fx.reflection: implement dynamic function calling on linux-x86_64

This commit is contained in:
2026-05-04 19:23:10 +01:00
parent e954a15d92
commit bebc67537d
3 changed files with 324 additions and 0 deletions
+177
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@@ -0,0 +1,177 @@
.global callvm_invoke_i
.type callvm_invoke_i, @function
# %rdi = (function ptr) impl
# %rsi = (struct callvm) context
callvm_invoke_i:
# save the stack frame pointer
push %rbp
mov %rsp, %rbp
# store function pointer for later
push %r12
push %r13
push %r14
push %r15
mov %rdi, %r11
mov %rsi, %r12
# First, set up the fixed arguments
# %r13 = fixed arg count
movq (%r12), %r13
# arg[0]
cmp $0, %r13
jle .idone
movq 48(%r12), %rdi
# arg[1]
cmp $1, %r13
jle .idone
movq 56(%r12), %rsi
# arg[2]
cmp $2, %r13
jle .idone
movq 64(%r12), %rdx
# arg[3]
cmp $3, %r13
jle .idone
movq 72(%r12), %rcx
# arg[4]
cmp $4, %r13
jle .idone
movq 80(%r12), %r8
# arg[5]
cmp $5, %r13
jle .idone
movq 88(%r12), %r9
.idone:
# Next, set up the fixed double arguments
# r13 = fixed double arg count
movq 8(%r12), %r13
# arg[0]
cmp $0, %r13
jle .vdone
movq 96(%r12), %xmm0
# arg[1]
cmp $1, %r13
jle .vdone
movq 104(%r12), %xmm1
# arg[2]
cmp $2, %r13
jle .vdone
movq 112(%r12), %xmm2
# arg[3]
cmp $3, %r13
jle .vdone
movq 120(%r12), %xmm3
# arg[4]
cmp $4, %r13
jle .vdone
movq 128(%r12), %xmm4
# arg[5]
cmp $5, %r13
jle .vdone
movq 136(%r12), %xmm5
# arg[6]
cmp $6, %r13
jle .vdone
movq 144(%r12), %xmm6
# arg[7]
cmp $7, %r13
jle .vdone
movq 152(%r12), %xmm7
.vdone:
# Finally, set up the variable arguments
# x8 = excess arg count
movq 32(%r12), %r13
# calculate the amount of stack space needed for the varargs
shl $3, %r13
andq $0xFFFFFFFFFFFFFFF0, %r13
addq $0x10, %r13
# allocate the stack space
sub %r13, %rsp
mov %rsp, %r14
# convert buffer size back to number of arguments
movq 32(%r12), %r13
# r13: number of var args (decrements with every iteration)
# r14: var arg dest pointer (increments with every iteration)
# r15: arg src buffer (increments with every iteration)
mov 160(%r12), %r15
.loop:
cmp $0, %r13
je .loop_end
# read the arg value from the src pointer
mov (%r15), %rax
# write it to the stack, and increment the dest pointer
mov %rax, (%r14)
add $8, %r14
# increment the src pointer, decrement the arg count
sub $1, %r13
add $8, %r15
jmp .loop
.loop_end:
# call the function implementation
mov 168(%r12), %rax
call *%r11
# de-allocate the stack varargs buffer (the size is now stored in x19)
movq 32(%r12), %r13
shl $3, %r13
andq $0xFFFFFFFFFFFFFFF0, %r13
addq $0x10, %r13
addq %r13, %rsp
pop %r15
pop %r14
pop %r13
pop %r12
# restore the saved stack frame and link pointer
pop %rbp
ret
.global callvm_invoke_d
.type callvm_invoke_d, @function
# %rdi = (function ptr) impl
# %rsi = (struct callvm *) context
callvm_invoke_d:
jmp callvm_invoke_i
.global callvm_invoke_v
.type callvm_invoke_v, @function
# %rdi = (function ptr) impl
# %rsi = (struct callvm *) context
callvm_invoke_v:
jmp callvm_invoke_i
+110
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#include <platform/callvm.h>
#include <stdlib.h>
#if 0
switch (arg->v_type.t_primitive) {
case FX_VALUE_TYPE_DOUBLE:
