Loop guards

src/ast.c

@@ -29,6 +29,13 @@ 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) {
+			int i = ast_stmt_is_after(s->stmtLoop.body, s1, s2);
+			if(i != -1) {
+				return i;
+			}
+		}
+		
 		if(s == s1) {
 			return 0;
 		}
@@ -41,11 +48,6 @@ int ast_stmt_is_after(const AST *chunk, const AST *s1, const AST *s2) {
 			if(i != -1) {
 				return i;
 			}
-		} else if(s->nodeKind == AST_STMT_LOOP) {
-			int i = ast_stmt_is_after(s->stmtLoop.body, s1, s2);
-			if(i != -1) {
-				return i;
-			}
 		}
 		
 		s = s->statement.next;

src/cg.c

@@ -179,6 +179,7 @@ void cg_chunk(AST *a) {
 			}
 		} else if(s->nodeKind == AST_STMT_ASSIGN) {
 			
+			if(s->stmtAssign.to) {
 				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_ADD || s->stmtAssign.to->exprBinOp.operator == BINOP_SUB) && s->stmtAssign.to->exprBinOp.operands[1]->nodeKind == AST_EXPR_PRIMITIVE && s->stmtAssign.to->exprBinOp.operands[1]->exprPrim.val == 1) {
 				
 					// inc or dec
@@ -205,6 +206,7 @@ void cg_chunk(AST *a) {
 					printf("mov %s, %s\n", xop(s->stmtAssign.what), xop(s->stmtAssign.to));
 					
 				}
+			}
 			
 		} else if(s->nodeKind == AST_STMT_LOOP) {
 		

src/dumberdowner.c

@@ -158,14 +158,14 @@ static AST *varify(AST *tlc, AST *chunk, AST *stmtPrev, AST *stmt, AST *e) {
 	// Assemble 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] = malloc(sizeof(UseDef));
 	ud[1]->stmt = stmt;
 	ud[1]->use = (AST*) ev[1];
 	ud[1]->def = (AST*) assign;

src/parse.c

@@ -44,6 +44,11 @@ typedef struct {
 	// 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;
+	ASTExprVar **guardedVars;
 } Parser;
 
 static Token get(Parser *P) {
@@ -167,6 +172,36 @@ static AST *exprvar(Parser *P, VarTableEntry *v) {
 		newusedef(P, v, a);
 	}
 	
+	if(P->loopScope) {
+		// XXX: O(n)!!!!!!!!!
+		
+		int inloop = 0;
+		for(VarTable *vt = v->owner; vt; vt = vt->parent) {
+			if(vt->parent == P->loopScope) {
+				inloop = 1;
+				break;
+			}
+		}
+		
+		if(!inloop) {
+			int alreadyAdded = 0;
+			for(size_t i = 0; i < P->guardedVarCount; i++) {
+				if(P->guardedVars[i]->thing == v) {
+					alreadyAdded = 1;
+					break;
+				}
+			}
+			
+			if(!alreadyAdded) {
+				ASTExprVar *ev = malloc(sizeof(*ev));
+				memcpy(ev, a, sizeof(*ev));
+				
+				P->guardedVars = realloc(P->guardedVars, sizeof(*P->guardedVars) * (P->guardedVarCount + 1));
+				P->guardedVars[P->guardedVarCount++] = ev;
+			}
+		}
+	}
+	
 	return a;
 }
 
@@ -614,6 +649,7 @@ static AST *parse_declaration(Parser *P) {
 		
 		ASTStmtAssign *assign = malloc(sizeof(*assign));
 		assign->nodeKind = AST_STMT_ASSIGN;
+		assign->next = NULL;
 		
 		entry->data.var.reachingDefs = reachingdefs_push(NULL);
 		reachingdefs_set(entry->data.var.reachingDefs, (AST*) assign);
@@ -765,10 +801,29 @@ void nct_parse_statement(Parser *P) {
 		ret->nodeKind = AST_STMT_LOOP;
 		ret->next = NULL;
 		
+		int isFirstLoop = P->loopScope == NULL;
+		
+		if(isFirstLoop) {
+			P->loopScope = P->scope;
+		}
+		
 		expect(P, TOKEN_SQUIGGLY_L);
 		ret->body = (AST*) nct_parse_chunk(P, 0, 1);
 		expect(P, TOKEN_SQUIGGLY_R);
 		
+		if(isFirstLoop) {
+			P->loopScope = NULL;
+			
+			for(size_t i = 0; i < P->guardedVarCount; i++) {
+				ASTExprVar *ev = P->guardedVars[i];
+				
+				newusedef(P, ev->thing, ev);
+			}
+			P->guardedVarCount = 0;
+			free(P->guardedVars);
+			P->guardedVars = NULL;
+		}
+		
 		loop_second_pass(ret->body);
 		
 		pushstat(P, ret);
@@ -958,6 +1013,7 @@ ASTChunk *nct_parse_chunk(Parser *P, int isTopLevel, int varPrioritize) {
 	for(size_t i = 0; i < P->scope->count; i++) {
 		if(P->scope->data[i]->kind == VARTABLEENTRY_VAR) {
 			P->topLevel->vars[P->topLevel->varCount++] = P->scope->data[i];
+			P->scope->data[i]->owner = P->topLevel;
 		}
 	}
 	

src/vartable.c

@@ -65,6 +65,7 @@ VarTableEntry *vartable_set(VarTable *this, const char *name, VarTableEntry *e)
 	this->data[this->count] = e;
 	this->count++;
 	if(e->kind == VARTABLEENTRY_VAR) e->data.var.name = name;
+	e->owner = this;
 	return e;
 }
 

src/vartable.h

@@ -27,9 +27,12 @@ struct ReachingDefs *reachingdefs_push(struct ReachingDefs*);
 struct ReachingDefs *reachingdefs_coalesce(struct ReachingDefs*);
 void reachingdefs_set(struct ReachingDefs*, union AST*);
 
+struct VarTable;
 typedef struct VarTableEntry {
 	Type *type;
 	
+	struct VarTable *owner;
+	
 	VarTableEntryKind kind;
 	struct {
 		union {

tests/loopregalloc.nct

@@ -0,0 +1,7 @@
+u8 a;
+
+loop {
+	a = 3;
+	
+	u8 b = 1;
+}