Bug Summary

File:lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp
Warning:line 80, column 27
The result of the left shift is undefined due to shifting by '32', which is greater or equal to the width of type 'unsigned int'

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 ARMUnwindOpAsm.cpp -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 _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/lib/Target/ARM/MCTargetDesc -I /build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM/MCTargetDesc -I /build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/lib/Target/ARM -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn345461/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/lib/Target/ARM/MCTargetDesc -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/lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp -faddrsig

/build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp

1//===-- ARMUnwindOpAsm.cpp - ARM Unwind Opcodes Assembler -------*- C++ -*-===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the unwind opcode assmebler for ARM exception handling
11// table.
12//
13//===----------------------------------------------------------------------===//
14
15#include "ARMUnwindOpAsm.h"
16#include "llvm/Support/ARMEHABI.h"
17#include "llvm/Support/LEB128.h"
18#include "llvm/Support/MathExtras.h"
19#include <cassert>
20
21using namespace llvm;
22
23namespace {
24
25 /// UnwindOpcodeStreamer - The simple wrapper over SmallVector to emit bytes
26 /// with MSB to LSB per uint32_t ordering. For example, the first byte will
27 /// be placed in Vec[3], and the following bytes will be placed in 2, 1, 0,
28 /// 7, 6, 5, 4, 11, 10, 9, 8, and so on.
29 class UnwindOpcodeStreamer {
30 private:
31 SmallVectorImpl<uint8_t> &Vec;
32 size_t Pos = 3;
33
34 public:
35 UnwindOpcodeStreamer(SmallVectorImpl<uint8_t> &V) : Vec(V) {}
36
37 /// Emit the byte in MSB to LSB per uint32_t order.
38 void EmitByte(uint8_t elem) {
39 Vec[Pos] = elem;
40 Pos = (((Pos ^ 0x3u) + 1) ^ 0x3u);
41 }
42
43 /// Emit the size prefix.
44 void EmitSize(size_t Size) {
45 size_t SizeInWords = (Size + 3) / 4;
46 assert(SizeInWords <= 0x100u &&((SizeInWords <= 0x100u && "Only 256 additional words are allowed for unwind opcodes"
) ? static_cast<void> (0) : __assert_fail ("SizeInWords <= 0x100u && \"Only 256 additional words are allowed for unwind opcodes\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp"
, 47, __PRETTY_FUNCTION__))
47 "Only 256 additional words are allowed for unwind opcodes")((SizeInWords <= 0x100u && "Only 256 additional words are allowed for unwind opcodes"
) ? static_cast<void> (0) : __assert_fail ("SizeInWords <= 0x100u && \"Only 256 additional words are allowed for unwind opcodes\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp"
, 47, __PRETTY_FUNCTION__))
;
48 EmitByte(static_cast<uint8_t>(SizeInWords - 1));
49 }
50
51 /// Emit the personality index prefix.
52 void EmitPersonalityIndex(unsigned PI) {
53 assert(PI < ARM::EHABI::NUM_PERSONALITY_INDEX &&((PI < ARM::EHABI::NUM_PERSONALITY_INDEX && "Invalid personality prefix"
) ? static_cast<void> (0) : __assert_fail ("PI < ARM::EHABI::NUM_PERSONALITY_INDEX && \"Invalid personality prefix\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp"
, 54, __PRETTY_FUNCTION__))
54 "Invalid personality prefix")((PI < ARM::EHABI::NUM_PERSONALITY_INDEX && "Invalid personality prefix"
) ? static_cast<void> (0) : __assert_fail ("PI < ARM::EHABI::NUM_PERSONALITY_INDEX && \"Invalid personality prefix\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp"
, 54, __PRETTY_FUNCTION__))
;
55 EmitByte(ARM::EHABI::EHT_COMPACT | PI);
56 }
57
58 /// Fill the rest of bytes with FINISH opcode.
59 void FillFinishOpcode() {
60 while (Pos < Vec.size())
61 EmitByte(ARM::EHABI::UNWIND_OPCODE_FINISH);
62 }
63 };
64
65} // end anonymous namespace
66
67void UnwindOpcodeAssembler::EmitRegSave(uint32_t RegSave) {
68 if (RegSave == 0u)
1
Assuming 'RegSave' is not equal to 0
2
Taking false branch
69 return;
70
71 // One byte opcode to save register r14 and r11-r4
72 if (RegSave & (1u << 4)) {
3
Assuming the condition is true
4
Taking true branch
73 // The one byte opcode will always save r4, thus we can't use the one byte
74 // opcode when r4 is not in .save directive.
75
76 // Compute the consecutive registers from r4 to r11.
77 uint32_t Mask = RegSave & 0xff0u;
78 uint32_t Range = countTrailingOnes(Mask >> 5); // Exclude r4.
5
Calling 'countTrailingOnes<unsigned int>'
15
Returning from 'countTrailingOnes<unsigned int>'
16
'Range' initialized to 32
79 // Mask off non-consecutive registers. Keep r4.
80 Mask &= ~(0xffffffe0u << Range);
17
The result of the left shift is undefined due to shifting by '32', which is greater or equal to the width of type 'unsigned int'
81
82 // Emit this opcode when the mask covers every registers.
83 uint32_t UnmaskedReg = RegSave & 0xfff0u & (~Mask);
84 if (UnmaskedReg == 0u) {
85 // Pop r[4 : (4 + n)]
86 EmitInt8(ARM::EHABI::UNWIND_OPCODE_POP_REG_RANGE_R4 | Range);
87 RegSave &= 0x000fu;
88 } else if (UnmaskedReg == (1u << 14)) {
89 // Pop r[14] + r[4 : (4 + n)]
90 EmitInt8(ARM::EHABI::UNWIND_OPCODE_POP_REG_RANGE_R4_R14 | Range);
91 RegSave &= 0x000fu;
92 }
93 }
94
95 // Two bytes opcode to save register r15-r4
96 if ((RegSave & 0xfff0u) != 0)
97 EmitInt16(ARM::EHABI::UNWIND_OPCODE_POP_REG_MASK_R4 | (RegSave >> 4));
98
99 // Opcode to save register r3-r0
100 if ((RegSave & 0x000fu) != 0)
101 EmitInt16(ARM::EHABI::UNWIND_OPCODE_POP_REG_MASK | (RegSave & 0x000fu));
102}
103
104/// Emit unwind opcodes for .vsave directives
105void UnwindOpcodeAssembler::EmitVFPRegSave(uint32_t VFPRegSave) {
106 // We only have 4 bits to save the offset in the opcode so look at the lower
107 // and upper 16 bits separately.
