diff --git a/vlib/builtin/array.c.v b/vlib/builtin/array.c.v
new file mode 100644
index 0000000000..b15fe4b882
--- /dev/null
+++ b/vlib/builtin/array.c.v
@@ -0,0 +1 @@
+module builtin
diff --git a/vlib/builtin/array.v b/vlib/builtin/array.v
index 559fe5baa6..0a6f4e06ec 100644
--- a/vlib/builtin/array.v
+++ b/vlib/builtin/array.v
@@ -71,7 +71,7 @@ fn new_array_from_c_array(len int, cap int, elm_size int, c_array voidptr) array
 		cap: cap_
 	}
 	// TODO Write all memory functions (like memcpy) in V
-	unsafe { C.memcpy(arr.data, c_array, len * elm_size) }
+	unsafe { vmemcpy(arr.data, c_array, len * elm_size) }
 	return arr
 }
 
@@ -98,7 +98,7 @@ fn (mut a array) ensure_cap(required int) {
 	new_size := cap * a.element_size
 	new_data := vcalloc(new_size)
 	if a.data != voidptr(0) {
-		unsafe { C.memcpy(new_data, a.data, a.len * a.element_size) }
+		unsafe { vmemcpy(new_data, a.data, a.len * a.element_size) }
 		// TODO: the old data may be leaked when no GC is used (ref-counting?)
 	}
 	a.data = new_data
@@ -136,9 +136,9 @@ pub fn (a array) repeat_to_depth(count int, depth int) array {
 		for i in 0 .. count {
 			if depth > 0 {
 				ary_clone := unsafe { a.clone_to_depth(depth) }
-				unsafe { C.memcpy(arr.get_unsafe(i * a.len), &byte(ary_clone.data), a.len * a.element_size) }
+				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &byte(ary_clone.data), a.len * a.element_size) }
 			} else {
-				unsafe { C.memcpy(arr.get_unsafe(i * a.len), &byte(a.data), a.len * a.element_size) }
+				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &byte(a.data), a.len * a.element_size) }
 			}
 		}
 	}
@@ -150,7 +150,7 @@ pub fn (mut a array) sort_with_compare(compare voidptr) {
 	$if freestanding {
 		panic('sort does not work with -freestanding')
 	} $else {
-		C.qsort(mut a.data, a.len, a.element_size, compare)
+		unsafe { vqsort(a.data, size_t(a.len), size_t(a.element_size), compare) }
 	}
 }
 
@@ -163,7 +163,7 @@ pub fn (mut a array) insert(i int, val voidptr) {
 	}
 	a.ensure_cap(a.len + 1)
 	unsafe {
-		C.memmove(a.get_unsafe(i + 1), a.get_unsafe(i), (a.len - i) * a.element_size)
+		vmemmove(a.get_unsafe(i + 1), a.get_unsafe(i), (a.len - i) * a.element_size)
 		a.set_unsafe(i, val)
 	}
 	a.len++
@@ -181,8 +181,8 @@ pub fn (mut a array) insert_many(i int, val voidptr, size int) {
 	elem_size := a.element_size
 	unsafe {
 		iptr := a.get_unsafe(i)
-		C.memmove(a.get_unsafe(i + size), iptr, (a.len - i) * elem_size)
-		C.memcpy(iptr, val, size * elem_size)
+		vmemmove(a.get_unsafe(i + size), iptr, (a.len - i) * elem_size)
+		vmemcpy(iptr, val, size * elem_size)
 	}
 	a.len += size
 }
@@ -217,9 +217,9 @@ pub fn (mut a array) delete_many(i int, size int) {
 	new_size := a.len - size
 	new_cap := if new_size == 0 { 1 } else { new_size }
 	a.data = vcalloc(new_cap * a.element_size)
-	unsafe { C.memcpy(a.data, old_data, i * a.element_size) }
+	unsafe { vmemcpy(a.data, old_data, i * a.element_size) }
 	unsafe {
-		C.memcpy(&byte(a.data) + i * a.element_size, &byte(old_data) + (i + size) * a.element_size,
+		vmemcpy(&byte(a.data) + i * a.element_size, &byte(old_data) + (i + size) * a.element_size,
 			(a.len - i - size) * a.element_size)
 	}
 	a.len = new_size
@@ -385,14 +385,14 @@ pub fn (a &array) clone_to_depth(depth int) array {
 	if depth > 0 && a.element_size == sizeof(array) && a.len >= 0 && a.cap >= a.len {
 		for i in 0 .. a.len {
 			ar := array{}
-			unsafe { C.memcpy(&ar, a.get_unsafe(i), int(sizeof(array))) }
+			unsafe { vmemcpy(&ar, a.get_unsafe(i), int(sizeof(array))) }
 			ar_clone := unsafe { ar.clone_to_depth(depth - 1) }
 			unsafe { arr.set_unsafe(i, &ar_clone) }
 		}
 		return arr
 	} else {
 		if !isnil(a.data) {
-			unsafe { C.memcpy(&byte(arr.data), a.data, a.cap * a.element_size) }
+			unsafe { vmemcpy(&byte(arr.data), a.data, a.cap * a.element_size) }
 		}
 		return arr
 	}
@@ -401,7 +401,7 @@ pub fn (a &array) clone_to_depth(depth int) array {
 // we manually inline this for single operations for performance without -prod
 [inline; unsafe]
 fn (mut a array) set_unsafe(i int, val voidptr) {
-	unsafe { C.memcpy(&byte(a.data) + a.element_size * i, val, a.element_size) }
+	unsafe { vmemcpy(&byte(a.data) + a.element_size * i, val, a.element_size) }
 }
 
