[llvm] r197271 - [block-freq] Add the APInt method extractBit.

[Michael Gottesman]

I was following the name tcExtractBit which performs the identical operation on bignums.

If people want testBit/bitTest, I am fine with that.

Michael

On Dec 13, 2013, at 12:56 PM, Chandler Carruth <chandlerc at google.com> wrote:

> This name doesn't feel quite right to me... testBit or bitTest maybe? Meh. Not sure.
> 
> On Dec 13, 2013 12:54 PM, "Michael Gottesman" <mgottesman at apple.com> wrote:
> Author: mgottesman
> Date: Fri Dec 13 14:47:34 2013
> New Revision: 197271
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=197271&view=rev
> Log:
> [block-freq] Add the APInt method extractBit.
> 
> Modified:
>     llvm/trunk/include/llvm/ADT/APInt.h
>     llvm/trunk/lib/Support/APInt.cpp
>     llvm/trunk/unittests/ADT/APIntTest.cpp
> 
> Modified: llvm/trunk/include/llvm/ADT/APInt.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/APInt.h?rev=197271&r1=197270&r2=197271&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/ADT/APInt.h (original)
> +++ llvm/trunk/include/llvm/ADT/APInt.h Fri Dec 13 14:47:34 2013
> @@ -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
>    /// @{
> 
> Modified: llvm/trunk/lib/Support/APInt.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/APInt.cpp?rev=197271&r1=197270&r2=197271&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Support/APInt.cpp (original)
> +++ llvm/trunk/lib/Support/APInt.cpp Fri Dec 13 14:47:34 2013
> @@ -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 ||
> 
> Modified: llvm/trunk/unittests/ADT/APIntTest.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/APIntTest.cpp?rev=197271&r1=197270&r2=197271&view=diff
> ==============================================================================
> --- llvm/trunk/unittests/ADT/APIntTest.cpp (original)
> +++ llvm/trunk/unittests/ADT/APIntTest.cpp Fri Dec 13 14:47:34 2013
> @@ -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<integerPart>(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));
> +    }
> +  }
> +}
> +
>  }
> 
> 
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