108 for (uint32_t Regs : {VFPRegSave & 0xffff0000u, VFPRegSave & 0x0000ffffu}) {
109 while (Regs) {
110 // Now look for a run of set bits. Remember the MSB and LSB of the run.
111 auto RangeMSB = 32 - countLeadingZeros(Regs);
112 auto RangeLen = countLeadingOnes(Regs << (32 - RangeMSB));
113 auto RangeLSB = RangeMSB - RangeLen;
114
115 int Opcode = RangeLSB >= 16
116 ? ARM::EHABI::UNWIND_OPCODE_POP_VFP_REG_RANGE_FSTMFDD_D16
117 : ARM::EHABI::UNWIND_OPCODE_POP_VFP_REG_RANGE_FSTMFDD;
118
119 EmitInt16(Opcode | ((RangeLSB % 16) << 4) | (RangeLen - 1));
120
121 // Zero out bits we're done with.
122 Regs &= ~(-1u << RangeLSB);
123 }
124 }
125}
126
127/// Emit unwind opcodes to copy address from source register to $sp.
128void UnwindOpcodeAssembler::EmitSetSP(uint16_t Reg) {
129 EmitInt8(ARM::EHABI::UNWIND_OPCODE_SET_VSP | Reg);
130}
131
132/// Emit unwind opcodes to add $sp with an offset.
133void UnwindOpcodeAssembler::EmitSPOffset(int64_t Offset) {
134 if (Offset > 0x200) {
135 uint8_t Buff[16];
136 Buff[0] = ARM::EHABI::UNWIND_OPCODE_INC_VSP_ULEB128;
137 size_t ULEBSize = encodeULEB128((Offset - 0x204) >> 2, Buff + 1);
138 EmitBytes(Buff, ULEBSize + 1);
139 } else if (Offset > 0) {
140 if (Offset > 0x100) {
141 EmitInt8(ARM::EHABI::UNWIND_OPCODE_INC_VSP | 0x3fu);
142 Offset -= 0x100;
143 }
144 EmitInt8(ARM::EHABI::UNWIND_OPCODE_INC_VSP |
145 static_cast<uint8_t>((Offset - 4) >> 2));
146 } else if (Offset < 0) {
147 while (Offset < -0x100) {
148 EmitInt8(ARM::EHABI::UNWIND_OPCODE_DEC_VSP | 0x3fu);
149 Offset += 0x100;
150 }
151 EmitInt8(ARM::EHABI::UNWIND_OPCODE_DEC_VSP |
152 static_cast<uint8_t>(((-Offset) - 4) >> 2));
153 }
154}
155
156void UnwindOpcodeAssembler::Finalize(unsigned &PersonalityIndex,
157 SmallVectorImpl<uint8_t> &Result) {
158 UnwindOpcodeStreamer OpStreamer(Result);
159
160 if (HasPersonality) {
161 // User-specifed personality routine: [ SIZE , OP1 , OP2 , ... ]
162 PersonalityIndex = ARM::EHABI::NUM_PERSONALITY_INDEX;
163 size_t TotalSize = Ops.size() + 1;
164 size_t RoundUpSize = (TotalSize + 3) / 4 * 4;
165 Result.resize(RoundUpSize);
166 OpStreamer.EmitSize(RoundUpSize);
167 } else {
168 // If no personalityindex is specified, select ane
169 if (PersonalityIndex == ARM::EHABI::NUM_PERSONALITY_INDEX)
170 PersonalityIndex = (Ops.size() <= 3) ? ARM::EHABI::AEABI_UNWIND_CPP_PR0
171 : ARM::EHABI::AEABI_UNWIND_CPP_PR1;
172 if (PersonalityIndex == ARM::EHABI::AEABI_UNWIND_CPP_PR0) {
173 // __aeabi_unwind_cpp_pr0: [ 0x80 , OP1 , OP2 , OP3 ]
174 assert(Ops.size() <= 3 && "too many opcodes for __aeabi_unwind_cpp_pr0")((Ops.size() <= 3 && "too many opcodes for __aeabi_unwind_cpp_pr0"
) ? static_cast<void> (0) : __assert_fail ("Ops.size() <= 3 && \"too many opcodes for __aeabi_unwind_cpp_pr0\""
, "/build/llvm-toolchain-snapshot-8~svn345461/lib/Target/ARM/MCTargetDesc/ARMUnwindOpAsm.cpp"
, 174, __PRETTY_FUNCTION__))
;
175 Result.resize(4);
176 OpStreamer.EmitPersonalityIndex(PersonalityIndex);
177 } else {
178 // __aeabi_unwind_cpp_pr{1,2}: [ {0x81,0x82} , SIZE , OP1 , OP2 , ... ]
179 size_t TotalSize = Ops.size() + 2;
180 size_t RoundUpSize = (TotalSize + 3) / 4 * 4;
181 Result.resize(RoundUpSize);
182 OpStreamer.EmitPersonalityIndex(PersonalityIndex);
183 OpStreamer.EmitSize(RoundUpSize);
184 }
185 }
186
187 // Copy the unwind opcodes
188 for (size_t i = OpBegins.size() - 1; i > 0; --i)
189 for (size_t j = OpBegins[i - 1], end = OpBegins[i]; j < end; ++j)
190 OpStreamer.EmitByte(Ops[j]);
191
192 // Emit the padding finish opcodes if the size is not multiple of 4.
193 OpStreamer.FillFinishOpcode();
194
195 // Reset the assembler state
196 Reset();
197}

/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h

1//===-- llvm/Support/MathExtras.h - Useful math functions -------*- C++ -*-===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains some functions that are useful for math stuff.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_SUPPORT_MATHEXTRAS_H
15#define LLVM_SUPPORT_MATHEXTRAS_H
16
17#include "llvm/Support/Compiler.h"
18#include "llvm/Support/SwapByteOrder.h"
19#include <algorithm>
20#include <cassert>
21#include <climits>
22#include <cstring>
23#include <limits>
24#include <type_traits>
25
26#ifdef __ANDROID_NDK__
27#include <android/api-level.h>
28#endif
29
30#ifdef _MSC_VER
31// Declare these intrinsics manually rather including intrin.h. It's very
32// expensive, and MathExtras.h is popular.
