diff --git a/Makefile b/Makefile
index 460f7bf..021c2fe 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,7 @@ ntc: $(SOURCES) $(HEADERS)
 ifdef OW
 	wcl386 -ml $(if $(GAS),-DSYNTAX_GAS=1,) $(if $(DEBUG),-DDEBUG=1,) -fe="ntc.exe" -bt=dos -l=dos4g -ml $(if $(DEBUG),,-d0 -os -om -ob -oi -ol -ox) -lr -za99 -i=src $(SOURCES)
 else
-	cc $(if $(GAS),-DSYNTAX_GAS=1,) $(if $(DEBUG),-DDEBUG=1,) -Wall -o ntc -fno-PIE -no-pie -std=gnu11 $(if $(DEBUG),-O0 -g,-Os -s) -fms-extensions -Isrc $(SOURCES)
+	cc $(if $(GAS),-DSYNTAX_GAS=1,) $(if $(DEBUGA),-DDEBUG=1,) -Wall -o ntc -fsanitize=address -fno-PIE -no-pie -std=gnu11 $(if $(DEBUG),-O0 -g,-Os -s) -fms-extensions -Isrc $(SOURCES) -Wno-array-bounds
 endif
 
 install: ntc
diff --git a/src/ast.c b/src/ast.c
index 3c11884..09a0f28 100644
--- a/src/ast.c
+++ b/src/ast.c
@@ -3,6 +3,12 @@
 #include<stdint.h>
 #include<string.h>
 #include<stdlib.h>
+#include<assert.h>
+#include<stdarg.h>
+
+const char *AST_KIND_STR[] = {
+	AST_KINDS(GEN_STRI)
+};
 
 AST *ast_expression_optimize(AST *ast) {
 	return ast;
@@ -19,6 +25,8 @@ int ast_expression_equal(AST *a, AST *b) {
 		return a->exprUnOp.operator == b->exprUnOp.operator && ast_expression_equal(a->exprUnOp.operand, b->exprUnOp.operand);
 	} else if(a->nodeKind == AST_EXPR_BINARY_OP) {
 		return a->exprBinOp.operator == b->exprBinOp.operator && ast_expression_equal(a->exprBinOp.operands[0], b->exprBinOp.operands[0]) && ast_expression_equal(a->exprBinOp.operands[1], b->exprBinOp.operands[1]);
+	} else if(a->nodeKind == AST_EXPR_STACK_POINTER) {
+		return 1;
 	}
 	
 	return 0;
@@ -28,8 +36,8 @@ int ast_expression_equal(AST *a, AST *b) {
 int ast_stmt_is_after(const AST *chunk, const AST *s1, const AST *s2) {
 	const AST *s = chunk->chunk.statementFirst;
 	
-	while(s) {
-		if(s->nodeKind == AST_STMT_LOOP) {
+	while(1) {
+		if(s && s->nodeKind == AST_STMT_LOOP) {
 			int i = ast_stmt_is_after(s->stmtLoop.body, s1, s2);
 			if(i != -1) {
 				return i;
@@ -43,6 +51,8 @@ int ast_stmt_is_after(const AST *chunk, const AST *s1, const AST *s2) {
 			return 1;
 		}
 		
+		if(!s) break;
+		
 		if(s->nodeKind == AST_STMT_IF) {
 			int i = ast_stmt_is_after(s->stmtIf.then, s1, s2);
 			if(i != -1) {
@@ -54,4 +64,439 @@ int ast_stmt_is_after(const AST *chunk, const AST *s1, const AST *s2) {
 	}
 	
