Detect calls to compiler intrinsics and emit an extern declarations

only for those. These extern declarations to intrinsics are currently 
being emitted at the bottom of generated .s file, which works fine with
gpasm(not sure about MPSAM though).
PIC16 linker generates errors for few cases (function-args/struct_args_5) if you do not include any
extern declarations (even if no intrinsics are being used), but that
needs to be fixed in the linker itself.

llvm-svn: 71423

lib/Target/PIC16/PIC16.h

@@ -114,7 +114,7 @@ namespace PIC16CC {
       case TEMPS_LABEL:       return ".temp.";
       case ARGS_LABEL:       return ".args.";
       case RET_LABEL:       return ".ret.";
-      case LIBCALL:       return ".lib.";
+      case LIBCALL:       return "__intrinsics";
       case FRAME_SECTION:       return ".fpdata.";
       case AUTOS_SECTION:       return ".fadata.";
       case CODE_SECTION:       return "code";
@@ -234,6 +234,12 @@ namespace PIC16CC {
        return o.str(); 
     }
 
+    static std::string getDeclSectionName(void) {
+       std::string dsname = "decl_section.1";
+       dsname = addPrefix(dsname);
+       return dsname; 
+    }
+
     inline static bool isLocalName (const std::string &Name) {
       if (getSymbolTag(Name) == AUTOS_LABEL)
         return true;

lib/Target/PIC16/PIC16AsmPrinter.cpp

@@ -87,6 +87,7 @@ bool PIC16AsmPrinter::runOnMachineFunction(MachineFunction &MF) {
           CurLine = line;
         }
       }
+        
       // Print the assembly for the instruction.
       printMachineInstruction(II);
     }
@@ -106,6 +107,8 @@ FunctionPass *llvm::createPIC16CodePrinterPass(raw_ostream &o,
   return new PIC16AsmPrinter(o, tm, tm.getTargetAsmInfo(), OptLevel, verbose);
 }
 
+
+// printOperand - print operand of insn.
 void PIC16AsmPrinter::printOperand(const MachineInstr *MI, int opNum) {
   const MachineOperand &MO = MI->getOperand(opNum);
 
@@ -126,8 +129,14 @@ void PIC16AsmPrinter::printOperand(const MachineInstr *MI, int opNum) {
       break;
     }
     case MachineOperand::MO_ExternalSymbol: {
-      std::string Name = MO.getSymbolName(); 
-      O  << MO.getSymbolName();
+       const char *Sname = MO.getSymbolName();
+
+      // If its a libcall name, record it to decls section.
+      if (PAN::getSymbolTag(Sname) == PAN::LIBCALL) {
+        Decls.push_back(Sname);
+      }
+
+      O  << Sname;
       break;
     }
     case MachineOperand::MO_MachineBasicBlock:
@@ -144,6 +153,23 @@ void PIC16AsmPrinter::printCCOperand(const MachineInstr *MI, int opNum) {
   O << PIC16CondCodeToString((PIC16CC::CondCodes)CC);
 }
 
+void PIC16AsmPrinter::printDecls(void) {
+  // If no libcalls used, return.
+  if (Decls.empty()) return;
+
+  const Section *S = TAI->getNamedSection(PAN::getDeclSectionName().c_str());
+  SwitchToSection(S);
+  // Remove duplicate entries.
+  Decls.sort();
+  Decls.unique();
+  for (std::list<const char*>::const_iterator I = Decls.begin(); 
+       I != Decls.end(); I++) {
+    O << TAI->getExternDirective() << *I << "\n";
+    // FIXME: Use PAN::getXXXLabel() funtions hrer.
+    O << TAI->getExternDirective() << *I << ".args." << "\n";
+    O << TAI->getExternDirective() << *I << ".ret." << "\n";
+  }
+}
 
 bool PIC16AsmPrinter::doInitialization (Module &M) {
   bool Result = AsmPrinter::doInitialization(M);
@@ -188,7 +214,7 @@ void PIC16AsmPrinter::EmitExternsAndGlobals (Module &M) {
 
   // Emit header file to include declaration of library functions
   // FIXME: find out libcall names.
-  O << "\t#include C16IntrinsicCalls.INC\n";
+  // O << "\t#include C16IntrinsicCalls.INC\n";
 
   // Emit declarations for external variable declarations and definitions.
   for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
@@ -212,7 +238,6 @@ void PIC16AsmPrinter::EmitExternsAndGlobals (Module &M) {
 void PIC16AsmPrinter::EmitRomData (Module &M)
 {
   SwitchToSection(TAI->getReadOnlySection());
-  IsRomData = true;
   for (Module::global_iterator I = M.global_begin(), E = M.global_end();
        I != E; ++I) {
     if (!I->hasInitializer())   // External global require no code.
@@ -238,10 +263,10 @@ void PIC16AsmPrinter::EmitRomData (Module &M)
       O << "\n";
     }
   }
-  IsRomData = false;
 }
 
 bool PIC16AsmPrinter::doFinalization(Module &M) {
+  printDecls();
   O << "\t" << "END\n";
   bool Result = AsmPrinter::doFinalization(M);
   return Result;

lib/Target/PIC16/PIC16AsmPrinter.h

@@ -21,6 +21,8 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Target/TargetAsmInfo.h"
 #include "llvm/Target/TargetMachine.h"
+#include <list>
+#include <string>
 
 namespace llvm {
   struct VISIBILITY_HIDDEN PIC16AsmPrinter : public AsmPrinter {
@@ -28,8 +30,6 @@ namespace llvm {
                              const TargetAsmInfo *T, CodeGenOpt::Level OL,
                              bool V)
       : AsmPrinter(O, TM, T, OL, V) {
-      FunctionLabelBegin = '@';
-      IsRomData = false;
       PTLI = TM.getTargetLowering();
     }
     private :
@@ -46,6 +46,7 @@ namespace llvm {
     void EmitGlobalData (Module &M);
     void EmitRomData (Module &M);
     void emitFunctionData(MachineFunction &MF);
+    void printDecls(void);
 
     protected:
     bool doInitialization(Module &M);
@@ -53,8 +54,7 @@ namespace llvm {
 
     private:
     PIC16TargetLowering *PTLI;
-    bool IsRomData;
-    char FunctionLabelBegin;
+    std::list<const char *> Decls; // List of extern decls.
   };
 } // end of namespace
 

lib/Target/PIC16/PIC16MemSelOpt.cpp

@@ -137,6 +137,8 @@ bool MemSelOpt::processInstruction(MachineInstr *MI) {
   }
 
   // Get the section name(NewBank) for MemOp.
+  // This assumes that the section names for globals are laready set by
+  // AsmPrinter->doInitialization.
   std::string NewBank = CurBank;
   if (Op.getType() ==  MachineOperand::MO_GlobalAddress &&
       Op.getGlobal()->getType()->getAddressSpace() == PIC16ISD::RAM_SPACE) {