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codegen.c
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codegen.c
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#include "slimcc.h"
#define GP_MAX 6
#define FP_MAX 8
#define GP_SLOTS 6
#define FP_SLOTS 6
static FILE *output_file;
static char *argreg8[] = {"%dil", "%sil", "%dl", "%cl", "%r8b", "%r9b"};
static char *argreg16[] = {"%di", "%si", "%dx", "%cx", "%r8w", "%r9w"};
static char *argreg32[] = {"%edi", "%esi", "%edx", "%ecx", "%r8d", "%r9d"};
static char *argreg64[] = {"%rdi", "%rsi", "%rdx", "%rcx", "%r8", "%r9"};
static char *tmpreg32[] = {"%edi", "%esi", "%r8d", "%r9d", "%r10d", "%r11d"};
static char *tmpreg64[] = {"%rdi", "%rsi", "%r8", "%r9", "%r10", "%r11"};
static Obj *current_fn;
static char *lvar_ptr;
static int va_gp_start;
static int va_fp_start;
static int va_st_start;
static int vla_base_ofs;
static int rtn_ptr_ofs;
static int lvar_stk_sz;
static int peak_stk_usage;
bool dont_reuse_stack;
typedef enum {
SL_GP,
SL_FP,
SL_ST,
} SlotKind;
typedef struct {
SlotKind kind;
int gp_depth;
int fp_depth;
int st_depth;
int st_ofs;
long loc;
} Slot;
struct {
Slot *data;
int capacity;
int depth;
} static tmp_stack;
static void store_gp2(char **reg, int sz, int ofs, char *ptr);
static void gen_expr(Node *node);
static void gen_stmt(Node *node);
static bool gen_expr_opt(Node *node);
static bool gen_addr_opt(Node *node);
static void imm_add(char *op, char *tmp, int64_t val);
static void imm_sub(char *op, char *tmp, int64_t val);
static void imm_and(char *op, char *tmp, int64_t val);
static void imm_cmp(char *op, char *tmp, int64_t val);
FMTCHK(1,2)
static void println(char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
vfprintf(output_file, fmt, ap);
va_end(ap);
fprintf(output_file, "\n");
}
static long resrvln(void) {
long loc = ftell(output_file);
fprintf(output_file, " \n");
return loc;
}
FMTCHK(1,3)
static void insrtln(char *fmt, long loc, ...) {
long cur_loc = ftell(output_file);
fseek(output_file, loc, SEEK_SET);
va_list ap;
va_start(ap, loc);
vfprintf(output_file, fmt, ap);
va_end(ap);
fseek(output_file, cur_loc, SEEK_SET);
}
static int count(void) {
static int i = 1;
return i++;
}
static bool is_gp_ty(Type *ty) {
return is_integer(ty) || ty->kind == TY_PTR;
}
static bool is_scalar(Type *ty) {
return is_numeric(ty) || ty->kind == TY_PTR;
}
static bool is_pow_of_two(uint64_t val) {
return !(val & (val - 1));
}
static bool in_imm_range (int64_t val) {
return val == (int32_t)val;
}
static bool is_imm_num(Node *node) {
return node->kind == ND_NUM && is_integer(node->ty) && in_imm_range(node->val);
}
static bool is_lvar(Node *node) {
return node->kind == ND_VAR && node->var->is_local;
}
bool is_trivial_arg(Node *arg) {
if (!opt_optimize)
return false;
return is_lvar(arg) || (arg->kind == ND_ADDR && is_lvar(arg->lhs)) ||
(arg->kind == ND_NUM && arg->ty->kind != TY_LDOUBLE) || is_nullptr(arg);
}
static bool is_int_to_int_cast(Node *node) {
return node->kind == ND_CAST && is_integer(node->ty) && is_integer(node->lhs->ty);
}
static bool has_defr(Node *node) {
return node->defr_start != node->defr_end;
}
static void clobber_all_regs(void) {
for (int i = 0; i < tmp_stack.depth; i++)
tmp_stack.data[i].kind = SL_ST;
}
static void clobber_gp(int i) {
if (tmp_stack.depth > 0) {
Slot *sl = &tmp_stack.data[tmp_stack.depth - 1];
sl->gp_depth = MAX(sl->gp_depth, i);
}
}
static void push_tmpstack(SlotKind kind) {
if (tmp_stack.depth == tmp_stack.capacity) {
tmp_stack.capacity += 4;
tmp_stack.data = realloc(tmp_stack.data, sizeof(Slot) * tmp_stack.capacity);
}
long loc = resrvln();
Slot sl = {.kind = kind, .loc = loc};
