Compiler now reuses existing strings in the data, read more

If a string exists in the data, instead of being written, the function
'emitCStringToData()' will instead return the address of the match
within the data section.

Then, I can search the jump table for that address, and use the existing
jump entry or append a new one.

Fixes #168

source/toy_module_bundle.c

@@ -126,7 +126,7 @@ void Toy_bindModuleBundle(Toy_ModuleBundle* bundle, unsigned char* ptr, unsigned
 	memcpy(bundle->ptr, ptr, size);
 	bundle->count = size;
 
-	//URGENT: test this
+	//TODO: test this
 	int valid = validateModuleBundleHeader(bundle);
 
 	if (valid < 0) {

source/toy_module_compiler.c

@@ -108,44 +108,76 @@ static void emitFloat(unsigned char** handle, unsigned int* capacity, unsigned i
 //simply get the address (always an integer)
 #define CURRENT_ADDRESS(mb, part) ((*mb)->part##Count)
 
-static void emitToJumpTable(Toy_ModuleCompiler** mb, unsigned int startAddr) {
-	EMIT_INT(mb, code, (*mb)->jumpsCount); //mark the jump index in the code
-	EMIT_INT(mb, jumps, startAddr); //save address at the jump index
+//Cached write to data, enabling string reuse, see #168
+static unsigned int emitCStringToData(unsigned char** dataHandle, unsigned int* capacity, unsigned int* count, const char* cstr) {
+	const unsigned int slen = (unsigned int)strlen(cstr) + 1; //+1 for null
+
+	//See if the string already exists in the data NOTE: assumes data only ever holds c-strings
+	unsigned int pos = 0;
+	while (pos < *count) {
+		const char* entry = ((char*)(*dataHandle)) + pos;
+		unsigned int elen = strlen(entry) + 1; //+1 for null
+
+		//compare
+		if (slen == elen && strncmp(cstr, entry, slen) == 0) {
+			return pos;
+		}
+
+		//next
+		pos += (elen + 3) & ~3;
+	}
+
+	//default, append the new entry
+	unsigned int addr = *count; //save the target address
+	expand(dataHandle, capacity, count, (slen + 3) & ~3); //4-byte aligned
+	memcpy((*dataHandle) + addr, cstr, slen);
+	*count += (slen + 3) & ~3;
+
+	return addr; //return the address of the string in the data section
 }
 
 static unsigned int emitString(Toy_ModuleCompiler** mb, Toy_String* str) {
 	//4-byte alignment
 	unsigned int length = str->info.length + 1;
-	if (length % 4 != 0) {
-		length += 4 - (length % 4); //ceil
-	}
+	length = (length + 3) & ~3;
 
-	//grab the current start address
-	unsigned int startAddr = (*mb)->dataCount;
+	//the address within the data section
+	unsigned int dataAddr = 0;
 
 	//move the string into the data section
-	expand((&((*mb)->data)), &((*mb)->dataCapacity), &((*mb)->dataCount), length);
-
 	if (str->info.type == TOY_STRING_NODE) {
 		char* buffer = Toy_getStringRawBuffer(str);
-		memcpy((*mb)->data + (*mb)->dataCount, buffer, str->info.length + 1);
+
+		dataAddr = emitCStringToData(&(*mb)->data, &(*mb)->dataCapacity, &(*mb)->dataCount, buffer);
+
 		free(buffer);
 	}
 	else if (str->info.type == TOY_STRING_LEAF) {
-		memcpy((*mb)->data + (*mb)->dataCount, str->leaf.data, str->info.length + 1);
+		dataAddr = emitCStringToData(&(*mb)->data, &(*mb)->dataCapacity, &(*mb)->dataCount, str->leaf.data);
 	}
 	else if (str->info.type == TOY_STRING_NAME) {
-		memcpy((*mb)->data + (*mb)->dataCount, str->name.data, str->info.length + 1);
+		dataAddr = emitCStringToData(&(*mb)->data, &(*mb)->dataCapacity, &(*mb)->dataCount, str->name.data);
 	}
 
-	(*mb)->dataCount += length;
+	//mark the position within the jump index, reusing an existing entry if it exists
+	for (unsigned int i = 0; i < (*mb)->jumpsCount; i++) {
+		if ((*mb)->jumps[i] == dataAddr) {
+			//reuse, and finish
+			EMIT_INT(mb, code, i);
+			return 1;
+		}
+	}
 