 // Private function. Used to implement assigment to the array element.
@@ -411,12 +411,12 @@ fn (mut a array) set(i int, val voidptr) {
 			panic('array.set: index out of range (i == $i, a.len == $a.len)')
 		}
 	}
-	unsafe { C.memcpy(&byte(a.data) + a.element_size * i, val, a.element_size) }
+	unsafe { vmemcpy(&byte(a.data) + a.element_size * i, val, a.element_size) }
 }
 
 fn (mut a array) push(val voidptr) {
 	a.ensure_cap(a.len + 1)
-	unsafe { C.memmove(&byte(a.data) + a.element_size * a.len, val, a.element_size) }
+	unsafe { vmemmove(&byte(a.data) + a.element_size * a.len, val, a.element_size) }
 	a.len++
 }
 
@@ -429,13 +429,13 @@ pub fn (mut a3 array) push_many(val voidptr, size int) {
 		copy := a3.clone()
 		a3.ensure_cap(a3.len + size)
 		unsafe {
-			// C.memcpy(a.data, copy.data, copy.element_size * copy.len)
-			C.memcpy(a3.get_unsafe(a3.len), copy.data, a3.element_size * size)
+			// vmemcpy(a.data, copy.data, copy.element_size * copy.len)
+			vmemcpy(a3.get_unsafe(a3.len), copy.data, a3.element_size * size)
 		}
 	} else {
 		a3.ensure_cap(a3.len + size)
 		if !isnil(a3.data) && !isnil(val) {
-			unsafe { C.memcpy(a3.get_unsafe(a3.len), val, a3.element_size * size) }
+			unsafe { vmemcpy(a3.get_unsafe(a3.len), val, a3.element_size * size) }
 		}
 	}
 	a3.len += size
@@ -449,10 +449,10 @@ pub fn (mut a array) reverse_in_place() {
 	unsafe {
 		mut tmp_value := malloc(a.element_size)
 		for i in 0 .. a.len / 2 {
-			C.memcpy(tmp_value, &byte(a.data) + i * a.element_size, a.element_size)
-			C.memcpy(&byte(a.data) + i * a.element_size, &byte(a.data) +
+			vmemcpy(tmp_value, &byte(a.data) + i * a.element_size, a.element_size)
+			vmemcpy(&byte(a.data) + i * a.element_size, &byte(a.data) +
 				(a.len - 1 - i) * a.element_size, a.element_size)
-			C.memcpy(&byte(a.data) + (a.len - 1 - i) * a.element_size, tmp_value, a.element_size)
+			vmemcpy(&byte(a.data) + (a.len - 1 - i) * a.element_size, tmp_value, a.element_size)
 		}
 		free(tmp_value)
 	}
@@ -587,7 +587,7 @@ pub fn (b []byte) hex() string {
 pub fn copy(dst []byte, src []byte) int {
 	min := if dst.len < src.len { dst.len } else { src.len }
 	if min > 0 {
-		unsafe { C.memcpy(&byte(dst.data), src.data, min) }
+		unsafe { vmemcpy(&byte(dst.data), src.data, min) }
 	}
 	return min
 }
diff --git a/vlib/builtin/array_d_gcboehm_opt.v b/vlib/builtin/array_d_gcboehm_opt.v
index 330977da5d..132ddc7e35 100644
--- a/vlib/builtin/array_d_gcboehm_opt.v
+++ b/vlib/builtin/array_d_gcboehm_opt.v
@@ -57,7 +57,7 @@ fn new_array_from_c_array_noscan(len int, cap int, elm_size int, c_array voidptr
 		cap: cap_
 	}
 	// TODO Write all memory functions (like memcpy) in V
-	unsafe { C.memcpy(arr.data, c_array, len * elm_size) }
+	unsafe { vmemcpy(arr.data, c_array, len * elm_size) }
 	return arr
 }
 
@@ -73,7 +73,7 @@ fn (mut a array) ensure_cap_noscan(required int) {
 	new_size := cap * a.element_size
 	new_data := vcalloc_noscan(new_size)
 	if a.data != voidptr(0) {
-		unsafe { C.memcpy(new_data, a.data, a.len * a.element_size) }
+		unsafe { vmemcpy(new_data, a.data, a.len * a.element_size) }
 		// TODO: the old data may be leaked when no GC is used (ref-counting?)
 	}
 	a.data = new_data
@@ -105,9 +105,9 @@ fn (a array) repeat_to_depth_noscan(count int, depth int) array {
 		for i in 0 .. count {
 			if depth > 0 {
 				ary_clone := unsafe { a.clone_to_depth_noscan(depth) }
-				unsafe { C.memcpy(arr.get_unsafe(i * a.len), &byte(ary_clone.data), a.len * a.element_size) }
+				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &byte(ary_clone.data), a.len * a.element_size) }
 			} else {
-				unsafe { C.memcpy(arr.get_unsafe(i * a.len), &byte(a.data), a.len * a.element_size) }
+				unsafe { vmemcpy(arr.get_unsafe(i * a.len), &byte(a.data), a.len * a.element_size) }
 			}
 		}
 	}
@@ -123,7 +123,7 @@ fn (mut a array) insert_noscan(i int, val voidptr) {
 	}
 	a.ensure_cap_noscan(a.len + 1)
 	unsafe {
-		C.memmove(a.get_unsafe(i + 1), a.get_unsafe(i), (a.len - i) * a.element_size)
+		vmemmove(a.get_unsafe(i + 1), a.get_unsafe(i), (a.len - i) * a.element_size)
 		a.set_unsafe(i, val)
 	}
 	a.len++
@@ -141,8 +141,8 @@ fn (mut a array) insert_many_noscan(i int, val voidptr, size int) {
 	elem_size := a.element_size
 	unsafe {
 		iptr := a.get_unsafe(i)
-		C.memmove(a.get_unsafe(i + size), iptr, (a.len - i) * elem_size)
-		C.memcpy(iptr, val, size * elem_size)
+		vmemmove(a.get_unsafe(i + size), iptr, (a.len - i) * elem_size)
+		vmemcpy(iptr, val, size * elem_size)
 	}
 	a.len += size
 }
@@ -198,14 +198,14 @@ fn (a &array) clone_to_depth_noscan(depth int) array {
 	if depth > 0 {
 		for i in 0 .. a.len {
 			ar := array{}
-			unsafe { C.memcpy(&ar, a.get_unsafe(i), int(sizeof(array))) }
+			unsafe { vmemcpy(&ar, a.get_unsafe(i), int(sizeof(array))) }
 			ar_clone := unsafe { ar.clone_to_depth_noscan(depth - 1) }
 			unsafe { arr.set_unsafe(i, &ar_clone) }
 		}
 		return arr
 	} else {
 		if !isnil(a.data) {
-			unsafe { C.memcpy(&byte(arr.data), a.data, a.cap * a.element_size) }
+			unsafe { vmemcpy(&byte(arr.data), a.data, a.cap * a.element_size) }
 		}
 		return arr
 	}
@@ -213,7 +213,7 @@ fn (a &array) clone_to_depth_noscan(depth int) array {
 
