[RS4GC] Simplify attribute handling code NFC

Avoids use of AttributeList::getNumSlots, making it easier to change the
underlying implementation.

llvm-svn: 301671

diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index f344eb1..c11247c 100644 (file)
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1128,39 +1128,23 @@ normalizeForInvokeSafepoint(BasicBlock *BB, BasicBlock *InvokeParent,
 
 // Create new attribute set containing only attributes which can be transferred
 // from original call to the safepoint.
-static AttributeList legalizeCallAttributes(AttributeList AS) {
-  AttributeList Ret;
-
-  for (unsigned Slot = 0; Slot < AS.getNumSlots(); Slot++) {
-    unsigned Index = AS.getSlotIndex(Slot);
-
-    if (Index == AttributeList::ReturnIndex ||
-        Index == AttributeList::FunctionIndex) {
-
-      for (Attribute Attr : make_range(AS.begin(Slot), AS.end(Slot))) {
-
-        // Do not allow certain attributes - just skip them
-        // Safepoint can not be read only or read none.
-        if (Attr.hasAttribute(Attribute::ReadNone) ||
-            Attr.hasAttribute(Attribute::ReadOnly))
-          continue;
-
-        // These attributes control the generation of the gc.statepoint call /
-        // invoke itself; and once the gc.statepoint is in place, they're of no
-        // use.
-        if (isStatepointDirectiveAttr(Attr))
-          continue;
-
-        Ret = Ret.addAttributes(
-            AS.getContext(), Index,
-            AttributeList::get(AS.getContext(), Index, AttrBuilder(Attr)));
-      }
-    }
-
-    // Just skip parameter attributes for now
-  }
-
-  return Ret;
+static AttributeList legalizeCallAttributes(AttributeList AL) {
+  if (AL.isEmpty())
+    return AL;
+
+  // Remove the readonly, readnone, and statepoint function attributes.
+  AttrBuilder FnAttrs = AL.getFnAttributes();
+  FnAttrs.removeAttribute(Attribute::ReadNone);
+  FnAttrs.removeAttribute(Attribute::ReadOnly);
+  for (Attribute A : AL.getFnAttributes()) {
+    if (isStatepointDirectiveAttr(A))
+      FnAttrs.remove(A);
+  }
+
+  // Just skip parameter and return attributes for now
+  LLVMContext &Ctx = AL.getContext();
+  return AttributeList::get(Ctx, AttributeList::FunctionIndex,
+                            AttributeSet::get(Ctx, FnAttrs));
 }
 
 /// Helper function to place all gc relocates necessary for the given
@@ -1402,13 +1386,10 @@ makeStatepointExplicitImpl(const CallSite CS, /* to replace */
     Call->setCallingConv(ToReplace->getCallingConv());
 
     // Currently we will fail on parameter attributes and on certain
-    // function attributes.
-    AttributeList NewAttrs = legalizeCallAttributes(ToReplace->getAttributes());
-    // In case if we can handle this set of attributes - set up function attrs
-    // directly on statepoint and return attrs later for gc_result intrinsic.
-    Call->setAttributes(AttributeList::get(Call->getContext(),
-                                           AttributeList::FunctionIndex,
-                                           NewAttrs.getFnAttributes()));
+    // function attributes.  In case if we can handle this set of attributes -
+    // set up function attrs directly on statepoint and return attrs later for
+    // gc_result intrinsic.
+    Call->setAttributes(legalizeCallAttributes(ToReplace->getAttributes()));
 
     Token = Call;
 
@@ -1431,13 +1412,10 @@ makeStatepointExplicitImpl(const CallSite CS, /* to replace */
     Invoke->setCallingConv(ToReplace->getCallingConv());
 
     // Currently we will fail on parameter attributes and on certain
-    // function attributes.
-    AttributeList NewAttrs = legalizeCallAttributes(ToReplace->getAttributes());
-    // In case if we can handle this set of attributes - set up function attrs
-    // directly on statepoint and return attrs later for gc_result intrinsic.
-    Invoke->setAttributes(AttributeList::get(Invoke->getContext(),
-                                             AttributeList::FunctionIndex,
-                                             NewAttrs.getFnAttributes()));
+    // function attributes.  In case if we can handle this set of attributes -
+    // set up function attrs directly on statepoint and return attrs later for
+    // gc_result intrinsic.
+    Invoke->setAttributes(legalizeCallAttributes(ToReplace->getAttributes()));
 
     Token = Invoke;