 	return -1;
-}
\ No newline at end of file
+}
+
+/*
+ * This pass is necessary for the purposes of optimization and regalloc.
+ * Because an AST may hold outdated UD-chains, this pass MUST be called
+ * before using the UD-chains to make sure they are valid.
+ * 
+ * Each local var (VTE of kind VARTABLEENTRY_VAR) holds its own UD-chain
+ * that specifies the exact nodes in the AST where:
+ * 1. It is used
+ * 2. The whole statement in which it is used
+ * 3. The definition that *might* be in use
+ * 
+ * Because multiple definitions may be in use (reachable) at the point
+ * of the use, a unique UseDef for each possible definition is appended
+ * to the chain.
+ * 
+ * Reachable definitions are kept track in a ReachingDefs, also held by
+ * each VTE. In the case of a single, simple block of code, we know
+ * exactly one definition (including undefined) can reach each variable,
+ * which would simplify the ReachingDefs structure to a single
+ * definition pointer.
+ * 
+ * Unfortunately, conditional blocks and loops ruin this simplicity.
+ * If you have code like
+ *   x = A
+ *   if B {
+ *     x = C
+ *   }
+ * then afterward two definitions may apply to x.
+ * 
+ * A solution here is to lay ReachingDefs as a graph, with each
+ * ReachingDefs having an optional parent. When we enter a new block of
+ * code, we create an empty ReachingDefs with the previous block as its
+ * parent. Any definitions replace the ones in the deepest
+ * ReachingDefs only.
+ * 
+ * How we exit a block depends on its type. If it is conditional,
+ * the reaching definitions should join the parent (mergedefs).
+ * If the block is a loop, it is even worse. Given
+ *   x = A
+ *   loop {
+ *     use x
+ *     x = B
+ *   }
+ * definitions can apply to uses that come before it!
+ * 
+ * Also, a different case:
+ *   x = A
+ *   loop {
+ *     use x
+ *     y = B
+ *   }
+ * Because, technically, the last use of x is before y = B, y and x may
+ * be assigned the same physical location, corrupting data as a result.
+ * To fix this, fake, "useless" statements are inserted during parsing
+ * that make the AST look as such:
+ *   x = A
+ *   loop {
+ *     use x
+ *     y = B
+ *   }
+ *   x;
+ * Until dead code removal is implemented, this will not be a problem.
+ */
+
+static void rawadduse(VarTableEntry *vte, UseDef *ud) {
+	assert(vte->kind == VARTABLEENTRY_VAR);
+	
+	assert(ud->next == NULL);
+	
+	assert(!!vte->data.var.usedefFirst == !!vte->data.var.usedefLast);
+	
+	if(!vte->data.var.usedefFirst) {
+		vte->data.var.usedefFirst = vte->data.var.usedefLast = ud;
+	} else {
+		vte->data.var.usedefLast->next = ud;
+		vte->data.var.usedefLast = ud;
+	}
+}
+
+static void adduse(VarTableEntry *vte, AST *use, AST *whole) {
+	assert(vte->kind == VARTABLEENTRY_VAR);
+	
+	assert(vte->data.var.reachingDefs != NULL);
+	
+	for(size_t d = 0; d < vte->data.var.reachingDefs->defCount; d++) {
+		UseDef *ud = malloc(sizeof(*ud));
+		ud->def = vte->data.var.reachingDefs->defs[d];
+		ud->use = use;
+		ud->stmt = whole;
+		ud->next = NULL;
+		
+		rawadduse(vte, ud);
+	}
+}
+
+static void overwritedefs(VarTableEntry *vte, AST *def) {
+	assert(vte->kind == VARTABLEENTRY_VAR);
+	
+	if(!vte->data.var.reachingDefs) {
+		vte->data.var.reachingDefs = calloc(1, sizeof(*vte->data.var.reachingDefs));
+	}
+	
+	vte->data.var.reachingDefs->defCount = 1;
+	
+	if(!vte->data.var.reachingDefs->defs) {
+		vte->data.var.reachingDefs->defs = calloc(1, sizeof(*vte->data.var.reachingDefs->defs));
+	}
+	
+	vte->data.var.reachingDefs->defs[0] = def;
+}
+
+static void mergedefs(VarTableEntry *vte) {
+	assert(vte->kind == VARTABLEENTRY_VAR);
+	
+	ReachingDefs *rdefs = vte->data.var.reachingDefs;
+	
+	assert(rdefs != NULL);
+	assert(rdefs->parent != NULL);
+	
+	rdefs->parent->defs = realloc(rdefs->parent->defs, sizeof(*rdefs->parent->defs) * (rdefs->parent->defCount + rdefs->defCount));
+	memcpy(rdefs->parent->defs + rdefs->parent->defCount, rdefs->defs, rdefs->defCount * sizeof(*rdefs->defs));
+	
+	vte->data.var.reachingDefs = rdefs->parent;
+	
+	free(rdefs->defs);
+	free(rdefs);
+}
+
+static void pushdefs(VarTableEntry *vte) {
+	assert(vte->kind == VARTABLEENTRY_VAR);
+	
+	ReachingDefs *rdefs = malloc(sizeof(*rdefs));
+	rdefs->defCount = 0;
+	rdefs->defs = NULL;
+	rdefs->excludeParent = 0;
+	rdefs->parent = vte->data.var.reachingDefs;
+	
+	vte->data.var.reachingDefs = rdefs;
+}
+
+static void pushdefsall(AST *tlc) {
+	for(size_t i = 0; i < tlc->chunk.varCount; i++) {
+		pushdefs(tlc->chunk.vars[i]);
+	}
+}
+
+static void mergedefsall(AST *tlc) {
+	for(size_t i = 0; i < tlc->chunk.varCount; i++) {
+		mergedefs(tlc->chunk.vars[i]);
+	}
+}
+
+static void mergedefsloop(AST *tlc, VarTableEntry *vte, AST *daLoopStmt) {
+	assert(vte->kind == VARTABLEENTRY_VAR);
+	
+	for(size_t d = 0; d < vte->data.var.reachingDefs->defCount; d++) {
+		UseDef *ud = vte->data.var.usedefFirst;
+		
+		while(ud) {
+			if(ast_stmt_is_after(daLoopStmt->stmtLoop.body, NULL, ud->stmt) == 1 && ud->def != vte->data.var.reachingDefs->defs[d]) {
+				UseDef *udnew = calloc(1, sizeof(*udnew));
+				udnew->next = ud->next;
+				ud->next = udnew;
+				
+				udnew->def = vte->data.var.reachingDefs->defs[d];
+				udnew->use = ud->use;
+				udnew->stmt = ud->stmt;
+				
+				if(udnew->next == NULL) {
+					vte->data.var.usedefLast = udnew;
+				}
+			}
+			
+			ud = ud->next;
+		}
+	}
+	
+	mergedefs(vte);
+}
+
+static void mergedefsloopall(AST *tlc, AST *daLoopStmt) {
+	for(size_t i = 0; i < tlc->chunk.varCount; i++) {
+		mergedefsloop(tlc, tlc->chunk.vars[i], daLoopStmt);
+	}
+}
+
+static void ast_usedef_pass(AST *tlc, AST *a, AST *wholestmt) {
+	if(a->nodeKind == AST_CHUNK) {
+		for(AST *s = a->chunk.statementFirst; s; s = s->statement.next) {
+			ast_usedef_pass(tlc, s, s);
+		}
+	} else if(a->nodeKind == AST_STMT_IF) {
+		pushdefsall(tlc);
+		
+		ast_usedef_pass(tlc, a->stmtIf.expression, wholestmt);
+		ast_usedef_pass(tlc, a->stmtIf.then, wholestmt);
+		
+		mergedefsall(tlc);
+	} else if(a->nodeKind == AST_STMT_LOOP) {
+		pushdefsall(tlc);
+		
+		ast_usedef_pass(tlc, a->stmtLoop.body, wholestmt);
+		
+		mergedefsloopall(tlc, a);
+	} else if(a->nodeKind == AST_STMT_ASSIGN) {
+		if(a->stmtAssign.what->nodeKind == AST_EXPR_VAR && a->stmtAssign.what->exprVar.thing->kind == VARTABLEENTRY_VAR) {
+			overwritedefs(a->stmtAssign.what->exprVar.thing, a);
+		}
+		
+		ast_usedef_pass(tlc, a->stmtAssign.what, wholestmt);
+		
+		if(a->stmtAssign.to) {
+			ast_usedef_pass(tlc, a->stmtAssign.to, wholestmt);
+		}
+	} else if(a->nodeKind == AST_STMT_EXPR) {
+		ast_usedef_pass(tlc, a->stmtExpr.expr, wholestmt);
+	} else if(a->nodeKind == AST_EXPR_VAR) {
+		if(a->exprVar.thing->kind == VARTABLEENTRY_VAR) {
+			adduse(a->exprVar.thing, a, wholestmt);
+		}
+	} else if(a->nodeKind == AST_EXPR_BINARY_OP) {
+		ast_usedef_pass(tlc, a->exprBinOp.operands[0], wholestmt);
+		ast_usedef_pass(tlc, a->exprBinOp.operands[1], wholestmt);
+	} else if(a->nodeKind == AST_EXPR_UNARY_OP) {
+		ast_usedef_pass(tlc, a->exprUnOp.operand, wholestmt);
+	} else if(a->nodeKind == AST_EXPR_CALL) {
+		ast_usedef_pass(tlc, a->exprCall.what, wholestmt);
+		
+		for(size_t p = 0; p < a->exprCall.what->expression.type->function.argCount; p++) {
+			ast_usedef_pass(tlc, a->exprCall.args[p], wholestmt);
+		}
+	} else if(a->nodeKind == AST_EXPR_PRIMITIVE) {
+	} else if(a->nodeKind == AST_EXPR_STRING_LITERAL) {
+	} else if(a->nodeKind == AST_EXPR_CAST) {
+		ast_usedef_pass(tlc, a->exprCast.what, wholestmt);
+	} else if(a->nodeKind == AST_EXPR_STACK_POINTER) {
+	} else if(a->nodeKind == AST_STMT_BREAK) {
+	} else if(a->nodeKind == AST_STMT_CONTINUE) {
+	} else if(a->nodeKind == AST_STMT_EXT_ALIGN) {
+	} else if(a->nodeKind == AST_STMT_EXT_ORG) {
+	} else if(a->nodeKind == AST_STMT_EXT_SECTION) {
+	} else if(a->nodeKind == AST_STMT_DECL) {
+		assert(a->stmtDecl.thing->kind != VARTABLEENTRY_VAR || a->stmtDecl.expression);
+	} else {
+		abort();
+	}
+}
+
+void ast_usedef_reset(AST *chu) {
+	for(size_t i = 0; i < chu->chunk.varCount; i++) {
+		VarTableEntry *vte = chu->chunk.vars[i];
+		
+		assert(vte->kind == VARTABLEENTRY_VAR);
+		
+		vte->data.var.reachingDefs = NULL;
+		vte->data.var.usedefFirst = NULL;
+		vte->data.var.usedefLast = NULL;
+	}
+	
+	pushdefsall(chu);
+	
+	return ast_usedef_pass(chu, chu, NULL);
+}
+
+static char *cat(char *a, const char *b) {
+	if(!a) {
+		return strdup(b);
+	}
+	
+	a = realloc(a, strlen(a) + strlen(b) + 1);
+	strcpy(a + strlen(a), b);
+	return a;
+}
+
+__attribute__((format(printf, 1, 2))) static char *malp(const char *fmt, ...) {
+	va_list v1, v2;
+	va_start(v1, fmt);
+	va_copy(v2, v1);
+	size_t len = vsnprintf(NULL, 0, fmt, v1);
+	va_end(v1);
+	va_start(v2, fmt);
+	char *str = malloc(len + 1);
+	vsnprintf(str, len + 1, fmt, v2);
+	str[len] = 0;
+	va_end(v2);
+	return str;
+}
+
+char *type_to_string(Type *t) {
+	if(t->type == TYPE_TYPE_PRIMITIVE) {
+		char ret[16] = {};
+		int i = 0;
+		
+		ret[i++] = t->primitive.isFloat ? 'f' : (t->primitive.isUnsigned ? 'u' : 'i');
+		snprintf(ret + i, sizeof(ret) - i, "%i", t->primitive.width);
+		
+		return strdup(ret);
+	} else if(t->type == TYPE_TYPE_POINTER) {
+		char *c = type_to_string(t->pointer.of);
+		char *r = malp("%s*", c);
+		free(c);
+		return r;
+	}
+	
+	return strdup("@unimp");
+}
+
+static char *ast_dumpe(AST *e) {
+	if(e->nodeKind == AST_EXPR_PRIMITIVE) {
+		return malp("%i", e->exprPrim.val);
+	} else if(e->nodeKind == AST_EXPR_VAR) {
+		VarTableEntry *vte = e->exprVar.thing;
+		
+		if(vte->kind == VARTABLEENTRY_VAR) {
+			return strdup(vte->data.var.name);
+		} else if(vte->kind == VARTABLEENTRY_SYMBOL) {
+			return strdup(vte->data.symbol.name);
+		} else abort();
+	} else if(e->nodeKind == AST_EXPR_UNARY_OP) {
+		const char *op;
+		switch(e->exprUnOp.operator) {
+		case UNOP_REF:
+			op = "&";
+			break;
+		case UNOP_DEREF:
+			op = "*";
+			break;
+		case UNOP_BITWISE_NOT:
+			op = "~";
+			break;
+		case UNOP_NEGATE:
+			op = "-";
+			break;
+		}
+		char *c = ast_dumpe(e->exprUnOp.operand);
+		char *r = malp("%s%s", op, c);
+		free(c);
+		return r;
+	} else if(e->nodeKind == AST_EXPR_BINARY_OP) {
+		char *a = ast_dumpe(e->exprBinOp.operands[0]);
+		char *b = ast_dumpe(e->exprBinOp.operands[1]);
+		const char *op;
+		switch(e->exprBinOp.operator) {
+		case BINOP_ADD:
+			op = "+";
+			break;
+		case BINOP_SUB:
+			op = "-";
+			break;
+		case BINOP_MUL:
+			op = "*";
+			break;
+		case BINOP_DIV:
+			op = "/";
+			break;
+		case BINOP_BITWISE_AND:
+			op = "&";
+			break;
+		case BINOP_BITWISE_OR:
+			op = "|";
+			break;
+		case BINOP_BITWISE_XOR:
+			op = "^";
+			break;
+		case BINOP_EQUAL:
+			op = "==";
+			break;
+		default:
+			abort();
+		}
+		char *r = malp("(%s %s %s)", a, op, b);
+		free(a);
+		free(b);
+		return r;
+	}
+	
+	return malp("@unimp:%s", AST_KIND_STR[e->nodeKind]);
+}
+
+static char *ast_dumps(AST *s) {
+	if(s->nodeKind == AST_STMT_DECL) {
+		VarTableEntry *vte = s->stmtDecl.thing;
+		
+		if(vte->kind == VARTABLEENTRY_SYMBOL) {
+			char *t = type_to_string(vte->type);
+			char *e = s->stmtDecl.expression ? ast_dumpe(s->stmtDecl.expression) : strdup("");
+			char *r = malp("%s%s %s: %s;\n", vte->data.symbol.isExternal ? "external " : "", t, vte->data.symbol.name, e);
+			free(t);
+			free(e);
+			return r;
+		}
+	} else if(s->nodeKind == AST_STMT_ASSIGN) {
+		char *a = ast_dumpe(s->stmtAssign.what);
+		char *b = ast_dumpe(s->stmtAssign.to);
+		char *r = malp("%s = %s;\n", a, b);
+		free(a);
+		free(b);
+		return r;
+	}
+	
+	return malp("@unimp:%s\n", AST_KIND_STR[s->nodeKind]);
+}
+
+char *ast_dump(AST *tlc) {
+	AST *stmt = tlc->chunk.statementFirst;
+	
+	char *ret = NULL;
+	
+	#define CAT(s) do { char *b = s; ret = cat(ret, (b)); free(b); } while(0)
+	
+	while(stmt) {
+		CAT(ast_dumps(stmt));
+		
+		stmt = stmt->statement.next;
+	}
+	
+	return ret;
+}
+
+static void *memdup(void *a, size_t len) {
+	void *r = malloc(len);
+	memcpy(r, a, len);
+	return r;
+}
+
+AST *ast_deep_copy(AST *src) {
+	if(src->nodeKind == AST_EXPR_VAR) {
+		return memdup(src, sizeof(ASTExprVar));
+	} else if(src->nodeKind == AST_EXPR_PRIMITIVE) {
+		return memdup(src, sizeof(ASTExprPrimitive));
+	}
+	
+	abort();
+}
diff --git a/src/ast.h b/src/ast.h
index 52b413e..8749f38 100644
--- a/src/ast.h
+++ b/src/ast.h
@@ -18,29 +18,35 @@
 #define ENUMPAK
 #endif
 
