[llvm] r187320 - [PowerPC] Add comment explaining preprocessor directive.

[Bill Schmidt]

Author: wschmidt
Date: Sat Jul 27 22:23:32 2013
New Revision: 187320

URL: http://llvm.org/viewvc/llvm-project?rev=187320&view=rev
Log:
[PowerPC] Add comment explaining preprocessor directive.

Modified:
    llvm/trunk/lib/Target/PowerPC/PPCJITInfo.cpp

Modified: llvm/trunk/lib/Target/PowerPC/PPCJITInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCJITInfo.cpp?rev=187320&r1=187319&r2=187320&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCJITInfo.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCJITInfo.cpp Sat Jul 27 22:23:32 2013
@@ -71,6 +71,8 @@ static void EmitBranchToAt(uint64_t At,
 extern "C" void PPC32CompilationCallback();
 extern "C" void PPC64CompilationCallback();
 
+// The first clause of the preprocessor directive looks wrong, but it is
+// necessary when compiling this code on non-PowerPC hosts.
 #if (!defined(__ppc__) && !defined(__powerpc__)) || defined(__powerpc64__) || defined(__ppc64__)
 void PPC32CompilationCallback() {
   llvm_unreachable("This is not a 32bit PowerPC, you can't execute this!");