tmp_stack.data[tmp_stack.depth] = sl;
tmp_stack.depth++;
return;
}
static Slot *pop_tmpstack(int sz) {
tmp_stack.depth--;
assert(tmp_stack.depth >= 0);
Slot *sl = &tmp_stack.data[tmp_stack.depth];
if ((sl->kind == SL_GP && sl->gp_depth >= GP_SLOTS) ||
(sl->kind == SL_FP && sl->fp_depth >= FP_SLOTS))
sl->kind = SL_ST;
if (tmp_stack.depth > 0) {
Slot *sl2 = &tmp_stack.data[tmp_stack.depth - 1];
sl2->gp_depth = MAX(sl2->gp_depth, sl->gp_depth + (sl->kind == SL_GP));
sl2->fp_depth = MAX(sl2->fp_depth, sl->fp_depth + (sl->kind == SL_FP));
sl2->st_depth = MAX(sl2->st_depth, sl->st_depth + (sl->kind == SL_ST) * sz);
}
if (sl->kind == SL_ST) {
if (dont_reuse_stack) {
peak_stk_usage += sz * 8;
sl->st_ofs = -peak_stk_usage;
} else {
int bottom = lvar_stk_sz + (sl->st_depth + sz) * 8;
peak_stk_usage = MAX(peak_stk_usage, bottom);
sl->st_ofs = -bottom;
}
}
return sl;
}
static void push(void) {
push_tmpstack(SL_GP);
}
static char *pop_gp(bool is_r64, char *dest_reg, bool must_be_dest) {
char *ax = is_r64 ? "%rax" : "%eax";
Slot *sl = pop_tmpstack(1);
if (sl->kind == SL_GP) {
char *pop_reg = (is_r64 ? tmpreg64 : tmpreg32)[sl->gp_depth];
insrtln(" mov %s, %s", sl->loc, ax, pop_reg);
if (!must_be_dest)
return pop_reg;
println(" mov %s, %s", pop_reg, dest_reg);
return dest_reg;
}
insrtln(" mov %s, %d(%s)", sl->loc, ax, sl->st_ofs, lvar_ptr);
println(" mov %d(%s), %s", sl->st_ofs, lvar_ptr, dest_reg);
return dest_reg;
}
static char *pop_inreg2(bool is_r64, char *fallback_reg) {
return pop_gp(is_r64, fallback_reg, false);
}
static char *pop_inreg(char *fallback_reg) {
return pop_inreg2(true, fallback_reg);
}
static void pop2(bool is_r64, char *arg) {
pop_gp(is_r64, arg, true);
}
static void pop(char *arg) {
pop2(true, arg);
}
static void pushf(void) {
push_tmpstack(SL_FP);
}
static int pop_fp(bool is_xmm64, int dest_reg, bool must_be_dest) {
Slot *sl = pop_tmpstack(1);
char *mv = is_xmm64 ? "movsd" : "movss";
if (sl->kind == SL_FP) {
int pop_reg = sl->fp_depth + 2;
insrtln(" %s %%xmm0, %%xmm%d", sl->loc, mv, pop_reg);
if (!must_be_dest)
return pop_reg;
println(" %s %%xmm%d, %%xmm%d", mv, pop_reg, dest_reg);
return dest_reg;
}
insrtln(" %s %%xmm0, %d(%s)", sl->loc, mv, sl->st_ofs, lvar_ptr);
println(" %s %d(%s), %%xmm%d", mv, sl->st_ofs, lvar_ptr, dest_reg);
return dest_reg;
}
static int popf_inreg(bool is_xmm64, int reg) {
return pop_fp(is_xmm64, reg, false);
}
static int popf(int reg) {
return pop_fp(true, reg, true);
}
static void push_x87(void) {
push_tmpstack(SL_ST);
}
static bool pop_x87(void) {
Slot *sl = pop_tmpstack(2);
insrtln(" fstpt %d(%s)", sl->loc, sl->st_ofs, lvar_ptr);
println(" fldt %d(%s)", sl->st_ofs, lvar_ptr);
return true;
}
static void push_by_ty(Type *ty) {
switch (ty->kind) {
case TY_LDOUBLE: push_x87(); return;
case TY_DOUBLE:
case TY_FLOAT: pushf(); return;
default: push(); return;
}
}
static void pop_by_ty(Type *ty) {
switch (ty->kind) {
case TY_LDOUBLE: pop_x87(); return;
case TY_DOUBLE:
case TY_FLOAT: popf(0); return;
default: pop("%rax"); return;
}
}
static void push_copy(int sz) {
assert(sz > 0);
for (int ofs = ((sz - 1) / 8 * 8); ofs >= 0; ofs -= 8)
push_tmpstack(SL_ST);
}
static void pop_copy(int sz, char *sptr) {
assert(sz > 0);
int pos;
for (int ofs = ((sz - 1) / 8 * 8); ofs >= 0; ofs -= 8) {
Slot *sl = pop_tmpstack(1);
pos = sl->st_ofs;
insrtln(" mov %d(%s), %%rdx; mov %%rdx, %d(%s)", sl->loc, ofs, sptr, sl->st_ofs, lvar_ptr);
}
println(" lea %d(%s), %s", pos, lvar_ptr, sptr);
}
// When we load a char or a short value to a register, we always
// extend them to the size of int, so we can assume the lower half of
// a register always contains a valid value.
