BasicPtxBuilderInterface.h

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//===- BasicPtxBuilderInterface.td - PTX builder interface -*- tablegen -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Defines the interface to build PTX (Parallel Thread Execution) from NVVM Ops
// automatically. It is used by NVVM to LLVM pass.
//
//===----------------------------------------------------------------------===//
 
#ifndef NVVM_DIALECT_NVVM_IR_BASICPTXBUILDERINTERFACE_H_
#define NVVM_DIALECT_NVVM_IR_BASICPTXBUILDERINTERFACE_H_
 
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/IR/BuiltinAttributes.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/IR/Value.h"
#include "llvm/Support/LogicalResult.h"
 
namespace mlir {
namespace NVVM {
/// Register read/write modifier to build constraint string for PTX inline
/// https://docs.nvidia.com/cuda/inline-ptx-assembly/index.html#parameters
enum class PTXRegisterMod {
  /// Read register with no modifier
  Read = 0,
  /// Write register with '=' modifier
  Write = 2,
  /// ReadWrite register with '+' modifier.
  /// Note that, this is not natively supported by LLVM, the Interface does
  /// mapping
  ReadWrite = 1,
};
 
inline llvm::raw_ostream &operator<<(llvm::raw_ostream &os,
                                     PTXRegisterMod mod) {
  switch (mod) {
  case PTXRegisterMod::Read:
    return os << "Read";
  case PTXRegisterMod::Write:
    return os << "Write";
  case PTXRegisterMod::ReadWrite:
    return os << "ReadWrite";
  }
  llvm_unreachable("Unknown PTXRegisterMod value");
}
} // namespace NVVM
} // namespace mlir
 
/// Include the generated interface declarations.
#include "mlir/Dialect/LLVMIR/BasicPtxBuilderInterface.h.inc"
 
namespace mlir {
 
namespace NVVM {
 
/// A class to build PTX assembly automatically. It is used by
/// BasicPtxBuilderInterface.
class PtxBuilder {
  // The interface op that is used to build the PTX.
  BasicPtxBuilderInterface interfaceOp;
  // Rewriter to create new operations.
  PatternRewriter &rewriter;
  // The operands for the PTX instruction
  SmallVector<Value> ptxOperands;
  // Register constraints (read, write, readwrite) and register data types
  std::string registerConstraints;
  // Modifiers
  SmallVector<PTXRegisterMod> registerModifiers;
  // Has return value as write-only or read-write
  bool hasResult = false;
  // Indicates if the Op will handle the register mapping manually.
  bool needsManualRegisterMapping = false;
 
public:
  /// Single constructor that only initializes members.
  PtxBuilder(Operation *op, PatternRewriter &rewriter,
             bool needsManualRegisterMapping = false)
      : interfaceOp(op), rewriter(rewriter),
        needsManualRegisterMapping(needsManualRegisterMapping) {}
 
  /// Add an operand with the read/write input type.
  LogicalResult insertValue(Value v,
                            PTXRegisterMod itype = PTXRegisterMod::Read);
 
  /// Builds the inline assembly Op and returns it. The `insertValue` needs to
  /// be called to pass operands before building the PTX.
  LLVM::InlineAsmOp build();
 
  /// Shortcut to build the inline assembly Op and replace or erase the original
  /// op with
  void buildAndReplaceOp();
};
 
/// Count the number of placeholder variables such as {$r}, {$w}, {$rw} in the
/// PTX code.
void countPlaceholderNumbers(StringRef ptxCode,
                             llvm::SmallDenseSet<unsigned> &seenRW,
                             llvm::SmallDenseSet<unsigned> &seenW,
                             llvm::SmallDenseSet<unsigned> &seenR,
                             llvm::SmallVectorImpl<unsigned> &rwNums,
                             llvm::SmallVectorImpl<unsigned> &wNums,
                             llvm::SmallVectorImpl<unsigned> &rNums);
 
} // namespace NVVM
} // namespace mlir
 
#endif // NVVM_DIALECT_NVVM_IR_BASICPTXBUILDERINTERFACE_H_