diff options
| -rw-r--r-- | lib/Analysis/ValueTracking.cpp | 7 | ||||
| -rw-r--r-- | test/Transforms/InstSimplify/AndOrXor.ll | 10 |
2 files changed, 16 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) || diff --git a/test/Transforms/InstSimplify/AndOrXor.ll b/test/Transforms/InstSimplify/AndOrXor.ll index 3d04d584f4..33a4d6b02d 100644 --- a/test/Transforms/InstSimplify/AndOrXor.ll +++ b/test/Transforms/InstSimplify/AndOrXor.ll @@ -10,3 +10,13 @@ define i64 @pow2(i32 %x) { ret i64 %e2 ; CHECK: ret i64 %e } + +define i64 @pow2b(i32 %x) { +; CHECK: @pow2b + %sh = shl i32 2, %x + %e = zext i32 %sh to i64 + %nege = sub i64 0, %e + %e2 = and i64 %e, %nege + ret i64 %e2 +; CHECK: ret i64 %e +} |