blu/lux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases 13 Wiki Activity

feat: add Perceus-inspired reference counting infrastructure

Browse Source 
Implements Phase 1-3 of the RC system for automatic memory management:

- Add LuxRcHeader with refcount and type tag for all heap objects
- Add lux_rc_alloc, lux_incref, lux_decref, and lux_drop functions
- Update list allocation to use RC (lux_list_new uses lux_rc_alloc)
- List operations (concat, reverse, take, drop) now incref shared elements
- Update boxing functions (box_int, box_bool, box_float) to use RC
- String operations (concat, int_to_string, readLine) return RC strings
- File and HTTP operations return RC-managed strings

The infrastructure is ready for automatic decref insertion at scope exit
(Phase 4) and closure RC (Phase 5) in future work.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Brandon Lucas
2026-02-14 12:27:54 -05:00
parent 2a2c6d2760
commit 56f0fa4eaa
3 changed files with 446 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

218
src/codegen/c_backend.rs
View File

@@ -375,12 +375,71 @@ impl CBackend {
self.writeln("// Closure representation: env pointer + function pointer");
self.writeln("typedef struct { void* env; void* fn_ptr; } LuxClosure;");
self.writeln("");
self.writeln("// === Reference Counting Infrastructure ===");
self.writeln("// Perceus-inspired RC system for automatic memory management.");
self.writeln("// See docs/REFERENCE_COUNTING.md for details.");
self.writeln("");
self.writeln("// Type tags for polymorphic drop - identifies the type of RC object");
self.writeln("typedef enum {");
self.writeln(" LUX_TAG_STRING = 1,");
self.writeln(" LUX_TAG_LIST = 2,");
self.writeln(" LUX_TAG_CLOSURE = 3,");
self.writeln(" LUX_TAG_BOXED_INT = 4,");
self.writeln(" LUX_TAG_BOXED_BOOL = 5,");
self.writeln(" LUX_TAG_BOXED_FLOAT = 6,");
self.writeln(" LUX_TAG_ENV = 7, // Closure environment");
self.writeln(" LUX_TAG_ADT = 100 // ADT types start at 100");
self.writeln("} LuxTypeTag;");
self.writeln("");
self.writeln("// RC header placed before every heap-allocated object");
self.writeln("typedef struct {");
self.writeln(" int32_t rc; // Reference count");
self.writeln(" int32_t tag; // Type tag for polymorphic drop");
self.writeln("} LuxRcHeader;");
self.writeln("");
self.writeln("// Get the RC header from an object pointer");
self.writeln("#define LUX_RC_HEADER(ptr) (((LuxRcHeader*)(ptr)) - 1)");
self.writeln("");
self.writeln("// Forward declaration of polymorphic drop");
self.writeln("static void lux_drop(void* ptr, int32_t tag);");
self.writeln("");
self.writeln("// Allocate RC-managed memory with initial refcount of 1");
self.writeln("static void* lux_rc_alloc(size_t size, int32_t tag) {");
self.writeln(" LuxRcHeader* hdr = (LuxRcHeader*)malloc(sizeof(LuxRcHeader) + size);");
self.writeln(" if (!hdr) return NULL;");
self.writeln(" hdr->rc = 1;");
self.writeln(" hdr->tag = tag;");
self.writeln(" return hdr + 1; // Return pointer after header");
self.writeln("}");
self.writeln("");
self.writeln("// Increment reference count");
self.writeln("static inline void lux_incref(void* ptr) {");
self.writeln(" if (ptr) LUX_RC_HEADER(ptr)->rc++;");
self.writeln("}");
self.writeln("");
self.writeln("// Decrement reference count, call drop if zero");
self.writeln("static inline void lux_decref(void* ptr) {");
self.writeln(" if (ptr) {");
self.writeln(" LuxRcHeader* hdr = LUX_RC_HEADER(ptr);");
self.writeln(" if (--hdr->rc == 0) {");
self.writeln(" lux_drop(ptr, hdr->tag);");
self.writeln(" }");
