[XCOFF][AIX] Differentiate usage of label symbol and csect symbol

Summary:
 We are using symbols to represent label and csect interchangeably before, and that could be a problem.
There are cases we would need to add storage mapping class to the symbol if that symbol is actually the name of a csect, but it's hard for us to figure out whether that symbol is a label or csect.

This patch intend to do the following:
    1. Construct a QualName (A name include the storage mapping class)
       MCSymbolXCOFF for every MCSectionXCOFF.
    2. Keep a pointer to that QualName inside of MCSectionXCOFF.
    3. Use that QualName whenever we need a symbol refers to that
       MCSectionXCOFF.
    4. Adapt the snowball effect from the above changes in
       XCOFFObjectWriter.cpp.

Reviewers: xingxue, DiggerLin, sfertile, daltenty, hubert.reinterpretcast

Reviewed By: DiggerLin, daltenty

Subscribers: wuzish, nemanjai, mgorny, hiraditya, kbarton, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69633

1 files changed, 28 insertions, 0 deletions

diff --git a/llvm/lib/BinaryFormat/XCOFF.cpp b/llvm/lib/BinaryFormat/XCOFF.cpp
new file mode 100644
index 00000000000..6613b6329c1
--- /dev/null
+++ b/llvm/lib/BinaryFormat/XCOFF.cpp
@@ -0,0 +1,28 @@
+//===-- llvm/BinaryFormat/XCOFF.cpp - The XCOFF file format -----*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/BinaryFormat/XCOFF.h"
+
+using namespace llvm;
+
+StringRef XCOFF::getMappingClassString(XCOFF::StorageMappingClass SMC) {
+  switch (SMC) {
+  case XCOFF::XMC_DS:
+    return "DS";
+  case XCOFF::XMC_RW:
+    return "RW";
+  case XCOFF::XMC_PR:
+    return "PR";
+  case XCOFF::XMC_TC0:
+    return "TC0";
+  case XCOFF::XMC_BS:
+    return "BS";
+  default:
+    report_fatal_error("Unhandled storage-mapping class.");
+  }
+}