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author | Dan Gohman <gohman@apple.com> | 2009-10-13 01:49:02 +0000 |
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committer | Dan Gohman <gohman@apple.com> | 2009-10-13 01:49:02 +0000 |
commit | cbc7cc63b6c7ee1008f92064388c37327c183328 (patch) | |
tree | 7658fbbdc579a3674ef2261cc546986c5f3dcff4 | |
parent | 5c78736f85579aa6de38cba2742ea13ff9f79e70 (diff) | |
download | llvm-cbc7cc63b6c7ee1008f92064388c37327c183328.tar.gz llvm-cbc7cc63b6c7ee1008f92064388c37327c183328.tar.bz2 llvm-cbc7cc63b6c7ee1008f92064388c37327c183328.tar.xz |
Add a ceilLogBase2 function to APInt.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83932 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | include/llvm/ADT/APInt.h | 5 | ||||
-rw-r--r-- | unittests/ADT/APIntTest.cpp | 11 |
2 files changed, 16 insertions, 0 deletions
diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h index 6c418bda62..88aa9956d9 100644 --- a/include/llvm/ADT/APInt.h +++ b/include/llvm/ADT/APInt.h @@ -1234,6 +1234,11 @@ public: return BitWidth - 1 - countLeadingZeros(); } + /// @returns the ceil log base 2 of this APInt. + unsigned ceilLogBase2() const { + return BitWidth - (*this - 1).countLeadingZeros(); + } + /// @returns the log base 2 of this APInt if its an exact power of two, -1 /// otherwise int32_t exactLogBase2() const { diff --git a/unittests/ADT/APIntTest.cpp b/unittests/ADT/APIntTest.cpp index 24a3d9b4ad..7b03d0f00c 100644 --- a/unittests/ADT/APIntTest.cpp +++ b/unittests/ADT/APIntTest.cpp @@ -315,6 +315,17 @@ TEST(APIntTest, StringBitsNeeded16) { EXPECT_EQ(9U, APInt::getBitsNeeded("-20", 16)); } +TEST(APIntTest, Log2) { + EXPECT_EQ(APInt(15, 7).logBase2(), 2); + EXPECT_EQ(APInt(15, 7).ceilLogBase2(), 3); + EXPECT_EQ(APInt(15, 7).exactLogBase2(), -1); + EXPECT_EQ(APInt(15, 8).logBase2(), 3); + EXPECT_EQ(APInt(15, 8).ceilLogBase2(), 3); + EXPECT_EQ(APInt(15, 8).exactLogBase2(), 3); + EXPECT_EQ(APInt(15, 9).logBase2(), 3); + EXPECT_EQ(APInt(15, 9).ceilLogBase2(), 4); + EXPECT_EQ(APInt(15, 9).exactLogBase2(), -1); +} #ifdef GTEST_HAS_DEATH_TEST TEST(APIntTest, StringDeath) { |