From: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Date: Fri, 14 Mar 2014 12:45:22 +0000 (+0000)
Subject: [ppc64] Avoid copy relocs in named rodata sections
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=0951eecae4ff281e8890651833d3835ed30b8531;p=oota-llvm.git

[ppc64] Avoid copy relocs in named rodata sections

Commit r181723 introduced code to avoid placing initialized variables
needing relocations into the .rodata section, which avoid copy relocs
that do not work as expected on ppc64 function references.

The same treatment is also needed for *named* .rodata.XXX sections.
This patch changes PPC64LinuxTargetObjectFile::SelectSectionForGlobal
to modify "Kind" *before* calling the default SelectSectionForGlobal
routine, instead of first calling the default routine and then just
checking for the (main) .rodata section afterwards.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203921 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Target/PowerPC/PPCTargetObjectFile.cpp b/lib/Target/PowerPC/PPCTargetObjectFile.cpp
index 2e8605c15ef..2903cc192aa 100644
--- a/lib/Target/PowerPC/PPCTargetObjectFile.cpp
+++ b/lib/Target/PowerPC/PPCTargetObjectFile.cpp
@@ -25,13 +25,6 @@ Initialize(MCContext &Ctx, const TargetMachine &TM) {
 const MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal(
     const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
     const TargetMachine &TM) const {
-
-  const MCSection *DefaultSection = 
-    TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind, Mang, TM);
-
-  if (DefaultSection != ReadOnlySection)
-    return DefaultSection;
-
   // Here override ReadOnlySection to DataRelROSection for PPC64 SVR4 ABI
   // when we have a constant that contains global relocations.  This is
   // necessary because of this ABI's handling of pointers to functions in
@@ -46,14 +39,17 @@ const MCSection *PPC64LinuxTargetObjectFile::SelectSectionForGlobal(
   // linker, so we must use DataRelROSection instead of ReadOnlySection.
   // For more information, see the description of ELIMINATE_COPY_RELOCS in
   // GNU ld.
-  const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
+  if (Kind.isReadOnly()) {
+    const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
 
-  if (GVar && GVar->isConstant() &&
-      (GVar->getInitializer()->getRelocationInfo() ==
-       Constant::GlobalRelocations))
-    return DataRelROSection;
+    if (GVar && GVar->isConstant() &&
+        (GVar->getInitializer()->getRelocationInfo() ==
+         Constant::GlobalRelocations))
+      Kind = SectionKind::getReadOnlyWithRel();
+  }
 
-  return DefaultSection;
+  return TargetLoweringObjectFileELF::SelectSectionForGlobal(GV, Kind,
+                                                             Mang, TM);
 }
 
 const MCExpr *PPC64LinuxTargetObjectFile::
diff --git a/test/CodeGen/PowerPC/vtable-reloc.ll b/test/CodeGen/PowerPC/vtable-reloc.ll
new file mode 100644
index 00000000000..995a5d03ba5
--- /dev/null
+++ b/test/CodeGen/PowerPC/vtable-reloc.ll
@@ -0,0 +1,11 @@
+; RUN: llc -O0 < %s | FileCheck %s
+
+target datalayout = "E-m:e-i64:64-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+@_ZTV3foo = linkonce_odr unnamed_addr constant [1 x i8*] [i8* bitcast (void ()* @__cxa_pure_virtual to i8*)]
+declare void @__cxa_pure_virtual()
+
+; CHECK: .section .data.rel.ro
+; CHECK: .quad __cxa_pure_virtual
+