1 files changed, 51 insertions, 12 deletions

diff --git a/codegen.c b/codegen.c
index bdc3cbf..44fccce 100644
--- a/codegen.c
+++ b/codegen.c
@@ -34,6 +34,7 @@ static const struct storage_location MULDIV_OVERFLOW_LOC = {
 
 static struct scope* scope;
 static const struct fn_decl_node* active_fn;
+static unsigned long long branch_counter = 0;
 
 static struct lval_def allocate_register(unsigned long long sz) {
     return (struct lval_def) {
@@ -173,19 +174,33 @@ static void emit_mov(
             emit_storage_loc(outfile, src, dst->sz);
             break;
         case STO_LABEL:
-            CGEN_PANIC("can't move value into label %s", dst->loc.label);
-        case STO_FN:
-            CGEN_PANIC(
-                "can't move value into function %s", dst->loc.decl->name);
         case STO_IMM:
-            CGEN_PANIC(
-                "can't move value into immediate value %lld", dst->loc.value);
+        case STO_FN:
         case STO_UNRESOLVED:
-            CGEN_PANIC("can't move value into unresolved storage");
+            CGEN_PANIC("can't move value into storage type");
     }
     fprintf(outfile, "\n");
 }
 
+static void emit_cmp_zero(FILE* outfile, const struct lval_def* lval) {
+    fprintf(outfile, "\tcmp ");
+    switch (lval->loc.type) {
+        case STO_REG:
+            emit_storage_loc(outfile, &lval->loc, lval->sz);
+            break;
+        case STO_STACK:
+            emit_size_const(outfile, lval->sz);
+            emit_storage_loc(outfile, &lval->loc, lval->sz);
+            break;
+        case STO_LABEL:
+        case STO_IMM:
+        case STO_FN:
+        case STO_UNRESOLVED:
+            CGEN_PANIC("can't compare this storage type")
+    }
+    fprintf(outfile, ", 0\n");
+}
+
 /* TODO: move this utility to the type checker and use evaluated_type */
 static unsigned long long get_type_size(const struct type_node* type) {
     if (type->ptr_level > 0) return PTR_SIZE;
@@ -524,7 +539,7 @@ static void emit_return(FILE* outfile, const struct return_node* node) {
     fprintf(outfile, "\tjmp " RETURN_LABEL_FMT "\n", active_fn->name);
 }
 
-static void emit_group(FILE* outfile, const struct group_node* node) {
+static void emit_group_contents(FILE* outfile, const struct group_node* node) {
     const struct stmt_node* body_node = node->head;
     while (body_node != NULL) {
         emit_stmt(outfile, body_node);
@@ -532,19 +547,40 @@ static void emit_group(FILE* outfile, const struct group_node* node) {
     }
 }
 
-static void emit_stmt_group(FILE* outfile, const struct group_node* node) {
+static void emit_group(FILE* outfile, const struct group_node* node) {
     if (node->scope->next_out != scope) CGEN_PANIC("scopes are misaligned");
 
     scope = node->scope;
     scope->bp_offset = scope->next_out->bp_offset; /* don't reset bp */
 
-    emit_group(outfile, node);
+    emit_group_contents(outfile, node);
 
     /* don't reset sp because alloca needs to work */
     scope->next_out->bp_offset = scope->bp_offset;
     scope = scope->next_out;
 }
 
+static void emit_if(FILE* outfile, const struct if_node* node) {
+    /* TODO: use type checked cond result size; using full reg size causes a segfault */
+    struct lval_def cond_result = allocate_temporary(outfile, FULL_REG_SZ);
+    emit_expr(outfile, node->cond, &cond_result);
+    emit_cmp_zero(outfile, &cond_result);
+
+    unsigned long long false_branch_num = branch_counter++;
+    fprintf(outfile, "\tjz branch%lld\n", false_branch_num);
+    emit_stmt(outfile, node->true_branch);
+
+    if (node->false_branch == NULL) {
+        fprintf(outfile, "branch%lld:\n", false_branch_num);
+    } else {
+        unsigned long long end_branch_num = branch_counter++;
+        fprintf(outfile, "\tjmp branch%lld\n", end_branch_num);
+        fprintf(outfile, "branch%lld:\n", false_branch_num);
+        emit_stmt(outfile, node->false_branch);
+        fprintf(outfile, "branch%lld:\n", end_branch_num);
+    }
+}
+
 static void emit_stmt(FILE* outfile, const struct stmt_node* node) {
     switch (node->type) {
         case STMT_EMPTY:
@@ -559,7 +595,10 @@ static void emit_stmt(FILE* outfile, const struct stmt_node* node) {
             emit_expr(outfile, &node->inner.expr, NULL);
             break;
         case STMT_GROUP:
-            emit_stmt_group(outfile, &node->inner.group);
+            emit_group(outfile, &node->inner.group);
+            break;
+        case STMT_IF:
+            emit_if(outfile, &node->inner.if_);
             break;
     }
 }
@@ -613,7 +652,7 @@ static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
         arg_decl = arg_decl->next;
     }
 
-    emit_group(outfile, &node->body);
+    emit_group_contents(outfile, &node->body);
 
     scope = scope->next_out;