Revert r44626, which turned off the use of readonly

and readnone for functions with bodies because it
broke llvm-gcc-4.2 bootstrap.  It turns out that,
because of LLVM's array_ref hack, gcc was computing
pure/const attributes wrong (now fixed by turning
off the gcc ipa-pure-const pass).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@44937 91177308-0d34-0410-b5e6-96231b3b80d8

lib/VMCore/Instruction.cpp

@@ -13,7 +13,6 @@
 
 #include "llvm/Type.h"
 #include "llvm/Instructions.h"
-#include "llvm/IntrinsicInst.h" // FIXME: remove
 #include "llvm/Function.h"
 #include "llvm/Support/CallSite.h"
 #include "llvm/Support/LeakDetector.h"
@@ -209,8 +208,6 @@ bool Instruction::mayWriteToMemory() const {
   case Instruction::VAArg:
     return true;
   case Instruction::Call:
-    if (!isa<IntrinsicInst>(this))
-      return true; // FIXME: workaround gcc bootstrap breakage
     return !cast<CallInst>(this)->onlyReadsMemory();
   case Instruction::Load:
     return cast<LoadInst>(this)->isVolatile();