-	//mark the jump position
-	emitToJumpTable(mb, startAddr);
+	EMIT_INT(mb, code, (*mb)->jumpsCount); //mark the new jump index in the code
+	EMIT_INT(mb, jumps, dataAddr); //append to the jump table
 
 	return 1;
 }
 
+// static unsigned int emitParameter(Toy_ModuleCompiler** mb, Toy_String* str) {
+//
+// }
+
 static unsigned int writeModuleCompilerCode(Toy_ModuleCompiler** mb, Toy_Ast* ast); //forward declare for recursion
 static unsigned int writeInstructionAssign(Toy_ModuleCompiler** mb, Toy_AstVarAssign ast, bool chainedAssignment); //forward declare for chaining of var declarations
 

tests/cases/test_module_compiler.c

@@ -1309,6 +1309,90 @@ int test_compiler_keywords(Toy_Bucket** bucketHandle) {
 	return 0;
 }
 
+int test_compiler_string_reuse(Toy_Bucket** bucketHandle) {
+	//test string literals
+	{
+		//setup
+		const char* source = "var first: string = \"Hello world\"; var second: string = \"Hello world\";";
+		Toy_Lexer lexer;
+		Toy_Parser parser;
+
+		Toy_bindLexer(&lexer, source);
+		Toy_bindParser(&parser, &lexer);
+		Toy_Ast* ast = Toy_scanParser(bucketHandle, &parser);
+
+		//run
+		unsigned char* buffer = Toy_compileModule(ast);
+
+		//check header
+		int* ptr = (int*)buffer;
+
+		if ((ptr++)[0] != 108 || //total size
+			(ptr++)[0] != 12 || //jump count
+			(ptr++)[0] != 0 || //param count
+			(ptr++)[0] != 28 || //data count
+			(ptr++)[0] != 0 || //subs count
+			(ptr++)[0] != 32 || //code addr
+			(ptr++)[0] != 68 || //jumps addr
+			(ptr++)[0] != 80 || //data addr
+			false) //terminator
+		{
+			fprintf(stderr, TOY_CC_ERROR "ERROR: failed to reuse strings in module header, source: %s\n" TOY_CC_RESET, source);
+
+			//cleanup and return
+			free(buffer);
+			return -1;
+		}
+
+		//check code
+		if (*((unsigned char*)(buffer + 32)) != TOY_OPCODE_READ ||
+			*((unsigned char*)(buffer + 33)) != TOY_VALUE_STRING ||
+			*((unsigned char*)(buffer + 34)) != TOY_STRING_LEAF ||
+			*((unsigned char*)(buffer + 35)) != 0 ||
+
+			*((unsigned int*)(buffer + 36)) != 0 ||
+
+			*((unsigned char*)(buffer + 40)) != TOY_OPCODE_DECLARE ||
+			*((unsigned char*)(buffer + 41)) != TOY_VALUE_STRING ||
+			*((unsigned char*)(buffer + 42)) != 5 ||
+			*((unsigned char*)(buffer + 43)) != 0 ||
+
+			*((unsigned int*)(buffer + 44)) != 4 ||
+
+			*((unsigned char*)(buffer + 48)) != TOY_OPCODE_READ ||
+			*((unsigned char*)(buffer + 49)) != TOY_VALUE_STRING ||
+			*((unsigned char*)(buffer + 50)) != TOY_STRING_LEAF ||
+			*((unsigned char*)(buffer + 51)) != 0 ||
+
+			*((unsigned int*)(buffer + 52)) != 0 || //duplicate
+
+			*((unsigned char*)(buffer + 56)) != TOY_OPCODE_DECLARE ||
+			*((unsigned char*)(buffer + 57)) != TOY_VALUE_STRING ||
+			*((unsigned char*)(buffer + 58)) != 6 ||
+			*((unsigned char*)(buffer + 59)) != 0 ||
+
+			*((unsigned int*)(buffer + 60)) != 8 ||
+
+			*((unsigned char*)(buffer + 64)) != TOY_OPCODE_RETURN ||
+			*((unsigned char*)(buffer + 65)) != 0 ||
+			*((unsigned char*)(buffer + 66)) != 0 ||
+			*((unsigned char*)(buffer + 67)) != 0
+		)
+		{
+			fprintf(stderr, TOY_CC_ERROR "ERROR: failed to produce the expected module code, source: %s\n" TOY_CC_RESET, source);
+
+			//cleanup and return
+			free(buffer);
+			return -1;
+		}
+
+		//cleanup
+		free(buffer);
+	}
+
+	return 0;
+}
+
 int main(void) {
 	//run each test set, returning the total errors given
 	int total = 0, res = 0;
@@ -1343,5 +1427,15 @@ int main(void) {
 		total += res;
 	}
 
+	{
+		Toy_Bucket* bucket = Toy_allocateBucket(TOY_BUCKET_IDEAL);
+		res = test_compiler_string_reuse(&bucket);
+		Toy_freeBucket(&bucket);
+		if (res == 0) {
+			printf(TOY_CC_NOTICE "All good\n" TOY_CC_RESET);
+		}
+		total += res;
+	}
+
 	return total;
 }