[AsmPrinter][TLOF] ARM64 MachO support for replacing GOT equivalents

Follow up r230264 and add ARM64 support for replacing global GOT
equivalent symbol accesses by references to the GOT entry for the final
symbol instead, example:

-- before

   .globl  _foo
  _foo:
   .long   42

   .globl  _gotequivalent
  _gotequivalent:
   .quad   _foo

   .globl  _delta
  _delta:
   .long   _gotequivalent-_delta

-- after

   .globl  _foo
  _foo:
   .long   42

   .globl  _delta
  Ltmp3:
   .long _foo@GOT-Ltmp3

llvm-svn: 231474

5 files changed, 33 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 569863315ac..22eae785c78 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -2084,9 +2084,13 @@ static void handleIndirectSymViaGOTPCRel(AsmPrinter &AP, const MCExpr **ME,
   //
   //    gotpcrelcst := <offset from @foo base> + <cst>
   //
+  // Only encode <cst> if the target supports it.
+  //
   int64_t GOTPCRelCst = Offset + MV.getConstant();
   if (GOTPCRelCst < 0)
     return;
+  if (!AP.getObjFileLowering().supportGOTPCRelWithOffset() && GOTPCRelCst != 0)
+    return;
 
   // Emit the GOT PC relative to replace the got equivalent global, i.e.:
   //
@@ -2110,7 +2114,8 @@ static void handleIndirectSymViaGOTPCRel(AsmPrinter &AP, const MCExpr **ME,
   const GlobalValue *FinalGV = dyn_cast<GlobalValue>(GV->getOperand(0));
   const MCSymbol *FinalSym = AP.getSymbol(FinalGV);
   *ME = AP.getObjFileLowering().getIndirectSymViaGOTPCRel(FinalSym,
-                                                          GOTPCRelCst);
+                                                          GOTPCRelCst,
+                                                          AP.OutStreamer);
 
   // Update GOT equivalent usage information
   --NumUses;
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
index 4069038dffe..3c0a3428ff3 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.cpp
@@ -23,6 +23,12 @@ void AArch64_ELFTargetObjectFile::Initialize(MCContext &Ctx,
   InitializeELF(TM.Options.UseInitArray);
 }
 
+AArch64_MachoTargetObjectFile::AArch64_MachoTargetObjectFile()
+  : TargetLoweringObjectFileMachO() {
+  SupportIndirectSymViaGOTPCRel = true;
+  SupportGOTPCRelWithOffset = false;
+}
+
 const MCExpr *AArch64_MachoTargetObjectFile::getTTypeGlobalReference(
     const GlobalValue *GV, unsigned Encoding, Mangler &Mang,
     const TargetMachine &TM, MachineModuleInfo *MMI,
@@ -50,3 +56,15 @@ MCSymbol *AArch64_MachoTargetObjectFile::getCFIPersonalitySymbol(
     MachineModuleInfo *MMI) const {
   return TM.getSymbol(GV, Mang);
 }
+
+const MCExpr *AArch64_MachoTargetObjectFile::getIndirectSymViaGOTPCRel(
+    const MCSymbol *Sym, int64_t Offset, MCStreamer &Streamer) const {
+  // On ARM64 Darwin, we can reference symbols with foo@GOT-., which
+  // is an indirect pc-relative reference.
+  const MCExpr *Res =
+      MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_GOT, getContext());
+  MCSymbol *PCSym = getContext().CreateTempSymbol();
+  Streamer.EmitLabel(PCSym);
+  const MCExpr *PC = MCSymbolRefExpr::Create(PCSym, getContext());
+  return MCBinaryExpr::CreateSub(Res, PC, getContext());
+}
diff --git a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
index 2e595f91961..067fda5952b 100644
--- a/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
+++ b/llvm/lib/Target/AArch64/AArch64TargetObjectFile.h
@@ -24,6 +24,8 @@ class AArch64_ELFTargetObjectFile : public TargetLoweringObjectFileELF {
 /// AArch64_MachoTargetObjectFile - This TLOF implementation is used for Darwin.
 class AArch64_MachoTargetObjectFile : public TargetLoweringObjectFileMachO {
 public:
+  AArch64_MachoTargetObjectFile();
+
   const MCExpr *getTTypeGlobalReference(const GlobalValue *GV,
                                         unsigned Encoding, Mangler &Mang,
                                         const TargetMachine &TM,
@@ -33,6 +35,10 @@ public:
   MCSymbol *getCFIPersonalitySymbol(const GlobalValue *GV, Mangler &Mang,
                                     const TargetMachine &TM,
                                     MachineModuleInfo *MMI) const override;
+
+  const MCExpr *
+    getIndirectSymViaGOTPCRel(const MCSymbol *Sym, int64_t Offset,
+                              MCStreamer &Streamer) const override;
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/Target/X86/X86TargetObjectFile.cpp b/llvm/lib/Target/X86/X86TargetObjectFile.cpp
index 16ce7365883..15a5fddd862 100644
--- a/llvm/lib/Target/X86/X86TargetObjectFile.cpp
+++ b/llvm/lib/Target/X86/X86TargetObjectFile.cpp
@@ -52,7 +52,7 @@ MCSymbol *X86_64MachoTargetObjectFile::getCFIPersonalitySymbol(
 }
 
 const MCExpr *X86_64MachoTargetObjectFile::getIndirectSymViaGOTPCRel(
-    const MCSymbol *Sym, int64_t Offset) const {
+    const MCSymbol *Sym, int64_t Offset, MCStreamer &Streamer) const {
   // On Darwin/X86-64, we need to use foo@GOTPCREL+4 to access the got entry
   // from a data section. In case there's an additional offset, then use
   // foo@GOTPCREL+4+<offset>.
diff --git a/llvm/lib/Target/X86/X86TargetObjectFile.h b/llvm/lib/Target/X86/X86TargetObjectFile.h
index a92c122838e..3c7caabdfdc 100644
--- a/llvm/lib/Target/X86/X86TargetObjectFile.h
+++ b/llvm/lib/Target/X86/X86TargetObjectFile.h
@@ -34,8 +34,8 @@ namespace llvm {
                                       MachineModuleInfo *MMI) const override;
 
     const MCExpr *
-      getIndirectSymViaGOTPCRel(const MCSymbol *Sym,
-                                int64_t Offset) const override;
+      getIndirectSymViaGOTPCRel(const MCSymbol *Sym, int64_t Offset,
+                                MCStreamer &Streamer) const override;
   };
 
   /// \brief This implemenatation is used for X86 ELF targets that don't