self.writeln(" }");
self.writeln("}");
self.writeln("");
self.writeln("// Get current reference count (for debugging)");
self.writeln("static inline int32_t lux_refcount(void* ptr) {");
self.writeln(" return ptr ? LUX_RC_HEADER(ptr)->rc : 0;");
self.writeln("}");
self.writeln("");
self.writeln("// === String Operations ===");
self.writeln("// Dynamically created strings are RC-managed.");
self.writeln("// Static string literals from source code are NOT RC-managed.");
self.writeln("");
self.writeln("static LuxString lux_string_concat(LuxString a, LuxString b) {");
self.writeln(" size_t len_a = strlen(a);");
self.writeln(" size_t len_b = strlen(b);");
self.writeln(" LuxString result = malloc(len_a + len_b + 1);");
self.writeln(" LuxString result = (LuxString)lux_rc_alloc(len_a + len_b + 1, LUX_TAG_STRING);");
self.writeln(" memcpy(result, a, len_a);");
self.writeln(" memcpy(result + len_a, b, len_b + 1);");
self.writeln(" return result;");
@@ -389,7 +448,10 @@ impl CBackend {
self.writeln("static LuxString lux_int_to_string(LuxInt n) {");
self.writeln(" char buffer[32];");
self.writeln(" snprintf(buffer, sizeof(buffer), \"%lld\", (long long)n);");
self.writeln(" return strdup(buffer);");
self.writeln(" size_t len = strlen(buffer);");
self.writeln(" LuxString result = (LuxString)lux_rc_alloc(len + 1, LUX_TAG_STRING);");
self.writeln(" memcpy(result, buffer, len + 1);");
self.writeln(" return result;");
self.writeln("}");
self.writeln("");
self.writeln("static LuxBool lux_string_eq(LuxString a, LuxString b) {");
@@ -411,9 +473,14 @@ impl CBackend {
self.writeln(" if (fgets(buffer, sizeof(buffer), stdin)) {");
self.writeln(" size_t len = strlen(buffer);");
self.writeln(" if (len > 0 && buffer[len-1] == '\\n') buffer[len-1] = '\\0';");
self.writeln(" return strdup(buffer);");
self.writeln(" len = strlen(buffer);");
self.writeln(" LuxString result = (LuxString)lux_rc_alloc(len + 1, LUX_TAG_STRING);");
self.writeln(" memcpy(result, buffer, len + 1);");
self.writeln(" return result;");
self.writeln(" }");
self.writeln(" return strdup(\"\");");
self.writeln(" LuxString result = (LuxString)lux_rc_alloc(1, LUX_TAG_STRING);");
self.writeln(" result[0] = '\\0';");
self.writeln(" return result;");
self.writeln("}");
self.writeln("");
self.writeln("// === Evidence Passing Types ===");
@@ -589,11 +656,15 @@ impl CBackend {
self.writeln("");
self.writeln("static LuxString lux_file_read(LuxString path) {");
self.writeln(" FILE* f = fopen(path, \"r\");");
self.writeln(" if (!f) return strdup(\"\");");
self.writeln(" if (!f) {");
self.writeln(" LuxString empty = (LuxString)lux_rc_alloc(1, LUX_TAG_STRING);");
self.writeln(" empty[0] = '\\0';");
self.writeln(" return empty;");
self.writeln(" }");
self.writeln(" fseek(f, 0, SEEK_END);");
self.writeln(" long size = ftell(f);");
self.writeln(" fseek(f, 0, SEEK_SET);");
self.writeln(" char* content = malloc(size + 1);");
self.writeln(" LuxString content = (LuxString)lux_rc_alloc(size + 1, LUX_TAG_STRING);");
self.writeln(" size_t read_size = fread(content, 1, size, f);");
self.writeln(" content[read_size] = '\\0';");
self.writeln(" fclose(f);");
@@ -712,16 +783,24 @@ impl CBackend {
self.writeln(" return 0;");
self.writeln("}");
self.writeln("");
self.writeln("// Helper to create RC-managed error string");
self.writeln("static LuxString lux_rc_string(const char* s) {");
self.writeln(" size_t len = strlen(s);");
self.writeln(" LuxString result = (LuxString)lux_rc_alloc(len + 1, LUX_TAG_STRING);");
self.writeln(" memcpy(result, s, len + 1);");
self.writeln(" return result;");