static void load_extend_int(Type *ty, int ofs, char *ptr, char *reg) {
char *insn = ty->is_unsigned ? "movz" : "movs";
switch (ty->size) {
case 1: println(" %sbl %d(%s), %s", insn, ofs, ptr, reg); return;
case 2: println(" %swl %d(%s), %s", insn, ofs, ptr, reg); return;
case 4: println(" movl %d(%s), %s", ofs, ptr, reg); return;
case 8: println(" mov %d(%s), %s", ofs, ptr, reg); return;
}
internal_error();
}
static void load_extend_int64(Node *node, char *reg) {
switch (node->ty->size) {
case 4: println(" movslq %d(%s), %s", node->var->ofs, node->var->ptr, reg); return;
case 2: println(" movswq %d(%s), %s", node->var->ofs, node->var->ptr, reg); return;
case 1: println(" movsbq %d(%s), %s", node->var->ofs, node->var->ptr, reg); return;
}
internal_error();
}
// Round up `n` to the nearest multiple of `align`. For instance,
// align_to(5, 8) returns 8 and align_to(11, 8) returns 16.
int align_to(int n, int align) {
return (n + align - 1) / align * align;
}
static char *reg_dx(int sz) {
switch (sz) {
case 1: return "%dl";
case 2: return "%dx";
case 4: return "%edx";
case 8: return "%rdx";
}
internal_error();
}
static char *reg_ax(int sz) {
switch (sz) {
case 1: return "%al";
case 2: return "%ax";
case 4: return "%eax";
case 8: return "%rax";
}
internal_error();
}
static char *regop_ax(Type *ty) {
switch (ty->size) {
case 1:
case 2:
case 4: return "%eax";
case 8: return "%rax";
}
internal_error();
}
static void gen_mem_copy(int sofs, char *sptr, int dofs, char *dptr, int sz) {
for (int i = 0; i < sz;) {
int rem = sz - i;
if (rem >= 16) {
println(" movups %d(%s), %%xmm0", i + sofs, sptr);
println(" movups %%xmm0, %d(%s)", i + dofs, dptr);
i += 16;
continue;
}
int p2 = (rem >= 8) ? 8 : (rem >= 4) ? 4 : (rem >= 2) ? 2 : 1;
println(" mov %d(%s), %s", i + sofs, sptr, reg_dx(p2));
println(" mov %s, %d(%s)", reg_dx(p2), i + dofs, dptr);
i += p2;
}
}
static void gen_mem_zero(int dofs, char *dptr, int sz) {
if (sz >= 16) {
println(" xorps %%xmm0, %%xmm0");
for (int i = 0; i < sz;) {
if (sz < i + 16)
i = sz - 16;
println(" movups %%xmm0, %d(%s)", i + dofs, dptr);
i += 16;
}
return;
}
println(" xor %%eax, %%eax");
for (int i = 0; i < sz;) {
int rem = sz - i;
int p2 = (rem >= 8) ? 8 : (rem >= 4) ? 4 : (rem >= 2) ? 2 : 1;
println(" mov %s, %d(%s)", reg_ax(p2), i + dofs, dptr);
i += p2;
}
}
static void gen_cmp_setx(NodeKind kind, bool is_unsigned) {
char *ins;
switch (kind) {
case ND_EQ: ins = "sete"; break;
case ND_NE: ins = "setne"; break;
case ND_LT: ins = is_unsigned ? "setb" : "setl"; break;
case ND_LE: ins = is_unsigned ? "setbe" : "setle"; break;
case ND_GT: ins = is_unsigned ? "seta" : "setg"; break;
case ND_GE: ins = is_unsigned ? "setae" : "setge"; break;
default: internal_error();
}
println(" %s %%al", ins);
println(" movzbl %%al, %%eax");
}
static void gen_bit_extract(Type *ty, int bit_width, int bit_offset) {
if (bit_offset == 0 && bit_width == ty->size * 8)
return;
char *ax;
int reg_width;
if (ty->size == 8)
ax = "%rax", reg_width = 64;
else
ax = "%eax", reg_width = 32;
if (bit_offset == 0 && ty->is_unsigned) {
imm_and(ax, "%rdx", (1LL << bit_width) - 1);
return;
}
println(" shl $%d, %s", reg_width - bit_width - bit_offset, ax);
if (ty->is_unsigned)
println(" shr $%d, %s", reg_width - bit_width, ax);
else
println(" sar $%d, %s", reg_width - bit_width, ax);
}
// Compute the absolute address of a given node.