33// #include <intrin.h>
34extern "C" {
35unsigned char _BitScanForward(unsigned long *_Index, unsigned long _Mask);
36unsigned char _BitScanForward64(unsigned long *_Index, unsigned __int64 _Mask);
37unsigned char _BitScanReverse(unsigned long *_Index, unsigned long _Mask);
38unsigned char _BitScanReverse64(unsigned long *_Index, unsigned __int64 _Mask);
39}
40#endif
41
42namespace llvm {
43/// The behavior an operation has on an input of 0.
44enum ZeroBehavior {
45 /// The returned value is undefined.
46 ZB_Undefined,
47 /// The returned value is numeric_limits<T>::max()
48 ZB_Max,
49 /// The returned value is numeric_limits<T>::digits
50 ZB_Width
51};
52
53namespace detail {
54template <typename T, std::size_t SizeOfT> struct TrailingZerosCounter {
55 static std::size_t count(T Val, ZeroBehavior) {
56 if (!Val)
57 return std::numeric_limits<T>::digits;
58 if (Val & 0x1)
59 return 0;
60
61 // Bisection method.
62 std::size_t ZeroBits = 0;
63 T Shift = std::numeric_limits<T>::digits >> 1;
64 T Mask = std::numeric_limits<T>::max() >> Shift;
65 while (Shift) {
66 if ((Val & Mask) == 0) {
67 Val >>= Shift;
68 ZeroBits |= Shift;
69 }
70 Shift >>= 1;
71 Mask >>= Shift;
72 }
73 return ZeroBits;
74 }
75};
76
77#if __GNUC__4 >= 4 || defined(_MSC_VER)
78template <typename T> struct TrailingZerosCounter<T, 4> {
79 static std::size_t count(T Val, ZeroBehavior ZB) {
80 if (ZB != ZB_Undefined && Val == 0)
8
Assuming 'Val' is equal to 0
9
Taking true branch
81 return 32;
10
Returning the value 32
82
83#if __has_builtin(__builtin_ctz)1 || LLVM_GNUC_PREREQ(4, 0, 0)((4 << 20) + (2 << 10) + 1 >= ((4) << 20
) + ((0) << 10) + (0))
84 return __builtin_ctz(Val);
85#elif defined(_MSC_VER)
86 unsigned long Index;
87 _BitScanForward(&Index, Val);
88 return Index;
89#endif
90 }
91};
92
93#if !defined(_MSC_VER) || defined(_M_X64)
94template <typename T> struct TrailingZerosCounter<T, 8> {
95 static std::size_t count(T Val, ZeroBehavior ZB) {
96 if (ZB != ZB_Undefined && Val == 0)
97 return 64;
98
99#if __has_builtin(__builtin_ctzll)1 || LLVM_GNUC_PREREQ(4, 0, 0)((4 << 20) + (2 << 10) + 1 >= ((4) << 20
) + ((0) << 10) + (0))
100 return __builtin_ctzll(Val);
101#elif defined(_MSC_VER)
102 unsigned long Index;
103 _BitScanForward64(&Index, Val);
104 return Index;
105#endif
106 }
107};
108#endif
109#endif
110} // namespace detail
111
112/// Count number of 0's from the least significant bit to the most
113/// stopping at the first 1.
114///
115/// Only unsigned integral types are allowed.
116///
117/// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are
118/// valid arguments.
119template <typename T>
120std::size_t countTrailingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
121 static_assert(std::numeric_limits<T>::is_integer &&
122 !std::numeric_limits<T>::is_signed,
123 "Only unsigned integral types are allowed.");
124 return llvm::detail::TrailingZerosCounter<T, sizeof(T)>::count(Val, ZB);
7
Calling 'TrailingZerosCounter::count'
11
Returning from 'TrailingZerosCounter::count'
12
Returning the value 32
125}
126
127namespace detail {
128template <typename T, std::size_t SizeOfT> struct LeadingZerosCounter {
129 static std::size_t count(T Val, ZeroBehavior) {
130 if (!Val)
131 return std::numeric_limits<T>::digits;
132
133 // Bisection method.
134 std::size_t ZeroBits = 0;
135 for (T Shift = std::numeric_limits<T>::digits >> 1; Shift; Shift >>= 1) {
136 T Tmp = Val >> Shift;
137 if (Tmp)
138 Val = Tmp;
139 else
140 ZeroBits |= Shift;
141 }
142 return ZeroBits;
143 }
144};
145
146#if __GNUC__4 >= 4 || defined(_MSC_VER)
147template <typename T> struct LeadingZerosCounter<T, 4> {
148 static std::size_t count(T Val, ZeroBehavior ZB) {
149 if (ZB != ZB_Undefined && Val == 0)
150 return 32;
151
152#if __has_builtin(__builtin_clz)1 || LLVM_GNUC_PREREQ(4, 0, 0)((4 << 20) + (2 << 10) + 1 >= ((4) << 20
) + ((0) << 10) + (0))
153 return __builtin_clz(Val);
154#elif defined(_MSC_VER)
155 unsigned long Index;
156 _BitScanReverse(&Index, Val);
157 return Index ^ 31;
158#endif
159 }
160};
161
162#if !defined(_MSC_VER) || defined(_M_X64)
163template <typename T> struct LeadingZerosCounter<T, 8> {
164 static std::size_t count(T Val, ZeroBehavior ZB) {
165 if (ZB != ZB_Undefined && Val == 0)
166 return 64;
167
168#if __has_builtin(__builtin_clzll)1 || LLVM_GNUC_PREREQ(4, 0, 0)((4 << 20) + (2 << 10) + 1 >= ((4) << 20
) + ((0) << 10) + (0))
169 return __builtin_clzll(Val);
170#elif defined(_MSC_VER)
171 unsigned long Index;
172 _BitScanReverse64(&Index, Val);
173 return Index ^ 63;
174#endif
175 }
176};
177#endif
178#endif
179} // namespace detail
180
181/// Count number of 0's from the most significant bit to the least
182/// stopping at the first 1.
183///
184/// Only unsigned integral types are allowed.
185///
186/// \param ZB the behavior on an input of 0. Only ZB_Width and ZB_Undefined are
187/// valid arguments.
