[llvm] r245711 - Disable Visual C++ 2013 Debug mode assert on null pointer in some STL algorithms,

[Yaron Keren via llvm-commits]

Author: yrnkrn
Date: Fri Aug 21 12:31:03 2015
New Revision: 245711

URL: http://llvm.org/viewvc/llvm-project?rev=245711&view=rev
Log:
Disable Visual C++ 2013 Debug mode assert on null pointer in some STL algorithms,
such as std::equal on the third argument. This reverts previous workarounds.

Predefining _DEBUG_POINTER_IMPL disables Visual C++ 2013 headers from defining
it to a function performing the null pointer check. In practice, it's not that
bad since any function actually using the nullptr will seg fault. The other
iterator sanity checks remain enabled in the headers.

Reviewed by Aaron Ballmanþ and Duncan P. N. Exon Smith.


Modified:
    llvm/trunk/cmake/modules/HandleLLVMOptions.cmake
    llvm/trunk/docs/CodingStandards.rst
    llvm/trunk/include/llvm/ADT/ArrayRef.h
    llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

Modified: llvm/trunk/cmake/modules/HandleLLVMOptions.cmake
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/modules/HandleLLVMOptions.cmake?rev=245711&r1=245710&r2=245711&view=diff
==============================================================================
--- llvm/trunk/cmake/modules/HandleLLVMOptions.cmake (original)
+++ llvm/trunk/cmake/modules/HandleLLVMOptions.cmake Fri Aug 21 12:31:03 2015
@@ -247,6 +247,12 @@ if( MSVC_IDE )
 endif()
 
 if( MSVC )
+  if( CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.0 )
+    # For MSVC 2013, disable iterator null pointer checking in debug mode,
+    # especially so std::equal(nullptr, nullptr, nullptr) will not assert.
+    add_llvm_definitions("-D_DEBUG_POINTER_IMPL=")
+  endif()
+  
   include(ChooseMSVCCRT)
 
   if( NOT (${CMAKE_VERSION} VERSION_LESS 2.8.11) )

Modified: llvm/trunk/docs/CodingStandards.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/CodingStandards.rst?rev=245711&r1=245710&r2=245711&view=diff
==============================================================================
--- llvm/trunk/docs/CodingStandards.rst (original)
+++ llvm/trunk/docs/CodingStandards.rst Fri Aug 21 12:31:03 2015
@@ -178,8 +178,6 @@ being aware of:
 * While most of the atomics library is well implemented, the fences are
   missing. Fortunately, they are rarely needed.
 * The locale support is incomplete.
-* ``std::equal()`` (and other algorithms) incorrectly assert in MSVC when given
-  ``nullptr`` as an iterator.
 
 Other than these areas you should assume the standard library is available and
 working as expected until some build bot tells you otherwise. If you're in an

Modified: llvm/trunk/include/llvm/ADT/ArrayRef.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/ArrayRef.h?rev=245711&r1=245710&r2=245711&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/ArrayRef.h (original)
+++ llvm/trunk/include/llvm/ADT/ArrayRef.h Fri Aug 21 12:31:03 2015
@@ -156,8 +156,6 @@ namespace llvm {
     bool equals(ArrayRef RHS) const {
       if (Length != RHS.Length)
         return false;
-      if (Length == 0)
-        return true;
       return std::equal(begin(), end(), RHS.begin());
     }
 

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=245711&r1=245710&r2=245711&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Fri Aug 21 12:31:03 2015
@@ -5676,7 +5676,7 @@ UpdateNodeOperands(SDNode *N, ArrayRef<S
          "Update with wrong number of operands");
 
   // If no operands changed just return the input node.
-  if (Ops.empty() || std::equal(Ops.begin(), Ops.end(), N->op_begin()))
+  if (std::equal(Ops.begin(), Ops.end(), N->op_begin()))
     return N;
 
   // See if the modified node already exists.