 fn (mut a array) push_noscan(val voidptr) {
 	a.ensure_cap_noscan(a.len + 1)
-	unsafe { C.memmove(&byte(a.data) + a.element_size * a.len, val, a.element_size) }
+	unsafe { vmemmove(&byte(a.data) + a.element_size * a.len, val, a.element_size) }
 	a.len++
 }
 
@@ -226,13 +226,12 @@ fn (mut a3 array) push_many_noscan(val voidptr, size int) {
 		copy := a3.clone()
 		a3.ensure_cap_noscan(a3.len + size)
 		unsafe {
-			// C.memcpy(a.data, copy.data, copy.element_size * copy.len)
-			C.memcpy(a3.get_unsafe(a3.len), copy.data, a3.element_size * size)
+			vmemcpy(a3.get_unsafe(a3.len), copy.data, a3.element_size * size)
 		}
 	} else {
 		a3.ensure_cap_noscan(a3.len + size)
 		if !isnil(a3.data) && !isnil(val) {
-			unsafe { C.memcpy(a3.get_unsafe(a3.len), val, a3.element_size * size) }
+			unsafe { vmemcpy(a3.get_unsafe(a3.len), val, a3.element_size * size) }
 		}
 	}
 	a3.len += size
diff --git a/vlib/builtin/builtin.c.v b/vlib/builtin/builtin.c.v
index 0b0ca802c7..0379c8336e 100644
--- a/vlib/builtin/builtin.c.v
+++ b/vlib/builtin/builtin.c.v
@@ -525,3 +525,23 @@ fn v_fixed_index(i int, len int) int {
 	}
 	return i
 }
+
+// print_backtrace shows a backtrace of the current call stack on stdout
+pub fn print_backtrace() {
+	// At the time of backtrace_symbols_fd call, the C stack would look something like this:
+	// * print_backtrace_skipping_top_frames
+	// * print_backtrace itself
+	// * the rest of the backtrace frames
+	// => top 2 frames should be skipped, since they will not be informative to the developer
+	$if !no_backtrace ? {
+		$if freestanding {
+			println(bare_backtrace())
+		} $else {
+			$if tinyc {
+				C.tcc_backtrace(c'Backtrace')
+			} $else {
+				print_backtrace_skipping_top_frames(2)
+			}
+		}
+	}
+}
diff --git a/vlib/builtin/builtin.v b/vlib/builtin/builtin.v
index d3a14744aa..beeb20ed71 100644
--- a/vlib/builtin/builtin.v
+++ b/vlib/builtin/builtin.v
@@ -15,26 +15,6 @@ fn on_panic(f fn(int)int) {
 }
 */
 
-// print_backtrace shows a backtrace of the current call stack on stdout
-pub fn print_backtrace() {
-	// At the time of backtrace_symbols_fd call, the C stack would look something like this:
-	// * print_backtrace_skipping_top_frames
-	// * print_backtrace itself
-	// * the rest of the backtrace frames
-	// => top 2 frames should be skipped, since they will not be informative to the developer
-	$if !no_backtrace ? {
-		$if freestanding {
-			println(bare_backtrace())
-		} $else {
-			$if tinyc {
-				C.tcc_backtrace(c'Backtrace')
-			} $else {
-				print_backtrace_skipping_top_frames(2)
-			}
-		}
-	}
-}
-
 struct VCastTypeIndexName {
 	tindex int
 	tname  string
diff --git a/vlib/builtin/builtin_d_gcboehm.v b/vlib/builtin/builtin_d_gcboehm.c.v
similarity index 100%
rename from vlib/builtin/builtin_d_gcboehm.v
rename to vlib/builtin/builtin_d_gcboehm.c.v
diff --git a/vlib/builtin/builtin_notd_gcboehm.v b/vlib/builtin/builtin_notd_gcboehm.c.v
similarity index 100%
rename from vlib/builtin/builtin_notd_gcboehm.v
rename to vlib/builtin/builtin_notd_gcboehm.c.v
diff --git a/vlib/builtin/cfns.c.v b/vlib/builtin/cfns.c.v
index b67da34422..75896647dd 100644
--- a/vlib/builtin/cfns.c.v
+++ b/vlib/builtin/cfns.c.v
@@ -1,11 +1,13 @@
 module builtin
 
 // <string.h>
-fn C.memcpy(dest &byte, src &byte, n int) voidptr
+fn C.memcpy(dest voidptr, const_src voidptr, n size_t) voidptr
 
-fn C.memcmp(&byte, &byte, int) int
+fn C.memcmp(const_s1 voidptr, const_s2 voidptr, n size_t) int
 
-fn C.memmove(&byte, &byte, int) voidptr
+fn C.memmove(dest voidptr, const_src voidptr, n size_t) voidptr
+
+fn C.memset(str voidptr, c int, n size_t) voidptr
 
