From f0469af63e10f8a78f717d943610593ca260413a Mon Sep 17 00:00:00 2001 From: Nick Lewycky Date: Mon, 21 Mar 2011 21:40:32 +0000 Subject: Fix INT_MIN gotcha pointed out by Eli Friedman. llvm-svn: 128028 --- llvm/lib/Analysis/ValueTracking.cpp | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'llvm') diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index c36f68c2aeb..0f4bfb7b0d9 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -725,9 +725,10 @@ bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, unsigned Depth) { isPowerOfTwo(SI->getFalseValue(), TD, Depth); // An exact divide or right shift can only shift off zero bits, so the result - // is a power of two only if the first operand is a power of two. - if (match(V, m_Shr(m_Value(), m_Value())) || - match(V, m_IDiv(m_Value(), m_Value()))) { + // is a power of two only if the first operand is a power of two and not + // copying a sign bit (sdiv int_min, 2). + if (match(V, m_LShr(m_Value(), m_Value())) || + match(V, m_UDiv(m_Value(), m_Value()))) { BinaryOperator *BO = cast(V); if (BO->isExact()) return isPowerOfTwo(BO->getOperand(0), TD, Depth); -- cgit v1.2.3