188template <typename T>
189std::size_t countLeadingZeros(T Val, ZeroBehavior ZB = ZB_Width) {
190 static_assert(std::numeric_limits<T>::is_integer &&
191 !std::numeric_limits<T>::is_signed,
192 "Only unsigned integral types are allowed.");
193 return llvm::detail::LeadingZerosCounter<T, sizeof(T)>::count(Val, ZB);
194}
195
196/// Get the index of the first set bit starting from the least
197/// significant bit.
198///
199/// Only unsigned integral types are allowed.
200///
201/// \param ZB the behavior on an input of 0. Only ZB_Max and ZB_Undefined are
202/// valid arguments.
203template <typename T> T findFirstSet(T Val, ZeroBehavior ZB = ZB_Max) {
204 if (ZB == ZB_Max && Val == 0)
205 return std::numeric_limits<T>::max();
206
207 return countTrailingZeros(Val, ZB_Undefined);
208}
209
210/// Create a bitmask with the N right-most bits set to 1, and all other
211/// bits set to 0. Only unsigned types are allowed.
212template <typename T> T maskTrailingOnes(unsigned N) {
213 static_assert(std::is_unsigned<T>::value, "Invalid type!");
214 const unsigned Bits = CHAR_BIT8 * sizeof(T);
215 assert(N <= Bits && "Invalid bit index")((N <= Bits && "Invalid bit index") ? static_cast<
void> (0) : __assert_fail ("N <= Bits && \"Invalid bit index\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 215, __PRETTY_FUNCTION__))
;
216 return N == 0 ? 0 : (T(-1) >> (Bits - N));
217}
218
219/// Create a bitmask with the N left-most bits set to 1, and all other
220/// bits set to 0. Only unsigned types are allowed.
221template <typename T> T maskLeadingOnes(unsigned N) {
222 return ~maskTrailingOnes<T>(CHAR_BIT8 * sizeof(T) - N);
223}
224
225/// Create a bitmask with the N right-most bits set to 0, and all other
226/// bits set to 1. Only unsigned types are allowed.
227template <typename T> T maskTrailingZeros(unsigned N) {
228 return maskLeadingOnes<T>(CHAR_BIT8 * sizeof(T) - N);
229}
230
231/// Create a bitmask with the N left-most bits set to 0, and all other
232/// bits set to 1. Only unsigned types are allowed.
233template <typename T> T maskLeadingZeros(unsigned N) {
234 return maskTrailingOnes<T>(CHAR_BIT8 * sizeof(T) - N);
235}
236
237/// Get the index of the last set bit starting from the least
238/// significant bit.
239///
240/// Only unsigned integral types are allowed.
241///
242/// \param ZB the behavior on an input of 0. Only ZB_Max and ZB_Undefined are
243/// valid arguments.
244template <typename T> T findLastSet(T Val, ZeroBehavior ZB = ZB_Max) {
245 if (ZB == ZB_Max && Val == 0)
246 return std::numeric_limits<T>::max();
247
248 // Use ^ instead of - because both gcc and llvm can remove the associated ^
249 // in the __builtin_clz intrinsic on x86.
250 return countLeadingZeros(Val, ZB_Undefined) ^
251 (std::numeric_limits<T>::digits - 1);
252}
253
254/// Macro compressed bit reversal table for 256 bits.
255///
256/// http://graphics.stanford.edu/~seander/bithacks.html#BitReverseTable
257static const unsigned char BitReverseTable256[256] = {
258#define R2(n) n, n + 2 * 64, n + 1 * 64, n + 3 * 64
259#define R4(n) R2(n), R2(n + 2 * 16), R2(n + 1 * 16), R2(n + 3 * 16)
260#define R6(n) R4(n), R4(n + 2 * 4), R4(n + 1 * 4), R4(n + 3 * 4)
261 R6(0), R6(2), R6(1), R6(3)
262#undef R2
263#undef R4
264#undef R6
265};
266
267/// Reverse the bits in \p Val.
268template <typename T>
269T reverseBits(T Val) {
270 unsigned char in[sizeof(Val)];
271 unsigned char out[sizeof(Val)];
272 std::memcpy(in, &Val, sizeof(Val));
273 for (unsigned i = 0; i < sizeof(Val); ++i)
274 out[(sizeof(Val) - i) - 1] = BitReverseTable256[in[i]];
275 std::memcpy(&Val, out, sizeof(Val));
276 return Val;
277}
278
279// NOTE: The following support functions use the _32/_64 extensions instead of
280// type overloading so that signed and unsigned integers can be used without
281// ambiguity.
282
283/// Return the high 32 bits of a 64 bit value.
284constexpr inline uint32_t Hi_32(uint64_t Value) {
285 return static_cast<uint32_t>(Value >> 32);
286}
287
288/// Return the low 32 bits of a 64 bit value.
289constexpr inline uint32_t Lo_32(uint64_t Value) {
290 return static_cast<uint32_t>(Value);
291}
292
293/// Make a 64-bit integer from a high / low pair of 32-bit integers.
294constexpr inline uint64_t Make_64(uint32_t High, uint32_t Low) {
295 return ((uint64_t)High << 32) | (uint64_t)Low;
296}
297
298/// Checks if an integer fits into the given bit width.
299template <unsigned N> constexpr inline bool isInt(int64_t x) {
300 return N >= 64 || (-(INT64_C(1)1L<<(N-1)) <= x && x < (INT64_C(1)1L<<(N-1)));
301}
302// Template specializations to get better code for common cases.
303template <> constexpr inline bool isInt<8>(int64_t x) {
304 return static_cast<int8_t>(x) == x;
305}
306template <> constexpr inline bool isInt<16>(int64_t x) {
307 return static_cast<int16_t>(x) == x;
308}
309template <> constexpr inline bool isInt<32>(int64_t x) {
310 return static_cast<int32_t>(x) == x;
311}
312
313/// Checks if a signed integer is an N bit number shifted left by S.
314template <unsigned N, unsigned S>
315constexpr inline bool isShiftedInt(int64_t x) {
316 static_assert(
317 N > 0, "isShiftedInt<0> doesn't make sense (refers to a 0-bit number.");
318 static_assert(N + S <= 64, "isShiftedInt<N, S> with N + S > 64 is too wide.");
319 return isInt<N + S>(x) && (x % (UINT64_C(1)1UL << S) == 0);
320}
321
322/// Checks if an unsigned integer fits into the given bit width.
