[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 @@ public:
   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;
   }
 

llvm/test/CodeGen/X86/global-access-pie-copyrelocs.ll

@@ -1,151 +0,0 @@
-; RUN: llc < %s -emulated-tls -mcpu=generic -mtriple=x86_64-linux-gnu -relocation-model=pic -pie-copy-relocations \
-; RUN:   | FileCheck -check-prefix=X64 %s
-; RUN: llc < %s -emulated-tls -mcpu=generic -mtriple=i386-linux-gnu -relocation-model=pic -pie-copy-relocations \
-; RUN:   | FileCheck -check-prefix=X32 %s
-
-; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux-gnu -relocation-model=pic -pie-copy-relocations \
-; RUN:   | FileCheck -check-prefix=X64 %s
-; RUN: llc < %s -mcpu=generic -mtriple=i386-linux-gnu -relocation-model=pic -pie-copy-relocations \
-; RUN:   | FileCheck -check-prefix=X32 %s
-
-; External Linkage
-@a = global i32 0, align 4
-
-define i32 @my_access_global_a() #0 {
-; X32-LABEL: my_access_global_a:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
-; X32-NEXT:  movl a@GOTOFF(%eax), %eax
-; X64-LABEL: my_access_global_a:
-; X64:       movl a(%rip), %eax
-
-entry:
-  %0 = load i32, i32* @a, align 4
-  ret i32 %0
-}
-
-; WeakAny Linkage
-@b = weak global i32 0, align 4
-
-define i32 @my_access_global_b() #0 {
-; X32-LABEL: my_access_global_b:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
-; X32-NEXT:  movl b@GOTOFF(%eax), %eax
-; X64-LABEL: my_access_global_b:
-; X64:       movl b(%rip), %eax
-
-entry:
-  %0 = load i32, i32* @b, align 4
-  ret i32 %0
-}
-
-; Internal Linkage
-@c = internal global i32 0, align 4
-
-define i32 @my_access_global_c() #0 {
-; X32-LABEL: my_access_global_c:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
-; X32-NEXT:  movl c@GOTOFF(%eax), %eax
-; X64-LABEL: my_access_global_c:
-; X64:       movl c(%rip), %eax
-
-entry:
-  %0 = load i32, i32* @c, align 4
-  ret i32 %0
-}
-
-; External Linkage, only declaration.
-@d = external global i32, align 4
-
-define i32 @my_access_global_load_d() #0 {
-; X32-LABEL: my_access_global_load_d:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
-; X32-NEXT:  movl d@GOTOFF(%eax), %eax
-; X64-LABEL: my_access_global_load_d:
-; X64:       movl d(%rip), %eax
-
-entry:
-  %0 = load i32, i32* @d, align 4
-  ret i32 %0
-}
-
-; ExternalWeak Linkage
-@e = extern_weak global i32, align 4
-
-define i32* @my_access_global_d() #0 {
-; X32-LABEL: my_access_global_d:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
-; X32:       movl e@GOT(%eax), %eax
-; X64-LABEL: my_access_global_d:
-; X64:       movq e@GOTPCREL(%rip), %rax
-
-entry:
-  ret i32* @e
-}
-
-; ExternalWeak hidden Linkage
-@he = extern_weak hidden global i32, align 4
-
-define i32* @my_access_global_he() #0 {
-; X32-LABEL: my_access_global_he:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
-; X32:       movl he@GOT(%eax), %eax
-; X64-LABEL: my_access_global_he:
-; X64:       movq he@GOTPCREL(%rip), %rax
-  ret i32* @he
-}
-
-
-; External Linkage, only declaration, store a value.
-
-define i32 @my_access_global_store_d() #0 {
-; X32-LABEL: my_access_global_store_d:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %eax
-; X32-NEXT:  movl $2, d@GOTOFF(%eax)
-; X64-LABEL: my_access_global_store_d:
-; X64:  movl $2, d(%rip)
-
-entry:
-  store i32 2, i32* @d, align 4
-  ret i32 0
-}
-
-; External Linkage, function pointer access.
-declare i32 @access_fp(i32 ()*)
-declare i32 @foo()
-
-define i32 @my_access_fp_foo() #0 {
-; X32-LABEL: my_access_fp_foo:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %ebx
-; X32-NEXT:  movl	foo@GOT(%ebx), %eax
-; X64-LABEL: my_access_fp_foo:
-; X64:       movq foo@GOTPCREL(%rip), %rdi
-
-entry:
-  %call = call i32 @access_fp(i32 ()* @foo)
-  ret i32 %call
-}
-
-; LinkOnceODR Linkage, function pointer access.
-
-$bar = comdat any
-
-define linkonce_odr i32 @bar() comdat {
-entry:
-  ret i32 0
-}
-
-define i32 @my_access_fp_bar() #0 {
-; X32-LABEL: my_access_fp_bar:
-; X32:       addl $_GLOBAL_OFFSET_TABLE_{{.*}}, %ebx
-; X32-NEXT:  leal	bar@GOTOFF(%ebx), %eax
-; X64-LABEL: my_access_fp_bar:
-; X64:       leaq bar(%rip), %rdi
-
-entry:
-  %call = call i32 @access_fp(i32 ()* @bar)
-  ret i32 %call
-}
-
-!llvm.module.flags = !{!0, !1}
-!0 = !{i32 1, !"PIC Level", i32 1}
-!1 = !{i32 1, !"PIE Level", i32 1}