 [trusted]
 fn C.calloc(int, int) &byte
@@ -125,8 +127,6 @@ fn C.rename(old_filename &char, new_filename &char) int
 
 fn C.fgets(str &char, n int, stream &C.FILE) int
 
-fn C.memset(str voidptr, c int, n size_t) int
-
 [trusted]
 fn C.sigemptyset() int
 
diff --git a/vlib/builtin/cfns_wrapper.c.v b/vlib/builtin/cfns_wrapper.c.v
new file mode 100644
index 0000000000..06f1348601
--- /dev/null
+++ b/vlib/builtin/cfns_wrapper.c.v
@@ -0,0 +1,72 @@
+module builtin
+
+// vstrlen returns the V length of the C string `s` (0 terminator is not counted).
+// The C string is expected to be a &byte pointer.
+[inline; unsafe]
+pub fn vstrlen(s &byte) int {
+	return unsafe { C.strlen(&char(s)) }
+}
+
+// vstrlen_char returns the V length of the C string `s` (0 terminator is not counted).
+// The C string is expected to be a &char pointer.
+[inline; unsafe]
+pub fn vstrlen_char(s &char) int {
+	return unsafe { C.strlen(s) }
+}
+
+// vmemcpy copies n bytes from memory area src to memory area dest.
+// The memory areas *MUST NOT OVERLAP*.  Use vmemmove, if the memory
+// areas do overlap. vmemcpy returns a pointer to `dest`.
+[inline; unsafe]
+pub fn vmemcpy(dest voidptr, const_src voidptr, n int) voidptr {
+	unsafe {
+		return C.memcpy(dest, const_src, n)
+	}
+}
+
+// vmemmove copies n bytes from memory area `src` to memory area `dest`.
+// The memory areas *MAY* overlap: copying takes place as though the bytes
+// in `src` are first copied into a temporary array that does not overlap
+// `src` or `dest`, and the bytes are then copied from the temporary array
+// to `dest`. vmemmove returns a pointer to `dest`.
+[inline; unsafe]
+pub fn vmemmove(dest voidptr, const_src voidptr, n int) voidptr {
+	unsafe {
+		return C.memmove(dest, const_src, n)
+	}
+}
+
+// vmemcmp compares the first n bytes (each interpreted as unsigned char)
+// of the memory areas s1 and s2. It returns an integer less than, equal to,
+// or greater than zero, if the first n bytes of s1 is found, respectively,
+// to be less than, to match, or be greater than the first n bytes of s2.
+// For a nonzero return value, the sign is determined by the sign of the
+// difference between the first pair of bytes (interpreted as unsigned char)
+// that differ in s1 and s2.
+// If n is zero, the return value is zero.
+// Do NOT use vmemcmp to compare security critical data, such as cryptographic
+// secrets, because the required CPU time depends on the number of equal bytes.
+// You should use a function that performs comparisons in constant time for
+// this.
+[inline; unsafe]
+pub fn vmemcmp(const_s1 voidptr, const_s2 voidptr, n int) int {
+	unsafe {
+		return C.memcmp(const_s1, const_s2, n)
+	}
+}
+
+// vmemset fills the first `n` bytes of the memory area pointed to by `s`,
+// with the constant byte `c`. It returns a pointer to the memory area `s`.
+[inline; unsafe]
+pub fn vmemset(s voidptr, c int, n int) voidptr {
+	unsafe {
+		return C.memset(s, c, n)
+	}
+}
+
+type FnSortCB = fn (const_a voidptr, const_b voidptr) int
+
+[inline; unsafe]
+fn vqsort(base voidptr, nmemb size_t, size size_t, sort_cb FnSortCB) {
+	C.qsort(base, nmemb, size, voidptr(sort_cb))
+}
diff --git a/vlib/builtin/float.v b/vlib/builtin/float.c.v
similarity index 100%
rename from vlib/builtin/float.v
rename to vlib/builtin/float.c.v
diff --git a/vlib/builtin/int.v b/vlib/builtin/int.v
index 9c769d999f..0af6ddd1d7 100644
--- a/vlib/builtin/int.v
+++ b/vlib/builtin/int.v
@@ -71,7 +71,7 @@ fn (nn int) str_l(max int) string {
 			buf[index] = `-`
 		}
 		diff := max - index
-		C.memmove(buf, buf + index, diff + 1)
+		vmemmove(buf, buf + index, diff + 1)
 		/*
 		// === manual memory move for bare metal ===
 		mut c:= 0
@@ -142,7 +142,7 @@ pub fn (nn u32) str() string {
 			index++
 		}
 		diff := max - index
-		C.memmove(buf, buf + index, diff + 1)
+		vmemmove(buf, buf + index, diff + 1)
 		return tos(buf, diff)
 
