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

[Jakub Kuderski]

================
@@ -190,8 +195,244 @@ struct DeleteTrivialRem : public OpRewritePattern<RemOp> {
   DataFlowSolver &solver;
 };
 
-struct IntRangeOptimizationsPass
-    : public arith::impl::ArithIntRangeOptsBase<IntRangeOptimizationsPass> {
+/// Check if `type` is index or integer type with `getWidth() > targetBitwidth`.
+static Type checkIntType(Type type, unsigned targetBitwidth) {
+  Type elemType = getElementTypeOrSelf(type);
+  if (isa<IndexType>(elemType))
+    return type;
+
+  if (auto intType = dyn_cast<IntegerType>(elemType))
+    if (intType.getWidth() > targetBitwidth)
+      return type;
+
+  return nullptr;
+}
+
+/// Check if op have same type for all operands and results and this type
+/// is suitable for truncation.
+/// Retuns args type or empty.
+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;
+      }
+
+      if (type != val.getType())
+        return nullptr;
+    }
+  }
+
+  return checkIntType(type, targetBitwidth);
+}
+
+/// Return union of all operands values ranges.
+static std::optional<ConstantIntRanges> getOperandsRange(DataFlowSolver &solver,
+                                                         ValueRange operands) {
+  std::optional<ConstantIntRanges> ret;
+  for (Value value : operands) {
+    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;
+}
+
+/// Return int type truncated to `targetBitwidth`. If `srcType` is shaped,
+/// return shaped type as well.
+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;
+}
+
+/// Check privided `range` is inside `smin, smax, umin, umax` bounds.
+static bool checkRange(const ConstantIntRanges &range, APInt smin, APInt smax,
+                       APInt umin, APInt umax) {
+  auto sge = [](APInt val1, APInt val2) -> bool {
+    unsigned width = std::max(val1.getBitWidth(), val2.getBitWidth());
+    val1 = val1.sext(width);
+    val2 = val2.sext(width);
+    return val1.sge(val2);
+  };
+  auto sle = [](APInt val1, APInt val2) -> bool {
+    unsigned width = std::max(val1.getBitWidth(), val2.getBitWidth());
+    val1 = val1.sext(width);
+    val2 = val2.sext(width);
+    return val1.sle(val2);
+  };
+  auto uge = [](APInt val1, APInt val2) -> bool {
+    unsigned width = std::max(val1.getBitWidth(), val2.getBitWidth());
+    val1 = val1.zext(width);
+    val2 = val2.zext(width);
+    return val1.uge(val2);
+  };
+  auto ule = [](APInt val1, APInt val2) -> bool {
+    unsigned width = std::max(val1.getBitWidth(), val2.getBitWidth());
+    val1 = val1.zext(width);
+    val2 = val2.zext(width);
+    return val1.ule(val2);
+  };
+  return sge(range.smin(), smin) && sle(range.smax(), smax) &&
+         uge(range.umin(), umin) && ule(range.umax(), umax);
+}
+
+static Value doCast(OpBuilder &builder, Location loc, Value src, Type dstType) {
+  Type srcType = src.getType();
+  assert(isa<VectorType>(srcType) == isa<VectorType>(dstType) &&
+         "Mixing vector and non-vector types");
+  Type srcElemType = getElementTypeOrSelf(srcType);
+  Type dstElemType = getElementTypeOrSelf(dstType);
+  assert(srcElemType.isIntOrIndex() && "Invalid src type");
+  assert(dstElemType.isIntOrIndex() && "Invalid dst type");
+  if (srcType == dstType)
+    return src;
+
+  if (isa<IndexType>(srcElemType) || isa<IndexType>(dstElemType))
+    return builder.create<arith::IndexCastUIOp>(loc, dstType, src);
+
+  auto srcInt = cast<IntegerType>(srcElemType);
+  auto dstInt = cast<IntegerType>(dstElemType);
+  if (dstInt.getWidth() < srcInt.getWidth())
+    return builder.create<arith::TruncIOp>(loc, dstType, src);
+
+  return builder.create<arith::ExtUIOp>(loc, dstType, src);
+}
+
+struct NarrowElementwise final : OpTraitRewritePattern<OpTrait::Elementwise> {
+  NarrowElementwise(MLIRContext *context, DataFlowSolver &s,
+                    ArrayRef<unsigned> target)
+      : OpTraitRewritePattern<OpTrait::Elementwise>(context), solver(s),
----------------
kuhar wrote:

```suggestion
      : OpTraitRewritePattern(context), solver(s),
```
?

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