From b48e27f5cc31af65d8bb92d4b81cd03a60c5bcdb Mon Sep 17 00:00:00 2001
From: Carson Fleming <cflems@cflems.net>
Date: Thu, 6 Aug 2026 00:24:49 -0400
Subject: clean up yesterday's hacks + functions in type system

---
 codegen.c | 87 ++++++++++++++++++++++++++++++---------------------------------
 1 file changed, 42 insertions(+), 45 deletions(-)

(limited to 'codegen.c')

diff --git a/codegen.c b/codegen.c
index 71350e4..3950912 100644
--- a/codegen.c
+++ b/codegen.c
@@ -7,6 +7,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <stddef.h>
 
 #define CGEN_PANIC(format, ...) {\
     fprintf(\
@@ -32,7 +33,7 @@ static struct reg* MULDIV_OVERFLOW_REG = &RDX;
 
 static struct hash_map dseg;
 static struct scope* scope;
-static const struct fn_decl_node* active_fn;
+struct var_def* active_fn;
 static integral_t branch_counter = 0;
 static integral_t loop_counter = 0;
 
@@ -90,8 +91,11 @@ static const struct data_type* get_effective_data_type(
             return type->data.data_type;
         case TP_PTR:
             return &long_long_type;
+        case TP_FN:
+            /* functions have size 1 I guess */
+            return &char_type;
     }
-    CGEN_PANIC("unhandled type of type case");
+    unreachable();
 }
 
 static struct lval_def allocate_stack(
@@ -132,11 +136,8 @@ static void release_temporary(FILE* outfile, const struct lval_def* tmp) {
             break;
         case STO_STACK:
         case STO_IMM:
-        case STO_FN:
         case STO_LABEL:
             break;
-        case STO_UNRESOLVED:
-            CGEN_PANIC("can't release unresolved storage");
     }
 }
 
@@ -149,9 +150,6 @@ static void emit_storage_loc(
         case STO_LABEL:
             fprintf(outfile, "%s", loc->label);
             break;
-        case STO_FN:
-            fprintf(outfile, "%s", loc->decl->name);
-            break;
         case STO_REG:
             if (sz > 4) fprintf(outfile, "%s", loc->reg->qword);
             else if (sz > 2) fprintf(outfile, "%s", loc->reg->dword);
@@ -169,8 +167,6 @@ static void emit_storage_loc(
         case STO_IMM:
             fprintf(outfile, "0x%llx", loc->value);
             break;
-        case STO_UNRESOLVED:
-            CGEN_PANIC("can't emit unresolved storage location");
     }
 }
 
@@ -189,12 +185,8 @@ static bool locs_equal(
             return a->bp_offset == b->bp_offset;
         case STO_LABEL:
             return strcmp(a->label, b->label) == 0;
-        case STO_FN:
-            return a->decl == b->decl;
-        case STO_UNRESOLVED:
-            return false;
     }
-    CGEN_PANIC("unhandled storage type case");
+    unreachable();
 }
 
 static void emit_size_const(FILE* outfile, integral_t sz) {
@@ -253,10 +245,8 @@ static void emit_label_lea(
             if (spill_reg) unspill_register(outfile, tmp_reg);
             else release_register(tmp_reg);
             return;
-        case STO_FN:
         case STO_IMM:
         case STO_LABEL:
-        case STO_UNRESOLVED:
             CGEN_PANIC("can't load label address into non-value storage");
     }
 }
@@ -331,9 +321,7 @@ static void emit_mov(
             break;
         case STO_LABEL:
         case STO_IMM:
-        case STO_FN:
-        case STO_UNRESOLVED:
-            CGEN_PANIC("can't move value into storage type");
+            CGEN_PANIC("can't move value into non-storage type");
     }
     fprintf(outfile, "\n");
 }
@@ -351,9 +339,7 @@ static void emit_cmp_zero(FILE* outfile, const struct lval_def* lval) {
             break;
         case STO_LABEL:
         case STO_IMM:
-        case STO_FN:
-        case STO_UNRESOLVED:
-            CGEN_PANIC("can't compare this storage type")
+            CGEN_PANIC("can't compare this non-storage type")
     }
     fprintf(outfile, ", 0\n");
 }
@@ -427,7 +413,7 @@ static void emit_var_ref(
     const struct lval_def* dst
 ) {
     if (dst != NULL) {
-        emit_mov(outfile, dst, &node->def_ref->loc);
+        emit_mov(outfile, dst, &node->def_ref->storage);
     }
 }
 
@@ -439,7 +425,7 @@ static void emit_decl(
 ) {
     struct lval_def var_dst =
         allocate_stack(outfile, node->def_ref->type);
-    node->def_ref->loc = var_dst.loc;
+    node->def_ref->storage = var_dst.loc;
 
     fprintf(outfile, "\t; %s\n", node->def_ref->name);
 
