[Assembler] Add a pointer to the inline assembly SourceMgr in MCContext.

[sanwou01]

Summary

This allows for proper error messages through the inline assembly
SourceMgr. The AsmPrinter's life time includes the MCContext's life
time.

[rnk]

These patches are too small and hard to justify in isolation. Each submitted patch should implement a small, testable unit of functionality.

[sanwou01]

Ready to land as D29441.

include/llvm/MC/MCContext.h

namespace llvm {
 
   public:
     typedef StringMap<MCSymbol *, BumpPtrAllocator &> SymbolTable;
 
   private:
     /// The SourceMgr for this object, if any.
     const SourceMgr *SrcMgr;
 
+    /// The SourceMgr for inline assembly, if any.
+    SourceMgr *InlineSrcMgr;
+
     /// The MCAsmInfo for this target.
     const MCAsmInfo *MAI;
 
     /// The MCRegisterInfo for this target.
     const MCRegisterInfo *MRI;
 
     /// The MCObjectFileInfo for this target.
     const MCObjectFileInfo *MOFI;
namespace llvm {
   public:
     explicit MCContext(const MCAsmInfo *MAI, const MCRegisterInfo *MRI,
                        const MCObjectFileInfo *MOFI,
                        const SourceMgr *Mgr = nullptr, bool DoAutoReset = true);
     ~MCContext();
 
     const SourceMgr *getSourceManager() const { return SrcMgr; }
 
+    void setInlineSourceManager(SourceMgr *SM) { InlineSrcMgr = SM; }
+
     const MCAsmInfo *getAsmInfo() const { return MAI; }
 
     const MCRegisterInfo *getRegisterInfo() const { return MRI; }
 
     const MCObjectFileInfo *getObjectFileInfo() const { return MOFI; }
 
     CodeViewContext &getCVContext();
 

lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

if (!MCAI->useIntegratedAssembler() &&
     OutStreamer->EmitRawText(Str);
     emitInlineAsmEnd(STI, nullptr);
     return;
   }
 
   SourceMgr &SrcMgr = *getInlineSourceManager();
   SrcMgr.setIncludeDirs(MCOptions.IASSearchPaths);
 
+  MCContext &Context = MMI->getContext();
+  Context.setInlineSourceManager(&SrcMgr);
 
   // If the current LLVMContext has an inline asm handler, set it in SourceMgr.
   LLVMContext &LLVMCtx = MMI->getModule()->getContext();
   bool HasDiagHandler = false;
   if (LLVMCtx.getInlineAsmDiagnosticHandler() != nullptr) {
     SrcMgrDiagInfo &DiagInfo = getNewDiagInfo();
     // If the source manager has an issue, we arrange for srcMgrDiagHandler
     // to be invoked, getting DiagInfo passed into it.