[AttributeSet] Overload AttributeSet::addAttribute to reduce compile

time.

The new overloaded function is used when an attribute is added to a
large number of slots of an AttributeSet (for example, to function
parameters). This is much faster than calling AttributeSet::addAttribute
once per slot, because AttributeSet::getImpl (which calls
FoldingSet::FIndNodeOrInsertPos) is called only once per function
instead of once per slot.

With this commit, clang compiles a file which used to take over 22
minutes in just 13 seconds.

rdar://problem/23581000

Differential Revision: http://reviews.llvm.org/D15085

llvm-svn: 254491

1 files changed, 14 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 26088bbe018..d2341c8c05d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1942,20 +1942,27 @@ Instruction *InstCombiner::visitCallSite(CallSite CS) {
   // Mark any parameters that are known to be non-null with the nonnull
   // attribute.  This is helpful for inlining calls to functions with null
   // checks on their arguments.
+  SmallVector<unsigned, 4> Indices;
   unsigned ArgNo = 0;
+
   for (Value *V : CS.args()) {
     if (V->getType()->isPointerTy() && !CS.paramHasAttr(ArgNo+1, Attribute::NonNull) &&
-        isKnownNonNullAt(V, CS.getInstruction(), DT, TLI)) {
-      AttributeSet AS = CS.getAttributes();
-      AS = AS.addAttribute(CS.getInstruction()->getContext(), ArgNo+1,
-                           Attribute::NonNull);
-      CS.setAttributes(AS);
-      Changed = true;
-    }
+        isKnownNonNullAt(V, CS.getInstruction(), DT, TLI))
+      Indices.push_back(ArgNo + 1);
     ArgNo++;
   }
+
   assert(ArgNo == CS.arg_size() && "sanity check");
 
+  if (!Indices.empty()) {
+    AttributeSet AS = CS.getAttributes();
+    LLVMContext &Ctx = CS.getInstruction()->getContext();
+    AS = AS.addAttribute(Ctx, Indices,
+                         Attribute::get(Ctx, Attribute::NonNull));
+    CS.setAttributes(AS);
+    Changed = true;
+  }
+
   // If the callee is a pointer to a function, attempt to move any casts to the
   // arguments of the call/invoke.
   Value *Callee = CS.getCalledValue();