-typedef enum ENUMPAK {
-	AST_CHUNK,
-	AST_STMT_DECL,
-	AST_TYPE_IDENTIFIER,
-	AST_EXPR_PRIMITIVE,
-	AST_STMT_IF,
-	AST_EXPR_BINARY_OP,
-	AST_EXPR_VAR,
-	AST_TYPE_POINTER,
-	AST_EXPR_UNARY_OP,
-	AST_STMT_LOOP,
-	AST_STMT_BREAK,
-	AST_STMT_CONTINUE,
-	AST_EXPR_CALL,
-	AST_STMT_EXPR,
-	AST_STMT_ASSIGN,
-	AST_STMT_EXT_ALIGN,
-	AST_EXPR_STRING_LITERAL,
-	AST_EXPR_CAST,
-	AST_EXPR_ARRAY,
-	AST_STMT_EXT_ORG,
-	AST_STMT_EXT_SECTION,
-} ASTKind;
+#define GEN_ENUM(x) x,
+#define GEN_STRI(x) #x,
+
+#define AST_KINDS(K)			\
+	K(AST_CHUNK)				\
+	K(AST_STMT_DECL)			\
+	K(AST_TYPE_IDENTIFIER)		\
+	K(AST_EXPR_PRIMITIVE)		\
+	K(AST_STMT_IF)				\
+	K(AST_EXPR_BINARY_OP)		\
+	K(AST_EXPR_VAR)				\
+	K(AST_EXPR_STACK_POINTER)	\
+	K(AST_TYPE_POINTER)			\
+	K(AST_EXPR_UNARY_OP)		\
+	K(AST_STMT_LOOP)			\
+	K(AST_STMT_BREAK)			\
+	K(AST_STMT_CONTINUE)		\
+	K(AST_EXPR_CALL)			\
+	K(AST_STMT_EXPR)			\
+	K(AST_STMT_ASSIGN)			\
+	K(AST_STMT_EXT_ALIGN)		\
+	K(AST_EXPR_STRING_LITERAL)	\
+	K(AST_EXPR_CAST)			\
+	K(AST_EXPR_ARRAY)			\
+	K(AST_STMT_EXT_ORG)			\
+	K(AST_STMT_EXT_SECTION)
+
+typedef enum ENUMPAK { AST_KINDS(GEN_ENUM) } ASTKind;
+extern const char *AST_KIND_STR[];
 
 typedef enum ENUMPAK {
 	BINOP_ADD = 0,
@@ -126,6 +132,10 @@ typedef struct {
 	char *data;
 } ASTExprStringLiteral;
 
+typedef struct {
+	ASTExpr;
+} ASTExprStackPointer;
+
 typedef struct {
 	ASTKind nodeKind;
 	
@@ -167,6 +177,8 @@ typedef struct {
 	
 	union AST *statementFirst;
 	union AST *statementLast;
+	
+	size_t stackReservation;
 } ASTChunk;
 
 typedef struct {
@@ -270,4 +282,10 @@ int ast_expression_equal(AST*, AST*);
 
 int ast_stmt_is_after(const AST *chunk, const AST *s1, const AST *s2);
 