self.writeln("}");
self.writeln("");
self.writeln("static LuxString lux_http_request(const char* method, LuxString url, LuxString body) {");
self.writeln(" char host[256], path[1024];");
self.writeln(" int port;");
self.writeln(" lux_http_parse_url(url, host, &port, path);");
self.writeln("");
self.writeln(" struct hostent* server = gethostbyname(host);");
self.writeln(" if (!server) return strdup(\"Error: Could not resolve host\");");
self.writeln(" if (!server) return lux_rc_string(\"Error: Could not resolve host\");");
self.writeln("");
self.writeln(" int sockfd = socket(AF_INET, SOCK_STREAM, 0);");
self.writeln(" if (sockfd < 0) return strdup(\"Error: Could not create socket\");");
self.writeln(" if (sockfd < 0) return lux_rc_string(\"Error: Could not create socket\");");
self.writeln("");
self.writeln(" struct sockaddr_in serv_addr;");
self.writeln(" memset(&serv_addr, 0, sizeof(serv_addr));");
@@ -731,7 +810,7 @@ impl CBackend {
self.writeln("");
self.writeln(" if (connect(sockfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0) {");
self.writeln(" close(sockfd);");
self.writeln(" return strdup(\"Error: Connection failed\");");
self.writeln(" return lux_rc_string(\"Error: Connection failed\");");
self.writeln(" }");
self.writeln("");
self.writeln(" char request[4096];");
@@ -753,7 +832,7 @@ impl CBackend {
self.writeln("");
self.writeln(" send(sockfd, request, strlen(request), 0);");
self.writeln("");
self.writeln(" char* response = malloc(65536);");
self.writeln(" char* response = (char*)malloc(65536);");
self.writeln(" size_t total = 0;");
self.writeln(" ssize_t n;");
self.writeln(" while ((n = recv(sockfd, response + total, 65536 - total - 1, 0)) > 0) {");
@@ -767,11 +846,14 @@ impl CBackend {
self.writeln(" char* body_start = strstr(response, \"\\r\\n\\r\\n\");");
self.writeln(" if (body_start) {");
self.writeln(" body_start += 4;");
self.writeln(" char* result = strdup(body_start);");
self.writeln(" LuxString result = lux_rc_string(body_start);");
self.writeln(" free(response);");
self.writeln(" return result;");
self.writeln(" }");
self.writeln(" return response;");
self.writeln(" // If no body separator, wrap the whole response");
self.writeln(" LuxString result = lux_rc_string(response);");
self.writeln(" free(response);");
self.writeln(" return result;");
self.writeln("}");
self.writeln("");
self.writeln("static LuxString lux_http_get(LuxString url) {");
@@ -843,11 +925,13 @@ impl CBackend {
self.writeln("typedef struct { Option_Tag tag; union { Option_Some_Data some; } data; } Option;");
self.writeln("");
self.writeln("// === List Operations ===");
self.writeln("// All lists are RC-managed. Elements are also RC-managed.");
self.writeln("");
self.writeln("static LuxList* lux_list_new(int64_t capacity) {");
self.writeln(" LuxList* list = malloc(sizeof(LuxList));");
self.writeln(" LuxList* list = (LuxList*)lux_rc_alloc(sizeof(LuxList), LUX_TAG_LIST);");
self.writeln(" if (!list) return NULL;");
self.writeln(" list->capacity = capacity > 0 ? capacity : 4;");
self.writeln(" list->elements = malloc(sizeof(void*) * list->capacity);");
self.writeln(" list->elements = (void**)malloc(sizeof(void*) * list->capacity);");
self.writeln(" list->length = 0;");
self.writeln(" return list;");
self.writeln("}");
@@ -857,15 +941,24 @@ impl CBackend {
self.writeln("");
self.writeln("static LuxList* lux_list_concat(LuxList* a, LuxList* b) {");
self.writeln(" LuxList* result = lux_list_new(a->length + b->length);");
self.writeln(" for (int64_t i = 0; i < a->length; i++) result->elements[i] = a->elements[i];");
