[Assembler] Always copy temp inline assembly string.

[sanwou01]

Summary

This ensures that string (which was previously kept on the stack) is
still alive during finalization.

[rengolin]

lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

115

Str is an argument, so guaranteed (on a single thread) to exist through the execution of this function, no?

Or is this about the report_fatal_error at the end, which could print garbage?

[sanwou01]

Ready to land as D29441.

lib/CodeGen/AsmPrinter/AsmPrinterInlineAsm.cpp

if (LLVMCtx.getInlineAsmDiagnosticHandler() != nullptr) {
     DiagInfo.LocInfo = LocMDNode;
     DiagInfo.DiagHandler = LLVMCtx.getInlineAsmDiagnosticHandler();
     DiagInfo.DiagContext = LLVMCtx.getInlineAsmDiagnosticContext();
     SrcMgr.setDiagHandler(srcMgrDiagHandler, &DiagInfo);
     HasDiagHandler = true;
   }
 
   std::unique_ptr<MemoryBuffer> Buffer;
-  if (isNullTerminated)
-    Buffer = MemoryBuffer::getMemBuffer(Str, "<inline asm>");
-  else
-    Buffer = MemoryBuffer::getMemBufferCopy(Str, "<inline asm>");
+  // Always copy the inline assembly string into the memory buffer to preserve
+  // it until after finalization.
 
   // Tell SrcMgr about this buffer, it takes ownership of the buffer.
   unsigned BufNum = SrcMgr.AddNewSourceBuffer(std::move(Buffer), SMLoc());
 
   std::unique_ptr<MCAsmParser> Parser(
       createMCAsmParser(SrcMgr, OutContext, *OutStreamer, *MAI, BufNum));
 
   // We create a new MCInstrInfo here since we might be at the module level