MC: split Win64EHUnwindEmitter into a shared streamer

This changes Win64EHEmitter into a utility WinEH UnwindEmitter that can be
shared across multiple architectures and a target specific bit which is
overridden (Win64::UnwindEmitter).  This enables sharing the section selection
code across X86 and the intended use in ARM for emitting unwind information for
Windows on ARM.

llvm-svn: 215050

1 files changed, 64 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCWinEH.cpp b/llvm/lib/MC/MCWinEH.cpp
new file mode 100644
index 00000000000..8faf70737bf
--- /dev/null
+++ b/llvm/lib/MC/MCWinEH.cpp
@@ -0,0 +1,64 @@
+//===- lib/MC/MCWinEH.cpp - Windows EH implementation ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCObjectFileInfo.h"
+#include "llvm/MC/MCSectionCOFF.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCWinEH.h"
+#include "llvm/Support/COFF.h"
+
+namespace llvm {
+namespace WinEH {
+const MCSection *UnwindEmitter::GetPDataSection(StringRef Suffix,
+                                                MCContext &Context) {
+  if (Suffix.empty())
+    return Context.getObjectFileInfo()->getPDataSection();
+  return Context.getCOFFSection((".pdata" + Suffix).str(),
+                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+                                COFF::IMAGE_SCN_MEM_READ,
+                                SectionKind::getDataRel());
+}
+
+const MCSection *UnwindEmitter::GetXDataSection(StringRef Suffix,
+                                                MCContext &Context) {
+  if (Suffix.empty())
+    return Context.getObjectFileInfo()->getXDataSection();
+  return Context.getCOFFSection((".xdata" + Suffix).str(),
+                                COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+                                COFF::IMAGE_SCN_MEM_READ,
+                                SectionKind::getDataRel());
+}
+
+StringRef UnwindEmitter::GetSectionSuffix(const MCSymbol *Function) {
+  if (!Function || !Function->isInSection())
+    return "";
+
+  const MCSection *FunctionSection = &Function->getSection();
+  if (const auto Section = dyn_cast<MCSectionCOFF>(FunctionSection)) {
+    StringRef Name = Section->getSectionName();
+    size_t Dollar = Name.find('$');
+    size_t Dot = Name.find('.', 1);
+
+    if (Dollar == StringRef::npos && Dot == StringRef::npos)
+      return "";
+    if (Dot == StringRef::npos)
+      return Name.substr(Dollar);
+    if (Dollar == StringRef::npos || Dot < Dollar)
+      return Name.substr(Dot);
+
+    return Name.substr(Dollar);
+  }
+
+  return "";
+}
+}
+}
+