[PATCH] D115036: [SelectionDAG] Use UnknownSize for VP memory ops

[Fraser Cormack via Phabricator via llvm-commits]

frasercrmck created this revision.
frasercrmck added reviewers: simoll, craig.topper, rogfer01, loralb.
Herald added subscribers: ecnelises, hiraditya.
frasercrmck requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

In the style of D113888 <https://reviews.llvm.org/D113888>, this patch updates the various VP memory
operations (load, store, gather, scatter) to use UnknownSize. This is
for the same reason as for masked loads and stores: the number of
elements accessed is not generally known at compile time.

This is somewhat pessimistic in the sense that we may still find
un-canonicalized intrinsics featuring both an all-true mask and an EVL
equal to the vector size. Arguably those should be canonicalized before
the SelectionDAG, so those have been left for future work.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115036

Files:
  llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7329,20 +7329,12 @@
   if (!isGather) {
     // Do not serialize variable-length loads of constant memory with
     // anything.
-    MemoryLocation ML;
-    if (VT.isScalableVector())
-      ML = MemoryLocation::getAfter(PtrOperand);
-    else
-      ML = MemoryLocation(
-          PtrOperand,
-          LocationSize::precise(
-              DAG.getDataLayout().getTypeStoreSize(VPIntrin.getType())),
-          AAInfo);
+    MemoryLocation ML = MemoryLocation::getAfter(PtrOperand, AAInfo);
     AddToChain = !AA || !AA->pointsToConstantMemory(ML);
     SDValue InChain = AddToChain ? DAG.getRoot() : DAG.getEntryNode();
     MachineMemOperand *MMO = DAG.getMachineFunction().getMachineMemOperand(
         MachinePointerInfo(PtrOperand), MachineMemOperand::MOLoad,
-        VT.getStoreSize().getKnownMinSize(), *Alignment, AAInfo, Ranges);
+        MemoryLocation::UnknownSize, *Alignment, AAInfo, Ranges);
     LD = DAG.getLoadVP(VT, DL, InChain, OpValues[0], OpValues[1], OpValues[2],
                        MMO, false /*IsExpanding */);
   } else {
@@ -7391,7 +7383,7 @@
   if (!isScatter) {
     MachineMemOperand *MMO = DAG.getMachineFunction().getMachineMemOperand(
         MachinePointerInfo(PtrOperand), MachineMemOperand::MOStore,
-        VT.getStoreSize().getKnownMinSize(), *Alignment, AAInfo);
+        MemoryLocation::UnknownSize, *Alignment, AAInfo);
     ST =
         DAG.getStoreVP(getMemoryRoot(), DL, OpValues[0], OpValues[1],
                        OpValues[2], OpValues[3], MMO, false /* IsTruncating */);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D115036.391608.patch
Type: text/x-patch
Size: 1785 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20211203/a7ac4f50/attachment.bin>