self.writeln(" for (int64_t i = 0; i < b->length; i++) result->elements[a->length + i] = b->elements[i];");
self.writeln(" for (int64_t i = 0; i < a->length; i++) {");
self.writeln(" lux_incref(a->elements[i]);");
self.writeln(" result->elements[i] = a->elements[i];");
self.writeln(" }");
self.writeln(" for (int64_t i = 0; i < b->length; i++) {");
self.writeln(" lux_incref(b->elements[i]);");
self.writeln(" result->elements[a->length + i] = b->elements[i];");
self.writeln(" }");
self.writeln(" result->length = a->length + b->length;");
self.writeln(" return result;");
self.writeln("}");
self.writeln("");
self.writeln("static LuxList* lux_list_reverse(LuxList* list) {");
self.writeln(" LuxList* result = lux_list_new(list->length);");
self.writeln(" for (int64_t i = 0; i < list->length; i++) result->elements[i] = list->elements[list->length - 1 - i];");
self.writeln(" for (int64_t i = 0; i < list->length; i++) {");
self.writeln(" lux_incref(list->elements[list->length - 1 - i]);");
self.writeln(" result->elements[i] = list->elements[list->length - 1 - i];");
self.writeln(" }");
self.writeln(" result->length = list->length;");
self.writeln(" return result;");
self.writeln("}");
@@ -874,17 +967,26 @@ impl CBackend {
self.writeln(" if (n <= 0) return lux_list_new(0);");
self.writeln(" if (n > list->length) n = list->length;");
self.writeln(" LuxList* result = lux_list_new(n);");
self.writeln(" for (int64_t i = 0; i < n; i++) result->elements[i] = list->elements[i];");
self.writeln(" for (int64_t i = 0; i < n; i++) {");
self.writeln(" lux_incref(list->elements[i]);");
self.writeln(" result->elements[i] = list->elements[i];");
self.writeln(" }");
self.writeln(" result->length = n;");
self.writeln(" return result;");
self.writeln("}");
self.writeln("");
self.writeln("static LuxList* lux_list_drop(LuxList* list, int64_t n) {");
self.writeln(" if (n >= list->length) return lux_list_new(0);");
self.writeln(" if (n <= 0) return list;");
self.writeln(" if (n <= 0) {");
self.writeln(" lux_incref(list); // Return same list with bumped refcount");
self.writeln(" return list;");
self.writeln(" }");
self.writeln(" int64_t new_len = list->length - n;");
self.writeln(" LuxList* result = lux_list_new(new_len);");
self.writeln(" for (int64_t i = 0; i < new_len; i++) result->elements[i] = list->elements[n + i];");
self.writeln(" for (int64_t i = 0; i < new_len; i++) {");
self.writeln(" lux_incref(list->elements[n + i]);");
self.writeln(" result->elements[i] = list->elements[n + i];");
self.writeln(" }");
self.writeln(" result->length = new_len;");
self.writeln(" return result;");
self.writeln("}");
@@ -894,7 +996,8 @@ impl CBackend {
self.writeln(" int64_t len = end - start;");
self.writeln(" LuxList* result = lux_list_new(len);");
self.writeln(" for (int64_t i = 0; i < len; i++) {");
self.writeln(" LuxInt* p = malloc(sizeof(LuxInt)); *p = start + i;");
self.writeln(" LuxInt* p = (LuxInt*)lux_rc_alloc(sizeof(LuxInt), LUX_TAG_BOXED_INT);");
self.writeln(" *p = start + i;");
self.writeln(" result->elements[i] = p;");
self.writeln(" }");
self.writeln(" result->length = len;");
@@ -905,14 +1008,81 @@ impl CBackend {
self.writeln("static Option lux_option_some(void* value) { return (Option){Option_TAG_SOME, .data.some = {value}}; }");
self.writeln("");
self.writeln("// === Boxing/Unboxing ===");
self.writeln("// All boxed values are RC-managed.");
self.writeln("");
self.writeln("static void* lux_box_int(LuxInt n) { LuxInt* p = malloc(sizeof(LuxInt)); *p = n; return p; }");
