[IR] Add bounds checking to paramHasAttr

Summary:
This is intended to make a later change simpler.

Note: adding this bounds checking required fixing `X86FastISel`.  As
far I can tell I've preserved original behavior but a careful review
will be appreciated.

Reviewers: reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D14304

llvm-svn: 252073
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 59ac99b..3394355 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -331,6 +331,8 @@
 }
 
 bool CallInst::paramHasAttr(unsigned i, Attribute::AttrKind A) const {
+  assert(i < (getNumArgOperands() + 1) && "Param index out of bounds!");
+
   if (AttributeList.hasAttribute(i, A))
     return true;
   if (const Function *F = getCalledFunction())
@@ -575,6 +577,8 @@
 }
 
 bool InvokeInst::paramHasAttr(unsigned i, Attribute::AttrKind A) const {
+  assert(i < (getNumArgOperands() + 1) && "Param index out of bounds!");
+
   if (AttributeList.hasAttribute(i, A))
     return true;
   if (const Function *F = getCalledFunction())