[llvm] 40d51de - [SelectionDAG] Use UnknownSize for VP memory ops

[Fraser Cormack via llvm-commits]

Author: Fraser Cormack
Date: 2021-12-07T10:51:02Z
New Revision: 40d51de5cb722d464f82b8116aec8614c1158f1b

URL: https://github.com/llvm/llvm-project/commit/40d51de5cb722d464f82b8116aec8614c1158f1b
DIFF: https://github.com/llvm/llvm-project/commit/40d51de5cb722d464f82b8116aec8614c1158f1b.diff

LOG: [SelectionDAG] Use UnknownSize for VP memory ops

In the style of 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.

Reviewed By: craig.topper

Differential Revision: https://reviews.llvm.org/D115036

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index f0fbdd86ff26..cd7b74ef17a8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7331,20 +7331,12 @@ void SelectionDAGBuilder::visitVPLoadGather(const VPIntrinsic &VPIntrin, EVT VT,
   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 {
@@ -7395,7 +7387,7 @@ void SelectionDAGBuilder::visitVPStoreScatter(const VPIntrinsic &VPIntrin,
   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 */);