From caa0c2caddcfb56de09e016c4c153d0609ffcf6e Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Wed, 18 Feb 2009 02:19:52 +0000
Subject: [PATCH] GV with null value initializer shouldn't go to BSS if it's
 meant for a mergeable strings section. Currently it only checks for Darwin.
 Someone else please check if it should apply to other targets as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64877 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp     | 4 +++-
 lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp | 3 ++-
 lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp  | 4 +++-
 test/CodeGen/X86/cstring.ll                     | 4 ++++
 4 files changed, 12 insertions(+), 3 deletions(-)
 create mode 100644 test/CodeGen/X86/cstring.ll

diff --git a/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp b/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
index 83df20cc170..822cc2eb75b 100644
--- a/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
+++ b/lib/Target/ARM/AsmPrinter/ARMAsmPrinter.cpp
@@ -835,7 +835,9 @@ void ARMAsmPrinter::printModuleLevelGV(const GlobalVariable* GVar) {
   if (Subtarget->isTargetELF())
     O << "\t.type " << name << ",%object\n";
 
-  if (C->isNullValue() && !GVar->hasSection() && !GVar->isThreadLocal()) {
+  if (C->isNullValue() && !GVar->hasSection() && !GVar->isThreadLocal() &&
+      !(isDarwin &&
+        TAI->SectionKindForGlobal(GVar) == SectionKind::RODataMergeStr)) {
     // FIXME: This seems to be pretty darwin-specific
 
     if (GVar->hasExternalLinkage()) {
diff --git a/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp b/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp
index 5f3ba931faf..6c5d8b9d476 100644
--- a/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/AsmPrinter/PPCAsmPrinter.cpp
@@ -915,7 +915,8 @@ void PPCDarwinAsmPrinter::printModuleLevelGV(const GlobalVariable* GVar) {
   if (C->isNullValue() && /* FIXME: Verify correct */
       !GVar->hasSection() &&
       (GVar->hasLocalLinkage() || GVar->hasExternalLinkage() ||
-       GVar->mayBeOverridden())) {
+       GVar->mayBeOverridden()) &&
+      TAI->SectionKindForGlobal(GVar) != SectionKind::RODataMergeStr) {
     if (Size == 0) Size = 1;   // .comm Foo, 0 is undefined, avoid it.
 
     if (GVar->hasExternalLinkage()) {
diff --git a/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp b/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp
index 75a34a6ec64..9af3ba62db0 100644
--- a/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp
+++ b/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp
@@ -799,7 +799,9 @@ void X86ATTAsmPrinter::printModuleLevelGV(const GlobalVariable* GVar) {
 
   SwitchToSection(TAI->SectionForGlobal(GVar));
 
-  if (C->isNullValue() && !GVar->hasSection()) {
+  if (C->isNullValue() && !GVar->hasSection() &&
+      !(Subtarget->isTargetDarwin() &&
+        TAI->SectionKindForGlobal(GVar) == SectionKind::RODataMergeStr)) {
     // FIXME: This seems to be pretty darwin-specific
     if (GVar->hasExternalLinkage()) {
       if (const char *Directive = TAI->getZeroFillDirective()) {
diff --git a/test/CodeGen/X86/cstring.ll b/test/CodeGen/X86/cstring.ll
new file mode 100644
index 00000000000..27d6181db8b
--- /dev/null
+++ b/test/CodeGen/X86/cstring.ll
@@ -0,0 +1,4 @@
+; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin | not grep comm
+; rdar://6479858
+
+@str1 = internal constant [1 x i8] zeroinitializer