[FXML-4614] Add EmitC index types, lower arith.index_cast, arith.index_castui (#183)

Author: cferry-AMD

mlir/include/mlir/Dialect/EmitC/IR/EmitC.h

@@ -43,6 +43,10 @@ bool isIntegerIndexOrOpaqueType(Type type);
 
 /// Determines whether \p type is a valid floating-point type in EmitC.
 bool isSupportedFloatType(mlir::Type type);
+
+/// Determines whether \p type is a emitc.size_t/ssize_t type.
+bool isAnySizeTType(mlir::Type type);
+
 } // namespace emitc
 } // namespace mlir
 

mlir/include/mlir/Dialect/EmitC/IR/EmitC.td

@@ -51,7 +51,8 @@ class EmitC_BinaryOp<string mnemonic, list<Trait> traits = []> :
 def CExpression : NativeOpTrait<"emitc::CExpression">;
 
 // Types only used in binary arithmetic operations.
-def IntegerIndexOrOpaqueType : AnyTypeOf<[EmitCIntegerType, Index, EmitC_OpaqueType]>;
+def IntegerIndexOrOpaqueType : AnyTypeOf<[EmitCIntegerType, Index,
+  EmitC_SignedSizeT, EmitC_SizeT, EmitC_OpaqueType]>;
 def FloatIntegerIndexOrOpaqueType : AnyTypeOf<[EmitCFloatType, IntegerIndexOrOpaqueType]>;
 
 def EmitC_AddOp : EmitC_BinaryOp<"add", [CExpression]> {
@@ -287,6 +288,7 @@ def EmitC_CastOp : EmitC_Op<"cast",
   let arguments = (ins EmitCType:$source);
   let results = (outs EmitCType:$dest);
   let assemblyFormat = "$source attr-dict `:` type($source) `to` type($dest)";
+  let hasFolder = 1;
 }
 
 def EmitC_CmpOp : EmitC_BinaryOp<"cmp", [CExpression]> {
@@ -470,7 +472,7 @@ def EmitC_ForOp : EmitC_Op<"for",
     upper bound and step respectively, and defines an SSA value for its
     induction variable. It has one region capturing the loop body. The induction
     variable is represented as an argument of this region. This SSA value is a
-    signless integer or index. The step is a value of same type.
+    signless integer, or an index. The step is a value of same type.
 
     This operation has no result. The body region must contain exactly one block
     that terminates with `emitc.yield`. Calling ForOp::build will create such a

mlir/include/mlir/Dialect/EmitC/IR/EmitCTypes.td

@@ -130,4 +130,12 @@ def EmitC_PointerType : EmitC_Type<"Pointer", "ptr"> {
   let assemblyFormat = "`<` qualified($pointee) `>`";
 }
 
+def EmitC_SignedSizeT : EmitC_Type<"SignedSizeT", "ssize_t"> {
+  let summary = "EmitC signed size type";
+}
+
+def EmitC_SizeT : EmitC_Type<"SizeT", "size_t"> {
+  let summary = "EmitC unsigned size type";
+}
+
 #endif // MLIR_DIALECT_EMITC_IR_EMITCTYPES

mlir/include/mlir/Dialect/EmitC/Transforms/TypeConversions.h

@@ -0,0 +1,13 @@
+//===- TypeConversions.h - Convert signless types into C/C++ types -------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "mlir/Transforms/DialectConversion.h"
+
+namespace mlir {
+void populateEmitCSizeTypeConversionPatterns(mlir::TypeConverter &converter);
+} // namespace mlir

mlir/lib/Conversion/ArithToEmitC/ArithToEmitC.cpp

@@ -15,6 +15,7 @@
 
 #include "mlir/Dialect/Arith/IR/Arith.h"
 #include "mlir/Dialect/EmitC/IR/EmitC.h"
+#include "mlir/Dialect/EmitC/Transforms/TypeConversions.h"
 #include "mlir/IR/BuiltinAttributes.h"
 #include "mlir/IR/BuiltinTypes.h"
 #include "mlir/Support/LogicalResult.h"
@@ -36,8 +37,11 @@ class ArithConstantOpConversionPattern
   matchAndRewrite(arith::ConstantOp arithConst,
                   arith::ConstantOp::Adaptor adaptor,
                   ConversionPatternRewriter &rewriter) const override {
-    rewriter.replaceOpWithNewOp<emitc::ConstantOp>(
-        arithConst, arithConst.getType(), adaptor.getValue());
+    Type newTy = this->getTypeConverter()->convertType(arithConst.getType());
+    if (!newTy)
+      return rewriter.notifyMatchFailure(arithConst, "type conversion failed");
+    rewriter.replaceOpWithNewOp<emitc::ConstantOp>(arithConst, newTy,
+                                                   adaptor.getValue());
     return success();
   }
 };
@@ -201,6 +205,35 @@ class CmpFOpConversion : public OpConversionPattern<arith::CmpFOp> {
   }
 };
 
