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[block-freq] Add the method APInt::nearestLogBase2().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197272 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1507,6 +1507,19 @@ public:
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return BitWidth - (*this - 1).countLeadingZeros();
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}
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/// \returns the nearest log base 2 of this APInt. Ties round up.
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unsigned nearestLogBase2() const {
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// This is implemented by taking the normal log 2 of a number and adding 1
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// to it if MSB - 1 is set.
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// We follow the model from logBase2 that logBase2(0) == UINT32_MAX. This
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// works since if we have 0, MSB will be 0. Then we subtract one yielding
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// UINT32_MAX. Finally extractBit of MSB - 1 will be UINT32_MAX implying
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// that we get BitWidth - 1.
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unsigned lg = logBase2();
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return lg + unsigned(extractBit(std::min(lg - 1, BitWidth - 1)));
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}
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/// \returns the log base 2 of this APInt if its an exact power of two, -1
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/// otherwise
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int32_t exactLogBase2() const {
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@ -609,10 +609,10 @@ TEST(APIntTest, extractBit) {
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// Multiword check.
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integerPart E2[4] = {
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0xeb6eb136591cba21ULL,
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0x7b9358bd6a33f10aULL,
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0x7e7ffa5eadd8846ULL,
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0x305f341ca00b613dULL
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0xEB6EB136591CBA21ULL,
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0x7B9358BD6A33F10AULL,
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0x7E7FFA5EADD8846ULL,
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0x305F341CA00B613DULL
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};
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APInt A2(integerPartWidth*4, ArrayRef<integerPart>(E2, 4));
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for (unsigned i = 0; i < 4; ++i) {
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@ -623,4 +623,40 @@ TEST(APIntTest, extractBit) {
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}
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}
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TEST(APIntTest, nearestLogBase2) {
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// Single word check.
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// Test round up.
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uint64_t I1 = 0x1800001;
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APInt A1(64, I1);
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EXPECT_EQ(A1.nearestLogBase2(), A1.ceilLogBase2());
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// Test round down.
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uint64_t I2 = 0x1000011;
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APInt A2(64, I2);
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EXPECT_EQ(A2.nearestLogBase2(), A2.logBase2());
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// Test ties round up.
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uint64_t I3 = 0x1800000;
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APInt A3(64, I3);
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EXPECT_EQ(A3.nearestLogBase2(), A3.ceilLogBase2());
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// Multiple word check.
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// Test round up.
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integerPart I4[4] = {0x0, 0xF, 0x18, 0x0};
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APInt A4(integerPartWidth*4, ArrayRef<integerPart>(I4, 4));
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EXPECT_EQ(A4.nearestLogBase2(), A4.ceilLogBase2());
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// Test round down.
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integerPart I5[4] = {0x0, 0xF, 0x10, 0x0};
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APInt A5(integerPartWidth*4, ArrayRef<integerPart>(I5, 4));
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EXPECT_EQ(A5.nearestLogBase2(), A5.logBase2());
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// Test ties round up.
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uint64_t I6[4] = {0x0, 0x0, 0x0, 0x18};
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APInt A6(integerPartWidth*4, ArrayRef<integerPart>(I6, 4));
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EXPECT_EQ(A6.nearestLogBase2(), A6.ceilLogBase2());
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}
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}
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