diff options
| author | Duncan Sands <baldrick@free.fr> | 2011-10-28 18:30:05 +0000 |
|---|---|---|
| committer | Duncan Sands <baldrick@free.fr> | 2011-10-28 18:30:05 +0000 |
| commit | 4604fc7791314af7ba7b66999e4c7fb75a4d9f6e (patch) | |
| tree | 3e33c7f131400070536fc37376e488bdb946ee02 /lib/Analysis/ValueTracking.cpp | |
| parent | c65c747bc4ee7d3ca8463d33708bbb2aed38a809 (diff) | |
A shift of a power of two is a power of two or zero.
For completeness - not spotted in the wild.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143211 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | lib/Analysis/ValueTracking.cpp | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp index 90757f9798..9f7b5b501a 100644 --- a/lib/Analysis/ValueTracking.cpp +++ b/lib/Analysis/ValueTracking.cpp @@ -769,6 +769,12 @@ bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero, if (Depth++ == MaxDepth) return false; + Value *X = 0, *Y = 0; + // A shift of a power of two is a power of two or zero. + if (OrZero && (match(V, m_Shl(m_Value(X), m_Value())) || + match(V, m_Shr(m_Value(X), m_Value())))) + return isPowerOfTwo(X, TD, /*OrZero*/true, Depth); + if (ZExtInst *ZI = dyn_cast<ZExtInst>(V)) return isPowerOfTwo(ZI->getOperand(0), TD, OrZero, Depth); @@ -776,7 +782,6 @@ bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero, return isPowerOfTwo(SI->getTrueValue(), TD, OrZero, Depth) && isPowerOfTwo(SI->getFalseValue(), TD, OrZero, Depth); - Value *X = 0, *Y = 0; if (OrZero && match(V, m_And(m_Value(X), m_Value(Y)))) { // A power of two and'd with anything is a power of two or zero. if (isPowerOfTwo(X, TD, /*OrZero*/true, Depth) || |