[ARM] Use TargetMachine over Subtarget in ARMAsmPrinter (#166329)

The subtarget may not be set if no functions are present in the module.
Attempt to use the TargetMachine directly in more cases.

Fixes #165422
Fixes #167577

Author: davemgreen

llvm/lib/Target/ARM/ARMAsmPrinter.cpp

@@ -97,7 +97,8 @@ void ARMAsmPrinter::emitXXStructor(const DataLayout &DL, const Constant *CV) {
 
   const MCExpr *E = MCSymbolRefExpr::create(
       GetARMGVSymbol(GV, ARMII::MO_NO_FLAG),
-      (Subtarget->isTargetELF() ? ARM::S_TARGET1 : ARM::S_None), OutContext);
+      (TM.getTargetTriple().isOSBinFormatELF() ? ARM::S_TARGET1 : ARM::S_None),
+      OutContext);
 
   OutStreamer->emitValue(E, Size);
 }
@@ -595,8 +596,7 @@ void ARMAsmPrinter::emitEndOfAsmFile(Module &M) {
   ARMTargetStreamer &ATS = static_cast<ARMTargetStreamer &>(TS);
 
   if (OptimizationGoals > 0 &&
-      (Subtarget->isTargetAEABI() || Subtarget->isTargetGNUAEABI() ||
-       Subtarget->isTargetMuslAEABI()))
+      (TT.isTargetAEABI() || TT.isTargetGNUAEABI() || TT.isTargetMuslAEABI()))
     ATS.emitAttribute(ARMBuildAttrs::ABI_optimization_goals, OptimizationGoals);
   OptimizationGoals = -1;
 
@@ -884,9 +884,10 @@ static uint8_t getModifierSpecifier(ARMCP::ARMCPModifier Modifier) {
 
 MCSymbol *ARMAsmPrinter::GetARMGVSymbol(const GlobalValue *GV,
                                         unsigned char TargetFlags) {
-  if (Subtarget->isTargetMachO()) {
+  const Triple &TT = TM.getTargetTriple();
+  if (TT.isOSBinFormatMachO()) {
     bool IsIndirect =
-        (TargetFlags & ARMII::MO_NONLAZY) && Subtarget->isGVIndirectSymbol(GV);
+        (TargetFlags & ARMII::MO_NONLAZY) && getTM().isGVIndirectSymbol(GV);
 
     if (!IsIndirect)
       return getSymbol(GV);
@@ -903,9 +904,8 @@ MCSymbol *ARMAsmPrinter::GetARMGVSymbol(const GlobalValue *GV,
       StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
                                                    !GV->hasInternalLinkage());
     return MCSym;
-  } else if (Subtarget->isTargetCOFF()) {
-    assert(Subtarget->isTargetWindows() &&
-           "Windows is the only supported COFF target");
+  } else if (TT.isOSBinFormatCOFF()) {
+    assert(TT.isOSWindows() && "Windows is the only supported COFF target");
 
     bool IsIndirect =
         (TargetFlags & (ARMII::MO_DLLIMPORT | ARMII::MO_COFFSTUB));
@@ -932,7 +932,7 @@ MCSymbol *ARMAsmPrinter::GetARMGVSymbol(const GlobalValue *GV,
     }
 
     return MCSym;
-  } else if (Subtarget->isTargetELF()) {
+  } else if (TT.isOSBinFormatELF()) {
     return getSymbolPreferLocal(*GV);
   }
   llvm_unreachable("unexpected target");
@@ -978,7 +978,8 @@ void ARMAsmPrinter::emitMachineConstantPoolValue(
 
     // On Darwin, const-pool entries may get the "FOO$non_lazy_ptr" mangling, so
     // flag the global as MO_NONLAZY.
-    unsigned char TF = Subtarget->isTargetMachO() ? ARMII::MO_NONLAZY : 0;
+    unsigned char TF =
+        TM.getTargetTriple().isOSBinFormatMachO() ? ARMII::MO_NONLAZY : 0;
     MCSym = GetARMGVSymbol(GV, TF);
   } else if (ACPV->isMachineBasicBlock()) {
     const MachineBasicBlock *MBB = cast<ARMConstantPoolMBB>(ACPV)->getMBB();

llvm/lib/Target/ARM/ARMSubtarget.cpp

@@ -318,17 +318,7 @@ bool ARMSubtarget::isRWPI() const {
 }
 
 bool ARMSubtarget::isGVIndirectSymbol(const GlobalValue *GV) const {
-  if (!TM.shouldAssumeDSOLocal(GV))
-    return true;
-
-  // 32 bit macho has no relocation for a-b if a is undefined, even if b is in
-  // the section that is being relocated. This means we have to use o load even
-  // for GVs that are known to be local to the dso.
-  if (isTargetMachO() && TM.isPositionIndependent() &&
-      (GV->isDeclarationForLinker() || GV->hasCommonLinkage()))
-    return true;
-
-  return false;
+  return TM.isGVIndirectSymbol(GV);
 }
 
 bool ARMSubtarget::isGVInGOT(const GlobalValue *GV) const {

llvm/lib/Target/ARM/ARMTargetMachine.h

@@ -98,6 +98,20 @@ class ARMBaseTargetMachine : public CodeGenTargetMachineImpl {
     return true;
   }
 
+  bool isGVIndirectSymbol(const GlobalValue *GV) const {
+    if (!shouldAssumeDSOLocal(GV))
+      return true;
+
+    // 32 bit macho has no relocation for a-b if a is undefined, even if b is in
+    // the section that is being relocated. This means we have to use o load
+    // even for GVs that are known to be local to the dso.
+    if (getTargetTriple().isOSBinFormatMachO() && isPositionIndependent() &&
+        (GV->isDeclarationForLinker() || GV->hasCommonLinkage()))
+      return true;
+
+    return false;
+  }
+
   yaml::MachineFunctionInfo *createDefaultFuncInfoYAML() const override;
   yaml::MachineFunctionInfo *
   convertFuncInfoToYAML(const MachineFunction &MF) const override;

llvm/test/CodeGen/ARM/xxstructor-nodef.ll

@@ -0,0 +1,7 @@
+; RUN: llc -mtriple=arm-unknown-linux-gnueabihf < %s | FileCheck %s
+
+; This test contains a llvm.global_ctors with no other definitions. Make sure we do not crash in that case.
+; CHECK: .section        .init_array,"aw",%init_array
+
+declare  ccc void @ghczmbignum_GHCziNumziBackendziSelected_init__prof_init()
+@llvm.global_ctors = appending global [1 x {i32, void ()*, i8* }] [{i32, void ()*, i8* }{i32  65535, void ()*  @ghczmbignum_GHCziNumziBackendziSelected_init__prof_init, i8*  null } ]