Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp =================================================================== --- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -3490,6 +3490,19 @@ } } } + + if (BO0) { + // Transform A & (L - 1) `ult` L --> L != 0 + Value *L; + auto LSubOne = m_Add(m_Value(L), m_AllOnes()); + auto BitwiseAnd = + m_CombineOr(m_And(m_Value(), LSubOne), m_And(LSubOne, m_Value())); + + if (match(BO0, BitwiseAnd) && I.getPredicate() == ICmpInst::ICMP_ULT) { + auto *Zero = Constant::getNullValue(BO0->getType()); + return new ICmpInst(ICmpInst::ICMP_NE, L, Zero); + } + } } { Value *A, *B; Index: llvm/trunk/test/Transforms/InstCombine/icmp.ll =================================================================== --- llvm/trunk/test/Transforms/InstCombine/icmp.ll +++ llvm/trunk/test/Transforms/InstCombine/icmp.ll @@ -1603,3 +1603,23 @@ %s = select i1 %cmp, i32 10000, i32 0 ret i32 %s } + +; CHECK: @f8( +; CHECK-NEXT: [[RESULT:%[a-z0-9]+]] = icmp ne i32 %lim, 0 +; CHECK-NEXT: ret i1 [[RESULT]] +define i1 @f8(i32 %val, i32 %lim) { + %lim.sub = add i32 %lim, -1 + %val.and = and i32 %val, %lim.sub + %r = icmp ult i32 %val.and, %lim + ret i1 %r +} + +; CHECK: @f9( +; CHECK-NEXT: [[RESULT:%[a-z0-9]+]] = icmp ne i32 %lim, 0 +; CHECK-NEXT: ret i1 [[RESULT]] +define i1 @f9(i32 %val, i32 %lim) { + %lim.sub = sub i32 %lim, 1 + %val.and = and i32 %val, %lim.sub + %r = icmp ult i32 %val.and, %lim + ret i1 %r +}