From 8bb51ef6d2a396715f1dbc6edc1599892779e4d6 Mon Sep 17 00:00:00 2001
From: David Chisnall <csdavec@swan.ac.uk>
Date: Fri, 17 Feb 2012 16:51:02 +0000
Subject: [PATCH] Revert r150814.  It turns out that there is a good reason for
 this after all...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150818 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/MC/MCObjectFileInfo.h |  5 ++++
 lib/MC/MCObjectFileInfo.cpp        | 48 ++++++++++++++----------------
 2 files changed, 27 insertions(+), 26 deletions(-)

diff --git a/include/llvm/MC/MCObjectFileInfo.h b/include/llvm/MC/MCObjectFileInfo.h
index 7525f003fb0..e58e7d68f7f 100644
--- a/include/llvm/MC/MCObjectFileInfo.h
+++ b/include/llvm/MC/MCObjectFileInfo.h
@@ -284,6 +284,8 @@ public:
   const MCSection *getXDataSection() const { return XDataSection; }
 
   const MCSection *getEHFrameSection() {
+    if (!EHFrameSection)
+      InitEHFrameSection();
     return EHFrameSection;
   }
 
@@ -298,6 +300,9 @@ private:
   void InitELFMCObjectFileInfo(Triple T);
   void InitCOFFMCObjectFileInfo(Triple T);
 
+  /// InitEHFrameSection - Initialize EHFrameSection on demand.
+  ///
+  void InitEHFrameSection();
 };
 
 } // end namespace llvm
diff --git a/lib/MC/MCObjectFileInfo.cpp b/lib/MC/MCObjectFileInfo.cpp
index 3c3b50c1349..1b8653531e8 100644
--- a/lib/MC/MCObjectFileInfo.cpp
+++ b/lib/MC/MCObjectFileInfo.cpp
@@ -142,14 +142,6 @@ void MCObjectFileInfo::InitMachOMCObjectFileInfo(Triple T) {
   }
 
   // Exception Handling.
-  EHFrameSection =
-    Ctx->getMachOSection("__TEXT", "__eh_frame",
-                         MCSectionMachO::S_COALESCED |
-                         MCSectionMachO::S_ATTR_NO_TOC |
-                         MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
-                         MCSectionMachO::S_ATTR_LIVE_SUPPORT,
-                         SectionKind::getReadOnly());
-
   LSDASection = Ctx->getMachOSection("__TEXT", "__gcc_except_tab", 0,
                                      SectionKind::getReadOnlyWithRel());
 
@@ -347,17 +339,6 @@ void MCObjectFileInfo::InitELFMCObjectFileInfo(Triple T) {
 
   // Exception Handling Sections.
 
-  // Solaris requires different flags for .eh_frame to seemingly every other
-  // platform.
-  unsigned EHSectionFlags = ELF::SHF_ALLOC;
-  if (T.getOS() == Triple::Solaris)
-    EHSectionFlags |= ELF::SHF_WRITE;
-
-  EHFrameSection =
-    Ctx->getELFSection(".eh_frame", ELF::SHT_PROGBITS, 
-                       EHSectionFlags,
-                       SectionKind::getDataRel());
-
   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
   // it contains relocatable pointers.  In PIC mode, this is probably a big
   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
@@ -434,13 +415,6 @@ void MCObjectFileInfo::InitCOFFMCObjectFileInfo(Triple T) {
                         COFF::IMAGE_SCN_MEM_WRITE,
                         SectionKind::getDataRel());
 
-  EHFrameSection =
-    Ctx->getCOFFSection(".eh_frame",
-                        COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
-                        COFF::IMAGE_SCN_MEM_READ |
-                        COFF::IMAGE_SCN_MEM_WRITE,
-                        SectionKind::getDataRel());
-
   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
   // though it contains relocatable pointers.  In PIC mode, this is probably a
   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
@@ -573,3 +547,25 @@ void MCObjectFileInfo::InitMCObjectFileInfo(StringRef TT, Reloc::Model relocm,
   }
 }
 
+void MCObjectFileInfo::InitEHFrameSection() {
+  if (Env == IsMachO)
+    EHFrameSection =
+      Ctx->getMachOSection("__TEXT", "__eh_frame",
+                           MCSectionMachO::S_COALESCED |
+                           MCSectionMachO::S_ATTR_NO_TOC |
+                           MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
+                           MCSectionMachO::S_ATTR_LIVE_SUPPORT,
+                           SectionKind::getReadOnly());
+  else if (Env == IsELF)
+    EHFrameSection =
+      Ctx->getELFSection(".eh_frame", ELF::SHT_PROGBITS,
+                         ELF::SHF_ALLOC,
+                         SectionKind::getDataRel());
+  else
+    EHFrameSection =
+      Ctx->getCOFFSection(".eh_frame",
+                          COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
+                          COFF::IMAGE_SCN_MEM_READ |
+                          COFF::IMAGE_SCN_MEM_WRITE,
+                          SectionKind::getDataRel());
+}