From 4c47434b25ea4683ff1794e2d1b24eaa16b5e30e Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Mon, 5 Jun 2017 21:26:39 +0000
Subject: CodeGen: add support for emitting ObjC image info

This ensures that we can emit the ObjC Image Info structure on COFF and
ELF as well.  The frontend already would attempt to emit this
information but would get dropped when generating assembly or an object
file.

llvm-svn: 304736
---
 llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp | 93 +++++++++++++++++------
 1 file changed, 70 insertions(+), 23 deletions(-)

(limited to 'llvm/lib')

diff --git a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
index 3ba4a3a2926..24baa59db5d 100644
--- a/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
@@ -61,10 +61,53 @@
 using namespace llvm;
 using namespace dwarf;
 
+static void GetObjCImageInfo(ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
+                             unsigned &Version, unsigned &Flags,
+                             StringRef &Section) {
+  for (const auto &MFE: ModuleFlags) {
+    // Ignore flags with 'Require' behaviour.
+    if (MFE.Behavior == Module::Require)
+      continue;
+
+    StringRef Key = MFE.Key->getString();
+    if (Key == "Objective-C Image Info Version") {
+      Version = mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
+    } else if (Key == "Objective-C Garbage Collection" ||
+               Key == "Objective-C GC Only" ||
+               Key == "Objective-C Is Simulated" ||
+               Key == "Objective-C Class Properties" ||
+               Key == "Objective-C Image Swift Version") {
+      Flags |= mdconst::extract<ConstantInt>(MFE.Val)->getZExtValue();
+    } else if (Key == "Objective-C Image Info Section") {
+      Section = cast<MDString>(MFE.Val)->getString();
+    }
+  }
+}
+
 //===----------------------------------------------------------------------===//
 //                                  ELF
 //===----------------------------------------------------------------------===//
 
+void TargetLoweringObjectFileELF::emitModuleFlags(
+    MCStreamer &Streamer, ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
+    const TargetMachine &TM) const {
+  unsigned Version = 0;
+  unsigned Flags = 0;
+  StringRef Section;
+
+  GetObjCImageInfo(ModuleFlags, Version, Flags, Section);
+  if (Section.empty())
+    return;
+
+  auto &C = getContext();
+  auto *S = C.getELFSection(Section, ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
+  Streamer.SwitchSection(S);
+  Streamer.EmitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
+  Streamer.EmitIntValue(Version, 4);
+  Streamer.EmitIntValue(Flags, 4);
+  Streamer.AddBlankLine();
+}
+
 MCSymbol *TargetLoweringObjectFileELF::getCFIPersonalitySymbol(
     const GlobalValue *GV, const TargetMachine &TM,
     MachineModuleInfo *MMI) const {
@@ -579,32 +622,12 @@ void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
 void TargetLoweringObjectFileMachO::emitModuleFlags(
     MCStreamer &Streamer, ArrayRef<Module::ModuleFlagEntry> ModuleFlags,
     const TargetMachine &TM) const {
-  unsigned VersionVal = 0;
-  unsigned ImageInfoFlags = 0;
   MDNode *LinkerOptions = nullptr;
-  StringRef SectionVal;
 
   for (const auto &MFE : ModuleFlags) {
-    // Ignore flags with 'Require' behavior.
-    if (MFE.Behavior == Module::Require)
-      continue;
-
     StringRef Key = MFE.Key->getString();
-    Metadata *Val = MFE.Val;
-
-    if (Key == "Objective-C Image Info Version") {
-      VersionVal = mdconst::extract<ConstantInt>(Val)->getZExtValue();
-    } else if (Key == "Objective-C Garbage Collection" ||
-               Key == "Objective-C GC Only" ||
-               Key == "Objective-C Is Simulated" ||
-               Key == "Objective-C Class Properties" ||
-               Key == "Objective-C Image Swift Version") {
-      ImageInfoFlags |= mdconst::extract<ConstantInt>(Val)->getZExtValue();
-    } else if (Key == "Objective-C Image Info Section") {
-      SectionVal = cast<MDString>(Val)->getString();
-    } else if (Key == "Linker Options") {
-      LinkerOptions = cast<MDNode>(Val);
-    }
+    if (Key == "Linker Options")
+      LinkerOptions = cast<MDNode>(MFE.Val);
   }
 
   // Emit the linker options if present.
@@ -617,8 +640,14 @@ void TargetLoweringObjectFileMachO::emitModuleFlags(
     }
   }
 
+  unsigned VersionVal = 0;
+  unsigned ImageInfoFlags = 0;
+  StringRef SectionVal;
+  GetObjCImageInfo(ModuleFlags, VersionVal, ImageInfoFlags, SectionVal);
+
   // The section is mandatory. If we don't have it, then we don't have GC info.
-  if (SectionVal.empty()) return;
+  if (SectionVal.empty())
+    return;
 
   StringRef Segment, Section;
   unsigned TAA = 0, StubSize = 0;
@@ -1156,6 +1185,24 @@ void TargetLoweringObjectFileCOFF::emitModuleFlags(
       }
     }
   }
+
+  unsigned Version = 0;
+  unsigned Flags = 0;
+  StringRef Section;
+
+  GetObjCImageInfo(ModuleFlags, Version, Flags, Section);
+  if (Section.empty())
+    return;
+
+  auto &C = getContext();
+  auto *S = C.getCOFFSection(
+      Section, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
+      SectionKind::getReadOnly());
+  Streamer.SwitchSection(S);
+  Streamer.EmitLabel(C.getOrCreateSymbol(StringRef("OBJC_IMAGE_INFO")));
+  Streamer.EmitIntValue(Version, 4);
+  Streamer.EmitIntValue(Flags, 4);
+  Streamer.AddBlankLine();
 }
 
 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
-- 
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