From 329a9a8a331ef87a1807e6d9d45d448338cc6224 Mon Sep 17 00:00:00 2001
From: David Blaikie <dblaikie@gmail.com>
Date: Tue, 22 Oct 2013 23:41:52 +0000
Subject: [PATCH] MC: Support multiple sections with the same name in the same
 comdat group

Code review by Eric Christopher and Rafael Espindola.

llvm-svn: 193209
---
 lib/MC/ELFObjectWriter.cpp          | 19 +++++++------
 lib/MC/MCContext.cpp                | 18 ++++++++-----
 test/MC/ELF/comdat-dup-group-name.s | 41 +++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 14 deletions(-)
 create mode 100644 test/MC/ELF/comdat-dup-group-name.s

diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index c5f7287bc22..eb197f2cec7 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -1298,10 +1298,12 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
     // Remove ".rel" and ".rela" prefixes.
     unsigned SecNameLen = (Section.getType() == ELF::SHT_REL) ? 4 : 5;
     StringRef SectionName = Section.getSectionName().substr(SecNameLen);
+    StringRef GroupName =
+        Section.getGroup() ? Section.getGroup()->getName() : "";
 
-    InfoSection = Asm.getContext().getELFSection(SectionName,
-                                                 ELF::SHT_PROGBITS, 0,
-                                                 SectionKind::getReadOnly());
+    InfoSection = Asm.getContext().getELFSection(SectionName, ELF::SHT_PROGBITS,
+                                                 0, SectionKind::getReadOnly(),
+                                                 0, GroupName);
     sh_info = SectionIndexMap.lookup(InfoSection);
     break;
   }
@@ -1351,11 +1353,12 @@ void ELFObjectWriter::WriteSection(MCAssembler &Asm,
                                        ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
                                        SectionKind::getText()));
     } else if (SecName.startswith(".ARM.exidx")) {
-      sh_link = SectionIndexMap.lookup(
-        Asm.getContext().getELFSection(SecName.substr(sizeof(".ARM.exidx") - 1),
-                                       ELF::SHT_PROGBITS,
-                                       ELF::SHF_EXECINSTR | ELF::SHF_ALLOC,
-                                       SectionKind::getText()));
+      StringRef GroupName =
+          Section.getGroup() ? Section.getGroup()->getName() : "";
+      sh_link = SectionIndexMap.lookup(Asm.getContext().getELFSection(
+          SecName.substr(sizeof(".ARM.exidx") - 1), ELF::SHT_PROGBITS,
+          ELF::SHF_EXECINSTR | ELF::SHF_ALLOC, SectionKind::getText(), 0,
+          GroupName));
     }
   }
 
diff --git a/lib/MC/MCContext.cpp b/lib/MC/MCContext.cpp
index 6e4d82b6e76..67904f6f74b 100644
--- a/lib/MC/MCContext.cpp
+++ b/lib/MC/MCContext.cpp
@@ -25,10 +25,15 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/SourceMgr.h"
+
+#include <map>
+
 using namespace llvm;
 
+typedef std::pair<std::string, std::string> SectionGroupPair;
+
 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
-typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
+typedef std::map<SectionGroupPair, const MCSectionELF *> ELFUniqueMapTy;
 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
 
 
@@ -249,8 +254,9 @@ getELFSection(StringRef Section, unsigned Type, unsigned Flags,
   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)ELFUniquingMap;
 
   // Do the lookup, if we have a hit, return it.
-  StringMapEntry<const MCSectionELF*> &Entry = Map.GetOrCreateValue(Section);
-  if (Entry.getValue()) return Entry.getValue();
+  std::pair<ELFUniqueMapTy::iterator, bool> Entry = Map.insert(
+      std::make_pair(SectionGroupPair(Section, Group), (MCSectionELF *)0));
+  if (!Entry.second) return Entry.first->second;
 
   // Possibly refine the entry size first.
   if (!EntrySize) {
@@ -261,9 +267,9 @@ getELFSection(StringRef Section, unsigned Type, unsigned Flags,
   if (!Group.empty())
     GroupSym = GetOrCreateSymbol(Group);
 
-  MCSectionELF *Result = new (*this) MCSectionELF(Entry.getKey(), Type, Flags,
-                                                  Kind, EntrySize, GroupSym);
-  Entry.setValue(Result);
+  MCSectionELF *Result = new (*this) MCSectionELF(
+      Entry.first->first.first, Type, Flags, Kind, EntrySize, GroupSym);
+  Entry.first->second = Result;
   return Result;
 }
 
diff --git a/test/MC/ELF/comdat-dup-group-name.s b/test/MC/ELF/comdat-dup-group-name.s
new file mode 100644
index 00000000000..1181e2eab02
--- /dev/null
+++ b/test/MC/ELF/comdat-dup-group-name.s
@@ -0,0 +1,41 @@
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -s -t | FileCheck %s
+
+// Test that we produce two foo sections, each in separate groups
+
+// CHECK: Index: 1
+// CHECK-NEXT: Name: .group
+
+// CHECK: Index: 2
+// CHECK-NEXT: Name: .group
+
+// CHECK: Index: 6
+// CHECK-NEXT: Name: .foo
+
+// CHECK: Index: 7
+// CHECK-NEXT: Name: .foo
+
+// CHECK: Symbols [
+
+// CHECK: Name: f1
+// CHECK-NOT: }
+// CHECK: Section: .group (0x1)
+
+// CHECK: Name: f2
+// CHECK-NOT: }
+// CHECK: Section: .group (0x2)
+
+// CHECK: Name: .foo
+// CHECK-NOT: }
+// CHECK: Section: .foo (0x6)
+
+// CHECK: Name: .foo
+// CHECK-NOT: }
+// CHECK: Section: .foo (0x7)
+
+
+	.section	.foo,"axG",@progbits,f1,comdat
+        nop
+
+	.section	.foo,"axG",@progbits,f2,comdat
+        nop
+