+void ast_usedef_reset(AST *chu);
+
+char *ast_dump(AST *tlc);
+
+AST *ast_deep_copy(AST*);
+
 #endif
diff --git a/src/cg.c b/src/cg.c
index 83c91bc..b35a1e5 100644
--- a/src/cg.c
+++ b/src/cg.c
@@ -8,7 +8,7 @@
 #include"x86.h"
 
 #define REGS 4
-static const char *regs[REGS][3] = {{"al", "ax", "eax"}, {"bl", "bx", "ebx"}, {"cl", "cx", "ecx"}, {"dl", "dx", "edx"}};
+static const char *regs[][3] = {{"al", "ax", "eax"}, {"bl", "bx", "ebx"}, {"cl", "cx", "ecx"}, {"dl", "dx", "edx"}, {"fu", "fk", "fck"}};
 
 static const char *BINOP_SIMPLE_INSTRS[] = {[BINOP_ADD] = "add", [BINOP_SUB] = "sub", [BINOP_BITWISE_AND] = "and", [BINOP_BITWISE_OR] = "or", [BINOP_BITWISE_XOR] = "xor"};
 
@@ -94,7 +94,9 @@ static const char *xop_sz(AST *e, int sz) {
 	
 	char *ret = bufs[bufidx];
 	
-	if(e->nodeKind == AST_EXPR_VAR) {
+	if(e->nodeKind == AST_EXPR_STACK_POINTER) {
+		snprintf(ret, XOPBUFSZ, "esp");
+	} else if(e->nodeKind == AST_EXPR_VAR) {
 		VarTableEntry *v = e->exprVar.thing;
 		
 		if(v->kind == VARTABLEENTRY_VAR) {
@@ -204,6 +206,10 @@ void cg_chunk(AST *a) {
 					static const char *instrs[] = {"inc", "dec"};
 					printf("%s %s %s\n", instrs[s->stmtAssign.to->exprBinOp.operator == BINOP_SUB], specexpr(s->stmtAssign.what), xop(s->stmtAssign.what));
 					
+				} else if(s->stmtAssign.to->nodeKind == AST_EXPR_BINARY_OP && ast_expression_equal(s->stmtAssign.what, s->stmtAssign.to->exprBinOp.operands[0]) && s->stmtAssign.to->exprBinOp.operator < BINOP_SIMPLES) {
+					
+					printf("%s %s, %s\n", BINOP_SIMPLE_INSTRS[s->stmtAssign.to->exprBinOp.operator], xop(s->stmtAssign.what), xop(s->stmtAssign.to->exprBinOp.operands[1]));
+					
 				} else if(s->stmtAssign.what->nodeKind == AST_EXPR_VAR && s->stmtAssign.to->nodeKind == AST_EXPR_BINARY_OP && s->stmtAssign.to->exprBinOp.operator == BINOP_ADD && s->stmtAssign.to->exprBinOp.operands[0]->nodeKind == AST_EXPR_VAR && s->stmtAssign.to->exprBinOp.operands[1]->nodeKind == AST_EXPR_VAR && s->stmtAssign.to->exprBinOp.operands[0]->exprVar.thing->kind == VARTABLEENTRY_VAR && s->stmtAssign.to->exprBinOp.operands[1]->exprVar.thing->kind == VARTABLEENTRY_VAR) {
 					
 					printf("lea %s, [%s + %s]\n",
@@ -228,6 +234,10 @@ void cg_chunk(AST *a) {
 				} else if(is_xop(s->stmtAssign.what) != NULL && s->stmtAssign.to->nodeKind == AST_EXPR_UNARY_OP && s->stmtAssign.to->exprUnOp.operator == UNOP_NEGATE && ast_expression_equal(s->stmtAssign.what, s->stmtAssign.to->exprUnOp.operand)) {
 					
 					printf("neg %s\n", xop(s->stmtAssign.what));
+				
+				} else if(is_xop(s->stmtAssign.what) && s->stmtAssign.to->nodeKind == AST_EXPR_CAST) {
+					
+					printf("movzx %s, %s\n", xop(s->stmtAssign.what), xop(s->stmtAssign.to->exprCast.what));
 					
 				} else {
 				
@@ -316,20 +326,91 @@ void cg_chunk(AST *a) {
 	}
 }
 
+static void spill_pass(AST *tlc, AST *a, VarTableEntry *vte) {
+	if(a->nodeKind == AST_CHUNK) {
+		for(AST *s = a->chunk.statementFirst; s; s = s->statement.next) {
+			ast_usedef_pass(tlc, s, s);
+		}
+	} else if(a->nodeKind == AST_STMT_IF) {
+		pushdefsall(tlc);
+		
+		ast_usedef_pass(tlc, a->stmtIf.expression, wholestmt);
+		ast_usedef_pass(tlc, a->stmtIf.then, wholestmt);
+		
+		mergedefsall(tlc);
+	} else if(a->nodeKind == AST_STMT_LOOP) {
+		pushdefsall(tlc);
+		
+		ast_usedef_pass(tlc, a->stmtLoop.body, wholestmt);
+		
+		mergedefsloopall(tlc, a);
+	} else if(a->nodeKind == AST_STMT_ASSIGN) {
+		if(a->stmtAssign.what->nodeKind == AST_EXPR_VAR && a->stmtAssign.what->exprVar.thing->kind == VARTABLEENTRY_VAR) {
+			overwritedefs(a->stmtAssign.what->exprVar.thing, a);
+		}
+		
+		ast_usedef_pass(tlc, a->stmtAssign.what, wholestmt);
+		
+		if(a->stmtAssign.to) {
+			ast_usedef_pass(tlc, a->stmtAssign.to, wholestmt);
+		}
+	} else if(a->nodeKind == AST_STMT_EXPR) {
+		ast_usedef_pass(tlc, a->stmtExpr.expr, wholestmt);
+	} else if(a->nodeKind == AST_EXPR_VAR) {
+		if(a->exprVar.thing->kind == VARTABLEENTRY_VAR) {
+			adduse(a->exprVar.thing, a, wholestmt);
+		}
+	} else if(a->nodeKind == AST_EXPR_BINARY_OP) {
+		ast_usedef_pass(tlc, a->exprBinOp.operands[0], wholestmt);
+		ast_usedef_pass(tlc, a->exprBinOp.operands[1], wholestmt);
+	} else if(a->nodeKind == AST_EXPR_UNARY_OP) {
+		ast_usedef_pass(tlc, a->exprUnOp.operand, wholestmt);
+	} else if(a->nodeKind == AST_EXPR_CALL) {
+		ast_usedef_pass(tlc, a->exprCall.what, wholestmt);
+		
+		for(size_t p = 0; p < a->exprCall.what->expression.type->function.argCount; p++) {
+			ast_usedef_pass(tlc, a->exprCall.args[p], wholestmt);
+		}
+	} else if(a->nodeKind == AST_EXPR_PRIMITIVE) {
+	} else if(a->nodeKind == AST_EXPR_STRING_LITERAL) {
+	} else if(a->nodeKind == AST_EXPR_CAST) {
+		ast_usedef_pass(tlc, a->exprCast.what, wholestmt);
+	} else if(a->nodeKind == AST_EXPR_STACK_POINTER) {
+	} else if(a->nodeKind == AST_STMT_BREAK) {
+	} else if(a->nodeKind == AST_STMT_CONTINUE) {
+	} else if(a->nodeKind == AST_STMT_EXT_ALIGN) {
+	} else if(a->nodeKind == AST_STMT_EXT_ORG) {
+	} else if(a->nodeKind == AST_STMT_EXT_SECTION) {
+	} else if(a->nodeKind == AST_STMT_DECL) {
+		assert(a->stmtDecl.thing->kind != VARTABLEENTRY_VAR || a->stmtDecl.expression);
+	} else {
+		abort();
+	}
+}
+
 /* Welsh-Powell graph coloring */
 static int comparator(const void *A, const void *B) {
 	VarTableEntry *const *a = A;
 	VarTableEntry *const *b = B;
 	return ((*a)->data.var.degree * (*a)->data.var.priority) - ((*b)->data.var.degree * (*b)->data.var.priority);
 }
-void cg_go(AST *a) {
+int cg_go(AST *a) {
 	typedef VarTableEntry *Adjacency[2];
 	