323///
324/// This is written as two functions rather than as simply
325///
326/// return N >= 64 || X < (UINT64_C(1) << N);
327///
328/// to keep MSVC from (incorrectly) warning on isUInt<64> that we're shifting
329/// left too many places.
330template <unsigned N>
331constexpr inline typename std::enable_if<(N < 64), bool>::type
332isUInt(uint64_t X) {
333 static_assert(N > 0, "isUInt<0> doesn't make sense");
334 return X < (UINT64_C(1)1UL << (N));
335}
336template <unsigned N>
337constexpr inline typename std::enable_if<N >= 64, bool>::type
338isUInt(uint64_t X) {
339 return true;
340}
341
342// Template specializations to get better code for common cases.
343template <> constexpr inline bool isUInt<8>(uint64_t x) {
344 return static_cast<uint8_t>(x) == x;
345}
346template <> constexpr inline bool isUInt<16>(uint64_t x) {
347 return static_cast<uint16_t>(x) == x;
348}
349template <> constexpr inline bool isUInt<32>(uint64_t x) {
350 return static_cast<uint32_t>(x) == x;
351}
352
353/// Checks if a unsigned integer is an N bit number shifted left by S.
354template <unsigned N, unsigned S>
355constexpr inline bool isShiftedUInt(uint64_t x) {
356 static_assert(
357 N > 0, "isShiftedUInt<0> doesn't make sense (refers to a 0-bit number)");
358 static_assert(N + S <= 64,
359 "isShiftedUInt<N, S> with N + S > 64 is too wide.");
360 // Per the two static_asserts above, S must be strictly less than 64. So
361 // 1 << S is not undefined behavior.
362 return isUInt<N + S>(x) && (x % (UINT64_C(1)1UL << S) == 0);
363}
364
365/// Gets the maximum value for a N-bit unsigned integer.
366inline uint64_t maxUIntN(uint64_t N) {
367 assert(N > 0 && N <= 64 && "integer width out of range")((N > 0 && N <= 64 && "integer width out of range"
) ? static_cast<void> (0) : __assert_fail ("N > 0 && N <= 64 && \"integer width out of range\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 367, __PRETTY_FUNCTION__))
;
368
369 // uint64_t(1) << 64 is undefined behavior, so we can't do
370 // (uint64_t(1) << N) - 1
371 // without checking first that N != 64. But this works and doesn't have a
372 // branch.
373 return UINT64_MAX(18446744073709551615UL) >> (64 - N);
374}
375
376/// Gets the minimum value for a N-bit signed integer.
377inline int64_t minIntN(int64_t N) {
378 assert(N > 0 && N <= 64 && "integer width out of range")((N > 0 && N <= 64 && "integer width out of range"
) ? static_cast<void> (0) : __assert_fail ("N > 0 && N <= 64 && \"integer width out of range\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 378, __PRETTY_FUNCTION__))
;
379
380 return -(UINT64_C(1)1UL<<(N-1));
381}
382
383/// Gets the maximum value for a N-bit signed integer.
384inline int64_t maxIntN(int64_t N) {
385 assert(N > 0 && N <= 64 && "integer width out of range")((N > 0 && N <= 64 && "integer width out of range"
) ? static_cast<void> (0) : __assert_fail ("N > 0 && N <= 64 && \"integer width out of range\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 385, __PRETTY_FUNCTION__))
;
386
387 // This relies on two's complement wraparound when N == 64, so we convert to
388 // int64_t only at the very end to avoid UB.
389 return (UINT64_C(1)1UL << (N - 1)) - 1;
390}
391
392/// Checks if an unsigned integer fits into the given (dynamic) bit width.
393inline bool isUIntN(unsigned N, uint64_t x) {
394 return N >= 64 || x <= maxUIntN(N);
395}
396
397/// Checks if an signed integer fits into the given (dynamic) bit width.
398inline bool isIntN(unsigned N, int64_t x) {
399 return N >= 64 || (minIntN(N) <= x && x <= maxIntN(N));
400}
401
402/// Return true if the argument is a non-empty sequence of ones starting at the
403/// least significant bit with the remainder zero (32 bit version).
404/// Ex. isMask_32(0x0000FFFFU) == true.
405constexpr inline bool isMask_32(uint32_t Value) {
406 return Value && ((Value + 1) & Value) == 0;
407}
408
409/// Return true if the argument is a non-empty sequence of ones starting at the
410/// least significant bit with the remainder zero (64 bit version).
411constexpr inline bool isMask_64(uint64_t Value) {
412 return Value && ((Value + 1) & Value) == 0;
413}
414
415/// Return true if the argument contains a non-empty sequence of ones with the
416/// remainder zero (32 bit version.) Ex. isShiftedMask_32(0x0000FF00U) == true.
417constexpr inline bool isShiftedMask_32(uint32_t Value) {
418 return Value && isMask_32((Value - 1) | Value);
419}
420
421/// Return true if the argument contains a non-empty sequence of ones with the
422/// remainder zero (64 bit version.)
423constexpr inline bool isShiftedMask_64(uint64_t Value) {
424 return Value && isMask_64((Value - 1) | Value);
425}
426
427/// Return true if the argument is a power of two > 0.
428/// Ex. isPowerOf2_32(0x00100000U) == true (32 bit edition.)
429constexpr inline bool isPowerOf2_32(uint32_t Value) {
430 return Value && !(Value & (Value - 1));
431}
432
433/// Return true if the argument is a power of two > 0 (64 bit edition.)
434constexpr inline bool isPowerOf2_64(uint64_t Value) {
435 return Value && !(Value & (Value - 1));
436}
437
438/// Return a byte-swapped representation of the 16-bit argument.
439inline uint16_t ByteSwap_16(uint16_t Value) {
440 return sys::SwapByteOrder_16(Value);
441}
442
443/// Return a byte-swapped representation of the 32-bit argument.
444inline uint32_t ByteSwap_32(uint32_t Value) {
445 return sys::SwapByteOrder_32(Value);
446}
447
448/// Return a byte-swapped representation of the 64-bit argument.
449inline uint64_t ByteSwap_64(uint64_t Value) {
450 return sys::SwapByteOrder_64(Value);
451}
452
453/// Count the number of ones from the most significant bit to the first
454/// zero bit.
455///
456/// Ex. countLeadingOnes(0xFF0FFF00) == 8.
457/// Only unsigned integral types are allowed.
458///
459/// \param ZB the behavior on an input of all ones. Only ZB_Width and
460/// ZB_Undefined are valid arguments.