 		// return tos(memdup(&buf[0] + index, (max - index)), (max - index))
@@ -196,7 +196,7 @@ pub fn (nn i64) str() string {
 			buf[index] = `-`
 		}
 		diff := max - index
-		C.memmove(buf, buf + index, diff + 1)
+		vmemmove(buf, buf + index, diff + 1)
 		return tos(buf, diff)
 		// return tos(memdup(&buf[0] + index, (max - index)), (max - index))
 	}
@@ -233,7 +233,7 @@ pub fn (nn u64) str() string {
 			index++
 		}
 		diff := max - index
-		C.memmove(buf, buf + index, diff + 1)
+		vmemmove(buf, buf + index, diff + 1)
 		return tos(buf, diff)
 		// return tos(memdup(&buf[0] + index, (max - index)), (max - index))
 	}
diff --git a/vlib/builtin/linux_bare/libc_impl.v b/vlib/builtin/linux_bare/libc_impl.v
index 735cac681c..a8d6d63f29 100644
--- a/vlib/builtin/linux_bare/libc_impl.v
+++ b/vlib/builtin/linux_bare/libc_impl.v
@@ -155,3 +155,8 @@ fn bare_backtrace() string {
 fn __exit(code int) {
 	sys_exit(code)
 }
+
+[export: 'qsort']
+fn __qsort(base voidptr, nmemb size_t, size size_t, sort_cb FnSortCB) {
+	panic('qsort() is not yet implemented in `-freestanding`')
+}
diff --git a/vlib/builtin/map.c.v b/vlib/builtin/map.c.v
new file mode 100644
index 0000000000..c0fc60cfbc
--- /dev/null
+++ b/vlib/builtin/map.c.v
@@ -0,0 +1,79 @@
+module builtin
+
+fn C.wyhash(&byte, u64, u64, &u64) u64
+
+fn C.wyhash64(u64, u64) u64
+
+// fast_string_eq is intended to be fast when
+// the strings are very likely to be equal
+// TODO: add branch prediction hints
+[inline]
+fn fast_string_eq(a string, b string) bool {
+	if a.len != b.len {
+		return false
+	}
+	unsafe {
+		return C.memcmp(a.str, b.str, b.len) == 0
+	}
+}
+
+fn map_hash_string(pkey voidptr) u64 {
+	key := *unsafe { &string(pkey) }
+	return C.wyhash(key.str, u64(key.len), 0, &u64(C._wyp))
+}
+
+fn map_hash_int_1(pkey voidptr) u64 {
+	return C.wyhash64(*unsafe { &byte(pkey) }, 0)
+}
+
+fn map_hash_int_2(pkey voidptr) u64 {
+	return C.wyhash64(*unsafe { &u16(pkey) }, 0)
+}
+
+fn map_hash_int_4(pkey voidptr) u64 {
+	return C.wyhash64(*unsafe { &u32(pkey) }, 0)
+}
+
+fn map_hash_int_8(pkey voidptr) u64 {
+	return C.wyhash64(*unsafe { &u64(pkey) }, 0)
+}
+
+// Move all zeros to the end of the array and resize array
+fn (mut d DenseArray) zeros_to_end() {
+	// TODO alloca?
+	mut tmp_value := unsafe { malloc(d.value_bytes) }
+	mut tmp_key := unsafe { malloc(d.key_bytes) }
+	mut count := 0
+	for i in 0 .. d.len {
+		if d.has_index(i) {
+			// swap (TODO: optimize)
+			unsafe {
+				if count != i {
+					// Swap keys
+					C.memcpy(tmp_key, d.key(count), d.key_bytes)
+					C.memcpy(d.key(count), d.key(i), d.key_bytes)
+					C.memcpy(d.key(i), tmp_key, d.key_bytes)
+					// Swap values
+					C.memcpy(tmp_value, d.value(count), d.value_bytes)
+					C.memcpy(d.value(count), d.value(i), d.value_bytes)
+					C.memcpy(d.value(i), tmp_value, d.value_bytes)
+				}
+			}
+			count++
+		}
+	}
+	unsafe {
+		free(tmp_value)
+		free(tmp_key)
+		d.deletes = 0
+		// TODO: reallocate instead as more deletes are likely
+		free(d.all_deleted)
+	}
+	d.len = count
+	old_cap := d.cap
+	d.cap = if count < 8 { 8 } else { count }
+	unsafe {
+		d.values = realloc_data(d.values, d.value_bytes * old_cap, d.value_bytes * d.cap)
+		d.keys = realloc_data(d.keys, d.key_bytes * old_cap, d.key_bytes * d.cap)
+	}
+}
diff --git a/vlib/builtin/map.v b/vlib/builtin/map.v
index 37b2e49317..5e67d796d8 100644
--- a/vlib/builtin/map.v
+++ b/vlib/builtin/map.v
@@ -3,10 +3,6 @@
 // that can be found in the LICENSE file.
 module builtin
 
-fn C.wyhash(&byte, u64, u64, &u64) u64
-
-fn C.wyhash64(u64, u64) u64
-
 /*
 This is a highly optimized hashmap implementation. It has several traits that
 in combination makes it very fast and memory efficient. Here is a short expl-
@@ -79,19 +75,6 @@ const (
 	probe_inc           = u32(0x01000000)
 )
 
-// fast_string_eq is intended to be fast when
-// the strings are very likely to be equal
-// TODO: add branch prediction hints
-[inline]
-fn fast_string_eq(a string, b string) bool {
-	if a.len != b.len {
-		return false
-	}
-	unsafe {
-		return C.memcmp(a.str, b.str, b.len) == 0
-	}
-}
-
 // DenseArray represents a dynamic array with very low growth factor
 struct DenseArray {
 	key_bytes   int
@@ -152,7 +135,7 @@ fn (mut d DenseArray) expand() int {
 			d.values = realloc_data(d.values, old_value_size, d.value_bytes * d.cap)
 			if d.deletes != 0 {
 				d.all_deleted = realloc_data(d.all_deleted, old_cap, d.cap)
-				C.memset(d.all_deleted + d.len, 0, d.cap - d.len)
+				vmemset(d.all_deleted + d.len, 0, d.cap - d.len)
 			}
 		}
 	}
@@ -166,46 +149,6 @@ fn (mut d DenseArray) expand() int {
 	return push_index
 }
 
-// Move all zeros to the end of the array and resize array
-fn (mut d DenseArray) zeros_to_end() {
-	// TODO alloca?
-	mut tmp_value := unsafe { malloc(d.value_bytes) }
-	mut tmp_key := unsafe { malloc(d.key_bytes) }
-	mut count := 0
-	for i in 0 .. d.len {
-		if d.has_index(i) {
-			// swap (TODO: optimize)
-			unsafe {
-				if count != i {
-					// Swap keys
-					C.memcpy(tmp_key, d.key(count), d.key_bytes)
-					C.memcpy(d.key(count), d.key(i), d.key_bytes)
-					C.memcpy(d.key(i), tmp_key, d.key_bytes)
-					// Swap values
-					C.memcpy(tmp_value, d.value(count), d.value_bytes)
-					C.memcpy(d.value(count), d.value(i), d.value_bytes)
-					C.memcpy(d.value(i), tmp_value, d.value_bytes)
-				}
-			}
-			count++
-		}
-	}
-	unsafe {
-		free(tmp_value)
-		free(tmp_key)
-		d.deletes = 0
-		// TODO: reallocate instead as more deletes are likely
-		free(d.all_deleted)
-	}
-	d.len = count
-	old_cap := d.cap
-	d.cap = if count < 8 { 8 } else { count }
-	unsafe {
-		d.values = realloc_data(d.values, d.value_bytes * old_cap, d.value_bytes * d.cap)
-		d.keys = realloc_data(d.keys, d.key_bytes * old_cap, d.key_bytes * d.cap)
-	}
-}
-
 type MapHashFn = fn (voidptr) u64
 
 type MapEqFn = fn (voidptr, voidptr) bool
@@ -246,27 +189,6 @@ pub mut:
 	len int
 }
 
