TosaToLinalg: Support unsigned tosa.clamp (llvm#91749)

This implements the lowering of tosa.clamp with unsigned operand to
linalg.

We interpret the `min/max : i64`  attributes on `clamp` to be signed.

This means that when the operand has type `ui64`, one cannot represent
limits across the whole range.

Author: mgehre-amd

mlir/include/mlir/Conversion/TosaToLinalg/TosaToLinalg.h

@@ -47,7 +47,8 @@ void addTosaToLinalgPasses(
 void registerTosaToLinalgPipelines();
 
 /// Populates conversion passes from TOSA dialect to Linalg dialect.
-void populateTosaToLinalgConversionPatterns(RewritePatternSet *patterns);
+void populateTosaToLinalgConversionPatterns(TypeConverter &converter,
+                                            RewritePatternSet *patterns);
 
 /// Populates conversion passes from TOSA dialect to Linalg named operations.
 void populateTosaToLinalgNamedConversionPatterns(

mlir/include/mlir/Dialect/Tosa/Utils/ConversionUtils.h

@@ -37,7 +37,7 @@ Value clampFloatHelper(Location loc, Value arg, Value min, Value max,
 // Takes the parameters for a clamp and turns it into a series of ops for
 // integer inputs.
 Value clampIntHelper(Location loc, Value arg, Value min, Value max,
-                     OpBuilder &rewriter);
+                     OpBuilder &rewriter, bool isUnsigned);
 
 // Determines whether the integer value falls witin the range of integer type.
 bool validIntegerRange(IntegerType ty, int64_t value);

mlir/lib/Conversion/TosaToLinalg/TosaToLinalg.cpp

@@ -46,10 +46,9 @@ createConstFromIntAttribute(Operation *op, const std::string &attrName,
       op->getLoc(), IntegerAttr::get(requiredAttrType, castedN));
 }
 
-static Value
-createLinalgBodyCalculationForElementwiseOp(Operation *op, ValueRange args,
-                                            ArrayRef<Type> resultTypes,
-                                            PatternRewriter &rewriter) {
+static Value createLinalgBodyCalculationForElementwiseOp(
+    Operation *op, ValueRange args, ArrayRef<Type> resultTypes,
+    ConversionPatternRewriter &rewriter) {
   Location loc = op->getLoc();
   auto elementTy =
       cast<ShapedType>(op->getOperand(0).getType()).getElementType();
@@ -186,7 +185,8 @@ createLinalgBodyCalculationForElementwiseOp(Operation *op, ValueRange args,
     Value max = rewriter.create<arith::ConstantIntOp>(
         loc, APInt::getSignedMaxValue(inputBitWidth).getSExtValue(),
         intermediateType);
-    auto clamp = clampIntHelper(loc, sub, min, max, rewriter);
+    auto clamp =
+        clampIntHelper(loc, sub, min, max, rewriter, /*isUnsigned=*/false);
 
     // Truncate to the final value.
     return rewriter.create<arith::TruncIOp>(loc, elementTy, clamp);
@@ -389,25 +389,33 @@ createLinalgBodyCalculationForElementwiseOp(Operation *op, ValueRange args,
     int64_t max =
         cast<IntegerAttr>(op->getAttr("max_int")).getValue().getSExtValue();
 
+    int64_t minRepresentable = std::numeric_limits<int64_t>::min();
+    int64_t maxRepresentable = std::numeric_limits<int64_t>::max();
     if (intTy.isUnsignedInteger()) {
-      min = std::max(min, (int64_t)0);
-      max = std::min(
-          max,
-          APInt::getMaxValue(intTy.getIntOrFloatBitWidth()).getSExtValue());
-    } else {
-      min =
-          std::max(min, APInt::getSignedMinValue(intTy.getIntOrFloatBitWidth())
-                            .getSExtValue());
-      max =
-          std::min(max, APInt::getSignedMaxValue(intTy.getIntOrFloatBitWidth())
-                            .getSExtValue());
+      minRepresentable = 0;
+      if (intTy.getIntOrFloatBitWidth() <= 63) {
+        maxRepresentable = (int64_t)APInt::getMaxValue(intTy.getIntOrFloatBitWidth())
+                          .getZExtValue();
+      }
+    } else if(intTy.getIntOrFloatBitWidth() <= 64) {
+      // Ensure that min & max fit into signed n-bit constants.
+      minRepresentable = APInt::getSignedMinValue(intTy.getIntOrFloatBitWidth())
+                            .getSExtValue();
+      maxRepresentable = APInt::getSignedMaxValue(intTy.getIntOrFloatBitWidth())
+                            .getSExtValue();
     }
+    // Ensure that the bounds are representable as n-bit signed/unsigned integers.
+    min = std::max(min, minRepresentable);
+    max = std::max(max, minRepresentable);
+    min = std::min(min, maxRepresentable);
+    max = std::min(max, maxRepresentable);
 