461template <typename T>
462std::size_t countLeadingOnes(T Value, ZeroBehavior ZB = ZB_Width) {
463 static_assert(std::numeric_limits<T>::is_integer &&
464 !std::numeric_limits<T>::is_signed,
465 "Only unsigned integral types are allowed.");
466 return countLeadingZeros<T>(~Value, ZB);
467}
468
469/// Count the number of ones from the least significant bit to the first
470/// zero bit.
471///
472/// Ex. countTrailingOnes(0x00FF00FF) == 8.
473/// Only unsigned integral types are allowed.
474///
475/// \param ZB the behavior on an input of all ones. Only ZB_Width and
476/// ZB_Undefined are valid arguments.
477template <typename T>
478std::size_t countTrailingOnes(T Value, ZeroBehavior ZB = ZB_Width) {
479 static_assert(std::numeric_limits<T>::is_integer &&
480 !std::numeric_limits<T>::is_signed,
481 "Only unsigned integral types are allowed.");
482 return countTrailingZeros<T>(~Value, ZB);
6
Calling 'countTrailingZeros<unsigned int>'
13
Returning from 'countTrailingZeros<unsigned int>'
14
Returning the value 32
483}
484
485namespace detail {
486template <typename T, std::size_t SizeOfT> struct PopulationCounter {
487 static unsigned count(T Value) {
488 // Generic version, forward to 32 bits.
489 static_assert(SizeOfT <= 4, "Not implemented!");
490#if __GNUC__4 >= 4
491 return __builtin_popcount(Value);
492#else
493 uint32_t v = Value;
494 v = v - ((v >> 1) & 0x55555555);
495 v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
496 return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
497#endif
498 }
499};
500
501template <typename T> struct PopulationCounter<T, 8> {
502 static unsigned count(T Value) {
503#if __GNUC__4 >= 4
504 return __builtin_popcountll(Value);
505#else
506 uint64_t v = Value;
507 v = v - ((v >> 1) & 0x5555555555555555ULL);
508 v = (v & 0x3333333333333333ULL) + ((v >> 2) & 0x3333333333333333ULL);
509 v = (v + (v >> 4)) & 0x0F0F0F0F0F0F0F0FULL;
510 return unsigned((uint64_t)(v * 0x0101010101010101ULL) >> 56);
511#endif
512 }
513};
514} // namespace detail
515
516/// Count the number of set bits in a value.
517/// Ex. countPopulation(0xF000F000) = 8
518/// Returns 0 if the word is zero.
519template <typename T>
520inline unsigned countPopulation(T Value) {
521 static_assert(std::numeric_limits<T>::is_integer &&
522 !std::numeric_limits<T>::is_signed,
523 "Only unsigned integral types are allowed.");
524 return detail::PopulationCounter<T, sizeof(T)>::count(Value);
525}
526
527/// Return the log base 2 of the specified value.
528inline double Log2(double Value) {
529#if defined(__ANDROID_API__) && __ANDROID_API__ < 18
530 return __builtin_log(Value) / __builtin_log(2.0);
531#else
532 return log2(Value);
533#endif
534}
535
536/// Return the floor log base 2 of the specified value, -1 if the value is zero.
537/// (32 bit edition.)
538/// Ex. Log2_32(32) == 5, Log2_32(1) == 0, Log2_32(0) == -1, Log2_32(6) == 2
539inline unsigned Log2_32(uint32_t Value) {
540 return 31 - countLeadingZeros(Value);
541}
542
543/// Return the floor log base 2 of the specified value, -1 if the value is zero.
544/// (64 bit edition.)
545inline unsigned Log2_64(uint64_t Value) {
546 return 63 - countLeadingZeros(Value);
547}
548
549/// Return the ceil log base 2 of the specified value, 32 if the value is zero.
550/// (32 bit edition).
551/// Ex. Log2_32_Ceil(32) == 5, Log2_32_Ceil(1) == 0, Log2_32_Ceil(6) == 3
552inline unsigned Log2_32_Ceil(uint32_t Value) {
553 return 32 - countLeadingZeros(Value - 1);
554}
555
556/// Return the ceil log base 2 of the specified value, 64 if the value is zero.
557/// (64 bit edition.)
558inline unsigned Log2_64_Ceil(uint64_t Value) {
559 return 64 - countLeadingZeros(Value - 1);
560}
561
562/// Return the greatest common divisor of the values using Euclid's algorithm.
563inline uint64_t GreatestCommonDivisor64(uint64_t A, uint64_t B) {
564 while (B) {
565 uint64_t T = B;
566 B = A % B;
567 A = T;
568 }
569 return A;
570}
571
572/// This function takes a 64-bit integer and returns the bit equivalent double.
573inline double BitsToDouble(uint64_t Bits) {
574 double D;
575 static_assert(sizeof(uint64_t) == sizeof(double), "Unexpected type sizes");
576 memcpy(&D, &Bits, sizeof(Bits));
577 return D;
578}
579
580/// This function takes a 32-bit integer and returns the bit equivalent float.
581inline float BitsToFloat(uint32_t Bits) {
582 float F;
583 static_assert(sizeof(uint32_t) == sizeof(float), "Unexpected type sizes");
584 memcpy(&F, &Bits, sizeof(Bits));
585 return F;
586}
587
588/// This function takes a double and returns the bit equivalent 64-bit integer.
589/// Note that copying doubles around changes the bits of NaNs on some hosts,
590/// notably x86, so this routine cannot be used if these bits are needed.
591inline uint64_t DoubleToBits(double Double) {
592 uint64_t Bits;
593 static_assert(sizeof(uint64_t) == sizeof(double), "Unexpected type sizes");
594 memcpy(&Bits, &Double, sizeof(Double));
595 return Bits;
596}
597
598/// This function takes a float and returns the bit equivalent 32-bit integer.
599/// Note that copying floats around changes the bits of NaNs on some hosts,
600/// notably x86, so this routine cannot be used if these bits are needed.
601inline uint32_t FloatToBits(float Float) {
602 uint32_t Bits;
603 static_assert(sizeof(uint32_t) == sizeof(float), "Unexpected type sizes");
604 memcpy(&Bits, &Float, sizeof(Float));
605 return Bits;
606}
607
608/// A and B are either alignments or offsets. Return the minimum alignment that
609/// may be assumed after adding the two together.