+	ast_usedef_reset(a);
+	
 	size_t adjCount = 0;
 	Adjacency *adjs = malloc(sizeof(*adjs) * adjCount);
 	
 	VarTableEntry **vars = a->chunk.vars;
 	
+	for(size_t vi = 0; vi < a->chunk.varCount; vi++) {
+		vars[vi]->data.var.priority = 1;
+		vars[vi]->data.var.color = 0;
+		vars[vi]->data.var.degree = 0;
+		vars[vi]->data.var.markedForSpill = 0;
+	}
+	
 	for(size_t v1i = 0; v1i < a->chunk.varCount; v1i++) {
 		for(size_t v2i = 0; v2i < a->chunk.varCount; v2i++) {
 			if(v1i == v2i) continue;
@@ -372,6 +453,8 @@ cont:;
 	
 	qsort(vars, a->chunk.varCount, sizeof(*vars), comparator);
 	
+	int lastColor = 0;
+	
 	/* Welsh plow my ass */
 	for(int v = 0; v < a->chunk.varCount; v++) {
 		for(int c = 0;; c++) {
@@ -384,6 +467,9 @@ cont:;
 			}
 		
 			vars[v]->data.var.color = c;
+			
+			lastColor = lastColor < c ? c : lastColor;
+			
 			break;
 
 nextColor:;
@@ -392,7 +478,16 @@ nextColor:;
 	
 	free(adjs);
 	
+	if(lastColor >= 4) {
+		// Spill node with highest degree
+		
+		spill_pass(a, a, vars[a->chunk.varCount - 1]);
+		
+		return 0;
+	}
+	
 	cg_chunk(a);
 	
-	free(vars);
+	return 1;
 }
+
diff --git a/src/cg.h b/src/cg.h
index 29e551c..bc74619 100644
--- a/src/cg.h
+++ b/src/cg.h
@@ -3,6 +3,6 @@
 
 #include"ast.h"
 
-void cg_go(union AST*);
+int cg_go(union AST*);
 
 #endif
diff --git a/src/dumberdowner.c b/src/dumberdowner.c
index 924ebc9..d3a3166 100644
--- a/src/dumberdowner.c
+++ b/src/dumberdowner.c
@@ -8,87 +8,11 @@
 // Complex expressions are to be "broken down" into simpler ones until the AST
 // can be trivially translated to the target architecture.
 //
-// This pass, along with CG is strictly dependent on x86 and will fail for
-// any other architecture.
+// This file along with CG is strictly for IA-32 and will fail for other
+// architecture.
 
 #include"x86.h"
 
-static void varify_change_usedefs(AST *e, AST *oldStmt, AST *newStmt) {
-	if(e->nodeKind == AST_EXPR_VAR) {
-		if(e->exprVar.thing->kind != VARTABLEENTRY_VAR) {
-			return;
-		}
-		
-		UseDef *swapWithPrev = NULL;
-		UseDef *swapWith = NULL;
-		
-		UseDef *udPrev = NULL;
-		UseDef *ud = e->exprVar.thing->data.var.usedefFirst;
-		while(ud && ud->use != e) {
-			if(ud->stmt == oldStmt && !swapWith) {
-				swapWithPrev = udPrev;
-				swapWith = ud;
-			}
-			
-			udPrev = ud;
-			ud = ud->next;
-		}
-		
-		if(ud) {
-			assert(ud->stmt == oldStmt);
-			ud->stmt = newStmt;
-			
-			// We must make sure all newStmt usedefs are before the oldStmt ones, so swap
-			if(swapWith) {
-				assert(!!swapWithPrev + !!udPrev != 0);
-				
-				if(swapWithPrev) {
-					swapWithPrev->next = ud;
-				} else {
-					e->exprVar.thing->data.var.usedefFirst = ud;
-				}
-				
-				if(udPrev) {
-					udPrev->next = swapWith;
-				} else {
-					e->exprVar.thing->data.var.usedefFirst = swapWith;
-				}
-				
-				UseDef *temp = ud->next;
-				ud->next = swapWith->next;
-				swapWith->next = temp;
-				
-				assert(!!ud->next + !!swapWith->next != 0);
-				if(!swapWith->next) {
-					e->exprVar.thing->data.var.usedefLast = swapWith;
-				}
-				if(!ud->next) {
-					e->exprVar.thing->data.var.usedefLast = ud;
-				}
-			}
-		}
-	} else if(e->nodeKind == AST_EXPR_BINARY_OP) {
-		varify_change_usedefs(e->exprBinOp.operands[0], oldStmt, newStmt);
-		varify_change_usedefs(e->exprBinOp.operands[1], oldStmt, newStmt);
-	} else if(e->nodeKind == AST_EXPR_UNARY_OP) {
-		varify_change_usedefs(e->exprUnOp.operand, oldStmt, newStmt);
-	} else if(e->nodeKind == AST_EXPR_CALL) {
-		varify_change_usedefs(e->exprCall.what, oldStmt, newStmt);
-		
-		int argCount = e->exprCall.what->expression.type->function.argCount;
-		for(int i = 0; i < argCount; i++) {
-			varify_change_usedefs(e->exprCall.args[i], oldStmt, newStmt);
-		}
-	} else if(e->nodeKind == AST_EXPR_ARRAY) {
-		int sz = e->exprArray.type->array.length;
-		for(int i = 0; i < sz; i++) {
-			varify_change_usedefs(e->exprArray.items[i], oldStmt, newStmt);
-		}
-	} else if(e->nodeKind == AST_EXPR_CAST) {
-		varify_change_usedefs(e->exprCast.what, oldStmt, newStmt);
-	}
-}
-
 /* Split away complex expression into a new local variable */
 static AST *varify(AST *tlc, AST *chunk, AST *stmtPrev, AST *stmt, AST *e) {
 	VarTableEntry *vte = malloc(sizeof(*vte));
@@ -125,28 +49,10 @@ static AST *varify(AST *tlc, AST *chunk, AST *stmtPrev, AST *stmt, AST *e) {
 	}
 	assign->next = stmt;
 	
-	// Assemble ud-chain
+	// Reset ud-chain
 	
-	UseDef *ud[2];
-	ud[0] = malloc(sizeof(UseDef));
-	ud[1] = malloc(sizeof(UseDef));
-	
-	ud[0]->stmt = (AST*) assign;
-	ud[0]->use = assign->what;
-	ud[0]->def = (AST*) assign;
-	ud[0]->next = ud[1];
-	
-	ud[1]->stmt = stmt;
-	ud[1]->use = (AST*) ev[1];
-	ud[1]->def = (AST*) assign;
-	ud[1]->next = NULL;
-	
-	vte->data.var.usedefFirst = ud[0];
-	vte->data.var.usedefLast = ud[1];
-	
-	// Correct the ud-chain of variables used in varified expression `e`
-	
-	varify_change_usedefs(e, stmt, (AST*) assign);
+	vte->data.var.usedefFirst = NULL;
+	vte->data.var.usedefLast = NULL;
 	
 	return (AST*) ev[1];
 }
@@ -155,28 +61,6 @@ static AST *xopify(AST *tlc, AST *chunk, AST *stmtPrev, AST *stmt, AST *e) {
 	return varify(tlc, chunk, stmtPrev, stmt, e);
 }
 
