[llvm-branch-commits] [llvm] [GOFF] Add writing of section symbols (PR #133799)

[Neumann Hon via llvm-branch-commits]

================
@@ -0,0 +1,148 @@
+//===- MCGOFFSymbolMapper.h - Maps MC section/symbol to GOFF symbols ------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Maps a section or a symbol to the GOFF symbols it is composed of, and their
+// attributes.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_MC_MCGOFFSYMBOLMAPPER_H
+#define LLVM_MC_MCGOFFSYMBOLMAPPER_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/BinaryFormat/GOFF.h"
+#include "llvm/Support/Alignment.h"
+#include <string>
+#include <utility>
+
+namespace llvm {
+class MCAssembler;
+class MCContext;
+class MCSectionGOFF;
+
+// An "External Symbol Definition" in the GOFF file has a type, and depending on
+// the type a different subset of the fields is used.
+//
+// Unlike other formats, a 2 dimensional structure is used to define the
+// location of data. For example, the equivalent of the ELF .text section is
+// made up of a Section Definition (SD) and a class (Element Definition; ED).
+// The name of the SD symbol depends on the application, while the class has the
+// predefined name C_CODE64.
+//
+// Data can be placed into this structure in 2 ways. First, the data (in a text
+// record) can be associated with an ED symbol. To refer to data, a Label
+// Definition (LD) is used to give an offset into the data a name. When binding,
+// the whole data is pulled into the resulting executable, and the addresses
+// given by the LD symbols are resolved.
+//
+// The alternative is to use a Part Defiition (PR). In this case, the data (in a
+// text record) is associated with the part. When binding, only the data of
+// referenced PRs is pulled into the resulting binary.
+//
+// Both approaches are used, which means that the equivalent of a section in ELF
+// results in 3 GOFF symbol, either SD/ED/LD or SD/ED/PR. Moreover, certain
----------------
Everybody0523 wrote:

```suggestion
// results in 3 GOFF symbols, either SD/ED/LD or SD/ED/PR. Moreover, certain
```

https://github.com/llvm/llvm-project/pull/133799