reduction_matcher.cc: affInvolvesOnlyInputDim: drop explicit check on local vars

There is no need to check whether the local variables involve
any input dimensions.  This is implicit in the entire expression
involving these input dimensions.

Author: Sven Verdoolaege

src/core/polyhedral/reduction_matcher.cc

@@ -81,21 +81,6 @@ bool affInvolvesOnlyInputDim(isl::aff aff, int redDimIdx) {
 
   bool hasPureDim = aff.involves_dims(isl::dim_type::in, redDimIdx, 1);
 
-  bool divsInvolveOtherDims = false;
-  bool divsInvolveDim = false;
-  for (int i = 0, ei = aff.dim(isl::dim_type::div); i < ei; ++i) {
-    // Ignore divs with coefficient 0 that may be referred to by the aff.
-    // This is particularly the case when we are already processing the div.
-    if (aff.get_coefficient_val(isl::dim_type::div, i).is_zero()) {
-      continue;
-    }
-    bool divR = affInvolvesOnlyInputDim(aff.get_div(i), redDimIdx);
-    divsInvolveDim |=
-        divR; // becomes true if at least one involves the given dim
-    divsInvolveOtherDims |=
-        !divR; // becomes true if at least one involves other dims
-  }
-
   bool involvesOtherDims = aff.involves_dims(isl::dim_type::in, 0, redDimIdx) ||
       aff.involves_dims(
           isl::dim_type::in,
@@ -105,10 +90,7 @@ bool affInvolvesOnlyInputDim(isl::aff aff, int redDimIdx) {
   if (involvesOtherDims) {
     return false;
   }
-  if (!hasPureDim && !divsInvolveDim) {
-    return false;
-  }
-  if (divsInvolveDim && divsInvolveOtherDims) {
+  if (!hasPureDim) {
     return false;
   }
   return true;