Add 'nonnull', a new parameter and return attribute which indicates that the pointer is not null. Instcombine will elide comparisons between these and null. Patch by Luqman Aden!

llvm-svn: 209185

2 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/IR/Attributes.cpp b/llvm/lib/IR/Attributes.cpp
index 0bbbd559780..a9074bb294d 100644
--- a/llvm/lib/IR/Attributes.cpp
+++ b/llvm/lib/IR/Attributes.cpp
@@ -193,6 +193,8 @@ std::string Attribute::getAsString(bool InAttrGrp) const {
     return "noinline";
   if (hasAttribute(Attribute::NonLazyBind))
     return "nonlazybind";
+  if (hasAttribute(Attribute::NonNull))
+    return "nonnull";
   if (hasAttribute(Attribute::NoRedZone))
     return "noredzone";
   if (hasAttribute(Attribute::NoReturn))
@@ -392,6 +394,7 @@ uint64_t AttributeImpl::getAttrMask(Attribute::AttrKind Val) {
   case Attribute::Builtin:         return 1ULL << 41;
   case Attribute::OptimizeNone:    return 1ULL << 42;
   case Attribute::InAlloca:        return 1ULL << 43;
+  case Attribute::NonNull:         return 1ULL << 44;
   }
   llvm_unreachable("Unsupported attribute type");
 }
@@ -1177,6 +1180,7 @@ AttributeSet AttributeFuncs::typeIncompatible(Type *Ty, uint64_t Index) {
       .addAttribute(Attribute::Nest)
       .addAttribute(Attribute::NoAlias)
       .addAttribute(Attribute::NoCapture)
+      .addAttribute(Attribute::NonNull)
       .addAttribute(Attribute::ReadNone)
       .addAttribute(Attribute::ReadOnly)
       .addAttribute(Attribute::StructRet)
diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
index de8e66f1bca..fe32c4613e7 100644
--- a/llvm/lib/IR/Function.cpp
+++ b/llvm/lib/IR/Function.cpp
@@ -76,6 +76,14 @@ unsigned Argument::getArgNo() const {
   return ArgIdx;
 }
 
+/// hasNonNullAttr - Return true if this argument has the nonnull attribute on
+/// it in its containing function.
+bool Argument::hasNonNullAttr() const {
+  if (!getType()->isPointerTy()) return false;
+  return getParent()->getAttributes().
+    hasAttribute(getArgNo()+1, Attribute::NonNull);
+}
+
 /// hasByValAttr - Return true if this argument has the byval attribute on it
 /// in its containing function.
 bool Argument::hasByValAttr() const {