     auto minVal = rewriter.create<arith::ConstantIntOp>(
         loc, min, intTy.getIntOrFloatBitWidth());
     auto maxVal = rewriter.create<arith::ConstantIntOp>(
         loc, max, intTy.getIntOrFloatBitWidth());
-    return clampIntHelper(loc, args[0], minVal, maxVal, rewriter);
+    return clampIntHelper(loc, args[0], minVal, maxVal, rewriter,
+                          intTy.isUnsignedInteger());
   }
 
   // tosa::SigmoidOp
@@ -615,10 +623,9 @@ static Value expandRank(PatternRewriter &rewriter, Location loc, Value tensor,
 }
 
 static SmallVector<Value> expandInputRanks(PatternRewriter &rewriter,
-                                           Location loc, Operation *operation) {
-  auto rank =
-      cast<RankedTensorType>(operation->getResultTypes().front()).getRank();
-  return llvm::map_to_vector(operation->getOperands(), [&](Value operand) {
+                                           Location loc, ValueRange operands,
+                                           int64_t rank) {
+  return llvm::map_to_vector(operands, [&](Value operand) {
     return expandRank(rewriter, loc, operand, rank);
   });
 }
@@ -843,11 +850,16 @@ broadcastDynamicDimensions(PatternRewriter &rewriter, Location loc,
 }
 
 static LogicalResult
-emitElementwiseComputation(PatternRewriter &rewriter, Location loc,
+emitElementwiseComputation(ConversionPatternRewriter &rewriter, Location loc,
                            Operation *operation, ValueRange operands,
-                           ArrayRef<OpFoldResult> targetShape) {
+                           ArrayRef<OpFoldResult> targetShape,
+                           const TypeConverter &converter) {
   // Generate output tensor
-  auto resultType = cast<RankedTensorType>(operation->getResultTypes().front());
+  auto resultType = cast_or_null<RankedTensorType>(
+      converter.convertType(operation->getResultTypes().front()));
+  if (!resultType) {
+    return rewriter.notifyMatchFailure(operation, "failed to convert type");
+  }
   Value outputTensor = rewriter.create<tensor::EmptyOp>(
       loc, targetShape, resultType.getElementType());
 
@@ -894,8 +906,9 @@ emitElementwiseComputation(PatternRewriter &rewriter, Location loc,
 }
 
 static LogicalResult
-elementwiseMatchAndRewriteHelper(Operation *operation,
-                                 PatternRewriter &rewriter) {
+elementwiseMatchAndRewriteHelper(Operation *operation, ValueRange operands,
+                                 ConversionPatternRewriter &rewriter,
+                                 const TypeConverter &converter) {
 
   // Collect op properties
   assert(operation->getNumResults() == 1 && "elementwise op expects 1 result");
@@ -908,13 +921,15 @@ elementwiseMatchAndRewriteHelper(Operation *operation,
   // Lower operation
   IndexPool indexPool;
   auto loc = operation->getLoc();
-  auto expandedOperands = expandInputRanks(rewriter, loc, operation);
+  auto rank =
+      cast<RankedTensorType>(operation->getResultTypes().front()).getRank();
+  auto expandedOperands = expandInputRanks(rewriter, loc, operands, rank);
   auto [targetShape, masterOperands] =
       computeTargetShape(rewriter, loc, indexPool, expandedOperands);
   auto broadcastOperands = broadcastDynamicDimensions(
       rewriter, loc, indexPool, expandedOperands, targetShape, masterOperands);
   return emitElementwiseComputation(rewriter, loc, operation, broadcastOperands,
-                                    targetShape);
+                                    targetShape, converter);
 }
 
 // Returns the constant initial value for a given reduction operation. The
@@ -1100,13 +1115,16 @@ static LogicalResult reduceMatchAndRewriteHelper(Operation *op, uint64_t axis,
 namespace {
 
 template <typename SrcOp>
-class PointwiseConverter : public OpRewritePattern<SrcOp> {
+class PointwiseConverter : public OpConversionPattern<SrcOp> {
 public:
-  using OpRewritePattern<SrcOp>::OpRewritePattern;
+  using OpConversionPattern<SrcOp>::OpConversionPattern;
+  using typename OpConversionPattern<SrcOp>::OpAdaptor;
 