+/// Check if the signedness of type \p ty matches the expected
+/// signedness, and issue a type with the correct signedness if
+/// necessary.
+Type adaptIntegralTypeSignedness(Type ty, bool needsUnsigned) {
+  if (isa<IntegerType>(ty)) {
+    // Turns signless integers into signed integers.
+    if (ty.isUnsignedInteger() != needsUnsigned) {
+      auto signedness = needsUnsigned
+                            ? IntegerType::SignednessSemantics::Unsigned
+                            : IntegerType::SignednessSemantics::Signed;
+      return IntegerType::get(ty.getContext(), ty.getIntOrFloatBitWidth(),
+                              signedness);
+    }
+  } else if (emitc::isAnySizeTType(ty)) {
+    if (isa<emitc::SizeTType>(ty) != needsUnsigned) {
+      if (needsUnsigned)
+        return emitc::SizeTType::get(ty.getContext());
+      return emitc::SignedSizeTType::get(ty.getContext());
+    }
+  }
+  return ty;
+}
+
+/// Insert a cast operation to type \p ty if \p val
+/// does not have this type.
+Value adaptValueType(Value val, ConversionPatternRewriter &rewriter, Type ty) {
+  return rewriter.createOrFold<emitc::CastOp>(val.getLoc(), ty, val);
+}
+
 class CmpIOpConversion : public OpConversionPattern<arith::CmpIOp> {
 public:
   using OpConversionPattern::OpConversionPattern;
@@ -250,31 +283,25 @@ class CmpIOpConversion : public OpConversionPattern<arith::CmpIOp> {
                   ConversionPatternRewriter &rewriter) const override {
 
     Type type = adaptor.getLhs().getType();
-    if (!isa_and_nonnull<IntegerType, IndexType>(type)) {
-      return rewriter.notifyMatchFailure(op, "expected integer or index type");
+    if (!isa_and_nonnull<IntegerType, emitc::SignedSizeTType, emitc::SizeTType>(
+            type)) {
+      return rewriter.notifyMatchFailure(
+          op, "expected integer or size_t/ssize_t type");
     }
 
     bool needsUnsigned = needsUnsignedCmp(op.getPredicate());
     emitc::CmpPredicate pred = toEmitCPred(op.getPredicate());
-    Type arithmeticType = type;
-    if (type.isUnsignedInteger() != needsUnsigned) {
-      arithmeticType = rewriter.getIntegerType(type.getIntOrFloatBitWidth(),
-                                               /*isSigned=*/!needsUnsigned);
-    }
-    Value lhs = adaptor.getLhs();
-    Value rhs = adaptor.getRhs();
-    if (arithmeticType != type) {
-      lhs = rewriter.template create<emitc::CastOp>(op.getLoc(), arithmeticType,
-                                                    lhs);
-      rhs = rewriter.template create<emitc::CastOp>(op.getLoc(), arithmeticType,
-                                                    rhs);
-    }
+
+    Type arithmeticType = adaptIntegralTypeSignedness(type, needsUnsigned);
+    Value lhs = adaptValueType(adaptor.getLhs(), rewriter, arithmeticType);
+    Value rhs = adaptValueType(adaptor.getRhs(), rewriter, arithmeticType);
+
     rewriter.replaceOpWithNewOp<emitc::CmpOp>(op, op.getType(), pred, lhs, rhs);
     return success();
   }
 };
 
-template <typename ArithOp, bool needsUnsigned>
+template <typename ArithOp, bool castToUnsigned>
 class CastConversion : public OpConversionPattern<ArithOp> {
 public:
   using OpConversionPattern<ArithOp>::OpConversionPattern;
@@ -284,52 +311,58 @@ class CastConversion : public OpConversionPattern<ArithOp> {
                   ConversionPatternRewriter &rewriter) const override {
 