break;
default:
callvm_push_int(&vm, (uintptr_t)arg->v_pointer);
break;
}
#endif
void callvm_reset(struct callvm* vm, unsigned int max_fixed_args)
{
vm->vm_arg_int_count = 0;
vm->vm_arg_double_count = 0;
vm->vm_arg_fixed = max_fixed_args;
vm->vm_arg_excess_count = 0;
vm->vm_double_excess_count = 0;
}
static void expand_excess(struct callvm* vm)
{
size_t new_capacity = vm->vm_arg_excess_max * 2;
if (!new_capacity) {
new_capacity = 4;
}
void* buf = realloc(
vm->vm_arg_excess,
new_capacity * sizeof *vm->vm_arg_excess);
if (!buf) {
return;
}
vm->vm_arg_excess = buf;
vm->vm_arg_excess_max = new_capacity;
}
static void push_excess(struct callvm* vm, uintptr_t value)
{
if (vm->vm_arg_excess_count + 1 > vm->vm_arg_excess_max) {
expand_excess(vm);
}
vm->vm_arg_excess[vm->vm_arg_excess_count++] = value;
vm->vm_arg_count++;
}
static void push_int(struct callvm* vm, uintptr_t value)
{
if (vm->vm_arg_int_count >= MAX_INT_ARGS) {
push_excess(vm, value);
return;
}
vm->vm_arg_int[vm->vm_arg_int_count++] = value;
vm->vm_arg_count++;
}
static void push_double(struct callvm* vm, double value)
{
if (vm->vm_arg_double_count >= MAX_DOUBLE_ARGS) {
push_excess(vm, *(uintptr_t*)&value);
return;
}
vm->vm_arg_double[vm->vm_arg_double_count++] = value;
vm->vm_arg_count++;
if (vm->vm_arg_count > vm->vm_arg_fixed) {
vm->vm_double_excess_count++;
}
}
void callvm_push(struct callvm* vm, const fx_value* value)
{
switch (value->v_type.t_primitive) {
case FX_VALUE_TYPE_DOUBLE:
push_double(vm, value->v_double);
break;
default:
push_int(vm, (uintptr_t)value->v_pointer);
break;
}
}
extern uintptr_t callvm_invoke_i(fx_function_impl impl, struct callvm* vm);
extern double callvm_invoke_d(fx_function_impl impl, struct callvm* vm);
extern void callvm_invoke_v(fx_function_impl impl, struct callvm* vm);
fx_value callvm_invoke(
struct callvm* vm,
fx_function_impl impl,
fx_value_type return_type)
{
switch (return_type) {
case FX_VALUE_TYPE_NONE:
callvm_invoke_v(impl, vm);
break;
case FX_VALUE_TYPE_DOUBLE:
return FX_VALUE_DOUBLE(callvm_invoke_d(impl, vm));
default:
return FX_VALUE_INT(callvm_invoke_i(impl, vm));
}
return FX_VALUE_EMPTY;
}
@@ -0,0 +1,37 @@
#ifndef FX_REFLECTION_DARWIN_ARM64_CALLVM_H_
#define FX_REFLECTION_DARWIN_ARM64_CALLVM_H_
#include <fx/reflection/function.h>
#include <fx/value.h>
#include <stdint.h>
#define MAX_FIXED_ARGS ((unsigned int)-1)
#define MAX_DOUBLE_ARGS 8
#define MAX_INT_ARGS 6
/* dyn-dispatch.S depends on the layout of this struct */
struct callvm {
uint64_t vm_arg_int_count;
uint64_t vm_arg_double_count;
/* any args pushed after this limit is reached will be stored in the
* excess buffer. used for calling varargs functions */
uint64_t vm_arg_count, vm_arg_fixed;
uint64_t vm_arg_excess_count;
uint64_t vm_arg_excess_max;
uintptr_t vm_arg_int[MAX_INT_ARGS];
double vm_arg_double[MAX_DOUBLE_ARGS];
uintptr_t *vm_arg_excess;
uint64_t vm_double_excess_count;
};
extern void callvm_reset(struct callvm *vm, unsigned int max_fixed_args);
extern void callvm_push(struct callvm *vm, const fx_value *value);
extern fx_value callvm_invoke(
struct callvm *vm,
fx_function_impl impl,
fx_value_type return_type);
#endif