-  LogicalResult matchAndRewrite(SrcOp op,
-                                PatternRewriter &rewriter) const final {
-    return elementwiseMatchAndRewriteHelper(op, rewriter);
+  LogicalResult
+  matchAndRewrite(SrcOp op, OpAdaptor operands,
+                  ConversionPatternRewriter &rewriter) const final {
+    return elementwiseMatchAndRewriteHelper(
+        op, operands.getOperands(), rewriter, *this->getTypeConverter());
   }
 };
 
@@ -1279,7 +1297,7 @@ class RescaleConverter : public OpRewritePattern<tosa::RescaleOp> {
               loc, nestedBuilder.getI32IntegerAttr(intMax));
 
           value = clampIntHelper(nestedLoc, value, intMinVal, intMaxVal,
-                                 nestedBuilder);
+                                 nestedBuilder, /*isUnsigned=*/false);
 
           if (outIntType.getWidth() < 32) {
             value = nestedBuilder.create<arith::TruncIOp>(
@@ -1643,7 +1661,7 @@ class GenericResizeConverter : public OpRewritePattern<tosa::ResizeOp> {
 
           auto offset = b.create<arith::SelectOp>(pred, one, zeroI32);
           val = b.create<arith::AddIOp>(val, offset);
-          val = clampIntHelper(loc, val, zeroI32, max, b);
+          val = clampIntHelper(loc, val, zeroI32, max, b, /*isUnsigned=*/false);
           return b.create<arith::IndexCastOp>(b.getIndexType(), val);
         };
 
@@ -1664,8 +1682,10 @@ class GenericResizeConverter : public OpRewritePattern<tosa::ResizeOp> {
                                   Value max, ImplicitLocOpBuilder &b) {
           val0 = in;
           val1 = b.create<arith::AddIOp>(val0, oneVal);
-          val0 = clampIntHelper(loc, val0, zeroI32, max, b);
-          val1 = clampIntHelper(loc, val1, zeroI32, max, b);
+          val0 =
+              clampIntHelper(loc, val0, zeroI32, max, b, /*isUnsigned=*/false);
+          val1 =
+              clampIntHelper(loc, val1, zeroI32, max, b, /*isUnsigned=*/false);
           val0 = b.create<arith::IndexCastOp>(b.getIndexType(), val0);
           val1 = b.create<arith::IndexCastOp>(b.getIndexType(), val1);
         };
@@ -2555,7 +2575,7 @@ struct FFT2dConverter final : OpRewritePattern<FFT2dOp> {
 } // namespace
 
 void mlir::tosa::populateTosaToLinalgConversionPatterns(
-    RewritePatternSet *patterns) {
+    TypeConverter &converter, RewritePatternSet *patterns) {
 
   // We have multiple resize coverters to handle degenerate cases.
   patterns->add<GenericResizeConverter>(patterns->getContext(),
@@ -2602,7 +2622,10 @@ void mlir::tosa::populateTosaToLinalgConversionPatterns(
       PointwiseConverter<tosa::CeilOp>,
       PointwiseConverter<tosa::FloorOp>,
       PointwiseConverter<tosa::ClampOp>,
-      PointwiseConverter<tosa::SigmoidOp>,
+      PointwiseConverter<tosa::SigmoidOp>
+        >(converter, patterns->getContext());
+
+  patterns->add<
       IdentityNConverter<tosa::IdentityOp>,
       ReduceConverter<tosa::ReduceAllOp>,
       ReduceConverter<tosa::ReduceAnyOp>,

mlir/lib/Conversion/TosaToLinalg/TosaToLinalgNamed.cpp

@@ -1015,7 +1015,8 @@ class AvgPool2dConverter : public OpRewritePattern<tosa::AvgPool2dOp> {
             auto max = rewriter.create<arith::ConstantIntOp>(
                 loc, APInt::getSignedMaxValue(outBitwidth).getSExtValue(),
                 accETy);
-            auto clamp = clampIntHelper(loc, scaled, min, max, rewriter);
+            auto clamp = clampIntHelper(loc, scaled, min, max, rewriter,
+                                        /*isUnsigned=*/false);
 
             poolVal = clamp;
             // Convert type.

mlir/lib/Conversion/TosaToLinalg/TosaToLinalgPass.cpp

@@ -63,8 +63,11 @@ struct TosaToLinalg : public impl::TosaToLinalgBase<TosaToLinalg> {
 
     target.markUnknownOpDynamicallyLegal([](Operation *) { return true; });
 
