[llvm] [RFC][RISCV] Support the large code model. (PR #70308)

[Jessica Clarke via llvm-commits]

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+//===--- RISCVConstantPoolValue.h - RISC-V constantpool value ---*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the RISC-V specific constantpool value class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_RISCV_RISCVCONSTANTPOOLVALUE_H
+#define LLVM_LIB_TARGET_RISCV_RISCVCONSTANTPOOLVALUE_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/ErrorHandling.h"
+
+namespace llvm {
+
+class BlockAddress;
+class GlobalValue;
+class LLVMContext;
+
+/// A RISCV-specific constant pool value.
+class RISCVConstantPoolValue : public MachineConstantPoolValue {
+protected:
+  enum class RISCVCPKind { ExtSymbol, GlobalValue, BlockAddress };
+
+  RISCVConstantPoolValue(LLVMContext &C, RISCVCPKind Kind);
+
+  RISCVConstantPoolValue(Type *Ty, RISCVCPKind Kind);
+
+  template <typename Derived>
+  int getExistingMachineCPValueImpl(MachineConstantPool *CP, Align Alignment) {
+    const std::vector<MachineConstantPoolEntry> &Constants = CP->getConstants();
+    for (unsigned i = 0, e = Constants.size(); i != e; ++i) {
+      if (Constants[i].isMachineConstantPoolEntry() &&
+          Constants[i].getAlign() >= Alignment) {
+        auto *CPV = static_cast<RISCVConstantPoolValue *>(
+            Constants[i].Val.MachineCPVal);
+        if (Derived *APC = dyn_cast<Derived>(CPV))
+          if (cast<Derived>(this)->equals(APC))
+            return i;
+      }
+    }
+
+    return -1;
+  }
+
+private:
+  RISCVCPKind Kind;
+
+public:
+  ~RISCVConstantPoolValue() = default;
+
+  bool isExtSymbol() const { return Kind == RISCVCPKind::ExtSymbol; }
+  bool isGlobalValue() const { return Kind == RISCVCPKind::GlobalValue; }
+  bool isBlockAddress() const { return Kind == RISCVCPKind::BlockAddress; }
+
+  int getExistingMachineCPValue(MachineConstantPool *CP,
+                                Align Alignment) override;
+
+  void addSelectionDAGCSEId(FoldingSetNodeID &ID) override {}
+};
+
+class RISCVConstantPoolConstant : public RISCVConstantPoolValue {
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jrtc27 wrote:

Do we really need these two subclasses? Why can't RISCVConstantPoolValue just check which it is?

https://github.com/llvm/llvm-project/pull/70308