codegen for dereference, subscript

4 files changed, 90 insertions, 24 deletions

diff --git a/05/codegen.b b/05/codegen.b
index a67a9db..7701391 100644
--- a/05/codegen.b
+++ b/05/codegen.b
@@ -963,6 +963,40 @@ function generate_stack_sub
 			emit_mov_qword_rsp_rax()             ; mov [rsp], rax			
 			return
 
+; pop a pointer off of the stack, then push the dereferenced value according to `type`
+function generate_stack_dereference
+	argument statement ; for errors
+	argument type
+	
+	local size
+	
+	size = type_sizeof(type)
+	emit_mov_rax_qword_rsp()       ; mov rax, [rsp]
+	emit_mov_reg(REG_RBX, REG_RAX) ; mov rbx, rax
+	if size == 1 goto gen_deref1
+	if size == 2 goto gen_deref2
+	if size == 4 goto gen_deref4
+	if size == 8 goto gen_deref8
+	
+	byte 0xcc ; @TODO
+	
+	:gen_deref_cast
+		emit_push_rax()
+		generate_cast_top_of_stack(statement, TYPE_UNSIGNED_LONG, type)
+		return
+	:gen_deref1
+		emit_mov_al_byte_rbx()
+		goto gen_deref_cast
+	:gen_deref2
+		emit_mov_ax_word_rbx()
+		goto gen_deref_cast
+	:gen_deref4
+		emit_mov_eax_dword_rbx()
+		goto gen_deref_cast
+	:gen_deref8
+		emit_mov_rax_qword_rbx()
+		goto gen_deref_cast
+	
 ; `statement` is used for errors
 ; returns pointer to end of expression
 function generate_push_expression
@@ -988,6 +1022,8 @@ function generate_push_expression
 	if c == EXPRESSION_SUB goto generate_sub
 	if c == EXPRESSION_GLOBAL_VARIABLE goto generate_global_variable
 	if c == EXPRESSION_LOCAL_VARIABLE goto generate_local_variable
+	if c == EXPRESSION_DEREFERENCE goto generate_dereference
+	if c == EXPRESSION_SUBSCRIPT goto generate_subscript
 	
 	die(.str_genpushexprNI)
 	:str_genpushexprNI
@@ -1075,9 +1111,10 @@ function generate_push_expression
 			goto generate_logical_not_cont
 	:generate_global_variable
 		expr += 8
-		d = *8expr ; address
-		expr += 8
-		b = type_is_array(type)
+		d = *4expr ; address
+		expr += 4
+		b = *4expr ; is array?
+		expr += 4
 		if b != 0 goto global_var_array
 		c = type_sizeof(type)
 		if c > 8 goto global_var_large
@@ -1107,11 +1144,28 @@ function generate_push_expression
 			emit_mov_rax_imm64(d) ; mov rax, (address)
 			emit_push_rax()       ; push rax
 			return expr
-	:generate_local_variable
+	:generate_dereference
+		expr += 8
+		expr = generate_push_expression(statement, expr)
+		generate_stack_dereference(statement, type)
+		return expr
+	:generate_subscript
 		expr += 8
-		d = *8expr ; rbp offset
+		c = expr + 4 ; type 1
+		c = *4c
+		expr = generate_push_expression(statement, expr)
+		d = expr + 4 ; type 2
+		d = *4d
+		expr = generate_push_expression(statement, expr)
+		generate_stack_add(statement, c, d, c)
+		generate_stack_dereference(statement, type)
+		return expr
+	:generate_local_variable
 		expr += 8
-		b = type_is_array(type)
+		d = sign_extend_32_to_64(*4expr) ; rbp offset
+		expr += 4
+		b = *4expr ; is array?
+		expr += 4
 		if b != 0 goto local_var_array
 		c = type_sizeof(type)
 		if c > 8 goto local_var_large
@@ -1139,7 +1193,6 @@ function generate_push_expression
 			emit_lea_rax_rbp_plus_imm32(d) ; lea rax, [rbp+X]
 			emit_push_rax()                ; push rax
 			return expr
-		byte 0xcc
 	:generate_float
 		expr += 8
 		emit_mov_rax_imm64(*8expr)
@@ -1211,7 +1264,7 @@ function generate_statement
 		dat1 += c
 		dat1 = 0 - dat1
 		emit_lea_rsp_rbp_plus_imm32(dat1)
-		if dat2 != 0 goto gen_local_decl_data_initializer
+		if dat4 != 0 goto gen_local_decl_data_initializer
 		return
 		
