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| author | Roman Lebedev <lebedev.ri@gmail.com> | 2019-10-26 22:46:09 +0300 |
|---|---|---|
| committer | Roman Lebedev <lebedev.ri@gmail.com> | 2019-10-26 23:20:58 +0300 |
| commit | 9d77ad57540c45b0a6e6ffcf8721a3189c0ed70e (patch) | |
| tree | 6f551dc17819858023523e6138760209b28222d6 /llvm/lib/Support/APInt.cpp | |
| parent | 11c920207afa92ad13fdf72daba14c9af336293a (diff) | |
| download | llvm-9d77ad57540c45b0a6e6ffcf8721a3189c0ed70e.zip llvm-9d77ad57540c45b0a6e6ffcf8721a3189c0ed70e.tar.gz llvm-9d77ad57540c45b0a6e6ffcf8721a3189c0ed70e.tar.bz2 | |
[APInt] Introduce APIntOps::GetMostSignificantDifferentBit()
Summary:
Compare two values, and if they are different, return the position of the
most significant bit that is different in the values.
Needed for D69387.
Reviewers: nikic, spatel, sanjoy, RKSimon
Reviewed By: nikic
Subscribers: xbolva00, hiraditya, dexonsmith, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69439
Diffstat (limited to 'llvm/lib/Support/APInt.cpp')
| -rw-r--r-- | llvm/lib/Support/APInt.cpp | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp index 08e9757..5f2686c 100644 --- a/llvm/lib/Support/APInt.cpp +++ b/llvm/lib/Support/APInt.cpp @@ -3027,6 +3027,14 @@ llvm::APIntOps::SolveQuadraticEquationWrap(APInt A, APInt B, APInt C, return X; } +Optional<unsigned> +llvm::APIntOps::GetMostSignificantDifferentBit(const APInt &A, const APInt &B) { + assert(A.getBitWidth() == B.getBitWidth() && "Must have the same bitwidth"); + if (A == B) + return llvm::None; + return A.getBitWidth() - ((A ^ B).countLeadingZeros() + 1); +} + /// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst /// with the integer held in IntVal. void llvm::StoreIntToMemory(const APInt &IntVal, uint8_t *Dst, |