Drop AffineMap::Null and IntegerSet::Null

Addresses b/122486036

This CL addresses some leftover crumbs in AffineMap and IntegerSet by removing
the Null method and cleaning up the constructors.

As the ::Null uses were tracked down, opportunities appeared to untangle some
of the Parsing logic and make it explicit where AffineMap/IntegerSet have
ambiguous syntax. Previously, ambiguous cases were hidden behind the implicit
pointer values of AffineMap* and IntegerSet* that were passed as function
parameters. Depending the values of those pointers one of 3 behaviors could
occur.

This parsing logic convolution is one of the rare cases where I would advocate
for code duplication. The more proper fix would be to make the syntax
unambiguous or to allow some lookahead.

PiperOrigin-RevId: 231058512

1 files changed, 4 insertions, 4 deletions

diff --git a/mlir/lib/Transforms/Utils/LoopUtils.cpp b/mlir/lib/Transforms/Utils/LoopUtils.cpp
index 66e7c5975da..d41614545d2 100644
--- a/mlir/lib/Transforms/Utils/LoopUtils.cpp
+++ b/mlir/lib/Transforms/Utils/LoopUtils.cpp
@@ -46,12 +46,12 @@ AffineMap mlir::getUnrolledLoopUpperBound(const ForInst &forInst,
 
   // Single result lower bound map only.
   if (lbMap.getNumResults() != 1)
-    return AffineMap::Null();
+    return AffineMap();
 
   // Sometimes, the trip count cannot be expressed as an affine expression.
   auto tripCount = getTripCountExpr(forInst);
   if (!tripCount)
-    return AffineMap::Null();
+    return AffineMap();
 
   AffineExpr lb(lbMap.getResult(0));
   unsigned step = forInst.getStep();
@@ -72,12 +72,12 @@ AffineMap mlir::getCleanupLoopLowerBound(const ForInst &forInst,
 
   // Single result lower bound map only.
   if (lbMap.getNumResults() != 1)
-    return AffineMap::Null();
+    return AffineMap();
 
   // Sometimes the trip count cannot be expressed as an affine expression.
   AffineExpr tripCount(getTripCountExpr(forInst));
   if (!tripCount)
-    return AffineMap::Null();
+    return AffineMap();
 
   AffineExpr lb(lbMap.getResult(0));
   unsigned step = forInst.getStep();