@@ -468,7 +454,7 @@ static void emit_assignment(
             struct var_ref_node* var_ref = &node->lval->inner.var_ref;
             lval_def = (struct lval_def) {
                 .type = var_ref->def_ref->type,
-                .loc = var_ref->def_ref->loc,
+                .loc = var_ref->def_ref->storage,
             };
             break;
         default:
@@ -532,10 +518,14 @@ static void emit_call(
     }
 
     /* 3. `call <label>` */
-    fprintf(outfile, "\tcall %s", node->fn_ref->name);
-    // TODO: this is kinda fukt we should probably keep an
-    // internal/external flag in the storage loc instead
-    if (node->fn_ref->body == NULL) fprintf(outfile, " WRT ..plt");
+    /* TODO: support function pointers */
+    if (node->expr->type != EXPR_VAR_REF)
+        CGEN_PANIC("function pointers are not supported");
+    const struct var_def* fn_def = node->expr->inner.var_ref.def_ref;
+    fprintf(outfile, "\tcall ");
+    emit_storage_loc(outfile, &fn_def->storage, 0);
+    /* TODO: this could be a part of emit_storage_loc for labels */
+    if (!fn_def->fn.resolved) fprintf(outfile, " WRT ..plt");
     fprintf(outfile, "\n");
 
     /* 4. `mov dst, rax` */
@@ -732,7 +722,7 @@ static void emit_return(FILE* outfile, const struct return_node* node) {
             outfile,
             node->ret_val,
             &(struct lval_def) {
-                .type = &active_fn->return_type,
+                .type = active_fn->type->fn.return_type,
                 .loc = {
                     .type = STO_REG,
                     .reg = RV_REG,
@@ -849,21 +839,24 @@ static void emit_stmt(FILE* outfile, const struct stmt_node* node) {
 }
 
 static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
-    if (node->body == NULL) return;
+    if (!scope_get_var(scope, &active_fn, node->name))
+        CGEN_PANIC("scopes are borked, missing symbol: '%s'", node->name);
 
-    if (active_fn != NULL)
-        CGEN_PANIC(
-            "can't define function %s inside function %s",
-            node->name,
-            active_fn->name);
-    active_fn = node;
+    const char* label = node->name;
+    active_fn->storage = (struct storage_location) {
+        .type = STO_LABEL,
+        .label = label,
+    };
 
-    /* TODO: we need to account for the base pointer moving in var locs */
-    fprintf(outfile, "%s:\n", node->name);
-    fprintf(outfile, "\tpush rbp\n");
-    fprintf(outfile, "\tmov rbp, rsp\n");
+    if (node->body == NULL) {
+        active_fn = NULL;
+        return;
+    }
 
     enter_scope(node->scope, 0);
+    fprintf(outfile, "%s:\n", label);
+    fprintf(outfile, "\tpush rbp\n");
+    fprintf(outfile, "\tmov rbp, rsp\n");
 
     sintegral_t spilled_bp_ofs = -16; // return address + spilled rbp
     struct arg_decl_node* arg_decl = node->args;
@@ -872,7 +865,7 @@ static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
         fprintf(outfile, "\t; %s\n", arg_def->name);
         struct lval_def arg_dst =
             allocate_stack(outfile, arg_def->type);
-        arg_def->loc = arg_dst.loc;
+        arg_def->storage = arg_dst.loc;
 
         struct storage_location arg_src;
         if (CALLING_CONV[i] != NULL) {
@@ -900,8 +893,8 @@ static void emit_fn_decl(FILE* outfile, const struct fn_decl_node* node) {
     fprintf(outfile, "\tpop rbp\n");
     fprintf(outfile, "\tret\n");
 
-    active_fn = NULL;
     exit_scope(node->scope, false);
+    active_fn = NULL;
 }
 
 static void emit_root_node(FILE* outfile, const struct root_node* node) {
@@ -924,7 +917,11 @@ void emit_code(struct ast* ast, const char* path) {
     for (; node != NULL; node = node->next) {
         if (node->type != ROOT_FN_DECL) continue;
         const struct fn_decl_node* fn = &node->inner.fn_decl;
-        if (fn->body != NULL)
+        struct var_def* fn_def;
+        if (!scope_get_var(scope, &fn_def, fn->name))
+            CGEN_PANIC("use of undeclared function '%s'", fn->name);
+
+        if (fn_def->fn.resolved)
             fprintf(outfile, "global %s\n", fn->name);
         else
             fprintf(outfile, "extern %s\n", fn->name);
-- 
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