     Type opReturnType = this->getTypeConverter()->convertType(op.getType());
-    if (!isa_and_nonnull<IntegerType>(opReturnType)) {
-      return rewriter.notifyMatchFailure(op, "expected integer result type");
-    }
+    if (!isa_and_nonnull<IntegerType, emitc::SignedSizeTType, emitc::SizeTType>(
+            opReturnType))
+      return rewriter.notifyMatchFailure(
+          op, "expected integer or size_t/ssize_t result type");
 
     if (adaptor.getOperands().size() != 1) {
       return rewriter.notifyMatchFailure(
           op, "CastConversion only supports unary ops");
     }
 
     Type operandType = adaptor.getIn().getType();
-    if (!isa_and_nonnull<IntegerType>(operandType)) {
-      return rewriter.notifyMatchFailure(op, "expected integer operand type");
+    if (!isa_and_nonnull<IntegerType, emitc::SignedSizeTType, emitc::SizeTType>(
+            operandType))
+      return rewriter.notifyMatchFailure(
+          op, "expected integer or size_t/ssize_t operand type");
+
+    // to-i1 conversions: arith semantics want truncation, whereas (bool)(v) is
+    // equivalent to (v != 0). Implementing as (bool)(v & 0x01) gives
+    // truncation.
+    if (opReturnType.isInteger(1)) {
+      Type attrType = (emitc::isAnySizeTType(operandType))
+                          ? rewriter.getIndexType()
+                          : operandType;
+      auto constOne = rewriter.create<emitc::ConstantOp>(
+          op.getLoc(), operandType, rewriter.getIntegerAttr(attrType, 1));
+      auto oneAndOperand = rewriter.create<emitc::BitwiseAndOp>(
+          op.getLoc(), operandType, adaptor.getIn(), constOne);
+      rewriter.replaceOpWithNewOp<emitc::CastOp>(op, opReturnType,
+                                                 oneAndOperand);
+      return success();
     }
 
-    bool isTruncation = operandType.getIntOrFloatBitWidth() >
-                        opReturnType.getIntOrFloatBitWidth();
-    bool doUnsigned = needsUnsigned || isTruncation;
-
-    Type castType = opReturnType;
-    // For int conversions: if the op is a ui variant and the type wanted as
-    // return type isn't unsigned, we need to issue an unsigned type to do
-    // the conversion.
-    if (castType.isUnsignedInteger() != doUnsigned) {
-      castType = rewriter.getIntegerType(opReturnType.getIntOrFloatBitWidth(),
-                                         /*isSigned=*/!doUnsigned);
-    }
+    bool isTruncation =
+        (isa<IntegerType>(operandType) && isa<IntegerType>(opReturnType) &&
+         operandType.getIntOrFloatBitWidth() >
+             opReturnType.getIntOrFloatBitWidth());
+    bool doUnsigned = castToUnsigned || isTruncation;
 
-    Value actualOp = adaptor.getIn();
-    // Fix the signedness of the operand if necessary
-    if (operandType.isUnsignedInteger() != doUnsigned) {
-      Type correctSignednessType =
-          rewriter.getIntegerType(operandType.getIntOrFloatBitWidth(),
-                                  /*isSigned=*/!doUnsigned);
-      actualOp = rewriter.template create<emitc::CastOp>(
-          op.getLoc(), correctSignednessType, actualOp);
-    }
+    // Adapt the signedness of the result (bitwidth-preserving cast)
+    // This is needed e.g., if the return type is signless.
+    Type castDestType = adaptIntegralTypeSignedness(opReturnType, doUnsigned);
 
-    auto result = rewriter.template create<emitc::CastOp>(op.getLoc(), castType,
-                                                          actualOp);
+    // Adapt the signedness of the operand (bitwidth-preserving cast)
+    Type castSrcType = adaptIntegralTypeSignedness(operandType, doUnsigned);
+    Value actualOp = adaptValueType(adaptor.getIn(), rewriter, castSrcType);
 
-    // Fix the signedness of what this operation returns (for integers,
-    // the arith ops want signless results)
-    if (castType != opReturnType) {
-      result = rewriter.template create<emitc::CastOp>(op.getLoc(),
-                                                       opReturnType, result);
-    }
+    // Actual cast (may change bitwidth)
+    auto cast = rewriter.template create<emitc::CastOp>(op.getLoc(),
+                                                        castDestType, actualOp);
+
+    // Cast to the expected output type
+    auto result = adaptValueType(cast, rewriter, opReturnType);
 
     rewriter.replaceOp(op, result);
     return success();
@@ -355,7 +388,11 @@ class ArithOpConversion final : public OpConversionPattern<ArithOp> {
   matchAndRewrite(ArithOp arithOp, typename ArithOp::Adaptor adaptor,
                   ConversionPatternRewriter &rewriter) const override {
 
