[MC][TargetMachine] Delete MCTargetOptions::MCPIECopyRelocations

clang/lib/CodeGen/CodeGenModule performs the -mpie-copy-relocations
check and sets dso_local on applicable global variables. We don't need
to duplicate the work in TargetMachine shouldAssumeDSOLocal.

Verified that -mpie-copy-relocations can still emit PC relative
relocations for external variable accesses.

clang -target x86_64 -fpie -mpie-copy-relocations -c => R_X86_64_PC32
clang -target aarch64 -fpie -mpie-copy-relocations -c => R_AARCH64_ADR_PREL_PG_HI21+R_AARCH64_LDST64_ABS_LO12_NC

clang/lib/CodeGen/BackendUtil.cpp

@@ -485,7 +485,6 @@ static void initTargetOptions(llvm::TargetOptions &Options,
   Options.MCOptions.MCNoExecStack = CodeGenOpts.NoExecStack;
   Options.MCOptions.MCIncrementalLinkerCompatible =
       CodeGenOpts.IncrementalLinkerCompatible;
-  Options.MCOptions.MCPIECopyRelocations = CodeGenOpts.PIECopyRelocations;
   Options.MCOptions.MCFatalWarnings = CodeGenOpts.FatalWarnings;
   Options.MCOptions.MCNoWarn = CodeGenOpts.NoWarn;
   Options.MCOptions.AsmVerbose = CodeGenOpts.AsmVerbose;

llvm/include/llvm/MC/MCTargetOptions.h

@@ -46,7 +46,6 @@ class MCTargetOptions {
   bool MCSaveTempLabels : 1;
   bool MCUseDwarfDirectory : 1;
   bool MCIncrementalLinkerCompatible : 1;
-  bool MCPIECopyRelocations : 1;
   bool ShowMCEncoding : 1;
   bool ShowMCInst : 1;
   bool AsmVerbose : 1;

llvm/include/llvm/MC/MCTargetOptionsCommandFlags.inc

@@ -28,8 +28,6 @@ static cl::opt<bool> IncrementalLinkerCompatible(
         "When used with filetype=obj, "
         "emit an object file which can be used with an incremental linker"));
 
-static cl::opt<bool> PIECopyRelocations("pie-copy-relocations", cl::desc("PIE Copy Relocations"));
-
 static cl::opt<int> DwarfVersion("dwarf-version", cl::desc("Dwarf version"),
                           cl::init(0));
 
@@ -55,7 +53,6 @@ static MCTargetOptions InitMCTargetOptionsFromFlags() {
   MCTargetOptions Options;
   Options.MCRelaxAll = RelaxAll;
   Options.MCIncrementalLinkerCompatible = IncrementalLinkerCompatible;
-  Options.MCPIECopyRelocations = PIECopyRelocations;
   Options.DwarfVersion = DwarfVersion;
   Options.ShowMCInst = ShowMCInst;
   Options.ABIName = ABIName;

llvm/lib/MC/MCTargetOptions.cpp

@@ -15,8 +15,8 @@ MCTargetOptions::MCTargetOptions()
     : MCRelaxAll(false), MCNoExecStack(false), MCFatalWarnings(false),
       MCNoWarn(false), MCNoDeprecatedWarn(false), MCSaveTempLabels(false),
       MCUseDwarfDirectory(false), MCIncrementalLinkerCompatible(false),
-      MCPIECopyRelocations(false), ShowMCEncoding(false), ShowMCInst(false),
-      AsmVerbose(false), PreserveAsmComments(true) {}
+      ShowMCEncoding(false), ShowMCInst(false), AsmVerbose(false),
+      PreserveAsmComments(true) {}
 
 StringRef MCTargetOptions::getABIName() const {
   return ABIName;

llvm/lib/Target/TargetMachine.cpp

@@ -184,15 +184,14 @@ bool TargetMachine::shouldAssumeDSOLocal(const Module &M,
     const Function *F = dyn_cast_or_null<Function>(GV);
     if (F && F->hasFnAttribute(Attribute::NonLazyBind))
       return false;
-
-    bool IsTLS = GV && GV->isThreadLocal();
-    bool IsAccessViaCopyRelocs =
-        GV && Options.MCOptions.MCPIECopyRelocations && isa<GlobalVariable>(GV);
     Triple::ArchType Arch = TT.getArch();
-    bool IsPPC =
-        Arch == Triple::ppc || Arch == Triple::ppc64 || Arch == Triple::ppc64le;
-    // Check if we can use copy relocations. PowerPC has no copy relocations.
-    if (!IsTLS && !IsPPC && (RM == Reloc::Static || IsAccessViaCopyRelocs))
+
+    // PowerPC prefers avoiding copy relocations.
+    if (Arch == Triple::ppc || TT.isPPC64())
+      return false;
+
+    // Check if we can use copy relocations.
+    if (!(GV && GV->isThreadLocal()) && RM == Reloc::Static)
       return true;
   }