-static UseDef *get_last_usedef_before_stmt(AST *tlc, VarTableEntry *v, AST *stmt) {
-	assert(v->kind == VARTABLEENTRY_VAR);
-	
-	UseDef *ud = v->data.var.usedefFirst;
-	
-	if(!ud) {
-		return NULL;
-	}
-	
-	UseDef *udPrev = NULL;
-	
-	while(ud) {
-		if(ast_stmt_is_after(tlc, ud->stmt, stmt)) {
-			break;
-		}
-		udPrev = ud;
-		ud = ud->next;
-	}
-	
-	return udPrev;
-}
-
 static int dumben_chunk(AST *tlc, AST *chu) {
 	AST *sPrev = NULL;
 	AST *s = chu->chunk.statementFirst;
@@ -230,24 +114,17 @@ static int dumben_chunk(AST *tlc, AST *chu) {
 				effective = 1;
 			}
 			
-			if(s->stmtAssign.what->nodeKind == AST_EXPR_VAR && s->stmtAssign.what->exprVar.thing->kind == VARTABLEENTRY_VAR && s->stmtAssign.to->nodeKind == AST_EXPR_UNARY_OP && s->stmtAssign.to->exprUnOp.operator == UNOP_NEGATE && (s->stmtAssign.to->exprUnOp.operand->nodeKind != AST_EXPR_VAR || s->stmtAssign.what->exprVar.thing != s->stmtAssign.to->exprUnOp.operand->exprVar.thing)) {
+			if(s->stmtAssign.to && s->stmtAssign.to->nodeKind == AST_EXPR_UNARY_OP && s->stmtAssign.to->exprUnOp.operator == UNOP_NEGATE && !ast_expression_equal(s->stmtAssign.what, s->stmtAssign.to->exprUnOp.operand)) {
 				// Turn this:
 				//  a = -b
 				// into
 				//  a = b
 				//  a = -a
-				// While keeping UD-chain valid.
 				
-				// Currently only for variables. While this could work for any XOP, it requires the ability to deep-copy `a`, which is not trivial when taking into account UD-chains.
-				// TODO: Scrap incremental UD-chain modifications. Simply rebuild them after each pass.
-				
-				ASTExprVar *ev[2];
-				for(int i = 0; i < 2; i++) {
-					ev[i] = malloc(sizeof(ASTExprVar));
-					ev[i]->nodeKind = AST_EXPR_VAR;
-					ev[i]->type = s->stmtAssign.what->expression.type;
-					ev[i]->thing = s->stmtAssign.what->exprVar.thing;
-				}
+				AST *ev[2] = {
+					ast_deep_copy(s->stmtAssign.what),
+					ast_deep_copy(s->stmtAssign.what)
+				};
 				
 				AST *negation = s->stmtAssign.to;
 				
@@ -261,28 +138,40 @@ static int dumben_chunk(AST *tlc, AST *chu) {
 				
 				assign2->statement.next = s->statement.next;
 				s->statement.next = assign2;
-
-				UseDef *link = get_last_usedef_before_stmt(tlc, ev[0]->thing, assign2->statement.next);
-				
-				UseDef *ud[2];
-				ud[0] = malloc(sizeof(UseDef));
-				ud[1] = malloc(sizeof(UseDef));
-
-				ud[0]->stmt = assign2;
-				ud[0]->use = (AST*) ev[1];
-				ud[0]->def = s;
-				ud[0]->next = ud[1];
-
-				ud[1]->stmt = assign2;
-				ud[1]->use = (AST*) ev[0];
-				ud[1]->def = s;
-				ud[1]->next = link->next;
-				
-				link->next = ud[0];
 				
 				effective = 1;
 			}
 			
+			if(is_xop(s->stmtAssign.to) == XOP_NOT_XOP) {
+				if(s->stmtAssign.to->nodeKind == AST_EXPR_UNARY_OP && s->stmtAssign.to->exprUnOp.operator == UNOP_DEREF) {
+					s->stmtAssign.to->exprUnOp.operand = varify(tlc, chu, sPrev, s, s->stmtAssign.to->exprUnOp.operand);
+					
+					effective = 1;
+				} else if(s->stmtAssign.to->nodeKind == AST_EXPR_BINARY_OP && s->stmtAssign.to->exprBinOp.operator < BINOP_SIMPLES && !ast_expression_equal(s->stmtAssign.what, s->stmtAssign.to->exprBinOp.operands[0])) {
+					// Turn this:
+					//  a = b op c
+					// into
+					//  a = b
+					//  a = a op c
+					
+					AST *assign2 = malloc(sizeof(ASTStmtAssign));
+					assign2->nodeKind = AST_STMT_ASSIGN;
+					assign2->stmtAssign.what = ast_deep_copy(s->stmtAssign.what);
+					assign2->stmtAssign.to = s->stmtAssign.to->exprBinOp.operands[0];
+					
+					sPrev->statement.next = assign2;
+					assign2->statement.next = s;
+					
+					s->stmtAssign.to->exprBinOp.operands[0] = ast_deep_copy(s->stmtAssign.what);
+					
+					effective = 1;
+				} else if(s->stmtAssign.to->nodeKind == AST_EXPR_BINARY_OP && !is_xop(s->stmtAssign.to->exprBinOp.operands[0])) {
+					s->stmtAssign.to->exprBinOp.operands[0] = xopify(tlc, chu, sPrev, s, s->stmtAssign.to->exprBinOp.operands[0]);
+				} else if(s->stmtAssign.to->nodeKind == AST_EXPR_BINARY_OP && !is_xop(s->stmtAssign.to->exprBinOp.operands[1])) {
+					s->stmtAssign.to->exprBinOp.operands[1] = xopify(tlc, chu, sPrev, s, s->stmtAssign.to->exprBinOp.operands[1]);
+				}
+			}
+			
 		} else if(s->nodeKind == AST_STMT_EXPR && s->stmtExpr.expr->nodeKind == AST_EXPR_CALL) {
 			
 			int argCount = s->stmtExpr.expr->exprCall.what->expression.type->function.argCount;
diff --git a/src/ntc.c b/src/ntc.c
index 105809f..60245c1 100644
--- a/src/ntc.c
+++ b/src/ntc.c
@@ -39,7 +39,12 @@ int main(int argc_, char **argv_) {
 	
 	dumben_go(chunk);
 	
-	cg_go(chunk);
+	while(!cg_go(chunk)) {
+		
+		puts(ast_dump(chunk));
+		
+		dumben_go(chunk);
+	}
 	
 	return 0;
 }
diff --git a/src/parse.c b/src/parse.c
index 18e97eb..a6b2e08 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -24,11 +24,6 @@ static inline int __builtin_clzl(unsigned long x) {
 }
 #endif
 
-typedef struct {
-	UseDef ud;
-	VarTableEntry *to;
-} UseDefToAdd;
-
 typedef struct {
 	Token *tokens;
 	intmax_t i;
@@ -41,10 +36,6 @@ typedef struct {
 	// Used by pushstat to add statements
 	ASTChunk *currentChunk;
 	
-	// Used by pushstmt to assemble use-def chain
-	size_t udsToAddCount;
-	UseDefToAdd *udsToAdd;
-	
 	// Used to place guard variable uses after loops to stop reg allocation from fucking up
 	VarTable *loopScope;
 	size_t guardedVarCount;
@@ -88,28 +79,6 @@ static int maybe(Parser *P, TokenKind t) {
 }
 
 static void pushstat(Parser *P, void *a) {
-	for(size_t i = 0; i < P->udsToAddCount; i++) {
-		VarTableEntry *to = P->udsToAdd[i].to;
-		
-		UseDef *ud = malloc(sizeof(*ud));
-		memcpy(ud, &P->udsToAdd[i].ud, sizeof(*ud));
-		ud->stmt = a;
-		
-		/*if(ud->stmt->nodeKind == AST_STMT_ASSIGN && ud->stmt->stmtAssign.what == ud->use) {
-			// Forget. The x in `x = y` is not a use of x.
-			continue;
-		}*/
-		
-		if(to->data.var.usedefFirst) {
-			to->data.var.usedefLast->next = ud;
-			to->data.var.usedefLast = ud;
-		} else {
-			to->data.var.usedefFirst = to->data.var.usedefLast = ud;
-		}
-	}
-	
-	P->udsToAddCount = 0;
-	
 	if(P->currentChunk->statementFirst) {
 		P->currentChunk->statementLast->statement.next = a;
 		P->currentChunk->statementLast = a;
@@ -141,7 +110,7 @@ static ASTExprPrimitive *parse_prim(Parser *P) {
 	return ret;
 }
 