-fn map_hash_string(pkey voidptr) u64 {
-	key := *unsafe { &string(pkey) }
-	return C.wyhash(key.str, u64(key.len), 0, &u64(C._wyp))
-}
-
-fn map_hash_int_1(pkey voidptr) u64 {
-	return C.wyhash64(*unsafe { &byte(pkey) }, 0)
-}
-
-fn map_hash_int_2(pkey voidptr) u64 {
-	return C.wyhash64(*unsafe { &u16(pkey) }, 0)
-}
-
-fn map_hash_int_4(pkey voidptr) u64 {
-	return C.wyhash64(*unsafe { &u32(pkey) }, 0)
-}
-
-fn map_hash_int_8(pkey voidptr) u64 {
-	return C.wyhash64(*unsafe { &u64(pkey) }, 0)
-}
-
 fn map_eq_string(a voidptr, b voidptr) bool {
 	return fast_string_eq(*unsafe { &string(a) }, *unsafe { &string(b) })
 }
@@ -367,7 +289,7 @@ fn new_map_init(hash_fn MapHashFn, key_eq_fn MapEqFn, clone_fn MapCloneFn, free_
 pub fn (mut m map) move() map {
 	r := *m
 	unsafe {
-		C.memset(m, 0, sizeof(map))
+		vmemset(m, 0, int(sizeof(map)))
 	}
 	return r
 }
@@ -428,7 +350,7 @@ fn (mut m map) ensure_extra_metas(probe_count u32) {
 		unsafe {
 			x := realloc_data(&byte(m.metas), int(size_of_u32 * old_mem_size), int(size_of_u32 * mem_size))
 			m.metas = &u32(x)
-			C.memset(m.metas + mem_size - extra_metas_inc, 0, int(sizeof(u32) * extra_metas_inc))
+			vmemset(m.metas + mem_size - extra_metas_inc, 0, int(sizeof(u32) * extra_metas_inc))
 		}
 		// Should almost never happen
 		if probe_count == 252 {
@@ -454,7 +376,7 @@ fn (mut m map) set(key voidptr, value voidptr) {
 		if m.key_eq_fn(key, pkey) {
 			unsafe {
 				pval := m.key_values.value(kv_index)
-				C.memcpy(pval, value, m.value_bytes)
+				vmemcpy(pval, value, m.value_bytes)
 			}
 			return
 		}
@@ -466,7 +388,7 @@ fn (mut m map) set(key voidptr, value voidptr) {
 		pkey := m.key_values.key(kv_index)
 		pvalue := m.key_values.value(kv_index)
 		m.clone_fn(pkey, key)
-		C.memcpy(&byte(pvalue), value, m.value_bytes)
+		vmemcpy(&byte(pvalue), value, m.value_bytes)
 	}
 	m.meta_greater(index, meta, u32(kv_index))
 	m.len++
@@ -498,7 +420,7 @@ fn (mut m map) rehash() {
 		// TODO: use realloc_data here too
 		x := v_realloc(&byte(m.metas), int(meta_bytes))
 		m.metas = &u32(x)
-		C.memset(m.metas, 0, meta_bytes)
+		vmemset(m.metas, 0, int(meta_bytes))
 	}
 	for i := 0; i < m.key_values.len; i++ {
 		if !m.key_values.has_index(i) {
@@ -663,7 +585,7 @@ pub fn (mut m map) delete(key voidptr) {
 				m.metas[index] = 0
 				m.free_fn(pkey)
 				// Mark key as deleted
-				C.memset(pkey, 0, m.key_bytes)
+				vmemset(pkey, 0, m.key_bytes)
 			}
 			if m.key_values.len <= 32 {
 				return
@@ -750,7 +672,7 @@ pub fn (m &map) clone() map {
 		clone_fn: m.clone_fn
 		free_fn: m.free_fn
 	}
-	unsafe { C.memcpy(res.metas, m.metas, metasize) }
+	unsafe { vmemcpy(res.metas, m.metas, metasize) }
 	if !m.has_string_keys {
 		return res
 	}
diff --git a/vlib/builtin/option.c.v b/vlib/builtin/option.c.v
new file mode 100644
index 0000000000..464cf87dfd
--- /dev/null
+++ b/vlib/builtin/option.c.v
@@ -0,0 +1,15 @@
+module builtin
+
+[typedef]
+struct C.IError {
+	_object voidptr
+}
+
+[unsafe]
+pub fn (ie &IError) free() {
+	unsafe {
+		ie.msg.free()
+		cie := &C.IError(ie)
+		free(cie._object)
+	}
+}
diff --git a/vlib/builtin/option.v b/vlib/builtin/option.v
index 4e8a14f194..1f1bdd9b61 100644
--- a/vlib/builtin/option.v
+++ b/vlib/builtin/option.v
@@ -74,7 +74,7 @@ fn opt_ok(data voidptr, mut option Option, size int) {
 	unsafe {
 		*option = Option{}
 		// use err to get the end of OptionBase and then memcpy into it
-		C.memcpy(&byte(&option.err) + sizeof(IError), data, size)
+		vmemcpy(&byte(&option.err) + sizeof(IError), data, size)
 	}
 }
 
