Fix for PR26378 (reset persistent state in PPCAsmPrinter)

[nemanjai]

Summary

We were not clearing the TOC vector in PPCAsmPrinter when initializing it. This caused duplicate definition asserts when the pass is reused on the module (i.e. with -compile-twice or in JIT contexts).

[nemanjai]

Added the test case from the PR that I initially forgot to svn add.

[nemanjai]

The %s was missing in the test case.

[kbarton]

LGTM

[nemanjai]

Committed revision 263338.

lib/Target/PowerPC/PPCAsmPrinter.cpp

explicit PPCAsmPrinter(TargetMachine &TM,
       : AsmPrinter(TM, std::move(Streamer)), SM(*this) {}
 
   const char *getPassName() const override {
     return "PowerPC Assembly Printer";
   }
 
     MCSymbol *lookUpOrCreateTOCEntry(MCSymbol *Sym);
 
+    virtual bool doInitialization(Module &M) override {
+      if (!TOC.empty())
+        TOC.clear();
+      return AsmPrinter::doInitialization(M);
+    }
+
     void EmitInstruction(const MachineInstr *MI) override;
 
     void printOperand(const MachineInstr *MI, unsigned OpNo, raw_ostream &O);
 
     bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
                          unsigned AsmVariant, const char *ExtraCode,
                          raw_ostream &O) override;
     bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,