Add support for the R_ARM_TARGET1 relocation, which should be given to relocations applied to all C++ constructors and destructors.

This enables the linker to match concrete relocation types (absolute or relative) with whatever library or C++ support code is being linked against.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@149057 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/AsmPrinter.h

@@ -268,6 +268,12 @@ namespace llvm {
 
     virtual void EmitMachineConstantPoolValue(MachineConstantPoolValue *MCPV);
 
+    /// EmitXXStructor - Targets can override this to change how global constants
+    /// that are part of a C++ static/global constructor list are emitted.
+    virtual void EmitXXStructor(const Constant *CV) {
+      EmitGlobalConstant(CV);
+    }
+
     /// isBlockOnlyReachableByFallthough - Return true if the basic block has
     /// exactly one predecessor and the control transfer mechanism between
     /// the predecessor and this block is a fall-through.

include/llvm/MC/MCExpr.h

@@ -169,6 +169,7 @@ public:
     VK_ARM_GOTOFF,
     VK_ARM_TPOFF,
     VK_ARM_GOTTPOFF,
+    VK_ARM_TARGET1,
 
     VK_PPC_TOC,
     VK_PPC_DARWIN_HA16,  // ha16(symbol)

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -1296,7 +1296,7 @@ void AsmPrinter::EmitXXStructorList(const Constant *List, bool isCtor) {
     OutStreamer.SwitchSection(OutputSection);
     if (OutStreamer.getCurrentSection() != OutStreamer.getPreviousSection())
       EmitAlignment(Align);
-    EmitGlobalConstant(Structors[i].second);
+    EmitXXStructor(Structors[i].second);
   }
 }
 

lib/MC/MCExpr.cpp

@@ -58,7 +58,8 @@ void MCExpr::print(raw_ostream &OS) const {
         SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT ||
         SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF ||
         SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF ||
-        SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF)
+        SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF ||
+        SRE.getKind() == MCSymbolRefExpr::VK_ARM_TARGET1)
       OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
     else if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
              SRE.getKind() != MCSymbolRefExpr::VK_PPC_DARWIN_HA16 &&
@@ -193,6 +194,7 @@ StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
   case VK_ARM_TPOFF: return "(tpoff)";
   case VK_ARM_GOTTPOFF: return "(gottpoff)";
   case VK_ARM_TLSGD: return "(tlsgd)";
+  case VK_ARM_TARGET1: return "(target1)";
   case VK_PPC_TOC: return "toc";
   case VK_PPC_DARWIN_HA16: return "ha16";
   case VK_PPC_DARWIN_LO16: return "lo16";

lib/Target/ARM/ARMAsmPrinter.cpp

@@ -299,6 +299,22 @@ void ARMAsmPrinter::EmitFunctionEntryLabel() {
   OutStreamer.EmitLabel(CurrentFnSym);
 }
 
+void ARMAsmPrinter::EmitXXStructor(const Constant *CV) {
+  uint64_t Size = TM.getTargetData()->getTypeAllocSize(CV->getType());
+  assert(Size && "C++ constructor pointer had zero size!");
+
+  const GlobalValue *GV = dyn_cast<GlobalValue>(CV);
+  assert(GV && "C++ constructor pointer was not a GlobalValue!");
+
+  const MCExpr *E = MCSymbolRefExpr::Create(Mang->getSymbol(GV),
+                                            (Subtarget->isTargetDarwin()
+                                             ? MCSymbolRefExpr::VK_None
+                                             : MCSymbolRefExpr::VK_ARM_TARGET1),
+                                            OutContext);
+  
+  OutStreamer.EmitValue(E, Size);
+}
+
 /// runOnMachineFunction - This uses the EmitInstruction()
 /// method to print assembly for each instruction.
 ///

lib/Target/ARM/ARMAsmPrinter.h

@@ -73,6 +73,7 @@ public:
   virtual void EmitFunctionEntryLabel();
   void EmitStartOfAsmFile(Module &M);
   void EmitEndOfAsmFile(Module &M);
+  void EmitXXStructor(const Constant *CV);
 
   // lowerOperand - Convert a MachineOperand into the equivalent MCOperand.
   bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp);

lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp

@@ -236,7 +236,10 @@ unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
       case MCSymbolRefExpr::VK_ARM_GOTOFF:
         Type = ELF::R_ARM_GOTOFF32;
         break;
-      }
+      case MCSymbolRefExpr::VK_ARM_TARGET1:
+        Type = ELF::R_ARM_TARGET1;
+        break;
+      } 
       break;
     case ARM::fixup_arm_ldst_pcrel_12:
     case ARM::fixup_arm_pcrel_10:

test/MC/ARM/cxx-global-constructor.ll

@@ -0,0 +1,12 @@
+; RUN: llc %s -mtriple=armv7-linux-gnueabi -relocation-model=pic \
+; RUN: -filetype=obj -o - | elf-dump --dump-section-data | FileCheck %s
+
+
+@llvm.global_ctors = appending global [1 x { i32, void ()* }] [{ i32, void ()* } { i32 65535, void ()* @f }]
+
+define void @f() {
+  ret void
+}
+
+; Check for a relocation of type R_ARM_TARGET1.
+; CHECK: ('r_type', 0x26)