// It's an error if a given node does not reside in memory.
static void gen_addr(Node *node) {
if (opt_optimize && gen_addr_opt(node))
return;
switch (node->kind) {
case ND_VAR:
// Variable-length array, which is always local.
if (node->var->ty->kind == TY_VLA) {
println(" mov %d(%s), %%rax", node->var->ofs, node->var->ptr);
return;
}
// Local variable
if (node->var->is_local) {
println(" lea %d(%s), %%rax", node->var->ofs, node->var->ptr);
return;
}
if (opt_fpic) {
// Thread-local variable
if (node->var->is_tls) {
clobber_all_regs();
println(" data16 lea \"%s\"@tlsgd(%%rip), %%rdi", node->var->name);
println(" .value 0x6666");
println(" rex64");
println(" call __tls_get_addr@PLT");
return;
}
// Function or global variable
println(" mov \"%s\"@GOTPCREL(%%rip), %%rax", node->var->name);
return;
}
// Thread-local variable
if (node->var->is_tls) {
println(" mov %%fs:0, %%rax");
println(" add $\"%s\"@tpoff, %%rax", node->var->name);
return;
}
// Here, we generate an absolute address of a function or a global
// variable. Even though they exist at a certain address at runtime,
// their addresses are not known at link-time for the following
// two reasons.
//
// - Address randomization: Executables are loaded to memory as a
// whole but it is not known what address they are loaded to.
// Therefore, at link-time, relative address in the same
// exectuable (i.e. the distance between two functions in the
// same executable) is known, but the absolute address is not
// known.
//
// - Dynamic linking: Dynamic shared objects (DSOs) or .so files
// are loaded to memory alongside an executable at runtime and
// linked by the runtime loader in memory. We know nothing
// about addresses of global stuff that may be defined by DSOs
// until the runtime relocation is complete.
//
// In order to deal with the former case, we use RIP-relative
// addressing, denoted by `(%rip)`. For the latter, we obtain an
// address of a stuff that may be in a shared object file from the
// Global Offset Table using `@GOTPCREL(%rip)` notation.
// Function
if (node->ty->kind == TY_FUNC) {
if (node->var->is_definition)
println(" lea \"%s\"(%%rip), %%rax", node->var->name);
else
println(" mov \"%s\"@GOTPCREL(%%rip), %%rax", node->var->name);
return;
}
// Global variable
println(" lea \"%s\"(%%rip), %%rax", node->var->name);
return;
case ND_DEREF:
gen_expr(node->lhs);
return;
case ND_CHAIN:
case ND_COMMA:
gen_expr(node->lhs);
gen_addr(node->rhs);
return;
case ND_MEMBER:
switch (node->lhs->kind) {
case ND_FUNCALL:
case ND_ASSIGN:
case ND_COND:
case ND_STMT_EXPR:
case ND_VA_ARG:
gen_expr(node->lhs);
imm_add("%rax", "%rdx", node->member->offset);
return;
default:
gen_addr(node->lhs);
imm_add("%rax", "%rdx", node->member->offset);
return;
}
}
error_tok(node->tok, "not an lvalue");
}
static void load2(Type *ty, int sofs, char *sptr) {
switch (ty->kind) {
case TY_FLOAT:
println(" movss %d(%s), %%xmm0", sofs, sptr);
return;
case TY_DOUBLE:
println(" movsd %d(%s), %%xmm0", sofs, sptr);
return;
case TY_LDOUBLE:
println(" fninit; fldt %d(%s)", sofs, sptr);
return;
}
load_extend_int(ty, sofs, sptr, regop_ax(ty));
}
// Load a value from where %rax is pointing to.
static void load(Type *ty) {
if (is_scalar(ty)) {
load2(ty, 0, "%rax");
return;
}
switch (ty->kind) {
case TY_ARRAY:
case TY_STRUCT:
case TY_UNION:
case TY_FUNC:
case TY_VLA:
// If it is an array, do not attempt to load a value to the
// register because in general we can't load an entire array to a
// register. As a result, the result of an evaluation of an array
// becomes not the array itself but the address of the array.
