Tests: Check always-defined platform macros with #if, not #ifdef

libeigen/eigen!3355

Co-authored-by: Rasmus Munk Larsen <rmlarsen@gmail.com>

Eigen/src/Core/NumTraits.h

diff --git a/Eigen/src/Core/NumTraits.h b/Eigen/src/Core/NumTraits.h
index 75c3789..417a71c 100644
--- a/Eigen/src/Core/NumTraits.h
+++ b/Eigen/src/Core/NumTraits.h
@@ -248,7 +248,7 @@
 struct NumTraits<long double> : GenericNumTraits<long double> {
   EIGEN_DEVICE_FUNC constexpr static long double dummy_precision() { return static_cast<long double>(1e-15l); }
 
-#if defined(EIGEN_ARCH_PPC) && (__LDBL_MANT_DIG__ == 106)
+#if EIGEN_ARCH_PPC && (__LDBL_MANT_DIG__ == 106)
   // PowerPC double double causes issues with some values
   EIGEN_DEVICE_FUNC constexpr static long double epsilon() {
     // 2^(-(__LDBL_MANT_DIG__)+1)

contrib/test/tensor_executor.cpp

diff --git a/contrib/test/tensor_executor.cpp b/contrib/test/tensor_executor.cpp
index e2cd7ea..da6b2ac 100644
--- a/contrib/test/tensor_executor.cpp
+++ b/contrib/test/tensor_executor.cpp
@@ -836,10 +836,12 @@
   for (Index i = 0; i < dst.size(); ++i) VERIFY_IS_EQUAL(dst.coeff(i), numext::maxi(lhs.coeff(i), rhs.coeff(i)));
 }
 
-#ifndef EIGEN_DONT_VECTORIZE
-#define EIGEN_DONT_VECTORIZE 0
+// Eigen defines EIGEN_DONT_VECTORIZE without a value, e.g. when EIGEN_DONT_ALIGN disables alignment.
+#ifdef EIGEN_DONT_VECTORIZE
+#define VECTORIZABLE(T, VAL) false
+#else
+#define VECTORIZABLE(T, VAL) (Eigen::internal::packet_traits<T>::Vectorizable && (VAL))
 #endif
-#define VECTORIZABLE(T, VAL) !EIGEN_DONT_VECTORIZE&& Eigen::internal::packet_traits<T>::Vectorizable&& VAL
 
 #define CALL_SUBTEST_PART(PART) CALL_SUBTEST_##PART
 

test/array_cwise.cpp

diff --git a/test/array_cwise.cpp b/test/array_cwise.cpp
index e427d8e..eba0db4 100644
--- a/test/array_cwise.cpp
+++ b/test/array_cwise.cpp
@@ -142,7 +142,7 @@
 template <typename Scalar>
 void binary_ops_test() {
   binary_op_test<Scalar>(BINARY_FUNCTOR_TEST_ARGS(pow));
-#ifndef EIGEN_COMP_MSVC
+#if !EIGEN_COMP_MSVC
   binary_op_test<Scalar>(BINARY_FUNCTOR_TEST_ARGS(atan2));
 #else
   binary_op_test<Scalar>(
@@ -376,7 +376,7 @@
             }
 
             Base a = eigenPow(j);
-#ifdef EIGEN_COMP_MSVC
+#if EIGEN_COMP_MSVC
             // Work around MSVC return value on underflow.
             // if std::pow returns 0 and Eigen returns a denormalized value, then skip the test
             int eigen_fpclass = std::fpclassify(a);

test/gpu_common.h

diff --git a/test/gpu_common.h b/test/gpu_common.h
index efd09c1..eb07860 100644
--- a/test/gpu_common.h
+++ b/test/gpu_common.h
@@ -133,7 +133,7 @@
   std::cout << "  EIGEN_CUDACC:                 " << int(EIGEN_CUDACC) << "\n";
 #endif
 
-#ifdef EIGEN_CUDA_SDK_VER
+#if EIGEN_CUDA_SDK_VER
   std::cout << "  EIGEN_CUDA_SDK_VER:             " << int(EIGEN_CUDA_SDK_VER) << "\n";
 #endif
 

test/packetmath.cpp

diff --git a/test/packetmath.cpp b/test/packetmath.cpp
index d66ae69..7b73f1d 100644
--- a/test/packetmath.cpp
+++ b/test/packetmath.cpp
@@ -2217,8 +2217,8 @@
     }
 
     RealScalar zero(0);
-#ifdef EIGEN_ARCH_ARM
-    // ARM automatically flushes denormals to zero.
+#if EIGEN_ARCH_ARM
+    // 32-bit ARM NEON flushes subnormals to zero.
     // Preserve sign by multiplying by +0.
     if (numext::abs(a) < (std::numeric_limits<RealScalar>::min)()) {
       a = a * zero;