[llvm] r353800 - [Statepoint Lowering] Update misleading comments about chains

[Philip Reames via llvm-commits]

Author: reames
Date: Mon Feb 11 22:25:58 2019
New Revision: 353800

URL: http://llvm.org/viewvc/llvm-project?rev=353800&view=rev
Log:
[Statepoint Lowering] Update misleading comments about chains


Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp?rev=353800&r1=353799&r2=353800&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp Mon Feb 11 22:25:58 2019
@@ -366,10 +366,6 @@ spillIncomingStatepointValue(SDValue Inc
     // We use TargetFrameIndex so that isel will not select it into LEA
     Loc = Builder.DAG.getTargetFrameIndex(Index, Builder.getFrameIndexTy());
 
-    // TODO: We can create TokenFactor node instead of
-    //       chaining stores one after another, this may allow
-    //       a bit more optimal scheduling for them
-
 #ifndef NDEBUG
     // Right now we always allocate spill slots that are of the same
     // size as the value we're about to spill (the size of spillee can
@@ -398,6 +394,9 @@ spillIncomingStatepointValue(SDValue Inc
 static void lowerIncomingStatepointValue(SDValue Incoming, bool LiveInOnly,
                                          SmallVectorImpl<SDValue> &Ops,
                                          SelectionDAGBuilder &Builder) {
+  // Note: We know all of these spills are independent, but don't bother to
+  // exploit that chain wise.  DAGCombine will happily do so as needed, so
+  // doing it here would be a small compile time win at most.
   SDValue Chain = Builder.getRoot();
 
   if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Incoming)) {
@@ -984,11 +983,11 @@ void SelectionDAGBuilder::visitGCRelocat
   }
 
   SDValue SpillSlot =
-      DAG.getTargetFrameIndex(*DerivedPtrLocation, getFrameIndexTy());
+    DAG.getTargetFrameIndex(*DerivedPtrLocation, getFrameIndexTy());
 
-  // Be conservative: flush all pending loads
-  // TODO: Probably we can be less restrictive on this,
-  // it may allow more scheduling opportunities.
+  // Note: We know all of these reloads are independent, but don't bother to
+  // exploit that chain wise.  DAGCombine will happily do so as needed, so
+  // doing it here would be a small compile time win at most.
   SDValue Chain = getRoot();
 
   SDValue SpillLoad =
@@ -998,7 +997,6 @@ void SelectionDAGBuilder::visitGCRelocat
                   MachinePointerInfo::getFixedStack(DAG.getMachineFunction(),
                                                     *DerivedPtrLocation));
 
-  // Again, be conservative, don't emit pending loads
   DAG.setRoot(SpillLoad.getValue(1));
 
   assert(SpillLoad.getNode());