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ir: Rewrite the bound checks in slice operator

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Closes #4777
This commit is contained in:
LemonBoy 2020-03-22 20:20:36 +01:00
parent 0dbf8aaab8
commit 855edd2949
1 changed files with 139 additions and 98 deletions
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237
src/codegen.cpp
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@ -5408,6 +5408,8 @@ static LLVMValueRef ir_render_memcpy(CodeGen *g, IrExecutableGen *executable, Ir
}
static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutableGen *executable, IrInstGenSlice *instruction) {
Error err;
LLVMValueRef array_ptr_ptr = ir_llvm_value(g, instruction->ptr);
ZigType *array_ptr_type = instruction->ptr->value->type;
assert(array_ptr_type->id == ZigTypeIdPointer);
@ -5416,15 +5418,16 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutableGen *executable, IrI
bool want_runtime_safety = instruction->safety_check_on && ir_want_runtime_safety(g, &instruction->base);
// The result is either a slice or a pointer to an array
ZigType *result_type = instruction->base.value->type;
if (!type_has_bits(g, result_type)) {
return nullptr;
}
// This is not whether the result type has a sentinel, but whether there should be a sentinel check,
// e.g. if they used [a..b :s] syntax.
ZigValue *sentinel = instruction->sentinel;
LLVMValueRef slice_start_ptr = nullptr;
LLVMValueRef len_value = nullptr;
if (array_type->id == ZigTypeIdArray ||
(array_type->id == ZigTypeIdPointer && array_type->data.pointer.ptr_len == PtrLenSingle))
{
@ -5438,111 +5441,86 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutableGen *executable, IrI
} else {
end_val = LLVMConstInt(g->builtin_types.entry_usize->llvm_type, array_type->data.array.len, false);
}
if (want_runtime_safety) {
// Safety check: start <= end
if (instruction->start->value->special == ConstValSpecialRuntime || instruction->end) {
add_bounds_check(g, start_val, LLVMIntEQ, nullptr, LLVMIntULE, end_val);
}
if (instruction->end) {
LLVMValueRef array_end = LLVMConstInt(g->builtin_types.entry_usize->llvm_type,
array_type->data.array.len, false);
add_bounds_check(g, end_val, LLVMIntEQ, nullptr, LLVMIntULE, array_end);
if (sentinel != nullptr) {
LLVMValueRef indices[] = {
LLVMConstNull(g->builtin_types.entry_usize->llvm_type),
end_val,
};
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, indices, 2, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
// Safety check: the last element of the slice (the sentinel if
// requested) must be inside the array
// XXX: Overflow is not checked here...
const size_t full_len = array_type->data.array.len +
(array_type->data.array.sentinel != nullptr);
LLVMValueRef array_end = LLVMConstInt(g->builtin_types.entry_usize->llvm_type,
full_len, false);
LLVMValueRef check_end_val = end_val;
if (sentinel != nullptr) {
LLVMValueRef usize_one = LLVMConstInt(g->builtin_types.entry_usize->llvm_type, 1, false);
check_end_val = LLVMBuildNUWAdd(g->builder, end_val, usize_one, "");
}
}
if (!type_has_bits(g, array_type)) {
LLVMValueRef tmp_struct_ptr = ir_llvm_value(g, instruction->result_loc);
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, slice_len_index, "");
// TODO if runtime safety is on, store 0xaaaaaaa in ptr field
LLVMValueRef len_value = LLVMBuildNSWSub(g->builder, end_val, start_val, "");
gen_store_untyped(g, len_value, len_field_ptr, 0, false);
return tmp_struct_ptr;
add_bounds_check(g, check_end_val, LLVMIntEQ, nullptr, LLVMIntULE, array_end);
}
LLVMValueRef indices[] = {
LLVMConstNull(g->builtin_types.entry_usize->llvm_type),
start_val,
};
LLVMValueRef slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, indices, 2, "");
if (result_type->id == ZigTypeIdPointer) {
ir_assert(instruction->result_loc == nullptr, &instruction->base);
LLVMTypeRef result_ptr_type = get_llvm_type(g, result_type);
return LLVMBuildBitCast(g->builder, slice_start_ptr, result_ptr_type, "");
} else {
LLVMValueRef tmp_struct_ptr = ir_llvm_value(g, instruction->result_loc);
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, slice_ptr_index, "");
gen_store_untyped(g, slice_start_ptr, ptr_field_ptr, 0, false);
bool value_has_bits;
if ((err = type_has_bits2(g, array_type, &value_has_bits)))
codegen_report_errors_and_exit(g);
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, slice_len_index, "");
LLVMValueRef len_value = LLVMBuildNSWSub(g->builder, end_val, start_val, "");
gen_store_untyped(g, len_value, len_field_ptr, 0, false);
