[llvm] [AMDGPU] Add AMDGPU specific variadic operation MCExprs (PR #82022)

[Pierre van Houtryve via llvm-commits]

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@@ -0,0 +1,73 @@
+//===- AMDGPUMCExpr.h - AMDGPU specific MC expression classes ---*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_AMDGPU_MCTARGETDESC_AMDGPUMCEXPR_H
+#define LLVM_LIB_TARGET_AMDGPU_MCTARGETDESC_AMDGPUMCEXPR_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/MC/MCExpr.h"
+
+namespace llvm {
+
+/// AMDGPU target specific variadic MCExpr operations.
+///
+/// Takes in a minimum of 1 argument to be used with an operation. The supported
+/// operations are:
+///   - (logic) or
+///   - max
+///
+/// \note If the 'or'/'max' operations are provided only a single argument, the
+/// operation will act as a no-op and simply resolve as the provided argument.
+///
+class AMDGPUVariadicMCExpr : public MCTargetExpr {
+public:
+  enum AMDGPUVariadicKind { AGVK_None, AGVK_Or, AGVK_Max };
+
+private:
+  AMDGPUVariadicKind Kind;
+  SmallVector<const MCExpr *, 2> Args;
+
+  AMDGPUVariadicMCExpr(AMDGPUVariadicKind Kind, ArrayRef<const MCExpr *> Args)
+      : Kind(Kind), Args(Args) {
+    assert(Args.size() >= 1 && "Needs a minimum of one expression.");
+  }
+
+public:
+  static const AMDGPUVariadicMCExpr *create(AMDGPUVariadicKind Kind,
+                                            ArrayRef<const MCExpr *> Args,
+                                            MCContext &Ctx);
+
+  static const AMDGPUVariadicMCExpr *createOr(ArrayRef<const MCExpr *> Args,
+                                              MCContext &Ctx) {
+    return create(AMDGPUVariadicKind::AGVK_Or, Args, Ctx);
+  }
+
+  static const AMDGPUVariadicMCExpr *createMax(ArrayRef<const MCExpr *> Args,
+                                               MCContext &Ctx) {
+    return create(AMDGPUVariadicKind::AGVK_Max, Args, Ctx);
+  }
+
+  AMDGPUVariadicKind getKind() const { return Kind; }
+  const MCExpr *GetSubExpr(size_t index) const;
----------------
Pierre-vh wrote:

Function needs to be camelCase, `index` needs to be CamelCase
```suggestion
  const MCExpr *getSubExpr(size_t Index) const;
```

https://github.com/llvm/llvm-project/pull/82022