self.writeln("static void* lux_box_int(LuxInt n) {");
self.writeln(" LuxInt* p = (LuxInt*)lux_rc_alloc(sizeof(LuxInt), LUX_TAG_BOXED_INT);");
self.writeln(" *p = n;");
self.writeln(" return p;");
self.writeln("}");
self.writeln("static LuxInt lux_unbox_int(void* p) { return *(LuxInt*)p; }");
self.writeln("static void* lux_box_bool(LuxBool b) { LuxBool* p = malloc(sizeof(LuxBool)); *p = b; return p; }");
self.writeln("");
self.writeln("static void* lux_box_bool(LuxBool b) {");
self.writeln(" LuxBool* p = (LuxBool*)lux_rc_alloc(sizeof(LuxBool), LUX_TAG_BOXED_BOOL);");
self.writeln(" *p = b;");
self.writeln(" return p;");
self.writeln("}");
self.writeln("static LuxBool lux_unbox_bool(void* p) { return *(LuxBool*)p; }");
self.writeln("static void* lux_box_string(LuxString s) { return s; }");
self.writeln("");
self.writeln("static void* lux_box_float(LuxFloat f) {");
self.writeln(" LuxFloat* p = (LuxFloat*)lux_rc_alloc(sizeof(LuxFloat), LUX_TAG_BOXED_FLOAT);");
self.writeln(" *p = f;");
self.writeln(" return p;");
self.writeln("}");
self.writeln("static LuxFloat lux_unbox_float(void* p) { return *(LuxFloat*)p; }");
self.writeln("");
self.writeln("static void* lux_box_string(LuxString s) {");
self.writeln(" // Strings are already char*, so we allocate a new RC-managed string");
self.writeln(" size_t len = strlen(s);");
self.writeln(" LuxString p = (LuxString)lux_rc_alloc(len + 1, LUX_TAG_STRING);");
self.writeln(" memcpy(p, s, len + 1);");
self.writeln(" return p;");
self.writeln("}");
self.writeln("static LuxString lux_unbox_string(void* p) { return (LuxString)p; }");
self.writeln("");
self.writeln("// === Polymorphic Drop Function ===");
self.writeln("// Called when an object's refcount reaches zero.");
self.writeln("// Recursively decrefs any owned references before freeing.");
self.writeln("");
self.writeln("static void lux_drop(void* ptr, int32_t tag) {");
self.writeln(" if (!ptr) return;");
self.writeln(" switch (tag) {");
self.writeln(" case LUX_TAG_STRING:");
self.writeln(" // Strings are just char arrays, no sub-references");
self.writeln(" break;");
self.writeln(" case LUX_TAG_LIST: {");
self.writeln(" LuxList* list = (LuxList*)ptr;");
self.writeln(" // Decref each element (they're all boxed/RC-managed)");
self.writeln(" for (int64_t i = 0; i < list->length; i++) {");
self.writeln(" lux_decref(list->elements[i]);");
self.writeln(" }");
self.writeln(" free(list->elements);");
self.writeln(" break;");
self.writeln(" }");
self.writeln(" case LUX_TAG_CLOSURE: {");
self.writeln(" LuxClosure* closure = (LuxClosure*)ptr;");
self.writeln(" // Decref the environment if it's RC-managed");
self.writeln(" lux_decref(closure->env);");
self.writeln(" break;");
self.writeln(" }");
self.writeln(" case LUX_TAG_BOXED_INT:");
self.writeln(" case LUX_TAG_BOXED_BOOL:");
self.writeln(" case LUX_TAG_BOXED_FLOAT:");
self.writeln(" // Primitive boxes have no sub-references");
self.writeln(" break;");
self.writeln(" case LUX_TAG_ENV:");
self.writeln(" // Environment structs may contain RC pointers");
self.writeln(" // For now, just free - proper drop needs type info");
self.writeln(" break;");
self.writeln(" default:");
self.writeln(" // ADT types (tag >= 100) - handled by generated drop functions");
self.writeln(" // For now, just free the object");
self.writeln(" break;");
self.writeln(" }");
self.writeln(" // Free the object and its RC header");
self.writeln(" free(LUX_RC_HEADER(ptr));");
self.writeln("}");
self.writeln("");
self.writeln("// === Forward Declarations ===");
self.writeln("");
}