if (value_has_bits) {
if (want_runtime_safety && sentinel != nullptr) {
LLVMValueRef indices[] = {
LLVMConstNull(g->builtin_types.entry_usize->llvm_type),
end_val,
};
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, indices, 2, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
return tmp_struct_ptr;
LLVMValueRef indices[] = {
LLVMConstNull(g->builtin_types.entry_usize->llvm_type),
start_val,
};
slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, indices, 2, "");
}
len_value = LLVMBuildNUWSub(g->builder, end_val, start_val, "");
} else if (array_type->id == ZigTypeIdPointer) {
assert(array_type->data.pointer.ptr_len != PtrLenSingle);
LLVMValueRef start_val = ir_llvm_value(g, instruction->start);
LLVMValueRef end_val = ir_llvm_value(g, instruction->end);
if (want_runtime_safety) {
// Safety check: start <= end
add_bounds_check(g, start_val, LLVMIntEQ, nullptr, LLVMIntULE, end_val);
if (sentinel != nullptr) {
}
bool value_has_bits;
if ((err = type_has_bits2(g, array_type, &value_has_bits)))
codegen_report_errors_and_exit(g);
if (value_has_bits) {
if (want_runtime_safety && sentinel != nullptr) {
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, &end_val, 1, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, &start_val, 1, "");
}
if (!type_has_bits(g, array_type)) {
LLVMValueRef tmp_struct_ptr = ir_llvm_value(g, instruction->result_loc);
size_t gen_len_index = result_type->data.structure.fields[slice_len_index]->gen_index;
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, gen_len_index, "");
LLVMValueRef len_value = LLVMBuildNSWSub(g->builder, end_val, start_val, "");
gen_store_untyped(g, len_value, len_field_ptr, 0, false);
return tmp_struct_ptr;
}
LLVMValueRef slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, &start_val, 1, "");
if (result_type->id == ZigTypeIdPointer) {
ir_assert(instruction->result_loc == nullptr, &instruction->base);
LLVMTypeRef result_ptr_type = get_llvm_type(g, result_type);
return LLVMBuildBitCast(g->builder, slice_start_ptr, result_ptr_type, "");
}
LLVMValueRef tmp_struct_ptr = ir_llvm_value(g, instruction->result_loc);
size_t gen_ptr_index = result_type->data.structure.fields[slice_ptr_index]->gen_index;
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, gen_ptr_index, "");
gen_store_untyped(g, slice_start_ptr, ptr_field_ptr, 0, false);
size_t gen_len_index = result_type->data.structure.fields[slice_len_index]->gen_index;
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, gen_len_index, "");
LLVMValueRef len_value = LLVMBuildNSWSub(g->builder, end_val, start_val, "");
gen_store_untyped(g, len_value, len_field_ptr, 0, false);
return tmp_struct_ptr;
len_value = LLVMBuildNUWSub(g->builder, end_val, start_val, "");
} else if (array_type->id == ZigTypeIdStruct) {
assert(array_type->data.structure.special == StructSpecialSlice);
assert(LLVMGetTypeKind(LLVMTypeOf(array_ptr)) == LLVMPointerTypeKind);
assert(LLVMGetTypeKind(LLVMGetElementType(LLVMTypeOf(array_ptr))) == LLVMStructTypeKind);
size_t ptr_index = array_type->data.structure.fields[slice_ptr_index]->gen_index;
assert(ptr_index != SIZE_MAX);
size_t len_index = array_type->data.structure.fields[slice_len_index]->gen_index;
assert(len_index != SIZE_MAX);
const size_t gen_len_index = array_type->data.structure.fields[slice_len_index]->gen_index;
assert(gen_len_index != SIZE_MAX);
LLVMValueRef prev_end = nullptr;
if (!instruction->end || want_runtime_safety) {
LLVMValueRef src_len_ptr = LLVMBuildStructGEP(g->builder, array_ptr, (unsigned)len_index, "");
LLVMValueRef src_len_ptr = LLVMBuildStructGEP(g->builder, array_ptr, gen_len_index, "");
prev_end = gen_load_untyped(g, src_len_ptr, 0, false, "");
}
@ -5554,41 +5532,104 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutableGen *executable, IrI
end_val = prev_end;
}
LLVMValueRef src_ptr_ptr = LLVMBuildStructGEP(g->builder, array_ptr, (unsigned)ptr_index, "");
LLVMValueRef src_ptr = gen_load_untyped(g, src_ptr_ptr, 0, false, "");
ZigType *ptr_field_type = array_type->data.structure.fields[slice_ptr_index]->type_entry;
if (want_runtime_safety) {
assert(prev_end);
// Safety check: start <= end
add_bounds_check(g, start_val, LLVMIntEQ, nullptr, LLVMIntULE, end_val);
if (instruction->end) {
add_bounds_check(g, end_val, LLVMIntEQ, nullptr, LLVMIntULE, prev_end);
if (sentinel != nullptr) {
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr, &end_val, 1, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
// Safety check: the sentinel counts as one more element
// XXX: Overflow is not checked here...