// This is where "array is automatically converted to a pointer to
// the first element of the array in C" occurs.
return;
}
internal_error();
}
static void store2(Type *ty, int dofs, char *dptr) {
switch (ty->kind) {
case TY_ARRAY:
case TY_STRUCT:
case TY_UNION:
gen_mem_copy(0, "%rax", dofs, dptr, ty->size);
return;
case TY_FLOAT:
println(" movss %%xmm0, %d(%s)", dofs, dptr);
return;
case TY_DOUBLE:
println(" movsd %%xmm0, %d(%s)", dofs, dptr);
return;
case TY_LDOUBLE:
println(" fstpt %d(%s)", dofs, dptr);
println(" fninit; fldt %d(%s)", dofs, dptr);
return;
}
println(" mov %s, %d(%s)", reg_ax(ty->size), dofs, dptr);
}
// Store %rax to an address that the stack top is pointing to.
static void store(Type *ty) {
char *reg = pop_inreg(tmpreg64[0]);
store2(ty, 0, reg);
}
static void cmp_zero(Type *ty) {
switch (ty->kind) {
case TY_FLOAT:
println(" xorps %%xmm1, %%xmm1");
println(" ucomiss %%xmm1, %%xmm0");
return;
case TY_DOUBLE:
println(" xorpd %%xmm1, %%xmm1");
println(" ucomisd %%xmm1, %%xmm0");
return;
case TY_LDOUBLE:
println(" fldz");
println(" fucomip");
println(" fstp %%st(0)");
return;
}
if (is_integer(ty) && ty->size <= 4)
println(" test %%eax, %%eax");
else
println(" test %%rax, %%rax");
}
static void load_val2(Type *ty, int64_t val, char *gp32, char *gp64) {
if (val == 0) {
println(" xor %s, %s", gp32, gp32);
return;
}
if (ty->size <= 4 ? in_imm_range(val) : (uint64_t)val <= UINT32_MAX) {
println(" movl $%"PRIi64", %s", val, gp32);
return;
}
println(" mov $%"PRIi64", %s", val, gp64);
}
static void load_val(Type *ty, int64_t val) {
load_val2(ty, val, "%eax", "%rax");
}
static void load_fval2(Type *ty, long double fval, int reg) {
if (ty->kind == TY_FLOAT) {
float pos_z = +0.0f;
float fv = fval;
if (!memcmp(&pos_z, &fv, sizeof(float))) {
println(" xorps %%xmm%d, %%xmm%d", reg, reg);
return;
}
union { float f32; uint32_t u32; } u = { fval };
println(" movl $%u, %%eax", u.u32);
println(" movd %%eax, %%xmm%d", reg);
return;
}
double pos_z = +0.0;
double dv = fval;
if (!memcmp(&pos_z, &dv, sizeof(double))) {
println(" xorps %%xmm%d, %%xmm%d", reg, reg);
return;
}
union { double f64; uint64_t u64; } u = { fval };
println(" movq $%lu, %%rax", u.u64);
println(" movq %%rax, %%xmm%d", reg);
return;
}
static void load_fval(Type *ty, long double fval) {
if (ty->kind == TY_FLOAT || ty->kind == TY_DOUBLE) {
load_fval2(ty, fval, 0);
return;
}
long double pos_z = +0.0L;
if (!memcmp(&pos_z, &fval, 10)) {
println(" fninit; fldz");
return;
}
long double neg_z = -0.0L;
if (!memcmp(&neg_z, &fval, 10)) {
println(" fninit; fldz");
println(" fchs");
return;
}
if (fval == 1) {
println(" fninit; fld1");
return;
}
if (fval == -1) {
println(" fninit; fld1");
println(" fchs");
return;
}
union { long double f80; uint64_t u64[2]; } u;
memset(&u, 0, sizeof(u));
u.f80 = fval;
println(" movq $%lu, %%rax", u.u64[0]);
println(" movw $%lu, %%dx", u.u64[1]);
println(" push %%rdx");
println(" push %%rax");
println(" fninit; fldt (%%rsp)");
println(" add $16, %%rsp");
return;
}
enum { I8, I16, I32, I64, U8, U16, U32, U64, F32, F64, F80 };
