Add the new @llvm.nacl.atomic.fence.all intrinsic

lib/IR/NaClAsm.cpp

Index: lib/IR/NaClAsm.cpp
diff --git a/lib/IR/NaClAsm.cpp b/lib/IR/NaClAsm.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..2d8d6ad4e72231b3a9c21eef8dad938b35023528
--- /dev/null
+++ b/lib/IR/NaClAsm.cpp
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+//===-- llvm/IR/NaClAsm.h - NaCl Assembly Handling --------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/InlineAsm.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/NaClAsm.h"
+#include <string>
+
+namespace llvm {
+
+namespace NaCl {
+
+bool isAsmMemory(const Instruction *I) {
+  if (!I)
+    return false;
+  const CallInst *CI = dyn_cast<CallInst>(I);
+  if (!CI || !CI->isInlineAsm())
+    return false;
+
+  const InlineAsm *A = cast<InlineAsm>(CI->getCalledValue());
+  std::string AsmString(A->getAsmString());
+  std::string Constraints(A->getConstraintString());
+  Type *T = CI->getType();
+
+  bool isEmptyAsm = AsmString.empty();
+  // Different triples will encode "touch everything" differently, e.g.:
+  //  - le32-unknown-nacl has "~{memory}".
+  //  - x86 "~{memory},~{dirflag},~{fpsr},~{flags}".
+  // The following code therefore only searches for memory: this pass
+  // deals with portable assembly, touching anything else than memory in
+  // an empty assembly statement is meaningless.
+  bool touchesMemory = Constraints.find("~{memory}") != std::string::npos;
+
+  return T->isVoidTy() && A->hasSideEffects() && isEmptyAsm && touchesMemory;
+}
+
+} // End NaCl namespace
+
+} // End llvm namespace