From e247dd28399445d4e65089f4c47883230bb1ecf0 Mon Sep 17 00:00:00 2001
From: Rafael Espindola <rafael.espindola@gmail.com>
Date: Wed, 4 Feb 2015 21:27:24 +0000
Subject: [PATCH] Don' try to make sections in comdats SHF_MERGE.

Parts of llvm were not expecting it and we wouldn't print
the entity size of the section.

Given what comdats are used for, having SHF_MERGE sections would be
just a small improvement, so just disable it for now.

Fixes pr22463.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228196 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/TargetLoweringObjectFileImpl.cpp | 8 ++++----
 test/CodeGen/X86/global-sections-comdat.ll   | 8 ++++++++
 2 files changed, 12 insertions(+), 4 deletions(-)
 create mode 100644 test/CodeGen/X86/global-sections-comdat.ll

diff --git a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 0cbd7753055..396d9e4fbfa 100644
--- a/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -166,7 +166,7 @@ static unsigned getELFSectionType(StringRef Name, SectionKind K) {
 
 
 static unsigned
-getELFSectionFlags(SectionKind K) {
+getELFSectionFlags(SectionKind K, bool InCOMDAT) {
   unsigned Flags = 0;
 
   if (!K.isMetadata())
@@ -181,7 +181,7 @@ getELFSectionFlags(SectionKind K) {
   if (K.isThreadLocal())
     Flags |= ELF::SHF_TLS;
 
-  if (K.isMergeableCString() || K.isMergeableConst())
+  if (!InCOMDAT && (K.isMergeableCString() || K.isMergeableConst()))
     Flags |= ELF::SHF_MERGE;
 
   if (K.isMergeableCString())
@@ -211,7 +211,7 @@ const MCSection *TargetLoweringObjectFileELF::getExplicitSectionGlobal(
   Kind = getELFKindForNamedSection(SectionName, Kind);
 
   StringRef Group = "";
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, GV->hasComdat());
   if (const Comdat *C = getELFComdat(GV)) {
     Group = C->getName();
     Flags |= ELF::SHF_GROUP;
@@ -243,7 +243,7 @@ static StringRef getSectionPrefixForGlobal(SectionKind Kind) {
 const MCSection *TargetLoweringObjectFileELF::
 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
                        Mangler &Mang, const TargetMachine &TM) const {
-  unsigned Flags = getELFSectionFlags(Kind);
+  unsigned Flags = getELFSectionFlags(Kind, GV->hasComdat());
 
   // If we have -ffunction-section or -fdata-section then we should emit the
   // global value to a uniqued section specifically for it.
diff --git a/test/CodeGen/X86/global-sections-comdat.ll b/test/CodeGen/X86/global-sections-comdat.ll
new file mode 100644
index 00000000000..a4804a7c5cf
--- /dev/null
+++ b/test/CodeGen/X86/global-sections-comdat.ll
@@ -0,0 +1,8 @@
+; RUN: llc < %s -mtriple=i386-unknown-linux | FileCheck %s -check-prefix=LINUX
+; RUN: llc < %s -mtriple=i386-unknown-linux -data-sections | FileCheck %s -check-prefix=LINUX-SECTIONS
+
+$G16 = comdat any
+@G16 = unnamed_addr constant i32 42, comdat
+
+; LINUX: .section	.rodata.G16,"aG",@progbits,G16,comdat
+; LINUX-SECTIONS: .section	.rodata.G16,"aG",@progbits,G16,comdat