Bug Summary

File:utils/benchmark/src/string_util.cc
Warning:line 151, column 3
Value stored to 'ret' is never read

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name string_util.cc -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -mrelocation-model pic -pic-level 2 -mthread-model posix -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-8/lib/clang/8.0.0 -D HAVE_POSIX_REGEX -D HAVE_STD_REGEX -D HAVE_STEADY_CLOCK -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/utils/benchmark/src -I /build/llvm-toolchain-snapshot-8~svn345461/utils/benchmark/src -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn345461/include -I /build/llvm-toolchain-snapshot-8~svn345461/utils/benchmark/include -I /build/llvm-toolchain-snapshot-8~svn345461/utils/benchmark/src/../include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/8.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-8/lib/clang/8.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/utils/benchmark/src -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -fobjc-runtime=gcc -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2018-10-27-211344-32123-1 -x c++ /build/llvm-toolchain-snapshot-8~svn345461/utils/benchmark/src/string_util.cc -faddrsig
1#include "string_util.h"
2
3#include <array>
4#include <cmath>
5#include <cstdarg>
6#include <cstdio>
7#include <memory>
8#include <sstream>
9
10#include "arraysize.h"
11
12namespace benchmark {
13namespace {
14
15// kilo, Mega, Giga, Tera, Peta, Exa, Zetta, Yotta.
16const char kBigSIUnits[] = "kMGTPEZY";
17// Kibi, Mebi, Gibi, Tebi, Pebi, Exbi, Zebi, Yobi.
18const char kBigIECUnits[] = "KMGTPEZY";
19// milli, micro, nano, pico, femto, atto, zepto, yocto.
20const char kSmallSIUnits[] = "munpfazy";
21
22// We require that all three arrays have the same size.
23static_assert(arraysize(kBigSIUnits)(sizeof(::benchmark::internal::ArraySizeHelper(kBigSIUnits))) == arraysize(kBigIECUnits)(sizeof(::benchmark::internal::ArraySizeHelper(kBigIECUnits))
)
,
24 "SI and IEC unit arrays must be the same size");
25static_assert(arraysize(kSmallSIUnits)(sizeof(::benchmark::internal::ArraySizeHelper(kSmallSIUnits)
))
== arraysize(kBigSIUnits)(sizeof(::benchmark::internal::ArraySizeHelper(kBigSIUnits))),
26 "Small SI and Big SI unit arrays must be the same size");
27
28static const int64_t kUnitsSize = arraysize(kBigSIUnits)(sizeof(::benchmark::internal::ArraySizeHelper(kBigSIUnits)));
29
30void ToExponentAndMantissa(double val, double thresh, int precision,
31 double one_k, std::string* mantissa,
32 int64_t* exponent) {
33 std::stringstream mantissa_stream;
34
35 if (val < 0) {
36 mantissa_stream << "-";
37 val = -val;
38 }
39
40 // Adjust threshold so that it never excludes things which can't be rendered
41 // in 'precision' digits.
