diff options
Diffstat (limited to 'llvm/lib/Analysis/ValueTracking.cpp')
| -rw-r--r-- | llvm/lib/Analysis/ValueTracking.cpp | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index 2b7611c..ed81c05 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -9108,6 +9108,17 @@ static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS, if (L0 == R0 && L1 == R1) return isImpliedCondMatchingOperands(LPred, RPred); + // It only really makes sense in the context of signed comparison for "X - Y + // must be positive if X >= Y and no overflow". + // Take SGT as an example: L0:x > L1:y and C >= 0 + // ==> R0:(x -nsw y) < R1:(-C) is false + if ((LPred == ICmpInst::ICMP_SGT || LPred == ICmpInst::ICMP_SGE) && + match(R0, m_NSWSub(m_Specific(L0), m_Specific(L1)))) { + if (match(R1, m_NonPositive()) && + isImpliedCondMatchingOperands(LPred, RPred) == false) + return false; + } + // L0 = R0 = L1 + R1, L0 >=u L1 implies R0 >=u R1, L0 <u L1 implies R0 <u R1 if (L0 == R0 && (LPred == ICmpInst::ICMP_ULT || LPred == ICmpInst::ICMP_UGE) && |