static int getTypeId(Type *ty) {
switch (ty->kind) {
case TY_PCHAR:
case TY_CHAR:
return ty->is_unsigned ? U8 : I8;
case TY_SHORT:
return ty->is_unsigned ? U16 : I16;
case TY_INT:
return ty->is_unsigned ? U32 : I32;
case TY_LONG:
case TY_LONGLONG:
return ty->is_unsigned ? U64 : I64;
case TY_FLOAT:
return F32;
case TY_DOUBLE:
return F64;
case TY_LDOUBLE:
return F80;
}
return U64;
}
// The table for type casts
static char i32i8[] = "movsbl %al, %eax";
static char i32u8[] = "movzbl %al, %eax";
static char i32i16[] = "movswl %ax, %eax";
static char i32u16[] = "movzwl %ax, %eax";
static char i32f32[] = "cvtsi2ssl %eax, %xmm0";
static char i32i64[] = "movslq %eax, %rax";
static char i32f64[] = "cvtsi2sdl %eax, %xmm0";
static char i32f80[] = "push %rax; fildl (%rsp); pop %rax";
static char u32f32[] = "mov %eax, %eax; cvtsi2ssq %rax, %xmm0";
static char u32i64[] = "mov %eax, %eax";
static char u32f64[] = "mov %eax, %eax; cvtsi2sdq %rax, %xmm0";
static char u32f80[] = "mov %eax, %eax; push %rax; fildll (%rsp); pop %rax";
static char i64f32[] = "cvtsi2ssq %rax, %xmm0";
static char i64f64[] = "cvtsi2sdq %rax, %xmm0";
static char i64f80[] = "push %rax; fildll (%rsp); pop %rax";
static char u64f32[] =
"test %rax,%rax; js 1f; pxor %xmm0,%xmm0; cvtsi2ss %rax,%xmm0; jmp 2f; "
"1: mov %rax,%rdx; and $1,%eax; pxor %xmm0,%xmm0; shr %rdx; "
"or %rax,%rdx; cvtsi2ss %rdx,%xmm0; addss %xmm0,%xmm0; 2:";
static char u64f64[] =
"test %rax,%rax; js 1f; pxor %xmm0,%xmm0; cvtsi2sd %rax,%xmm0; jmp 2f; "
"1: mov %rax,%rdx; and $1,%eax; pxor %xmm0,%xmm0; shr %rdx; "
"or %rax,%rdx; cvtsi2sd %rdx,%xmm0; addsd %xmm0,%xmm0; 2:";
static char u64f80[] =
"push %rax; fildq (%rsp); test %rax, %rax; jns 1f;"
"mov $1602224128, %eax; mov %eax, 4(%rsp); fadds 4(%rsp); 1:; pop %rax";
static char f32i8[] = "cvttss2sil %xmm0, %eax; movsbl %al, %eax";
static char f32u8[] = "cvttss2sil %xmm0, %eax; movzbl %al, %eax";
static char f32i16[] = "cvttss2sil %xmm0, %eax; movswl %ax, %eax";
static char f32u16[] = "cvttss2sil %xmm0, %eax; movzwl %ax, %eax";
static char f32i32[] = "cvttss2sil %xmm0, %eax";
static char f32u32[] = "cvttss2siq %xmm0, %rax";
static char f32i64[] = "cvttss2siq %xmm0, %rax";
static char f32u64[] =
"cvttss2siq %xmm0, %rcx; movq %rcx, %rdx; movl $0x5F000000, %eax; "
"movd %eax, %xmm1; subss %xmm1, %xmm0; cvttss2siq %xmm0, %rax; "
"sarq $63, %rdx; andq %rdx, %rax; orq %rcx, %rax;";
static char f32f64[] = "cvtss2sd %xmm0, %xmm0";
static char f32f80[] = "sub $8, %rsp; movss %xmm0, (%rsp); flds (%rsp); add $8, %rsp";
static char f64i8[] = "cvttsd2sil %xmm0, %eax; movsbl %al, %eax";
static char f64u8[] = "cvttsd2sil %xmm0, %eax; movzbl %al, %eax";
static char f64i16[] = "cvttsd2sil %xmm0, %eax; movswl %ax, %eax";
static char f64u16[] = "cvttsd2sil %xmm0, %eax; movzwl %ax, %eax";
static char f64i32[] = "cvttsd2sil %xmm0, %eax";
static char f64u32[] = "cvttsd2siq %xmm0, %rax";
static char f64i64[] = "cvttsd2siq %xmm0, %rax";
static char f64u64[] =
"cvttsd2siq %xmm0, %rcx; movq %rcx, %rdx; mov $0x43e0000000000000, %rax; "