42 const double adjusted_threshold =
43 std::max(thresh, 1.0 / std::pow(10.0, precision));
44 const double big_threshold = adjusted_threshold * one_k;
45 const double small_threshold = adjusted_threshold;
46 // Values in ]simple_threshold,small_threshold[ will be printed as-is
47 const double simple_threshold = 0.01;
48
49 if (val > big_threshold) {
50 // Positive powers
51 double scaled = val;
52 for (size_t i = 0; i < arraysize(kBigSIUnits)(sizeof(::benchmark::internal::ArraySizeHelper(kBigSIUnits))); ++i) {
53 scaled /= one_k;
54 if (scaled <= big_threshold) {
55 mantissa_stream << scaled;
56 *exponent = i + 1;
57 *mantissa = mantissa_stream.str();
58 return;
59 }
60 }
61 mantissa_stream << val;
62 *exponent = 0;
63 } else if (val < small_threshold) {
64 // Negative powers
65 if (val < simple_threshold) {
66 double scaled = val;
67 for (size_t i = 0; i < arraysize(kSmallSIUnits)(sizeof(::benchmark::internal::ArraySizeHelper(kSmallSIUnits)
))
; ++i) {
68 scaled *= one_k;
69 if (scaled >= small_threshold) {
70 mantissa_stream << scaled;
71 *exponent = -static_cast<int64_t>(i + 1);
72 *mantissa = mantissa_stream.str();
73 return;
74 }
75 }
76 }
77 mantissa_stream << val;
78 *exponent = 0;
79 } else {
80 mantissa_stream << val;
81 *exponent = 0;
82 }
83 *mantissa = mantissa_stream.str();
84}
85
86std::string ExponentToPrefix(int64_t exponent, bool iec) {
87 if (exponent == 0) return "";
88
89 const int64_t index = (exponent > 0 ? exponent - 1 : -exponent - 1);
90 if (index >= kUnitsSize) return "";
91
92 const char* array =
93 (exponent > 0 ? (iec ? kBigIECUnits : kBigSIUnits) : kSmallSIUnits);
94 if (iec)
95 return array[index] + std::string("i");
96 else
97 return std::string(1, array[index]);
98}
99
100std::string ToBinaryStringFullySpecified(double value, double threshold,
101 int precision, double one_k = 1024.0) {
102 std::string mantissa;
103 int64_t exponent;
104 ToExponentAndMantissa(value, threshold, precision, one_k, &mantissa,
105 &exponent);
106 return mantissa + ExponentToPrefix(exponent, false);
107}
108
109} // end namespace
110
111void AppendHumanReadable(int n, std::string* str) {
112 std::stringstream ss;
113 // Round down to the nearest SI prefix.
114 ss << ToBinaryStringFullySpecified(n, 1.0, 0);
115 *str += ss.str();
116}
117
118std::string HumanReadableNumber(double n, double one_k) {
119 // 1.1 means that figures up to 1.1k should be shown with the next unit down;
120 // this softens edge effects.
121 // 1 means that we should show one decimal place of precision.
122 return ToBinaryStringFullySpecified(n, 1.1, 1, one_k);
123}
124
125std::string StrFormatImp(const char* msg, va_list args) {
126 // we might need a second shot at this, so pre-emptivly make a copy
127 va_list args_cp;
128 va_copy(args_cp, args)__builtin_va_copy(args_cp, args);
129
130 // TODO(ericwf): use std::array for first attempt to avoid one memory
131 // allocation guess what the size might be
132 std::array<char, 256> local_buff;
133 std::size_t size = local_buff.size();
134 // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
135 // in the android-ndk
136 auto ret = vsnprintf(local_buff.data(), size, msg, args_cp);
137
138 va_end(args_cp)__builtin_va_end(args_cp);
139
140 // handle empty expansion
141 if (ret == 0) return std::string{};
142 if (static_cast<std::size_t>(ret) < size)
143 return std::string(local_buff.data());
144
145 // we did not provide a long enough buffer on our first attempt.
146 // add 1 to size to account for null-byte in size cast to prevent overflow
147 size = static_cast<std::size_t>(ret) + 1;
148 auto buff_ptr = std::unique_ptr<char[]>(new char[size]);
149 // 2015-10-08: vsnprintf is used instead of snd::vsnprintf due to a limitation
150 // in the android-ndk
151 ret = vsnprintf(buff_ptr.get(), size, msg, args);
Value stored to 'ret' is never read
152 return std::string(buff_ptr.get());
153}
154
155std::string StrFormat(const char* format, ...) {
156 va_list args;
157 va_start(args, format)__builtin_va_start(args, format);
158 std::string tmp = StrFormatImp(format, args);
159 va_end(args)__builtin_va_end(args);
160 return tmp;
161}
162
163void ReplaceAll(std::string* str, const std::string& from,
164 const std::string& to) {
165 std::size_t start = 0;
166 while ((start = str->find(from, start)) != std::string::npos) {
167 str->replace(start, from.length(), to);
168 start += to.length();
169 }
170}
171
172} // end namespace benchmark