diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index 666e7f2fa96..118579d5b72 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -1993,6 +1993,22 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS, Upper = Upper + 1; assert(Upper != Lower && "Upper part of range has wrapped!"); } + } else if (match(LHS, m_NUWShl(m_ConstantInt(CI2), m_Value()))) { + // 'shl nuw CI2, x' produces [CI2, CI2 << CLZ(CI2)] + Lower = CI2->getValue(); + Upper = Lower.shl(Lower.countLeadingZeros()) + 1; + } else if (match(LHS, m_NSWShl(m_ConstantInt(CI2), m_Value()))) { + if (CI2->isNegative()) { + // 'shl nsw CI2, x' produces [CI2 << CLO(CI2)-1, CI2] + unsigned ShiftAmount = CI2->getValue().countLeadingOnes() - 1; + Lower = CI2->getValue().shl(ShiftAmount); + Upper = CI2->getValue() + 1; + } else { + // 'shl nsw CI2, x' produces [CI2, CI2 << CLZ(CI2)-1] + unsigned ShiftAmount = CI2->getValue().countLeadingZeros() - 1; + Lower = CI2->getValue(); + Upper = CI2->getValue().shl(ShiftAmount) + 1; + } } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) { // 'lshr x, CI2' produces [0, UINT_MAX >> CI2]. APInt NegOne = APInt::getAllOnesValue(Width); diff --git a/test/Transforms/InstSimplify/compare.ll b/test/Transforms/InstSimplify/compare.ll index 27fe1bead23..764d76690e6 100644 --- a/test/Transforms/InstSimplify/compare.ll +++ b/test/Transforms/InstSimplify/compare.ll @@ -982,3 +982,30 @@ define i1 @icmp_known_bits(i4 %x, i4 %y) { ; CHECK-LABEL: @icmp_known_bits ; CHECK-NEXT: ret i1 false } + +define i1 @icmp_shl_nuw_1(i64 %a) { + %shl = shl nuw i64 1, %a + %cmp = icmp ne i64 %shl, 0 + ret i1 %cmp + +; CHECK-LABEL: @icmp_shl_nuw_1 +; CHECK-NEXT: ret i1 true +} + +define i1 @icmp_shl_nsw_neg1(i64 %a) { + %shl = shl nsw i64 -1, %a + %cmp = icmp sge i64 %shl, 3 + ret i1 %cmp + +; CHECK-LABEL: @icmp_shl_nsw_neg1 +; CHECK-NEXT: ret i1 false +} + +define i1 @icmp_shl_nsw_1(i64 %a) { + %shl = shl nsw i64 1, %a + %cmp = icmp sge i64 %shl, 0 + ret i1 %cmp + +; CHECK-LABEL: @icmp_shl_nsw_1 +; CHECK-NEXT: ret i1 true +}