assertion error in the KrnlToLLVM conversion pass krnl.global with 128+ string elements.

[negiyas]

The following assertion error occurs in the KrnlToLLVM conversion pass with the attached krnl.global op. It seems that the logic for a large array to use "denseAttr.getRawData()" cannot support string type. We avoid this issue by adding a condition to check it the type is not string (e.g. if ((!denseAttr.isSplat()) && (sizeInBytes > 1024)) { to if ((!denseAttr.getElementType().isa<StringType>()) && (!denseAttr.isSplat()) && (sizeInBytes > 1024)) { ).

However the compilation time will be increased especially for models with large category map tables (e.g. Bidaf-9), because many string constant ops are generated.

Assertion error

onnx-mlir-opt: /home1/negishi/src/dlc.git/onnx-mlir.opt/src/Conversion/KrnlToLLVM/KrnlGlobal.cpp:161: mlir::LLVM::GlobalOp onnx_mlir::krnl::KrnlGlobalOpLowering::lowerDenseConstant(mlir::KrnlGlobalOp&, mlir::Type, mlir::ConversionPatternRewriter&) const: Assertion `((int64_t)rawData.size() == sizeInBytes) && "Data size mismatch."' failed.

Sample input

// Test CategorMapper lowering when the input is a list of strings.
func.func private @test_category_mapper3_string_to_int64() -> memref<129x!krnl.string> {
  %4 = "krnl.global"() {name = "cats_strings", shape = [129], value = dense<["1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "50", "51", "52", "53", "54", "55", "56", "57", "58", "59", "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", "100", "101", "102", "103", "104", "105", "106", "107", "108", "109", "110", "111", "112", "113", "114", "115", "116", "117", "118", "119", "120", "121", "122", "123", "124", "125", "126", "127", "128", "129"]> : tensor<129x!krnl.string>} : () -> memref<129x!krnl.string>
  return %4 : memref<129x!krnl.string>
}

Conversion code

  LLVM::GlobalOp lowerDenseConstant(KrnlGlobalOp &krnlGlobalOp, Type globalType,
      ConversionPatternRewriter &rewriter) const {
    assert(krnlGlobalOp.getValue().has_value() &&
           "Expecting KrnlGlobalOp with a valid value");
    assert(krnlGlobalOp.getValue().value().isa<DenseElementsAttr>() &&
           "Expecting a global with an dense elements attribute");

    MLIRContext *context = krnlGlobalOp.getContext();
    Location loc = krnlGlobalOp.getLoc();
    ModuleOp module = krnlGlobalOp->getParentOfType<ModuleOp>();
    MultiDialectBuilder<LLVMBuilder> create(rewriter, loc);

    OpBuilder::InsertionGuard insertGuard(rewriter);
    rewriter.setInsertionPointToStart(module.getBody());

    DenseElementsAttr denseAttr =
        krnlGlobalOp.getValue().value().cast<DenseElementsAttr>();

    int64_t sizeInBytes = computeSizeInBytes(krnlGlobalOp);
    LLVM::GlobalOp global;
    if ((!denseAttr.isSplat()) && (sizeInBytes > 1024)) {
      ArrayRef<char> rawData = denseAttr.getRawData();
      assert(((int64_t)rawData.size() == sizeInBytes) && "Data size mismatch.");

      StringRef data(rawData.data(), rawData.size());
      StringAttr llvmStringAttr = StringAttr::get(context, data);
      auto llvmArrayI8Ty =
          LLVM::LLVMArrayType::get(IntegerType::get(context, 8), sizeInBytes);
      global = create.llvm.globalOp(llvmArrayI8Ty,
          /*isConstant=*/true, LLVM::Linkage::Internal, krnlGlobalOp.getName(),
          llvmStringAttr);
    } else {
      if (denseAttr.getElementType().isa<StringType>())
        global = lowerStringLiteral(krnlGlobalOp, globalType, rewriter);
      else
        global = create.llvm.globalOp(globalType,
            /*isConstant=*/true, LLVM::Linkage::Internal,
            krnlGlobalOp.getName(), krnlGlobalOp.getValue().value());
    }

    LLVM_DEBUG(llvm::dbgs() << "global: " << global << "\n";);
    return global;
  }

[negiyas]

Fixed by PR#2055.