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Improve code generation for loading bit_field fields

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gingerBill
2024-04-24 13:10:58 +01:00
parent 75fcd50b9a
commit ec5a84a537
2 changed files with 75 additions and 20 deletions
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src/llvm_backend_general.cpp
+65 -15
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@@ -774,13 +774,23 @@ gb_internal void lb_addr_store(lbProcedure *p, lbAddr addr, lbValue value) {
if (addr.kind == lbAddr_BitField) {
lbValue dst = addr.addr;
lbValue src = lb_address_from_load_or_generate_local(p, value);
auto args = array_make<lbValue>(temporary_allocator(), 4);
args[0] = dst;
args[1] = lb_address_from_load_or_generate_local(p, value);
args[2] = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_offset);
args[3] = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_size);
lb_emit_runtime_call(p, "__write_bits", args);
if ((addr.bitfield.bit_offset & 7) == 0 &&
(addr.bitfield.bit_size & 7) == 0) {
lbValue byte_offset = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_offset/8);
lbValue byte_size = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_size/8);
lbValue dst_offset = lb_emit_conv(p, dst, t_u8_ptr);
dst_offset = lb_emit_ptr_offset(p, dst_offset, byte_offset);
lb_mem_copy_non_overlapping(p, dst_offset, src, byte_size);
} else {
auto args = array_make<lbValue>(temporary_allocator(), 4);
args[0] = dst;
args[1] = src;
args[2] = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_offset);
args[3] = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_size);
lb_emit_runtime_call(p, "__write_bits", args);
}
return;
} else if (addr.kind == lbAddr_RelativePointer) {
Type *rel_ptr = base_type(lb_addr_type(addr));
@@ -1088,23 +1098,63 @@ gb_internal lbValue lb_addr_load(lbProcedure *p, lbAddr const &addr) {
GB_ASSERT(addr.addr.value != nullptr);
if (addr.kind == lbAddr_BitField) {
lbAddr dst = lb_add_local_generated(p, addr.bitfield.type, true);
Type *ct = core_type(addr.bitfield.type);
bool do_mask = false;
if (is_type_unsigned(ct) || is_type_boolean(ct)) {
// Mask
if (addr.bitfield.bit_size != 8*type_size_of(ct)) {
do_mask = true;
}
}
i64 total_bitfield_bit_size = 8*type_size_of(lb_addr_type(addr));
i64 dst_byte_size = type_size_of(addr.bitfield.type);
lbAddr dst = lb_add_local_generated(p, addr.bitfield.type, false);
lbValue src = addr.addr;
auto args = array_make<lbValue>(temporary_allocator(), 4);
args[0] = dst.addr;
args[1] = src;
args[2] = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_offset);
args[3] = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_size);
lb_emit_runtime_call(p, "__read_bits", args);
lbValue bit_offset = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_offset);
lbValue bit_size = lb_const_int(p->module, t_uintptr, addr.bitfield.bit_size);
lbValue byte_offset = lb_const_int(p->module, t_uintptr, (addr.bitfield.bit_offset+7)/8);
lbValue byte_size = lb_const_int(p->module, t_uintptr, (addr.bitfield.bit_size+7)/8);
GB_ASSERT(type_size_of(addr.bitfield.type) >= ((addr.bitfield.bit_size+7)/8));
if ((addr.bitfield.bit_offset & 7) == 0) {
lbValue copy_size = byte_size;
lbValue src_offset = lb_emit_conv(p, src, t_u8_ptr);
src_offset = lb_emit_ptr_offset(p, src_offset, byte_offset);
if (addr.bitfield.bit_offset + dst_byte_size <= total_bitfield_bit_size) {
do_mask = true;
copy_size = lb_const_int(p->module, t_uintptr, dst_byte_size);
}
lb_mem_copy_non_overlapping(p, dst.addr, src_offset, copy_size, false);
} else {
auto args = array_make<lbValue>(temporary_allocator(), 4);
args[0] = dst.addr;
args[1] = src;
args[2] = bit_offset;
args[3] = bit_size;
lb_emit_runtime_call(p, "__read_bits", args);
}
lbValue r = lb_addr_load(p, dst);
Type *t = addr.bitfield.type;
if (!is_type_unsigned(core_type(addr.bitfield.type))) {
if (do_mask) {
GB_ASSERT(addr.bitfield.bit_size < 8*type_size_of(ct));
LLVMTypeRef lt = lb_type(p->module, t);
LLVMValueRef mask = LLVMConstInt(lt, 1, false);
mask = LLVMConstShl(mask, LLVMConstInt(lt, addr.bitfield.bit_size, false));
mask = LLVMConstSub(mask, LLVMConstInt(lt, 1, false));
lbValue m = {mask, t};
r = lb_emit_arith(p, Token_And, r, m, t);
}
if (!is_type_unsigned(ct) && !is_type_boolean(ct)) {
// Sign extension
// m := 1<<(bit_size-1)
// r = (r XOR m) - m
Type *t = addr.bitfield.type;
lbValue m = lb_const_int(p->module, t, 1ull<<(addr.bitfield.bit_size-1));
r = lb_emit_arith(p, Token_Xor, r, m, t);
r = lb_emit_arith(p, Token_Sub, r, m, t);