map_type = base_type(map_type);
 	GB_ASSERT(map_type->kind == Type_Map);
 
-	lbValue key_ptr = {};
-	lbValue key_hash = lb_gen_map_key_hash(p, map_key, map_type->Map.key, &key_ptr);
+	lbValue key_ptr = lb_address_from_load_or_generate_local(p, map_key);
+	key_ptr = lb_emit_conv(p, key_ptr, t_rawptr);
 	lbValue v = lb_emit_conv(p, map_value, map_type->Map.value);
 
 	lbAddr value_addr = lb_add_local_generated(p, v.type, false);
 	lb_addr_store(p, value_addr, v);
 
-	auto args = array_make<lbValue>(permanent_allocator(), 6);
+	auto args = array_make<lbValue>(permanent_allocator(), 5);
 	args[0] = lb_emit_conv(p, map_ptr, t_rawptr);
-	args[1] = lb_gen_map_header_table_internal(p, map_type);
-	args[2] = key_hash;
-	args[3] = key_ptr;
-	args[4] = lb_emit_conv(p, value_addr.addr, t_rawptr);
-	args[5] = lb_emit_source_code_location_as_global(p, node);
+	args[1] = lb_gen_map_info_ptr(p, map_type);
+	args[2] = key_ptr;
+	args[3] = lb_emit_conv(p, value_addr.addr, t_rawptr);
+	args[4] = lb_emit_source_code_location_as_global(p, node);
 	lb_emit_runtime_call(p, "__dynamic_map_set", args);
 }
 
@@ -660,8 +676,8 @@ void lb_dynamic_map_reserve(lbProcedure *p, lbValue const &map_ptr, isize const
 
 	auto args = array_make<lbValue>(permanent_allocator(), 4);
 	args[0] = lb_emit_conv(p, map_ptr, t_rawptr);
-	args[1] = lb_gen_map_header_table_internal(p, type_deref(map_ptr.type));
-	args[2] = lb_const_int(p->module, t_int, capacity);
+	args[1] = lb_gen_map_info_ptr(p, type_deref(map_ptr.type));
+	args[2] = lb_const_int(p->module, t_uint, capacity);
 	args[3] = lb_emit_source_code_location_as_global(p, proc_name, pos);
 	lb_emit_runtime_call(p, "__dynamic_map_reserve", args);
 }
diff --git a/src/llvm_backend.hpp b/src/llvm_backend.hpp
index a8ff1571c..b797f28f9 100644
--- a/src/llvm_backend.hpp
+++ b/src/llvm_backend.hpp
@@ -160,7 +160,7 @@ struct lbModule {
 	StringMap<lbAddr> objc_classes;
 	StringMap<lbAddr> objc_selectors;
 
-	PtrMap<Type *, lbAddr> map_header_table_map;
+	PtrMap<Type *, lbAddr> map_info_map;
 };
 
 struct lbGenerator {
diff --git a/src/llvm_backend_general.cpp b/src/llvm_backend_general.cpp
index 87f8afa05..69b1fce20 100644
--- a/src/llvm_backend_general.cpp
+++ b/src/llvm_backend_general.cpp
@@ -75,7 +75,7 @@ void lb_init_module(lbModule *m, Checker *c) {
 	string_map_init(&m->objc_classes, a);
 	string_map_init(&m->objc_selectors, a);
 
-	map_init(&m->map_header_table_map, a, 0);
+	map_init(&m->map_info_map, a, 0);
 
 }
 
@@ -1939,27 +1939,13 @@ LLVMTypeRef lb_type_internal(lbModule *m, Type *type) {
 			defer (m->internal_type_level += 1);
 
 			unsigned field_count = cast(unsigned)(internal_type->Struct.fields.count);
-			GB_ASSERT(field_count == 2);
-			LLVMTypeRef *fields = gb_alloc_array(temporary_allocator(), LLVMTypeRef, field_count);
+			GB_ASSERT(field_count == 3);
 
