diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h index d494ad25351..2073fa08cbf 100644 --- a/include/llvm/ADT/APInt.h +++ b/include/llvm/ADT/APInt.h @@ -1244,6 +1244,9 @@ public: /// as "bitPosition". void flipBit(unsigned bitPosition); + /// \brief Returns true if the bit in bitPosition is set. + bool extractBit(unsigned bitPosition) const; + /// @} /// \name Value Characterization Functions /// @{ diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp index 89f96bd5774..731c8cc9cae 100644 --- a/lib/Support/APInt.cpp +++ b/lib/Support/APInt.cpp @@ -607,6 +607,14 @@ void APInt::flipBit(unsigned bitPosition) { else setBit(bitPosition); } +bool APInt::extractBit(unsigned bitPosition) const { + assert(bitPosition < BitWidth && "Out of the bit-width range!"); + if (isSingleWord()) + return VAL & maskBit(bitPosition); + else + return pVal[whichWord(bitPosition)] & maskBit(bitPosition); +} + unsigned APInt::getBitsNeeded(StringRef str, uint8_t radix) { assert(!str.empty() && "Invalid string length"); assert((radix == 10 || radix == 8 || radix == 16 || radix == 2 || diff --git a/unittests/ADT/APIntTest.cpp b/unittests/ADT/APIntTest.cpp index 3c0dfe14404..1d330f0d369 100644 --- a/unittests/ADT/APIntTest.cpp +++ b/unittests/ADT/APIntTest.cpp @@ -597,4 +597,30 @@ TEST(APIntTest, tcDecrement) { EXPECT_EQ(APInt::tcCompare(test, expected, 4), 0); } } + +TEST(APIntTest, extractBit) { + // Single word check. + uint64_t E1 = 0x2CA7F46BF6569915ULL; + APInt A1(64, E1); + for (unsigned i = 0, e = 64; i < e; ++i) { + EXPECT_EQ(bool(E1 & (1ULL << i)), + A1.extractBit(i)); + } + + // Multiword check. + integerPart E2[4] = { + 0xeb6eb136591cba21ULL, + 0x7b9358bd6a33f10aULL, + 0x7e7ffa5eadd8846ULL, + 0x305f341ca00b613dULL + }; + APInt A2(integerPartWidth*4, ArrayRef(E2, 4)); + for (unsigned i = 0; i < 4; ++i) { + for (unsigned j = 0; j < integerPartWidth; ++j) { + EXPECT_EQ(bool(E2[i] & (1ULL << j)), + A2.extractBit(i*integerPartWidth + j)); + } + } +} + }