1// Copyright (c) 2017 Google Inc.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15// Validates literal numbers.
16
17#include "source/val/validate.h"
18
19#include <cassert>
20
21#include "source/diagnostic.h"
22#include "source/opcode.h"
23#include "source/val/instruction.h"
24#include "source/val/validation_state.h"
25
26namespace spvtools {
27namespace val {
28namespace {
29
30// Returns true if the operand holds a literal number
31bool IsLiteralNumber(const spv_parsed_operand_t& operand) {
32 switch (operand.number_kind) {
33 case SPV_NUMBER_SIGNED_INT:
34 case SPV_NUMBER_UNSIGNED_INT:
35 case SPV_NUMBER_FLOATING:
36 return true;
37 default:
38 return false;
39 }
40}
41
42// Verifies that the upper bits of the given upper |word| with given
43// lower |width| are zero- or sign-extended when |signed_int| is true
44bool VerifyUpperBits(uint32_t word, uint32_t width, bool signed_int) {
45 assert(width < 32);
46 assert(0 < width);
47 const uint32_t upper_mask = 0xFFFFFFFFu << width;
48 const uint32_t upper_bits = word & upper_mask;
49
50 bool result = false;
51 if (signed_int) {
52 const uint32_t sign_bit = word & (1u << (width - 1));
53 if (sign_bit) {
54 result = upper_bits == upper_mask;
55 } else {
56 result = upper_bits == 0;
57 }
58 } else {
59 result = upper_bits == 0;
60 }
61 return result;
62}
63
64} // namespace
65
66// Validates that literal numbers are represented according to the spec
67spv_result_t LiteralsPass(ValidationState_t& _, const Instruction* inst) {
68 // For every operand that is a literal number
69 for (size_t i = 0; i < inst->operands().size(); i++) {
70 const spv_parsed_operand_t& operand = inst->operand(i);
71 if (!IsLiteralNumber(operand)) continue;
72
73 // The upper bits are always in the last word (little-endian)
74 int last_index = operand.offset + operand.num_words - 1;
75 const uint32_t upper_word = inst->word(last_index);
76
77 // TODO(jcaraban): is the |word size| defined in some header?
78 const uint32_t word_size = 32;
79 uint32_t bit_width = operand.number_bit_width;
80
81 // Bit widths that are a multiple of the word size have no upper bits
82 const auto remaining_value_bits = bit_width % word_size;
83 if (remaining_value_bits == 0) continue;
84
85 const bool signedness = operand.number_kind == SPV_NUMBER_SIGNED_INT;
86
87 if (!VerifyUpperBits(upper_word, remaining_value_bits, signedness)) {
88 return _.diag(SPV_ERROR_INVALID_VALUE, inst)
89 << "The high-order bits of a literal number in instruction <id> "
90 << inst->id() << " must be 0 for a floating-point type, "
91 << "or 0 for an integer type with Signedness of 0, "
92 << "or sign extended when Signedness is 1";
93 }
94 }
95 return SPV_SUCCESS;
96}
97
98} // namespace val
99} // namespace spvtools
100