@@ -87,17 +87,3 @@ pub fn (e &Error) free() {
 pub fn (n &None__) free() {
 	unsafe { n.msg.free() }
 }
-
-[typedef]
-struct C.IError {
-	_object voidptr
-}
-
-[unsafe]
-pub fn (ie &IError) free() {
-	unsafe {
-		ie.msg.free()
-		cie := &C.IError(ie)
-		free(cie._object)
-	}
-}
diff --git a/vlib/builtin/rune.v b/vlib/builtin/rune.v
index f756452696..0f78a11412 100644
--- a/vlib/builtin/rune.v
+++ b/vlib/builtin/rune.v
@@ -55,7 +55,7 @@ pub fn (b []byte) clone() []byte {
 pub fn (b []byte) bytestr() string {
 	unsafe {
 		buf := malloc_noscan(b.len + 1)
-		C.memcpy(buf, b.data, b.len)
+		vmemcpy(buf, b.data, b.len)
 		buf[b.len] = 0
 		return tos(buf, b.len)
 	}
diff --git a/vlib/builtin/sorted_map.v b/vlib/builtin/sorted_map.v
index 2567a3cca4..0f31424a45 100644
--- a/vlib/builtin/sorted_map.v
+++ b/vlib/builtin/sorted_map.v
@@ -80,7 +80,7 @@ fn (mut m SortedMap) set(key string, value voidptr) {
 			parent.split_child(child_index, mut node)
 			if key == parent.keys[child_index] {
 				unsafe {
-					C.memcpy(parent.values[child_index], value, m.value_bytes)
+					vmemcpy(parent.values[child_index], value, m.value_bytes)
 				}
 				return
 			}
@@ -96,7 +96,7 @@ fn (mut m SortedMap) set(key string, value voidptr) {
 		}
 		if i != node.len && key == node.keys[i] {
 			unsafe {
-				C.memcpy(node.values[i], value, m.value_bytes)
+				vmemcpy(node.values[i], value, m.value_bytes)
 			}
 			return
 		}
@@ -110,7 +110,7 @@ fn (mut m SortedMap) set(key string, value voidptr) {
 			node.keys[j + 1] = key
 			unsafe {
 				node.values[j + 1] = malloc(m.value_bytes)
-				C.memcpy(node.values[j + 1], value, m.value_bytes)
+				vmemcpy(node.values[j + 1], value, m.value_bytes)
 			}
 			node.len++
 			m.len++
@@ -169,7 +169,7 @@ fn (m SortedMap) get(key string, out voidptr) bool {
 		}
 		if i != -1 && key == node.keys[i] {
 			unsafe {
-				C.memcpy(out, node.values[i], m.value_bytes)
+				vmemcpy(out, node.values[i], m.value_bytes)
 			}
 			return true
 		}
diff --git a/vlib/builtin/string.v b/vlib/builtin/string.v
index 5e9edd57ee..1b56a4e24f 100644
--- a/vlib/builtin/string.v
+++ b/vlib/builtin/string.v
@@ -55,12 +55,6 @@ mut:
 	is_lit int
 }
 
-// vstrlen returns the V length of the C string `s` (0 terminator is not counted).
-[unsafe]
-pub fn vstrlen(s &byte) int {
-	return unsafe { C.strlen(&char(s)) }
-}
-
 pub fn (s string) runes() []rune {
 	mut runes := []rune{cap: s.len}
 	for i := 0; i < s.len; i++ {
@@ -118,7 +112,7 @@ pub fn tos3(s &char) string {
 	}
 	return string{
 		str: &byte(s)
-		len: unsafe { C.strlen(s) }
+		len: unsafe { vstrlen_char(s) }
 	}
 }
 
@@ -147,7 +141,7 @@ pub fn tos5(s &char) string {
 pub fn (bp &byte) vstring() string {
 	return string{
 		str: unsafe { bp }
-		len: unsafe { C.strlen(&char(bp)) }
+		len: unsafe { vstrlen(bp) }
 	}
 }
 
@@ -168,7 +162,7 @@ pub fn (bp &byte) vstring_with_len(len int) string {
 pub fn (cp &char) vstring() string {
 	return string{
 		str: &byte(cp)
-		len: unsafe { C.strlen(cp) }
+		len: unsafe { vstrlen_char(cp) }
 		is_lit: 0
 	}
 }
@@ -195,7 +189,7 @@ pub fn (cp &char) vstring_with_len(len int) string {
 pub fn (bp &byte) vstring_literal() string {
 	return string{
 		str: unsafe { bp }
-		len: unsafe { C.strlen(&char(bp)) }
+		len: unsafe { vstrlen(bp) }
 		is_lit: 1
 	}
 }
@@ -218,7 +212,7 @@ pub fn (bp &byte) vstring_literal_with_len(len int) string {
 pub fn (cp &char) vstring_literal() string {
 	return string{
 		str: &byte(cp)
-		len: unsafe { C.strlen(cp) }
+		len: unsafe { vstrlen_char(cp) }
 		is_lit: 1
 	}
 }
@@ -251,7 +245,7 @@ pub fn (a string) clone() string {
 		len: a.len
 	}
 	unsafe {
-		C.memcpy(b.str, a.str, a.len)
+		vmemcpy(b.str, a.str, a.len)
 		b.str[a.len] = 0
 	}
 	return b
@@ -453,13 +447,11 @@ pub fn (s string) i16() i16 {
 
 // f32 returns the value of the string as f32 `'1.0'.f32() == f32(1)`.
 pub fn (s string) f32() f32 {
-	// return C.atof(&char(s.str))
 	return f32(strconv.atof64(s))
 }
 
 // f64 returns the value of the string as f64 `'1.0'.f64() == f64(1)`.
 pub fn (s string) f64() f64 {
-	// return C.atof(&char(s.str))
 	return strconv.atof64(s)
 }
 
@@ -494,7 +486,7 @@ fn (s string) == (a string) bool {
 		}
 	}
 	unsafe {
-		return C.memcmp(s.str, a.str, a.len) == 0
+		return vmemcmp(s.str, a.str, a.len) == 0
 	}
 }
 