-			LLVMTypeRef entries_fields[] = {
-				lb_type(m, t_rawptr), // data
-				lb_type(m, t_int), // len
-				lb_type(m, t_int), // cap
+			LLVMTypeRef fields[3] = {
+				lb_type(m, t_uintptr),   // data
+				lb_type(m, t_uintptr),   // len
 				lb_type(m, t_allocator), // allocator
 			};
-
-			fields[0] = lb_type(m, internal_type->Struct.fields[0]->type);
-			fields[1] = LLVMStructTypeInContext(ctx, entries_fields, gb_count_of(entries_fields), false);
-			
-			{ // Add this to simplify things
-				lbStructFieldRemapping entries_field_remapping = {};
-				slice_init(&entries_field_remapping, permanent_allocator(), gb_count_of(entries_fields));
-				for_array(i, entries_field_remapping) {
-					entries_field_remapping[i] = cast(i32)i;
-				}
-				map_set(&m->struct_field_remapping, cast(void *)fields[1], entries_field_remapping);
-			}
 			
 			return LLVMStructTypeInContext(ctx, fields, field_count, false);
 		}
diff --git a/src/types.cpp b/src/types.cpp
index b9f2b375f..220d1a6ab 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -226,7 +226,6 @@ struct TypeProc {
 	TYPE_KIND(Map, struct {                                   \
 		Type *key;                                        \
 		Type *value;                                      \
-		Type *entry_type;                                 \
 		Type *internal_type;                              \
 		Type *lookup_result_type;                         \
 	})                                                        \
@@ -685,9 +684,8 @@ gb_global Type *t_allocator_error                = nullptr;
 gb_global Type *t_source_code_location           = nullptr;
 gb_global Type *t_source_code_location_ptr       = nullptr;
 
-gb_global Type *t_map_hash                       = nullptr;
-gb_global Type *t_map_header                     = nullptr;
-gb_global Type *t_map_header_table               = nullptr;
+gb_global Type *t_map_info                       = nullptr;
+gb_global Type *t_map_cell_info                  = nullptr;
 
 
 gb_global Type *t_equal_proc  = nullptr;
@@ -3330,8 +3328,6 @@ Selection lookup_field_with_selection(Type *type_, String field_name, bool is_ty
 			}
 		}
 	} else if (type->kind == Type_DynamicArray) {
-		// IMPORTANT TODO(bill): Should these members be available to should I only allow them with
-		// `Raw_Dynamic_Array` type?
 		GB_ASSERT(t_allocator != nullptr);
 		String allocator_str = str_lit("allocator");
 		gb_local_persist Entity *entity__allocator = alloc_entity_field(nullptr, make_token_ident(allocator_str), t_allocator, false, 3);
@@ -3342,15 +3338,12 @@ Selection lookup_field_with_selection(Type *type_, String field_name, bool is_ty
 			return sel;
 		}
 	} else if (type->kind == Type_Map) {
-		// IMPORTANT TODO(bill): Should these members be available to should I only allow them with
-		// `Raw_Map` type?
 		GB_ASSERT(t_allocator != nullptr);
 		String allocator_str = str_lit("allocator");
-		gb_local_persist Entity *entity__allocator = alloc_entity_field(nullptr, make_token_ident(allocator_str), t_allocator, false, 3);
+		gb_local_persist Entity *entity__allocator = alloc_entity_field(nullptr, make_token_ident(allocator_str), t_allocator, false, 2);
 
 		if (field_name == allocator_str) {
-			selection_add_index(&sel, 1);
-			selection_add_index(&sel, 3);
+			selection_add_index(&sel, 2);
 			sel.entity = entity__allocator;
 			return sel;
 		}
@@ -3795,11 +3788,12 @@ i64 type_size_of_internal(Type *t, TypePath *path) {
 	case Type_Map:
 		/*
 			struct {
-				hashes:  []int,               // 2 words
-				entries: [dynamic]Entry_Type, // 5 words
+				data:      uintptr,           // 1 word
+				size:      uintptr,           // 1 word
+				allocator: runtime.Allocator, // 2 words
 			}
 		*/
-		return (2 + (3 + 2))*build_context.word_size;
+		return (1 + 1 + 2)*build_context.word_size;
 
 	case Type_Tuple: {
 		i64 count, align, size;