-static void newusedef(Parser *P, VarTableEntry *v, AST *expr) {
+/*static void newusedef(Parser *P, VarTableEntry *v, AST *expr) {
 	ReachingDefs *defs = v->data.var.reachingDefs;
 	
 	while(defs) {
@@ -160,7 +129,7 @@ static void newusedef(Parser *P, VarTableEntry *v, AST *expr) {
 		
 		defs = defs->parent;
 	}
-}
+}*/
 
 static AST *exprvar(Parser *P, VarTableEntry *v) {
 	AST *a = malloc(sizeof(ASTExprVar));
@@ -168,10 +137,6 @@ static AST *exprvar(Parser *P, VarTableEntry *v) {
 	a->exprVar.type = v->type;
 	a->exprVar.thing = v;
 	
-	if(v->kind == VARTABLEENTRY_VAR) {
-		newusedef(P, v, a);
-	}
-	
 	if(P->loopScope) {
 		// XXX: O(n)!!!!!!!!!
 		
@@ -254,9 +219,6 @@ AST *nct_cast_expr(AST *what, Type *to) {
 		ret->val = what->exprPrim.val & (((int64_t) 1 << to->primitive.width) - 1);
 		return (AST*) ret;
 	} else {
-		// Silently fail :)
-		return what;
-		
 		ASTExprCast *ret = malloc(sizeof(*ret));
 		ret->nodeKind = AST_EXPR_CAST;
 		ret->type = to;
@@ -273,6 +235,15 @@ AST *nct_parse_expression(Parser *P, int lOP) {
 		if(peek(P, 0).type == TOKEN_NUMBER) {
 			return (AST*) parse_prim(P);
 		} else if(peek(P, 0).type == TOKEN_IDENTIFIER) {
+			if(!strcmp(peek(P, 0).content, "@stack")) {
+				get(P);
+				
+				ASTExprStackPointer *ret = malloc(sizeof(*ret));
+				ret->nodeKind = AST_EXPR_STACK_POINTER;
+				ret->type = primitive_parse("u32");
+				return ret;
+			}
+			
 			return exprvar(P, vartable_find(P->scope, get(P).content));
 		} else if(peek(P, 0).type == TOKEN_STRING) {
 			ASTExprStringLiteral *ret = malloc(sizeof(*ret));
@@ -478,10 +449,20 @@ AST *nct_parse_expression(Parser *P, int lOP) {
 				
 				ASTExpr *operand = &(astop->operands[1] = nct_parse_expression(P, lOP + 1))->expression;
 				
-				if(operand->type->type != TYPE_TYPE_PRIMITIVE) {
-					stahp(P->tokens[P->i].row, P->tokens[P->i].column, "Invalid combination of operator and operand types.");
-  				}
-  				
+				if(!type_is_number(astop->operands[0]->expression.type)
+					|| !type_is_number(astop->operands[1]->expression.type)) {
+					
+					stahp(P->tokens[P->i].row, P->tokens[P->i].column, "Attempt to perform arithmetic on non-number types.");
+				}
+				
+				if(type_size(astop->operands[0]->expression.type) < type_size(astop->operands[1]->expression.type)) {
+					astop->operands[0] = nct_cast_expr(astop->operands[0], astop->operands[1]->expression.type);
+				}
+				
+				if(type_size(astop->operands[1]->expression.type) < type_size(astop->operands[0]->expression.type)) {
+					astop->operands[1] = nct_cast_expr(astop->operands[1], astop->operands[0]->expression.type);
+				}
+				
   				if(!astop->type) {
 					astop->type = operand->type;
 				} else {
@@ -655,8 +636,8 @@ static AST *parse_declaration(Parser *P) {
 		assign->nodeKind = AST_STMT_ASSIGN;
 		assign->next = NULL;
 		
-		entry->data.var.reachingDefs = reachingdefs_push(NULL);
-		reachingdefs_set(entry->data.var.reachingDefs, (AST*) assign);
+		//entry->data.var.reachingDefs = reachingdefs_push(NULL);
+		//reachingdefs_set(entry->data.var.reachingDefs, (AST*) assign);
 		
 		assign->what = exprvar(P, entry);
 		assign->to = peek(P, 0).type == TOKEN_SEMICOLON ? NULL : nct_parse_expression(P, 0);
@@ -710,77 +691,6 @@ backtrack:
 	return NULL;
 }
 
-/*	Imagine the following pseudocode:
-	x = ...
-	while ... {
-		(do something with x)
-		x = ...
-	}
-	The second definition of x reaches the code *before* it.
-	Therefore we must go over the loop body a second time with known reaching definitions and add the necessary usedefs.*/
-static void loop_second_pass(AST *a) {
-	if(a->nodeKind == AST_CHUNK) {
-		for(AST *s = a->chunk.statementFirst; s; s = s->statement.next) {
-			loop_second_pass(s);
-		}
-	} else if(a->nodeKind == AST_STMT_IF) {
-		loop_second_pass(a->stmtIf.expression);
-		loop_second_pass(a->stmtIf.then);
-	} else if(a->nodeKind == AST_STMT_LOOP) {
-		loop_second_pass(a->stmtLoop.body);
-	} else if(a->nodeKind == AST_STMT_ASSIGN) {
-		loop_second_pass(a->stmtAssign.what);
-		loop_second_pass(a->stmtAssign.to);
-		
-		/* TODO: Per-variable flag.to cease additional usedefs after assignment?
-			It is okay to have too many usedefs, so this isn't high priority.*/
-	} else if(a->nodeKind == AST_STMT_EXPR) {
-		loop_second_pass(a->stmtExpr.expr);
-	} else if(a->nodeKind == AST_EXPR_VAR) {
-		UseDef *udPrev = NULL;
-		UseDef *ud = a->exprVar.thing->data.var.usedefFirst;
-		while(ud && ud->use != a) {
-			udPrev = ud;
-			ud = ud->next;
-		}
-		
-		if(ud) {
-			ReachingDefs *defs = a->exprVar.thing->data.var.reachingDefs;
-			while(defs) {
-				for(size_t i = 0; i < defs->defCount; i++) {
-					UseDef *newud = calloc(1, sizeof(*newud));
-					memcpy(newud, ud, sizeof(*ud));
-					newud->def = defs->defs[i];
-					
-					udPrev->next = newud;
-					newud->next = ud;
-					ud = newud;
-				}
-				
-				if(defs->excludeParent) {
-					break;
-				}
-				
-				defs = defs->parent;
-			}
-		}
-	} else if(a->nodeKind == AST_EXPR_BINARY_OP) {
-		loop_second_pass(a->exprBinOp.operands[0]);
-		loop_second_pass(a->exprBinOp.operands[1]);
-	} else if(a->nodeKind == AST_EXPR_UNARY_OP) {
-		loop_second_pass(a->exprUnOp.operand);
-	} else if(a->nodeKind == AST_EXPR_CAST) {
-		loop_second_pass(a->exprCast.what);
-	} else if(a->nodeKind == AST_EXPR_CALL) {
-		loop_second_pass(a->exprCall.what);
-		
-		size_t argCount = a->exprCall.what->expression.type->function.argCount;
-		for(size_t i = 0; i < argCount; i++) {
-			loop_second_pass(a->exprCall.args[i]);
-		}
-	}
-}
-
 ASTChunk *nct_parse_chunk(Parser*, int, int);
 void nct_parse_statement(Parser *P) {
 	if(maybe(P, TOKEN_IF)) {
@@ -815,22 +725,26 @@ void nct_parse_statement(Parser *P) {
 		ret->body = (AST*) nct_parse_chunk(P, 0, 1);
 		expect(P, TOKEN_SQUIGGLY_R);
 		
