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ir: More changes to sentinel-terminated const arrays

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* Don't add an extra slot for the sentinel. Most of the code keeps using
  the constant value from the type descriptor, let's harmonize all the
  code dealing with sentinels.

* Properly write out sentinel values when reinterpreting pointers at
  comptime.

* Allow the reading of the 0th element in a `[0:S]T` type.
This commit is contained in:
LemonBoy
2020-03-19 11:52:15 +01:00
committed by Andrew Kelley
parent 7a361751e5
commit e3c92d0532
4 changed files with 44 additions and 28 deletions
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39
src/codegen.cpp
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@@ -3584,9 +3584,7 @@ static bool value_is_all_undef(CodeGen *g, ZigValue *const_val) {
}
return true;
} else if (const_val->type->id == ZigTypeIdArray) {
const size_t full_len = const_val->type->data.array.len +
(const_val->type->data.array.sentinel != nullptr);
return value_is_all_undef_array(g, const_val, full_len);
return value_is_all_undef_array(g, const_val, const_val->type->data.array.len);
} else if (const_val->type->id == ZigTypeIdVector) {
return value_is_all_undef_array(g, const_val, const_val->type->data.vector.len);
} else {
@@ -6792,6 +6790,22 @@ static LLVMValueRef pack_const_int(CodeGen *g, LLVMTypeRef big_int_type_ref, Zig
used_bits += packed_bits_size;
}
}
if (type_entry->data.array.sentinel != nullptr) {
ZigValue *elem_val = type_entry->data.array.sentinel;
LLVMValueRef child_val = pack_const_int(g, big_int_type_ref, elem_val);
if (is_big_endian) {
LLVMValueRef shift_amt = LLVMConstInt(big_int_type_ref, packed_bits_size, false);
val = LLVMConstShl(val, shift_amt);
val = LLVMConstOr(val, child_val);
} else {
LLVMValueRef shift_amt = LLVMConstInt(big_int_type_ref, used_bits, false);
LLVMValueRef child_val_shifted = LLVMConstShl(child_val, shift_amt);
val = LLVMConstOr(val, child_val_shifted);
used_bits += packed_bits_size;
}
}
return val;
}
case ZigTypeIdVector:
@@ -6858,20 +6872,11 @@ static LLVMValueRef gen_const_val_ptr(CodeGen *g, ZigValue *const_val, const cha
ZigValue *array_const_val = const_val->data.x_ptr.data.base_array.array_val;
assert(array_const_val->type->id == ZigTypeIdArray);
if (!type_has_bits(g, array_const_val->type)) {
if (array_const_val->type->data.array.sentinel != nullptr) {
ZigValue *pointee = array_const_val->type->data.array.sentinel;
render_const_val(g, pointee, "");
render_const_val_global(g, pointee, "");
const_val->llvm_value = LLVMConstBitCast(pointee->llvm_global,
get_llvm_type(g, const_val->type));
return const_val->llvm_value;
} else {
// make this a null pointer
ZigType *usize = g->builtin_types.entry_usize;
const_val->llvm_value = LLVMConstIntToPtr(LLVMConstNull(usize->llvm_type),
get_llvm_type(g, const_val->type));
return const_val->llvm_value;
}
// make this a null pointer
ZigType *usize = g->builtin_types.entry_usize;
const_val->llvm_value = LLVMConstIntToPtr(LLVMConstNull(usize->llvm_type),
get_llvm_type(g, const_val->type));
return const_val->llvm_value;
}
size_t elem_index = const_val->data.x_ptr.data.base_array.elem_index;
LLVMValueRef uncasted_ptr_val = gen_const_ptr_array_recursive(g, array_const_val, elem_index);