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External mode compiler: Detect some non-lvalue modification attempts
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@solardiz
solardiz committed May 19, 2024
1 parent 658bd0d commit f693040
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Showing 2 changed files with 30 additions and 19 deletions.
47 changes: 29 additions & 18 deletions src/compiler.c
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Original file line number Diff line number Diff line change
Expand Up @@ -104,12 +104,15 @@ static char *c_reserved[] = {
#define C_CLASS_LEFT 1
#define C_CLASS_RIGHT 2

#define C_LVALUE 1

struct c_op {
int prec;
int dir;
int class;
char *name;
void (*op)(void);
int lvalue;
};

#ifdef __GNUC__
Expand Down Expand Up @@ -441,6 +444,10 @@ static void c_subexpr(void (**last)(void), const struct c_op *op)
{
/* Compile-time evaluate binary op after push_imm_imm */
if (op->class == C_CLASS_BINARY && *last == c_op_push_imm_imm) {
if (op->lvalue) {
c_errno = C_ERROR_EXPR;
return;
}
/* Patch push_imm_imm to push_imm of operation result */
*last = c_op_push_imm;
if (c_pass) {
Expand All @@ -460,9 +467,13 @@ static void c_subexpr(void (**last)(void), const struct c_op *op)
/* Unimplemented, need to start tracking penultimate op first */

/* Compile-time evaluate unary op after any push ending in imm */
if (op->class == C_CLASS_LEFT && (*last == c_op_push_imm ||
if (op->class != C_CLASS_BINARY && (*last == c_op_push_imm ||
*last == c_op_push_imm_imm || *last == c_op_push_mem_imm ||
*last == c_op_push_mem_mem_mem_imm)) {
if (op->lvalue) {
c_errno = C_ERROR_EXPR;
return;
}
/* Patch the last immediate operand with operation result */
if (c_pass) {
c_stack[1].mem = &(c_code_ptr - 1)->imm;
Expand Down Expand Up @@ -575,7 +586,7 @@ static int c_expr(char term, struct c_ident *vars, char *token, int pop)
if ((c == ')' && stack[sp] >= 0) ||
(c == ']' && stack[sp]) ||
((c == ';' || (term != ')' && c == term)) && sp))
c_errno = C_ERROR_COUNT;
c_errno = C_ERROR_EXPR;
if (c_errno || (!sp && c == term)) break;

left = 1;
Expand Down Expand Up @@ -661,7 +672,7 @@ static int c_expr(char term, struct c_ident *vars, char *token, int pop)

if (c_errno) return c_errno;

if (sp || balance) c_errno = C_ERROR_COUNT;
if (sp || balance) c_errno = C_ERROR_EXPR;

if (pop) {
if (last == c_op_assign) {
Expand Down Expand Up @@ -1653,17 +1664,17 @@ static void (*c_op_assign_pop)(void) = c_f_op_assign_pop;
/* Must be in the same order as ops[] in c_execute_fast() */
static struct c_op c_ops[] = {
{1, C_LEFT_TO_RIGHT, C_CLASS_BINARY, "[", c_op_index},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "=", c_f_op_assign},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "+=", c_op_add_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "-=", c_op_sub_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "*=", c_op_mul_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "/=", c_op_div_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "%=", c_op_mod_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "|=", c_op_or_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "^=", c_op_xor_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "&=", c_op_and_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "<<=", c_op_shl_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, ">>=", c_op_shr_a},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "=", c_f_op_assign, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "+=", c_op_add_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "-=", c_op_sub_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "*=", c_op_mul_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "/=", c_op_div_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "%=", c_op_mod_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "|=", c_op_or_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "^=", c_op_xor_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "&=", c_op_and_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, "<<=", c_op_shl_a, C_LVALUE},
{2, C_RIGHT_TO_LEFT, C_CLASS_BINARY, ">>=", c_op_shr_a, C_LVALUE},
{3, C_LEFT_TO_RIGHT, C_CLASS_BINARY, "||", c_op_or_i},
{4, C_LEFT_TO_RIGHT, C_CLASS_BINARY, "&&", c_op_and_b},
{5, C_LEFT_TO_RIGHT, C_CLASS_BINARY, "|", c_op_or_i},
Expand All @@ -1685,10 +1696,10 @@ static struct c_op c_ops[] = {
{13, C_RIGHT_TO_LEFT, C_CLASS_LEFT, "!", c_op_not_b},
{13, C_RIGHT_TO_LEFT, C_CLASS_LEFT, "~", c_op_not_i},
{13, C_RIGHT_TO_LEFT, C_CLASS_LEFT, "-", c_op_neg},
{13, C_RIGHT_TO_LEFT, C_CLASS_LEFT, "++", c_op_inc_l},
{13, C_RIGHT_TO_LEFT, C_CLASS_LEFT, "--", c_op_dec_l},
{14, C_LEFT_TO_RIGHT, C_CLASS_RIGHT, "++", c_op_inc_r},
{14, C_LEFT_TO_RIGHT, C_CLASS_RIGHT, "--", c_op_dec_r},
{13, C_RIGHT_TO_LEFT, C_CLASS_LEFT, "++", c_op_inc_l, C_LVALUE},
{13, C_RIGHT_TO_LEFT, C_CLASS_LEFT, "--", c_op_dec_l, C_LVALUE},
{14, C_LEFT_TO_RIGHT, C_CLASS_RIGHT, "++", c_op_inc_r, C_LVALUE},
{14, C_LEFT_TO_RIGHT, C_CLASS_RIGHT, "--", c_op_dec_r, C_LVALUE},
#ifdef PRINT_INSNS
{0, 0, 0, "return", c_f_op_return},
{0, 0, 0, "bz", c_f_op_bz},
Expand Down
2 changes: 1 addition & 1 deletion src/compiler.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@
#define C_ERROR_NONE 0
#define C_ERROR_UNKNOWN 1
#define C_ERROR_UNEXPECTED 2
#define C_ERROR_COUNT 3
#define C_ERROR_EXPR 3
#define C_ERROR_TOOLONG 4
#define C_ERROR_TOOCOMPLEX 5
#define C_ERROR_ARRAYSIZE 6
Expand Down

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