@@ -1411,13 +1403,13 @@ pub fn (a []string) join(sep string) string {
 	mut idx := 0
 	for i, val in a {
 		unsafe {
-			C.memcpy(res.str + idx, val.str, val.len)
+			vmemcpy(res.str + idx, val.str, val.len)
 			idx += val.len
 		}
 		// Add sep if it's not last
 		if i != a.len - 1 {
 			unsafe {
-				C.memcpy(res.str + idx, sep.str, sep.len)
+				vmemcpy(res.str + idx, sep.str, sep.len)
 				idx += sep.len
 			}
 		}
@@ -1482,7 +1474,7 @@ pub fn (s string) bytes() []byte {
 		return []
 	}
 	mut buf := []byte{len: s.len}
-	unsafe { C.memcpy(buf.data, s.str, s.len) }
+	unsafe { vmemcpy(buf.data, s.str, s.len) }
 	return buf
 }
 
diff --git a/vlib/builtin/string_charptr_byteptr_helpers.v b/vlib/builtin/string_charptr_byteptr_helpers.v
index e738ee2111..5b81b392ce 100644
--- a/vlib/builtin/string_charptr_byteptr_helpers.v
+++ b/vlib/builtin/string_charptr_byteptr_helpers.v
@@ -1,6 +1,6 @@
 module builtin
 
-// NB: this file will be removed soon 
+// NB: this file will be removed soon
 
 // byteptr.vbytes() - makes a V []byte structure from a C style memory buffer. NB: the data is reused, NOT copied!
 [unsafe]
@@ -15,7 +15,7 @@ pub fn (data byteptr) vbytes(len int) []byte {
 pub fn (bp byteptr) vstring() string {
 	return string{
 		str: bp
-		len: unsafe { C.strlen(&char(bp)) }
+		len: unsafe { vstrlen(bp) }
 	}
 }
 
@@ -36,7 +36,7 @@ pub fn (bp byteptr) vstring_with_len(len int) string {
 pub fn (cp charptr) vstring() string {
 	return string{
 		str: byteptr(cp)
-		len: unsafe { C.strlen(&char(cp)) }
+		len: unsafe { vstrlen_char(cp) }
 		is_lit: 0
 	}
 }
@@ -63,7 +63,7 @@ pub fn (cp charptr) vstring_with_len(len int) string {
 pub fn (bp byteptr) vstring_literal() string {
 	return string{
 		str: bp
-		len: unsafe { C.strlen(&char(bp)) }
+		len: unsafe { vstrlen(bp) }
 		is_lit: 1
 	}
 }
@@ -86,7 +86,7 @@ pub fn (bp byteptr) vstring_literal_with_len(len int) string {
 pub fn (cp charptr) vstring_literal() string {
 	return string{
 		str: byteptr(cp)
-		len: unsafe { C.strlen(&char(cp)) }
+		len: unsafe { vstrlen_char(cp) }
 		is_lit: 1
 	}
 }
diff --git a/vlib/v/pref/should_compile.v b/vlib/v/pref/should_compile.v
index 5f69fa4fe6..6eec8d0ad3 100644
--- a/vlib/v/pref/should_compile.v
+++ b/vlib/v/pref/should_compile.v
@@ -36,9 +36,14 @@ pub fn (prefs &Preferences) should_compile_filtered_files(dir string, files_ []s
 			}
 			mut allowed := false
 			for cdefine in prefs.compile_defines {
-				file_postfix := '_d_${cdefine}.v'
-				if file.ends_with(file_postfix) {
-					allowed = true
+				file_postfixes := ['_d_${cdefine}.v', '_d_${cdefine}.c.v']
+				for file_postfix in file_postfixes {
+					if file.ends_with(file_postfix) {
+						allowed = true
+						break
+					}
+				}
+				if allowed {
 					break
 				}
 			}
@@ -49,9 +54,14 @@ pub fn (prefs &Preferences) should_compile_filtered_files(dir string, files_ []s
 		if file.contains('_notd_') {
 			mut allowed := true
 			for cdefine in prefs.compile_defines {
-				file_postfix := '_notd_${cdefine}.v'
-				if file.ends_with(file_postfix) {
-					allowed = false
+				file_postfixes := ['_notd_${cdefine}.v', '_notd_${cdefine}.c.v']
+				for file_postfix in file_postfixes {
+					if file.ends_with(file_postfix) {
+						allowed = false
+						break
+					}
+				}
+				if !allowed {
 					break
 				}
 			}
@@ -142,27 +152,28 @@ pub fn (prefs &Preferences) should_compile_c(file string) bool {
 	if prefs.backend != .native && file.ends_with('_native.v') {
 		return false
 	}
+	if prefs.os == .windows && (file.ends_with('_nix.c.v') || file.ends_with('_nix.v')) {
+		return false
+	}
 	if prefs.os != .windows && (file.ends_with('_windows.c.v') || file.ends_with('_windows.v')) {
 		return false
 	}
+	//
 	if prefs.os != .linux && (file.ends_with('_linux.c.v') || file.ends_with('_linux.v')) {
 		return false
 	}
+	//
 	if prefs.os != .macos && (file.ends_with('_darwin.c.v') || file.ends_with('_darwin.v')) {
 		return false
 	}
-	if (file.ends_with('_ios.c.v') || file.ends_with('_ios.v')) && prefs.os != .ios {
-		return false
-	}
-	if file.ends_with('_nix.c.v') && prefs.os == .windows {
-		return false
-	}
 	if prefs.os != .macos && (file.ends_with('_macos.c.v') || file.ends_with('_macos.v')) {
 		return false
 	}
-	if prefs.os == .windows && file.ends_with('_nix.c.v') {
+	//
+	if prefs.os != .ios && (file.ends_with('_ios.c.v') || file.ends_with('_ios.v')) {
 		return false
 	}
+	//
 	if prefs.os != .android && file.ends_with('_android.c.v') {
 		return false
 	}