610constexpr inline uint64_t MinAlign(uint64_t A, uint64_t B) {
611 // The largest power of 2 that divides both A and B.
612 //
613 // Replace "-Value" by "1+~Value" in the following commented code to avoid
614 // MSVC warning C4146
615 // return (A | B) & -(A | B);
616 return (A | B) & (1 + ~(A | B));
617}
618
619/// Aligns \c Addr to \c Alignment bytes, rounding up.
620///
621/// Alignment should be a power of two. This method rounds up, so
622/// alignAddr(7, 4) == 8 and alignAddr(8, 4) == 8.
623inline uintptr_t alignAddr(const void *Addr, size_t Alignment) {
624 assert(Alignment && isPowerOf2_64((uint64_t)Alignment) &&((Alignment && isPowerOf2_64((uint64_t)Alignment) &&
"Alignment is not a power of two!") ? static_cast<void>
(0) : __assert_fail ("Alignment && isPowerOf2_64((uint64_t)Alignment) && \"Alignment is not a power of two!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 625, __PRETTY_FUNCTION__))
625 "Alignment is not a power of two!")((Alignment && isPowerOf2_64((uint64_t)Alignment) &&
"Alignment is not a power of two!") ? static_cast<void>
(0) : __assert_fail ("Alignment && isPowerOf2_64((uint64_t)Alignment) && \"Alignment is not a power of two!\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 625, __PRETTY_FUNCTION__))
;
626
627 assert((uintptr_t)Addr + Alignment - 1 >= (uintptr_t)Addr)(((uintptr_t)Addr + Alignment - 1 >= (uintptr_t)Addr) ? static_cast
<void> (0) : __assert_fail ("(uintptr_t)Addr + Alignment - 1 >= (uintptr_t)Addr"
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 627, __PRETTY_FUNCTION__))
;
628
629 return (((uintptr_t)Addr + Alignment - 1) & ~(uintptr_t)(Alignment - 1));
630}
631
632/// Returns the necessary adjustment for aligning \c Ptr to \c Alignment
633/// bytes, rounding up.
634inline size_t alignmentAdjustment(const void *Ptr, size_t Alignment) {
635 return alignAddr(Ptr, Alignment) - (uintptr_t)Ptr;
636}
637
638/// Returns the next power of two (in 64-bits) that is strictly greater than A.
639/// Returns zero on overflow.
640inline uint64_t NextPowerOf2(uint64_t A) {
641 A |= (A >> 1);
642 A |= (A >> 2);
643 A |= (A >> 4);
644 A |= (A >> 8);
645 A |= (A >> 16);
646 A |= (A >> 32);
647 return A + 1;
648}
649
650/// Returns the power of two which is less than or equal to the given value.
651/// Essentially, it is a floor operation across the domain of powers of two.
652inline uint64_t PowerOf2Floor(uint64_t A) {
653 if (!A) return 0;
654 return 1ull << (63 - countLeadingZeros(A, ZB_Undefined));
655}
656
657/// Returns the power of two which is greater than or equal to the given value.
658/// Essentially, it is a ceil operation across the domain of powers of two.
659inline uint64_t PowerOf2Ceil(uint64_t A) {
660 if (!A)
661 return 0;
662 return NextPowerOf2(A - 1);
663}
664
665/// Returns the next integer (mod 2**64) that is greater than or equal to
666/// \p Value and is a multiple of \p Align. \p Align must be non-zero.
667///
668/// If non-zero \p Skew is specified, the return value will be a minimal
669/// integer that is greater than or equal to \p Value and equal to
670/// \p Align * N + \p Skew for some integer N. If \p Skew is larger than
671/// \p Align, its value is adjusted to '\p Skew mod \p Align'.
672///
673/// Examples:
674/// \code
675/// alignTo(5, 8) = 8
676/// alignTo(17, 8) = 24
677/// alignTo(~0LL, 8) = 0
678/// alignTo(321, 255) = 510
679///
680/// alignTo(5, 8, 7) = 7
681/// alignTo(17, 8, 1) = 17
682/// alignTo(~0LL, 8, 3) = 3
683/// alignTo(321, 255, 42) = 552
684/// \endcode
685inline uint64_t alignTo(uint64_t Value, uint64_t Align, uint64_t Skew = 0) {
686 assert(Align != 0u && "Align can't be 0.")((Align != 0u && "Align can't be 0.") ? static_cast<
void> (0) : __assert_fail ("Align != 0u && \"Align can't be 0.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 686, __PRETTY_FUNCTION__))
;
687 Skew %= Align;
688 return (Value + Align - 1 - Skew) / Align * Align + Skew;
689}
690
691/// Returns the next integer (mod 2**64) that is greater than or equal to
692/// \p Value and is a multiple of \c Align. \c Align must be non-zero.
693template <uint64_t Align> constexpr inline uint64_t alignTo(uint64_t Value) {
694 static_assert(Align != 0u, "Align must be non-zero");
695 return (Value + Align - 1) / Align * Align;
696}
697
698/// Returns the integer ceil(Numerator / Denominator).
699inline uint64_t divideCeil(uint64_t Numerator, uint64_t Denominator) {
700 return alignTo(Numerator, Denominator) / Denominator;
701}
702
703/// \c alignTo for contexts where a constant expression is required.
704/// \sa alignTo
705///
706/// \todo FIXME: remove when \c constexpr becomes really \c constexpr
707template <uint64_t Align>
708struct AlignTo {
709 static_assert(Align != 0u, "Align must be non-zero");
710 template <uint64_t Value>
711 struct from_value {
712 static const uint64_t value = (Value + Align - 1) / Align * Align;
713 };
714};
715
716/// Returns the largest uint64_t less than or equal to \p Value and is
717/// \p Skew mod \p Align. \p Align must be non-zero
718inline uint64_t alignDown(uint64_t Value, uint64_t Align, uint64_t Skew = 0) {
719 assert(Align != 0u && "Align can't be 0.")((Align != 0u && "Align can't be 0.") ? static_cast<
void> (0) : __assert_fail ("Align != 0u && \"Align can't be 0.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 719, __PRETTY_FUNCTION__))
;
720 Skew %= Align;
721 return (Value - Skew) / Align * Align + Skew;
722}
723
724/// Returns the offset to the next integer (mod 2**64) that is greater than
725/// or equal to \p Value and is a multiple of \p Align. \p Align must be
726/// non-zero.