+		pushstat(P, ret);
+		
 		if(isFirstLoop) {
 			P->loopScope = NULL;
 			
 			for(size_t i = 0; i < P->guardedVarCount; i++) {
 				ASTExprVar *ev = P->guardedVars[i];
 				
-				newusedef(P, ev->thing, ev);
+				AST *es = calloc(1, sizeof(ASTStmtExpr));
+				es->nodeKind = AST_STMT_EXPR;
+				es->stmtExpr.expr = ev;
+				
+				pushstat(P, es);
 			}
+			
 			P->guardedVarCount = 0;
 			free(P->guardedVars);
 			P->guardedVars = NULL;
 		}
 		
-		loop_second_pass(ret->body);
-		
-		pushstat(P, ret);
 		return;
 	} else if(maybe(P, TOKEN_BREAK)) {
 		ASTStmtBreak *ret = malloc(sizeof(*ret));
@@ -840,6 +754,7 @@ void nct_parse_statement(Parser *P) {
 		expect(P, TOKEN_SEMICOLON);
 		
 		pushstat(P, ret);
+		
 		return;
 	} else if(maybe(P, TOKEN_CONTINUE)) {
 		ASTStmtContinue *ret = malloc(sizeof(*ret));
@@ -849,6 +764,7 @@ void nct_parse_statement(Parser *P) {
 		expect(P, TOKEN_SEMICOLON);
 		
 		pushstat(P, ret);
+		
 		return;
 	} else if(peek(P, 0).type == TOKEN_IDENTIFIER) {
 		if(!strcmp(peek(P, 0).content, "@align")) {
@@ -920,9 +836,9 @@ void nct_parse_statement(Parser *P) {
  		ret->what = e;
 		ret->to = nct_cast_expr(nct_parse_expression(P, 0), ret->what->expression.type);
 		
-		if(ret->what->nodeKind == AST_EXPR_VAR) {
-			reachingdefs_set(ret->what->exprVar.thing->data.var.reachingDefs, (AST*) ret);
-		}
+		//if(ret->what->nodeKind == AST_EXPR_VAR) {
+		//	reachingdefs_set(ret->what->exprVar.thing->data.var.reachingDefs, (AST*) ret);
+		//}
 		
 		expect(P, TOKEN_SEMICOLON);
 		
@@ -942,7 +858,7 @@ void nct_parse_statement(Parser *P) {
 }
 
 ASTChunk *nct_parse_chunk(Parser *P, int isTopLevel, int varPrioritize) {
-	AST *ret = malloc(sizeof(ASTChunk));
+	AST *ret = calloc(1, sizeof(ASTChunk));
 	ret->nodeKind = AST_CHUNK;
 	ret->chunk.statementFirst = ret->chunk.statementLast = NULL;
 	ret->chunk.varCount = 0;
@@ -957,7 +873,7 @@ ASTChunk *nct_parse_chunk(Parser *P, int isTopLevel, int varPrioritize) {
 		P->topLevel = &ret->chunk;
 	}
 	
-	vartable_new_reachingdefs_for_all_vars(P->scope);
+	//vartable_new_reachingdefs_for_all_vars(P->scope);
 	
 	/* Find all symbol names and struct types ahead of time. Searches for colons as those can only mean symbol declarations */
 	
@@ -1001,7 +917,7 @@ ASTChunk *nct_parse_chunk(Parser *P, int isTopLevel, int varPrioritize) {
 		nct_parse_statement(P);
 	}
 	
-	vartable_coalesce_reachingdefs_for_all_vars(P->scope);
+	//vartable_coalesce_reachingdefs_for_all_vars(P->scope);
 	
 	size_t nonSymbols = 0;
 	for(size_t i = 0; i < P->scope->count; i++) {
diff --git a/src/reporting.h b/src/reporting.h
index 5aed95c..ead912c 100644
--- a/src/reporting.h
+++ b/src/reporting.h
@@ -1,7 +1,7 @@
 #ifndef NCTREF_REPORTING_H
 #define NCTREF_REPORTING_H
 
-#ifndef _GNUC
+#ifndef __GNUC__
 #define __attribute__(x)
 #endif
 
diff --git a/src/types.c b/src/types.c
index d390f40..e4894f4 100644
--- a/src/types.c
+++ b/src/types.c
@@ -132,6 +132,10 @@ Type *type_pointer_wrap(Type *t) {
 	return (Type*) ret;
 }
 
+int type_is_number(Type *t) {
+	return t->type == TYPE_TYPE_POINTER || t->type == TYPE_TYPE_PRIMITIVE;
+}
+
 int type_is_castable(Type *from, Type *to) {
 	if(type_equal(from, to)) return 2;
 	
@@ -152,4 +156,4 @@ int type_is_castable(Type *from, Type *to) {
 	}
 	
 	return 0;
-}
\ No newline at end of file
+}
diff --git a/src/types.h b/src/types.h
index 8136fdc..ed2b0c4 100644
--- a/src/types.h
+++ b/src/types.h
@@ -71,4 +71,8 @@ Type *type_pointer_wrap(Type*);
 /* 0 = not castable, 1 = explicitly castable, 2 = implicitly castable */
 int type_is_castable(Type *from, Type *to);
 
+int type_is_number(Type *t);
+
+char *type_to_string(Type*);
+
 #endif
diff --git a/src/vartable.h b/src/vartable.h
index a97f7fb..95385d9 100644
--- a/src/vartable.h
+++ b/src/vartable.h
@@ -2,9 +2,10 @@
 #define NCTREF_VARTABLE_H
 
 #include"types.h"
+#include<stdbool.h>
 
 typedef enum {
-	VARTABLEENTRY_SYMBOL, VARTABLEENTRY_TYPE, VARTABLEENTRY_VAR
+	VARTABLEENTRY_SYMBOL, VARTABLEENTRY_STACK, VARTABLEENTRY_VAR
 } VarTableEntryKind;
 
 union AST;
@@ -49,7 +50,7 @@ typedef struct VarTableEntry {
 				// Register allocation
 				
 				// vars in loops have higher priority
-				// a more advanced approach would be to use weights for different colors (e.g. vars for mul "should" be in eax)
+				// a more advanced approach would be to use weights for different colors (e.g. multipliers "should" be in eax)
 				uint8_t priority;
 				uint16_t color, degree;
 				
diff --git a/src/x86.h b/src/x86.h
index 8550f0c..3666d06 100644
--- a/src/x86.h
+++ b/src/x86.h
@@ -29,6 +29,8 @@ static inline int is_xop(AST *e) {
 				}
 			}
 		}
+	} else if(e->nodeKind == AST_EXPR_STACK_POINTER) {
+		return XOP_NOT_MEM;
 	}
 	
 	return XOP_NOT_XOP;
diff --git a/tests/bit-rounding.nct b/tests/bit-rounding.nct
index dae6e2d..3228620 100644
--- a/tests/bit-rounding.nct
+++ b/tests/bit-rounding.nct
@@ -1,6 +1,11 @@
 u32 x: 123;
 u33 y: 5;
 
-u3 *o = 5000;
-u3 z = *o;
+u3* o = 5000;
+u32 z = *o;
 u3 p = *(o + z);
+u3 *g = o - z;
+p = *g;
+
+u32 c = 566;
+u16 j = c;
diff --git a/tests/spill.nct b/tests/spill.nct
new file mode 100644
index 0000000..d84a62f
--- /dev/null
+++ b/tests/spill.nct
@@ -0,0 +1,6 @@
+u8 a = 4;
+u8 b = 1;
+u8 c = 9;
+u8 d = 5;
+u8 e = 22;
+u8 f = a + b + c + d + e;
diff --git a/tests/stack.nct b/tests/stack.nct
new file mode 100644
index 0000000..422e742
--- /dev/null
+++ b/tests/stack.nct
@@ -0,0 +1 @@
+@stack = @stack - 123;