"movq %rax, %xmm1; subsd %xmm1, %xmm0; cvttsd2siq %xmm0, %rax; "
"sarq $63, %rdx; andq %rdx, %rax; orq %rcx, %rax";
static char f64f32[] = "cvtsd2ss %xmm0, %xmm0";
static char f64f80[] = "sub $8, %rsp; movsd %xmm0, (%rsp); fldl (%rsp); add $8, %rsp";
#define FROM_F80_1 \
"sub $24, %rsp; fnstcw 14(%rsp); movzwl 14(%rsp), %eax; or $12, %ah; " \
"mov %ax, 12(%rsp); fldcw 12(%rsp); "
#define FROM_F80_2 " (%rsp); fldcw 14(%rsp); "
#define FROM_F80_3 "; add $24, %rsp"
static char f80i8[] = FROM_F80_1 "fistps" FROM_F80_2 "movsbl (%rsp), %eax" FROM_F80_3;
static char f80u8[] = FROM_F80_1 "fistps" FROM_F80_2 "movzbl (%rsp), %eax" FROM_F80_3;
static char f80i16[] = FROM_F80_1 "fistps" FROM_F80_2 "movzbl (%rsp), %eax" FROM_F80_3;
static char f80u16[] = FROM_F80_1 "fistpl" FROM_F80_2 "movswl (%rsp), %eax" FROM_F80_3;
static char f80i32[] = FROM_F80_1 "fistpl" FROM_F80_2 "mov (%rsp), %eax" FROM_F80_3;
static char f80u32[] = FROM_F80_1 "fistpl" FROM_F80_2 "mov (%rsp), %eax" FROM_F80_3;
static char f80i64[] = FROM_F80_1 "fistpq" FROM_F80_2 "mov (%rsp), %rax" FROM_F80_3;
static char f80u64[] =
"sub $16, %rsp; movl $0x5f000000, 12(%rsp); flds 12(%rsp); fucomi %st(1), %st; setbe %al;"
"fldz; fcmovbe %st(1), %st; fstp %st(1); fsubrp %st, %st(1); fnstcw 4(%rsp);"
"movzwl 4(%rsp), %ecx; orl $3072, %ecx; movw %cx, 6(%rsp); fldcw 6(%rsp);"
"fistpll 8(%rsp); fldcw 4(%rsp); shlq $63, %rax; xorq 8(%rsp), %rax; add $16, %rsp";
static char f80f32[] = "sub $8, %rsp; fstps (%rsp); movss (%rsp), %xmm0; add $8, %rsp";
static char f80f64[] = "sub $8, %rsp; fstpl (%rsp); movsd (%rsp), %xmm0; add $8, %rsp";
static char *cast_table[][11] = {
// i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 f80
{NULL, NULL, NULL, i32i64, i32u8, i32u16, NULL, i32i64, i32f32, i32f64, i32f80}, // i8
{i32i8, NULL, NULL, i32i64, i32u8, i32u16, NULL, i32i64, i32f32, i32f64, i32f80}, // i16
{i32i8, i32i16, NULL, i32i64, i32u8, i32u16, NULL, i32i64, i32f32, i32f64, i32f80}, // i32
{i32i8, i32i16, NULL, NULL, i32u8, i32u16, NULL, NULL, i64f32, i64f64, i64f80}, // i64
{i32i8, NULL, NULL, i32i64, NULL, NULL, NULL, i32i64, i32f32, i32f64, i32f80}, // u8
{i32i8, i32i16, NULL, i32i64, i32u8, NULL, NULL, i32i64, i32f32, i32f64, i32f80}, // u16
{i32i8, i32i16, NULL, u32i64, i32u8, i32u16, NULL, u32i64, u32f32, u32f64, u32f80}, // u32
{i32i8, i32i16, NULL, NULL, i32u8, i32u16, NULL, NULL, u64f32, u64f64, u64f80}, // u64
{f32i8, f32i16, f32i32, f32i64, f32u8, f32u16, f32u32, f32u64, NULL, f32f64, f32f80}, // f32
{f64i8, f64i16, f64i32, f64i64, f64u8, f64u16, f64u32, f64u64, f64f32, NULL, f64f80}, // f64
{f80i8, f80i16, f80i32, f80i64, f80u8, f80u16, f80u32, f80u64, f80f32, f80f64, NULL}, // f80
};
static void cast(Type *from, Type *to) {
if (to->kind == TY_VOID)
return;
if (to->kind == TY_BOOL) {
cmp_zero(from);
gen_cmp_setx(ND_NE, false);
return;
}
int t1 = getTypeId(from);
int t2 = getTypeId(to);
if (cast_table[t1][t2])
println(" %s", cast_table[t1][t2]);
}
// Structs or unions equal or smaller than 16 bytes are passed
// using up to two registers.
