[llvm-commits] [llvm] r169047 - /llvm/trunk/lib/Support/APFloat.cpp

[Alexey Samsonov]

Author: samsonov
Date: Fri Nov 30 16:27:54 2012
New Revision: 169047

URL: http://llvm.org/viewvc/llvm-project?rev=169047&view=rev
Log:
Fix a bug in APFloat.cpp: declare APFloat after fltSemantics it
uses. APFloat::convert() takes the pointer to the fltSemantics
variable, which is later accessed it in ~APFloat() desctructor.
That is, semantics must still be alive at the moment we delete
APFloat.

Found by experimental AddressSanitizer use-after-scope checker.

Modified:
    llvm/trunk/lib/Support/APFloat.cpp

Modified: llvm/trunk/lib/Support/APFloat.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/APFloat.cpp?rev=169047&r1=169046&r2=169047&view=diff
==============================================================================
--- llvm/trunk/lib/Support/APFloat.cpp (original)
+++ llvm/trunk/lib/Support/APFloat.cpp Fri Nov 30 16:27:54 2012
@@ -2761,9 +2761,11 @@
   // normalize against the "double" minExponent first, and only *then*
   // truncate the mantissa.  The result of that second conversion
   // may be inexact, but should never underflow.
-  APFloat extended(*this);
+  // Declare fltSemantics before APFloat that uses it (and
+  // saves pointer to it) to ensure correct destruction order.
   fltSemantics extendedSemantics = *semantics;
   extendedSemantics.minExponent = IEEEdouble.minExponent;
+  APFloat extended(*this);
   fs = extended.convert(extendedSemantics, rmNearestTiesToEven, &losesInfo);
   assert(fs == opOK && !losesInfo);
   (void)fs;