-    rewriter.template replaceOpWithNewOp<EmitCOp>(arithOp, arithOp.getType(),
+    Type newTy = this->getTypeConverter()->convertType(arithOp.getType());
+    if (!newTy)
+      return rewriter.notifyMatchFailure(arithOp,
+                                         "converting result type failed");
+    rewriter.template replaceOpWithNewOp<EmitCOp>(arithOp, newTy,
                                                   adaptor.getOperands());
 
     return success();
@@ -372,17 +409,17 @@ class IntegerOpConversion final : public OpConversionPattern<ArithOp> {
                   ConversionPatternRewriter &rewriter) const override {
 
     Type type = this->getTypeConverter()->convertType(op.getType());
-    if (!isa_and_nonnull<IntegerType, IndexType>(type)) {
-      return rewriter.notifyMatchFailure(op, "expected integer type");
+    if (!isa_and_nonnull<IntegerType, emitc::SignedSizeTType, emitc::SizeTType>(
+            type)) {
+      return rewriter.notifyMatchFailure(
+          op, "expected integer or size_t/ssize_t type");
     }
 
     if (type.isInteger(1)) {
       // arith expects wrap-around arithmethic, which doesn't happen on `bool`.
       return rewriter.notifyMatchFailure(op, "i1 type is not implemented");
     }
 
-    Value lhs = adaptor.getLhs();
-    Value rhs = adaptor.getRhs();
     Type arithmeticType = type;
     if ((type.isSignlessInteger() || type.isSignedInteger()) &&
         !bitEnumContainsAll(op.getOverflowFlags(),
@@ -392,20 +429,15 @@ class IntegerOpConversion final : public OpConversionPattern<ArithOp> {
       arithmeticType = rewriter.getIntegerType(type.getIntOrFloatBitWidth(),
                                                /*isSigned=*/false);
     }
-    if (arithmeticType != type) {
-      lhs = rewriter.template create<emitc::CastOp>(op.getLoc(), arithmeticType,
-                                                    lhs);
-      rhs = rewriter.template create<emitc::CastOp>(op.getLoc(), arithmeticType,
-                                                    rhs);
-    }
 
-    Value result = rewriter.template create<EmitCOp>(op.getLoc(),
-                                                     arithmeticType, lhs, rhs);
+    Value lhs = adaptValueType(adaptor.getLhs(), rewriter, arithmeticType);
+    Value rhs = adaptValueType(adaptor.getRhs(), rewriter, arithmeticType);
+
+    Value arithmeticResult = rewriter.template create<EmitCOp>(
+        op.getLoc(), arithmeticType, lhs, rhs);
+
+    Value result = adaptValueType(arithmeticResult, rewriter, type);
 
-    if (arithmeticType != type) {
-      result =
-          rewriter.template create<emitc::CastOp>(op.getLoc(), type, result);
-    }
     rewriter.replaceOp(op, result);
     return success();
   }
@@ -535,6 +567,8 @@ void mlir::populateArithToEmitCPatterns(TypeConverter &typeConverter,
                                         RewritePatternSet &patterns) {
   MLIRContext *ctx = patterns.getContext();
 
+  mlir::populateEmitCSizeTypeConversionPatterns(typeConverter);
+
   // clang-format off
   patterns.add<
     ArithConstantOpConversionPattern,
@@ -554,6 +588,8 @@ void mlir::populateArithToEmitCPatterns(TypeConverter &typeConverter,
     UnsignedCastConversion<arith::TruncIOp>,
     SignedCastConversion<arith::ExtSIOp>,
     UnsignedCastConversion<arith::ExtUIOp>,
+    SignedCastConversion<arith::IndexCastOp>,
+    UnsignedCastConversion<arith::IndexCastUIOp>,
     ItoFCastOpConversion<arith::SIToFPOp>,
     ItoFCastOpConversion<arith::UIToFPOp>,
     FtoICastOpConversion<arith::FPToSIOp>,

mlir/lib/Conversion/ArithToEmitC/CMakeLists.txt

@@ -11,6 +11,7 @@ add_mlir_conversion_library(MLIRArithToEmitC
   LINK_LIBS PUBLIC
   MLIRArithDialect
   MLIREmitCDialect
+  MLIREmitCTransforms
   MLIRPass
   MLIRTransformUtils
   )