//
// If the first 8 bytes contains only floating-point type members,
// they are passed in an XMM register. Otherwise, they are passed
// in a general-purpose register.
//
// If a struct/union is larger than 8 bytes, the same rule is
// applied to the the next 8 byte chunk.
//
// This function returns true if `ty` has only floating-point
// members in its byte range [lo, hi).
static bool has_flonum(Type *ty, int lo, int hi, int offset) {
if (ty->kind == TY_STRUCT || ty->kind == TY_UNION) {
for (Member *mem = ty->members; mem; mem = mem->next)
if (!has_flonum(mem->ty, lo, hi, offset + mem->offset))
return false;
return true;
}
if (ty->kind == TY_ARRAY) {
for (int i = 0; i < ty->array_len; i++)
if (!has_flonum(ty->base, lo, hi, offset + ty->base->size * i))
return false;
return true;
}
return offset < lo || hi <= offset || ty->kind == TY_FLOAT || ty->kind == TY_DOUBLE;
}
static bool has_flonum1(Type *ty) {
return has_flonum(ty, 0, 8, 0);
}
static bool has_flonum2(Type *ty) {
return has_flonum(ty, 8, 16, 0);
}
bool va_arg_need_copy(Type *ty) {
if (ty->size > 8 && ty->size <= 16) {
return has_flonum1(ty) || has_flonum2(ty);
}
return false;
}
static int calling_convention(Obj *var, int *gp_count, int *fp_count, int *stack_align) {
int stack = 0;
int max_align = 16;
int gp = *gp_count, fp = *fp_count;
for (; var; var = var->param_next) {
Type *ty = var->ty;
assert(ty->size != 0);
switch (ty->kind) {
case TY_STRUCT:
case TY_UNION:
if (ty->size <= 16) {
int fp_inc = has_flonum1(ty) + (ty->size > 8 && has_flonum2(ty));
int gp_inc = !has_flonum1(ty) + (ty->size > 8 && !has_flonum2(ty));
if ((!fp_inc || (fp + fp_inc <= FP_MAX)) &&
(!gp_inc || (gp + gp_inc <= GP_MAX))) {
fp += fp_inc;
gp += gp_inc;
continue;
}
}
break;
case TY_FLOAT:
case TY_DOUBLE:
if (fp++ < FP_MAX)
continue;
break;
case TY_LDOUBLE:
break;
default:
if (gp++ < GP_MAX)
continue;
}
var->pass_by_stack = true;
if (ty->align > 8) {
stack = align_to(stack, ty->align);
max_align = MAX(max_align, ty->align);
}
var->stack_offset = stack;
stack += align_to(ty->size, 8);
}
*gp_count = MIN(gp, GP_MAX);
*fp_count = MIN(fp, FP_MAX);
if (stack_align)
*stack_align = max_align;
return stack;
}
// Load function call arguments. Arguments are already evaluated and
// stored to the stack as local variables. What we need to do in this
// function is to load them to registers or push them to the stack as
// specified by the x86-64 psABI. Here is what the spec says:
//
// - Up to 6 arguments of integral type are passed using RDI, RSI,
// RDX, RCX, R8 and R9.
//
// - Up to 8 arguments of floating-point type are passed using XMM0 to
// XMM7.
//
// - If all registers of an appropriate type are already used, push an
// argument to the stack in the right-to-left order.
//
// - Each argument passed on the stack takes 8 bytes, and the end of
// the argument area must be aligned to a 16 byte boundary.
//
// - If a function is variadic, set the number of floating-point type
// arguments to RAX.
static void place_stack_args(Node *node) {
for (Obj *var = node->args; var; var = var->param_next) {
if (!var->pass_by_stack)
continue;
Node *arg = var->param_arg;
if (is_trivial_arg(arg)) {
if (arg->kind == ND_NUM || is_nullptr(arg)) {
if (is_flonum(arg->ty))
load_fval(arg->ty, arg->fval);
else
load_val(arg->ty, arg->val);
store2(arg->ty, var->stack_offset, "%rsp");
continue;
}
if (arg->kind == ND_ADDR && is_lvar(arg->lhs)) {
gen_addr(arg->lhs);
store2(arg->ty, var->stack_offset, "%rsp");
continue;
}
if (!is_lvar(arg))
internal_error();
}
int ofs;
char *ptr;
if (is_lvar(arg)) {
ofs = arg->var->ofs;
ptr = arg->var->ptr;
} else {
ofs = var->ofs;
ptr = var->ptr;
}