LLVMValueRef check_prev_end = prev_end;
if (ptr_field_type->data.pointer.sentinel != nullptr) {
LLVMValueRef usize_one = LLVMConstInt(g->builtin_types.entry_usize->llvm_type, 1, false);
check_prev_end = LLVMBuildNUWAdd(g->builder, prev_end, usize_one, "");
}
LLVMValueRef check_end_val = end_val;
if (sentinel != nullptr) {
LLVMValueRef usize_one = LLVMConstInt(g->builtin_types.entry_usize->llvm_type, 1, false);
check_end_val = LLVMBuildNUWAdd(g->builder, end_val, usize_one, "");
}
add_bounds_check(g, check_end_val, LLVMIntEQ, nullptr, LLVMIntULE, check_prev_end);
}
LLVMValueRef slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr, &start_val, 1, "");
if (result_type->id == ZigTypeIdPointer) {
ir_assert(instruction->result_loc == nullptr, &instruction->base);
LLVMTypeRef result_ptr_type = get_llvm_type(g, result_type);
return LLVMBuildBitCast(g->builder, slice_start_ptr, result_ptr_type, "");
} else {
LLVMValueRef tmp_struct_ptr = ir_llvm_value(g, instruction->result_loc);
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, (unsigned)ptr_index, "");
gen_store_untyped(g, slice_start_ptr, ptr_field_ptr, 0, false);
bool ptr_has_bits;
if ((err = type_has_bits2(g, ptr_field_type, &ptr_has_bits)))
codegen_report_errors_and_exit(g);
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, (unsigned)len_index, "");
LLVMValueRef len_value = LLVMBuildNSWSub(g->builder, end_val, start_val, "");
gen_store_untyped(g, len_value, len_field_ptr, 0, false);
if (ptr_has_bits) {
const size_t gen_ptr_index = array_type->data.structure.fields[slice_ptr_index]->gen_index;
assert(gen_ptr_index != SIZE_MAX);
return tmp_struct_ptr;
LLVMValueRef src_ptr_ptr = LLVMBuildStructGEP(g->builder, array_ptr, gen_ptr_index, "");
LLVMValueRef src_ptr = gen_load_untyped(g, src_ptr_ptr, 0, false, "");
if (sentinel != nullptr) {
LLVMValueRef sentinel_elem_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr, &end_val, 1, "");
add_sentinel_check(g, sentinel_elem_ptr, sentinel);
}
slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, src_ptr, &start_val, 1, "");
}
len_value = LLVMBuildNUWSub(g->builder, end_val, start_val, "");
} else {
zig_unreachable();
}
bool result_has_bits;
if ((err = type_has_bits2(g, result_type, &result_has_bits)))
codegen_report_errors_and_exit(g);
// Nothing to do, we're only interested in the bound checks emitted above
if (!result_has_bits)
return nullptr;
// The starting pointer for the slice may be null in case of zero-sized
// arrays, the length value is always defined.
assert(len_value != nullptr);
// The slice decays into a pointer to an array, the size is tracked in the
// type itself
if (result_type->id == ZigTypeIdPointer) {
ir_assert(instruction->result_loc == nullptr, &instruction->base);
LLVMTypeRef result_ptr_type = get_llvm_type(g, result_type);
if (slice_start_ptr != nullptr) {
return LLVMBuildBitCast(g->builder, slice_start_ptr, result_ptr_type, "");
}
return LLVMGetUndef(result_ptr_type);
}
ir_assert(instruction->result_loc != nullptr, &instruction->base);
// Create a new slice
LLVMValueRef tmp_struct_ptr = ir_llvm_value(g, instruction->result_loc);
ZigType *slice_ptr_type = result_type->data.structure.fields[slice_ptr_index]->type_entry;
// The slice may not have a pointer at all if it points to a zero-sized type
const size_t gen_ptr_index = result_type->data.structure.fields[slice_ptr_index]->gen_index;
if (gen_ptr_index != SIZE_MAX) {
LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, gen_ptr_index, "");
if (slice_start_ptr != nullptr) {
gen_store_untyped(g, slice_start_ptr, ptr_field_ptr, 0, false);
} else if (want_runtime_safety) {
gen_undef_init(g, slice_ptr_type->abi_align, slice_ptr_type, ptr_field_ptr);
} else {
gen_store_untyped(g, LLVMGetUndef(get_llvm_type(g, slice_ptr_type)), ptr_field_ptr, 0, false);
}
}
const size_t gen_len_index = result_type->data.structure.fields[slice_len_index]->gen_index;
assert(gen_len_index != SIZE_MAX);
LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, gen_len_index, "");
gen_store_untyped(g, len_value, len_field_ptr, 0, false);
return tmp_struct_ptr;
}
static LLVMValueRef get_trap_fn_val(CodeGen *g) {