+    TypeConverter converter;
+    tosa::populateTosaTypeConversion(converter);
+
     FunctionOpInterface func = getOperation();
-    mlir::tosa::populateTosaToLinalgConversionPatterns(&patterns);
+    mlir::tosa::populateTosaToLinalgConversionPatterns(converter, &patterns);
     if (failed(applyFullConversion(func, target, std::move(patterns))))
       signalPassFailure();
   }

mlir/lib/Dialect/Tosa/Utils/ConversionUtils.cpp

@@ -38,7 +38,11 @@ Value mlir::tosa::clampFloatHelper(Location loc, Value arg, Value min,
 }
 
 Value mlir::tosa::clampIntHelper(Location loc, Value arg, Value min, Value max,
-                                 OpBuilder &rewriter) {
+                                 OpBuilder &rewriter, bool isUnsigned) {
+  if (isUnsigned) {
+    auto minOrArg = rewriter.create<arith::MaxUIOp>(loc, min, arg);
+    return rewriter.create<arith::MinUIOp>(loc, max, minOrArg);
+  }
   auto minOrArg = rewriter.create<arith::MaxSIOp>(loc, min, arg);
   return rewriter.create<arith::MinSIOp>(loc, max, minOrArg);
 }

mlir/test/Conversion/TosaToLinalg/tosa-to-linalg.mlir

@@ -606,7 +606,7 @@ func.func @test_simple_ui8(%arg0: tensor<1xui8>) -> () {
 // -----
 
 // CHECK-LABEL: @test_simple_i32
-func.func @test_simple_i32(%arg0: tensor<1xi32>) -> () {
+func.func @test_simple_i32(%arg0: tensor<1xi32>, %unsigned: tensor<1xui32>, %unsigned64: tensor<1xui64>) -> () {
   // CHECK: linalg.generic
   // CHECK: arith.addi
   %0 = tosa.add %arg0, %arg0 : (tensor<1xi32>, tensor<1xi32>) -> tensor<1xi32>
@@ -700,6 +700,34 @@ func.func @test_simple_i32(%arg0: tensor<1xi32>) -> () {
   // CHECK-DAG: arith.minsi
   %19 = tosa.clamp %0 {min_int = 1 : i64, max_int = 5 : i64, min_fp = 1.0 : f32, max_fp = 5.0 : f32} : (tensor<1xi32>) -> tensor<1xi32>
 
+  // CHECK: linalg.generic
+  // CHECK-DAG: %[[LB:.*]] = arith.constant 4 : i32
+  // CHECK-DAG: %[[UB:.*]] = arith.constant 32 : i32
+  // CHECK-DAG: arith.maxui %[[LB]],
+  // CHECK-DAG: arith.minui %[[UB]],
+  %u0 = tosa.clamp %unsigned {min_int = 4 : i64, max_int = 32 : i64, min_fp = 1.0 : f32, max_fp = 5.0 : f32} : (tensor<1xui32>) -> tensor<1xui32>
+
+  // CHECK: linalg.generic
+  // CHECK-DAG: %[[LB:.*]] = arith.constant -1 : i32
+  // CHECK-DAG: %[[UB:.*]] = arith.constant -1 : i32
+  // CHECK-DAG: arith.maxui %[[LB]],
+  // CHECK-DAG: arith.minui %[[UB]],
+  %u1 = tosa.clamp %unsigned {min_int = 9223372036854775807 : i64, max_int = 9223372036854775807 : i64, min_fp = 1.0 : f32, max_fp = 5.0 : f32} : (tensor<1xui32>) -> tensor<1xui32>
+
+  // CHECK: linalg.generic
+  // CHECK-DAG: %[[LB:.*]] = arith.constant 0 : i32
+  // CHECK-DAG: %[[UB:.*]] = arith.constant 0 : i32
+  // CHECK-DAG: arith.maxui %[[LB]],
+  // CHECK-DAG: arith.minui %[[UB]],
+  %u2 = tosa.clamp %unsigned {min_int = -3 : i64, max_int = -2 : i64, min_fp = 1.0 : f32, max_fp = 5.0 : f32} : (tensor<1xui32>) -> tensor<1xui32>
+
+  // CHECK: linalg.generic
+  // CHECK-DAG: %[[LB:.*]] = arith.constant 0 : i64
+  // CHECK-DAG: %[[UB:.*]] = arith.constant 9223372036854775807 : i64
+  // CHECK-DAG: arith.maxui %[[LB]],
+  // CHECK-DAG: arith.minui %[[UB]],
+  %u3 = tosa.clamp %unsigned64 {min_int = -3 : i64, max_int = 9223372036854775807 : i64, min_fp = 1.0 : f32, max_fp = 5.0 : f32} : (tensor<1xui64>) -> tensor<1xui64>
+
   // CHECK: linalg.generic
   // CHECK: arith.trunci
   %20 = tosa.cast %0 : (tensor<1xi32>) -> tensor<1xi16>