727inline uint64_t OffsetToAlignment(uint64_t Value, uint64_t Align) {
728 return alignTo(Value, Align) - Value;
729}
730
731/// Sign-extend the number in the bottom B bits of X to a 32-bit integer.
732/// Requires 0 < B <= 32.
733template <unsigned B> constexpr inline int32_t SignExtend32(uint32_t X) {
734 static_assert(B > 0, "Bit width can't be 0.");
735 static_assert(B <= 32, "Bit width out of range.");
736 return int32_t(X << (32 - B)) >> (32 - B);
737}
738
739/// Sign-extend the number in the bottom B bits of X to a 32-bit integer.
740/// Requires 0 < B < 32.
741inline int32_t SignExtend32(uint32_t X, unsigned B) {
742 assert(B > 0 && "Bit width can't be 0.")((B > 0 && "Bit width can't be 0.") ? static_cast<
void> (0) : __assert_fail ("B > 0 && \"Bit width can't be 0.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 742, __PRETTY_FUNCTION__))
;
743 assert(B <= 32 && "Bit width out of range.")((B <= 32 && "Bit width out of range.") ? static_cast
<void> (0) : __assert_fail ("B <= 32 && \"Bit width out of range.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 743, __PRETTY_FUNCTION__))
;
744 return int32_t(X << (32 - B)) >> (32 - B);
745}
746
747/// Sign-extend the number in the bottom B bits of X to a 64-bit integer.
748/// Requires 0 < B < 64.
749template <unsigned B> constexpr inline int64_t SignExtend64(uint64_t x) {
750 static_assert(B > 0, "Bit width can't be 0.");
751 static_assert(B <= 64, "Bit width out of range.");
752 return int64_t(x << (64 - B)) >> (64 - B);
753}
754
755/// Sign-extend the number in the bottom B bits of X to a 64-bit integer.
756/// Requires 0 < B < 64.
757inline int64_t SignExtend64(uint64_t X, unsigned B) {
758 assert(B > 0 && "Bit width can't be 0.")((B > 0 && "Bit width can't be 0.") ? static_cast<
void> (0) : __assert_fail ("B > 0 && \"Bit width can't be 0.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 758, __PRETTY_FUNCTION__))
;
759 assert(B <= 64 && "Bit width out of range.")((B <= 64 && "Bit width out of range.") ? static_cast
<void> (0) : __assert_fail ("B <= 64 && \"Bit width out of range.\""
, "/build/llvm-toolchain-snapshot-8~svn345461/include/llvm/Support/MathExtras.h"
, 759, __PRETTY_FUNCTION__))
;
760 return int64_t(X << (64 - B)) >> (64 - B);
761}
762
763/// Subtract two unsigned integers, X and Y, of type T and return the absolute
764/// value of the result.
765template <typename T>
766typename std::enable_if<std::is_unsigned<T>::value, T>::type
767AbsoluteDifference(T X, T Y) {
768 return std::max(X, Y) - std::min(X, Y);
769}
770
771/// Add two unsigned integers, X and Y, of type T. Clamp the result to the
772/// maximum representable value of T on overflow. ResultOverflowed indicates if
773/// the result is larger than the maximum representable value of type T.
774template <typename T>
775typename std::enable_if<std::is_unsigned<T>::value, T>::type
776SaturatingAdd(T X, T Y, bool *ResultOverflowed = nullptr) {
777 bool Dummy;
778 bool &Overflowed = ResultOverflowed ? *ResultOverflowed : Dummy;
779 // Hacker's Delight, p. 29
780 T Z = X + Y;
781 Overflowed = (Z < X || Z < Y);
782 if (Overflowed)
783 return std::numeric_limits<T>::max();
784 else
785 return Z;
786}
787
788/// Multiply two unsigned integers, X and Y, of type T. Clamp the result to the
789/// maximum representable value of T on overflow. ResultOverflowed indicates if
790/// the result is larger than the maximum representable value of type T.
791template <typename T>
792typename std::enable_if<std::is_unsigned<T>::value, T>::type
793SaturatingMultiply(T X, T Y, bool *ResultOverflowed = nullptr) {
794 bool Dummy;
795 bool &Overflowed = ResultOverflowed ? *ResultOverflowed : Dummy;
796
797 // Hacker's Delight, p. 30 has a different algorithm, but we don't use that
798 // because it fails for uint16_t (where multiplication can have undefined
799 // behavior due to promotion to int), and requires a division in addition
800 // to the multiplication.
801
802 Overflowed = false;
803
804 // Log2(Z) would be either Log2Z or Log2Z + 1.
805 // Special case: if X or Y is 0, Log2_64 gives -1, and Log2Z
806 // will necessarily be less than Log2Max as desired.
807 int Log2Z = Log2_64(X) + Log2_64(Y);
808 const T Max = std::numeric_limits<T>::max();
809 int Log2Max = Log2_64(Max);
810 if (Log2Z < Log2Max) {
811 return X * Y;
812 }
813 if (Log2Z > Log2Max) {
814 Overflowed = true;
815 return Max;
816 }
817
818 // We're going to use the top bit, and maybe overflow one
819 // bit past it. Multiply all but the bottom bit then add
820 // that on at the end.
821 T Z = (X >> 1) * Y;
822 if (Z & ~(Max >> 1)) {
823 Overflowed = true;
824 return Max;
825 }
826 Z <<= 1;
827 if (X & 1)
828 return SaturatingAdd(Z, Y, ResultOverflowed);
829
830 return Z;
831}
832
833/// Multiply two unsigned integers, X and Y, and add the unsigned integer, A to
834/// the product. Clamp the result to the maximum representable value of T on
835/// overflow. ResultOverflowed indicates if the result is larger than the
836/// maximum representable value of type T.
837template <typename T>
838typename std::enable_if<std::is_unsigned<T>::value, T>::type
839SaturatingMultiplyAdd(T X, T Y, T A, bool *ResultOverflowed = nullptr) {
840 bool Dummy;
841 bool &Overflowed = ResultOverflowed ? *ResultOverflowed : Dummy;
842
843 T Product = SaturatingMultiply(X, Y, &Overflowed);
844 if (Overflowed)
845 return Product;
846
847 return SaturatingAdd(A, Product, &Overflowed);
848}
849
850/// Use this rather than HUGE_VALF; the latter causes warnings on MSVC.
851extern const float huge_valf;
852} // End llvm namespace
853
854#endif