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| author | David Bolvansky <david.bolvansky@gmail.com> | 2019-06-20 17:04:14 +0000 |
|---|---|---|
| committer | David Bolvansky <david.bolvansky@gmail.com> | 2019-06-20 17:04:14 +0000 |
| commit | 01511192b23f531b8d378fa522d46647ce7b41a7 (patch) | |
| tree | 8f38f9e83a88570ecc9d444275729eb96e2915b4 /llvm/lib | |
| parent | 5dbe4a99266393008aaff354f45b977afaecc3c8 (diff) | |
| download | bcm5719-llvm-01511192b23f531b8d378fa522d46647ce7b41a7.tar.gz bcm5719-llvm-01511192b23f531b8d378fa522d46647ce7b41a7.zip | |
[InstCombine] cttz(-x) -> cttz(x)
Summary: Signedness does not change number of trailing zeros.
Reviewers: spatel, lebedev.ri, nikic
Reviewed By: spatel
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63534
llvm-svn: 363951
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp index e366c379e9b..4bd1246cbf7 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp @@ -1194,6 +1194,12 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) { return CallInst::Create(F, {X, II.getArgOperand(1)}); } + // cttz(-x) -> cttz(x) + if (IsTZ && match(Op0, m_Neg(m_Value(X)))) { + II.setOperand(0, X); + return &II; + } + KnownBits Known = IC.computeKnownBits(Op0, 0, &II); // Create a mask for bits above (ctlz) or below (cttz) the first known one. |
