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slicing with comptime start and end results in array

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implements #863
This commit is contained in:
Andrew Kelley
2020-03-15 20:55:07 -04:00
parent e3c92d0532
commit 2182d28cb0
3 changed files with 119 additions and 37 deletions
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79
src/ir.cpp
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@@ -849,11 +849,6 @@ static bool is_slice(ZigType *type) {
return type->id == ZigTypeIdStruct && type->data.structure.special == StructSpecialSlice;
}
static bool slice_is_const(ZigType *type) {
assert(is_slice(type));
return type->data.structure.fields[slice_ptr_index]->type_entry->data.pointer.is_const;
}
// This function returns true when you can change the type of a ZigValue and the
// value remains meaningful.
static bool types_have_same_zig_comptime_repr(CodeGen *codegen, ZigType *expected, ZigType *actual) {
@@ -26206,7 +26201,6 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
return ira->codegen->invalid_inst_gen;
}
ZigType *return_type;
ZigValue *sentinel_val = nullptr;
if (instruction->sentinel) {
IrInstGen *uncasted_sentinel = instruction->sentinel->child;
@@ -26218,6 +26212,46 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
sentinel_val = ir_resolve_const(ira, sentinel, UndefBad);
if (sentinel_val == nullptr)
return ira->codegen->invalid_inst_gen;
}
// If start index and end index are both comptime known, then the result type is a pointer to array
// not a slice.
ZigType *return_type;
if (value_is_comptime(casted_start->value) &&
((end != nullptr && value_is_comptime(end->value)) || array_type->id == ZigTypeIdArray ))
{
ZigValue *start_val = ir_resolve_const(ira, casted_start, UndefBad);
if (!start_val)
return ira->codegen->invalid_inst_gen;
uint64_t start_scalar = bigint_as_u64(&start_val->data.x_bigint);
uint64_t end_scalar;
if (end != nullptr) {
ZigValue *end_val = ir_resolve_const(ira, end, UndefBad);
if (!end_val)
return ira->codegen->invalid_inst_gen;
end_scalar = bigint_as_u64(&end_val->data.x_bigint);
} else {
end_scalar = array_type->data.array.len;
}
ZigValue *array_sentinel = (array_type->id == ZigTypeIdArray && end_scalar == array_type->data.array.len)
? sentinel_val : nullptr;
if (start_scalar > end_scalar) {
ir_add_error(ira, &instruction->base.base, buf_sprintf("out of bounds slice"));
return ira->codegen->invalid_inst_gen;
}
ZigType *return_array_type = get_array_type(ira->codegen, elem_type, end_scalar - start_scalar,
array_sentinel);
return_type = get_pointer_to_type_extra(ira->codegen, return_array_type,
non_sentinel_slice_ptr_type->data.pointer.is_const,
non_sentinel_slice_ptr_type->data.pointer.is_volatile,
PtrLenSingle,
0, 0, 0, false);
} else if (sentinel_val != nullptr) {
ZigType *slice_ptr_type = adjust_ptr_sentinel(ira->codegen, non_sentinel_slice_ptr_type, sentinel_val);
return_type = get_slice_type(ira->codegen, slice_ptr_type);
} else {
@@ -26401,15 +26435,25 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
}
IrInstGen *result = ir_const(ira, &instruction->base.base, return_type);
ZigValue *out_val = result->value;
out_val->data.x_struct.fields = alloc_const_vals_ptrs(ira->codegen, 2);
ZigValue *ptr_val = out_val->data.x_struct.fields[slice_ptr_index];
ZigValue *ptr_val;
if (return_type->id == ZigTypeIdPointer) {
// pointer to array
ptr_val = result->value;
} else {
// slice
result->value->data.x_struct.fields = alloc_const_vals_ptrs(ira->codegen, 2);
ptr_val = result->value->data.x_struct.fields[slice_ptr_index];
ZigValue *len_val = result->value->data.x_struct.fields[slice_len_index];
init_const_usize(ira->codegen, len_val, end_scalar - start_scalar);
}
bool return_type_is_const = non_sentinel_slice_ptr_type->data.pointer.is_const;
if (array_val) {
size_t index = abs_offset + start_scalar;
bool is_const = slice_is_const(return_type);
init_const_ptr_array(ira->codegen, ptr_val, array_val, index, is_const, PtrLenUnknown);
init_const_ptr_array(ira->codegen, ptr_val, array_val, index, return_type_is_const, PtrLenUnknown);
if (array_type->id == ZigTypeIdArray) {
ptr_val->data.x_ptr.mut = ptr_ptr->value->data.x_ptr.mut;
} else if (is_slice(array_type)) {
@@ -26419,15 +26463,15 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
}
} else if (ptr_is_undef) {
ptr_val->type = get_pointer_to_type(ira->codegen, parent_ptr->type->data.pointer.child_type,
slice_is_const(return_type));
return_type_is_const);
ptr_val->special = ConstValSpecialUndef;
} else switch (parent_ptr->data.x_ptr.special) {
case ConstPtrSpecialInvalid:
case ConstPtrSpecialDiscard:
zig_unreachable();
case ConstPtrSpecialRef:
init_const_ptr_ref(ira->codegen, ptr_val,
parent_ptr->data.x_ptr.data.ref.pointee, slice_is_const(return_type));
init_const_ptr_ref(ira->codegen, ptr_val, parent_ptr->data.x_ptr.data.ref.pointee,
return_type_is_const);
break;
case ConstPtrSpecialBaseArray:
zig_unreachable();
@@ -26443,7 +26487,7 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
init_const_ptr_hard_coded_addr(ira->codegen, ptr_val,
parent_ptr->type->data.pointer.child_type,
parent_ptr->data.x_ptr.data.hard_coded_addr.addr + start_scalar,
slice_is_const(return_type));
return_type_is_const);
break;
case ConstPtrSpecialFunction:
zig_panic("TODO");
@@ -26451,9 +26495,8 @@ static IrInstGen *ir_analyze_instruction_slice(IrAnalyze *ira, IrInstSrcSlice *i
zig_panic("TODO");
}
ZigValue *len_val = out_val->data.x_struct.fields[slice_len_index];
init_const_usize(ira->codegen, len_val, end_scalar - start_scalar);
// In the case of pointer-to-array, we must restore this because above it overwrites ptr_val->type
result->value->type = return_type;
return result;
}