[Mlir-commits] [mlir] [mlir] Add `arith-int-range-narrowing` pass (PR #112404)

[Jakub Kuderski]

================
@@ -184,6 +189,232 @@ struct DeleteTrivialRem : public OpRewritePattern<RemOp> {
   DataFlowSolver &solver;
 };
 
+static Type checkArithType(Type type, unsigned targetBitwidth) {
+  type = getElementTypeOrSelf(type);
+  if (isa<IndexType>(type))
+    return type;
+
+  if (auto intType = dyn_cast<IntegerType>(type))
+    if (intType.getWidth() > targetBitwidth)
+      return type;
+
+  return nullptr;
+}
+
+static Type checkElementwiseOpType(Operation *op, unsigned targetBitwidth) {
+  if (op->getNumOperands() == 0 || op->getNumResults() == 0)
+    return nullptr;
+
+  Type type;
+  for (auto range :
+       {ValueRange(op->getOperands()), ValueRange(op->getResults())}) {
+    for (Value val : range) {
+      if (!type) {
+        type = val.getType();
+        continue;
+      } else if (type != val.getType()) {
+        return nullptr;
+      }
+    }
+  }
+
+  return checkArithType(type, targetBitwidth);
+}
+
+static std::optional<ConstantIntRanges> getOperandsRange(DataFlowSolver &solver,
+                                                         ValueRange results) {
+  std::optional<ConstantIntRanges> ret;
+  for (Value value : results) {
+    auto *maybeInferredRange =
+        solver.lookupState<IntegerValueRangeLattice>(value);
+    if (!maybeInferredRange || maybeInferredRange->getValue().isUninitialized())
+      return std::nullopt;
+
+    const ConstantIntRanges &inferredRange =
+        maybeInferredRange->getValue().getValue();
+
+    if (!ret) {
+      ret = inferredRange;
+    } else {
+      ret = ret->rangeUnion(inferredRange);
+    }
+  }
+  return ret;
+}
+
+static Type getTargetType(Type srcType, unsigned targetBitwidth) {
+  auto dstType = IntegerType::get(srcType.getContext(), targetBitwidth);
+  if (auto shaped = dyn_cast<ShapedType>(srcType))
+    return shaped.clone(dstType);
+
+  assert(srcType.isIntOrIndex() && "Invalid src type");
+  return dstType;
+}
+
+static bool checkRange(const ConstantIntRanges &range, APInt smin, APInt smax,
----------------
kuhar wrote:

Not clear what the result is. Could you add a comment what is being checked and maybe use `LogicalResult` for the return type? 

https://github.com/llvm/llvm-project/pull/112404