From: Yaron Keren <yaron.keren@gmail.com>
Date: Mon, 24 Mar 2014 19:48:13 +0000 (+0000)
Subject: In Release modes, Visual Studio complains that the Operator destructor in User.cpp
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=d816eda3c794b940f9d9f539456e21c2031868b6;p=oota-llvm.git

In Release modes, Visual Studio complains that the Operator destructor in User.cpp
never returns, which is true by design.

Initially assumed that the reason is llvm_unreachable being dependent on NDEBUG.

However, even if llvm_unreachable is replaced by __assume(false), VC still warns in
Release modes but not in Debug modes...

The real reason turned out to be optimization flags.
With /Od in Debug modes the warning is not issued whereas with /O1 it is.

I could not find any documentation to this effect, but it is reproducable:

Try compiling http://msdn.microsoft.com/en-us/library/khwfyc5d(v=vs.90).aspx
with /O1 and then with /Od.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204659 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/IR/User.cpp b/lib/IR/User.cpp
index 940682826ac..cd124df1e93 100644
--- a/lib/IR/User.cpp
+++ b/lib/IR/User.cpp
@@ -83,8 +83,28 @@ void User::operator delete(void *Usr) {
 //                             Operator Class
 //===----------------------------------------------------------------------===//
 
+#if defined(_MSC_VER)
+// In Release modes, Visual Studio complains that the Operator destructor
+// never returns, which is true by design. 
+// This does *not* depend on llvm_unreachable being dependent on NDEBUG:
+// even if llvm_unreachable is replaced by __assume(false), VC still warns in
+// Release modes but not in Debug modes. The real reason is optimization flags.
+// With /Od in Debug modes the warning is not issued whereas with /O1 it is.
+// I could not find any documentation to this effect, it is reproducable:
+// Try compiling http://msdn.microsoft.com/en-us/library/khwfyc5d(v=vs.90).aspx
+// with /O1 and then with /Od.
+// Anyhow, solution is same as lib/Support/Process.cpp:~self_process().
+
+#pragma warning(push)
+#pragma warning(disable:4722)
+#endif
+
 Operator::~Operator() {
   llvm_unreachable("should never destroy an Operator");
 }
 
+#if defined(_MSC_VER)
+#pragma warning(pop)
+#endif
+
 } // End llvm namespace