I found myself typing this code several times at different places
by now, so time to make this a general utility instead. Given
a permutation, it returns the permuted position of the input,
for example (i,j,k) -> (k,i,j) yields position 1 for input 0.
Reviewed By: ftynse
Differential Revision: https://reviews.llvm.org/D108347
/// when the caller knows it is safe to do so.
unsigned getDimPosition(unsigned idx) const;
+ /// Extracts the permuted position where given input index resides.
+ /// Fails when called on a non-permutation.
+ unsigned getPermutedPosition(unsigned input) const;
+
/// Return true if any affine expression involves AffineDimExpr `position`.
bool isFunctionOfDim(unsigned position) const {
return llvm::any_of(getResults(), [&](AffineExpr e) {
return getResult(idx).cast<AffineDimExpr>().getPosition();
}
+unsigned AffineMap::getPermutedPosition(unsigned input) const {
+ assert(isPermutation() && "invalid permutation request");
+ for (unsigned i = 0, numResults = getNumResults(); i < numResults; i++)
+ if (getDimPosition(i) == input)
+ return i;
+ llvm_unreachable("incorrect permutation request");
+}
+
/// Folds the results of the application of an affine map on the provided
/// operands to a constant if possible. Returns false if the folding happens,
/// true otherwise.