[llvm] r219484 - Don't use an unqualified 'abs' function call with a builtin type.

[Chandler Carruth]

Author: chandlerc
Date: Fri Oct 10 03:27:19 2014
New Revision: 219484

URL: http://llvm.org/viewvc/llvm-project?rev=219484&view=rev
Log:
Don't use an unqualified 'abs' function call with a builtin type.

This is dangerous for numerous reasons. The primary risk here is with
floating point or double types where if the wrong header files are
included in a strange order this can implicitly convert to integers and
then call the C abs function on the integers. There is a secondary risk
that even impacts integers where if the namespace the code is written in
ever defines an abs overload for types within that namespace the global
abs will be hidden. The correct form is to call std::abs or write 'using
std::abs' for builtin types (and only the latter is correct in any
generic context).

I've also added the requisite header to be a bit more explicit here.

Modified:
    llvm/trunk/lib/Target/X86/X86FrameLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86FrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FrameLowering.cpp?rev=219484&r1=219483&r2=219484&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FrameLowering.cpp Fri Oct 10 03:27:19 2014
@@ -30,6 +30,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Support/Debug.h"
+#include <cstdlib>
 
 using namespace llvm;
 
@@ -763,7 +764,7 @@ void X86FrameLowering::emitPrologue(Mach
       // will restore SP to (BP - SEHFrameOffset)
       for (const CalleeSavedInfo &Info : MFI->getCalleeSavedInfo()) {
         int offset = MFI->getObjectOffset(Info.getFrameIdx());
-        SEHFrameOffset = std::max(SEHFrameOffset, abs(offset));
+        SEHFrameOffset = std::max(SEHFrameOffset, std::abs(offset));
       }
       SEHFrameOffset += SEHFrameOffset % 16; // ensure alignmant
 
@@ -1176,7 +1177,7 @@ bool X86FrameLowering::assignCalleeSaved
 
     const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg);
     // ensure alignment
-    SpillSlotOffset -= abs(SpillSlotOffset) % RC->getAlignment();
+    SpillSlotOffset -= std::abs(SpillSlotOffset) % RC->getAlignment();
     // spill into slot
     SpillSlotOffset -= RC->getSize();
     int SlotIndex =