 		:gen_local_decl_initializer
@@ -1222,7 +1275,13 @@ function generate_statement
 			generate_push_expression_casted(statement, dat3, dat2)
 			return
 		:gen_local_decl_data_initializer
-			byte 0xcc ; @TODO
+			emit_mov_rax_imm64(dat4)       ; mov rax, (data address)
+			emit_mov_reg(REG_RSI, REG_RAX) ; mov rsi, rax
+			emit_mov_reg(REG_RDI, REG_RSP) ; mov rdi, rsp
+			emit_mov_rax_imm64(c)          ; mov rax, (size)
+			emit_mov_reg(REG_RCX, REG_RAX) ; mov rcx, rax
+			emit_rep_movsb()               ; rep movsb
+			return
 			
 		
 function generate_function
diff --git a/05/constants.b b/05/constants.b
index 79cd8e5..9a39ecd 100644
--- a/05/constants.b
+++ b/05/constants.b
@@ -152,8 +152,8 @@
 ;    uint type
 ; immediately following the header in memory are the arguments of the expression
 ;    - for functions, a pointer to the name of the function (we don't know where it is yet)
-;    - for local variables, the 64-bit rbp offset (number to be subtracted from rbp)
-;    - for global variables, the 64-bit runtime address
+;    - for local variables, the 32-bit rbp offset (number to be subtracted from rbp), followed by a 32-bit number, which is 1 if the variable is an array, and 0 otherwise (we can't just check `type` because that might have been decayed into a pointer) 
+;    - for global variables, the 32-bit runtime address, followed by 32-bit is_array
 ;    - for constant ints, the 64-bit integral value
 ;    - for constant floats, the 64-bit double value (even if expression has type float)
 ;    - for unary operators, the operand
diff --git a/05/main.c b/05/main.c
index f09e5ca..bf93d6f 100644
--- a/05/main.c
+++ b/05/main.c
@@ -1,7 +1,6 @@
 static char x = -2;
-
 long main(int argc, char **argv) {
-	int y = 38;
-	int z = y + x;
-	return z + x;
+	int y[] = {38, 55, -22};
+	int *z = (y+2)[-1];
+	return *z;
 }
diff --git a/05/parse.b b/05/parse.b
index e6cf2df..19593a2 100644
--- a/05/parse.b
+++ b/05/parse.b
@@ -2641,6 +2641,7 @@ function parse_expression
 		if *1p == TYPE_POINTER goto type_long ; pointer difference
 		goto type_binary_left ; pointer minus integer
 	:type_subscript
+		; @NONSTANDARD: technically 1["hello"] is legal. but why
 		type_decay_array_to_pointer_in_place(a)
 		p = types + b
 		if *1p > TYPE_UNSIGNED_LONG goto subscript_non_integer
@@ -3075,10 +3076,13 @@ function parse_expression
 			; it is a global variable
 			*1out = EXPRESSION_GLOBAL_VARIABLE
 			out += 4
-			*4out = c > 32 ; extract type
+			a = c > 32 ; extract type
+			*4out = type_create_copy(a)
+			out += 4
+			*4out = c & 0xffffffff ; extract address
+			out += 4
+			*4out = type_is_array(a)
 			out += 4
-			*8out = c & 0xffffffff ; extract address
-			out += 8
 			return out
 		:not_global
 		
@@ -3103,11 +3107,14 @@ function parse_expression
 			; it's a local variable
 			*1out = EXPRESSION_LOCAL_VARIABLE
 			out += 4
-			*4out = c > 32 ; extract type
+			a = c > 32 ; extract type
+			*4out = type_create_copy(a)
+			out += 4
+			c &= 0xffffffff ; extract rbp offset
+			*4out = c
+			out += 4
+			*4out = type_is_array(a)
 			out += 4
-			c &= 0xffffffff
-			*8out = sign_extend_32_to_64(c) ; extract rbp offset
-			out += 8
 			return out
 	:expression_integer
 		*1out = EXPRESSION_CONSTANT_INT
@@ -4100,7 +4107,8 @@ function print_expression
 	:print_local_variable
 		puts(.str_local_prefix)
 		expression += 8
-		putn_with_sign(*8expression)
+		b = sign_extend_32_to_64(*4expression)
+		putn_with_sign(b)
 		putc('])
 		expression += 8
 		return expression
@@ -4115,7 +4123,7 @@ function print_expression
 	:print_global_variable
 		puts(.str_global_at)
 		expression += 8
-		putx32(*8expression)
+		putx32(*4expression)
 		expression += 8
 		return expression
 	:print_cast