[PATCH] D137844: [DAG] Fold zext/sext into masked loads with multiple truncate uses

[Benjamin Maxwell via Phabricator via llvm-commits]

benmxwl-arm updated this revision to Diff 474786.
benmxwl-arm added a comment.

Remove accidentally committed file


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137844/new/

https://reviews.llvm.org/D137844

Files:
  llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  llvm/test/CodeGen/AArch64/sve-load-compare-store.ll


Index: llvm/test/CodeGen/AArch64/sve-load-compare-store.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sve-load-compare-store.ll
+++ llvm/test/CodeGen/AArch64/sve-load-compare-store.ll
@@ -6,9 +6,7 @@
 ; CHECK:       // %bb.0: // %entry
 ; CHECK-NEXT:    ptrue p0.b
 ; CHECK-NEXT:    ld1h { z0.s }, p0/z, [x0]
-; CHECK-NEXT:    mov z1.d, z0.d
-; CHECK-NEXT:    and z1.s, z1.s, #0xffff
-; CHECK-NEXT:    cmphs p0.s, p0/z, z1.s, #0
+; CHECK-NEXT:    cmphs p0.s, p0/z, z0.s, #0
 ; CHECK-NEXT:    st1b { z0.s }, p0, [x1]
 ; CHECK-NEXT:    ret
 entry:
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -12097,13 +12097,29 @@
                                         SDNode *N, SDValue N0,
                                         ISD::LoadExtType ExtLoadType,
                                         ISD::NodeType ExtOpc) {
-  if (!N0.hasOneUse())
-    return SDValue();
 
   MaskedLoadSDNode *Ld = dyn_cast<MaskedLoadSDNode>(N0);
   if (!Ld || Ld->getExtensionType() != ISD::NON_EXTLOAD)
     return SDValue();
 
+  auto AllUsesCanBeReplaced = [&](SDValue V) {
+    for (SDNode::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
+         ++UI) {
+      SDNode *User = *UI;
+      // Skip chain uses and the extension dag node N
+      if (UI.getUse().getResNo() != 0 || User == N)
+        continue;
+      // If all other uses of the load are just truncates we're fine to just
+      // truncate the extended type.
+      if (User->getOpcode() != ISD::TRUNCATE)
+        return false;
+    }
+    return true;
+  };
+
+  if (!AllUsesCanBeReplaced(N0))
+    return SDValue();
+
   if (!TLI.isLoadExtLegalOrCustom(ExtLoadType, VT, Ld->getValueType(0)))
     return SDValue();
 
@@ -12630,9 +12646,8 @@
                              ISD::ZEXTLOAD, ISD::ZERO_EXTEND))
     return foldedExt;
 
-  if (SDValue foldedExt =
-      tryToFoldExtOfMaskedLoad(DAG, TLI, VT, N, N0, ISD::ZEXTLOAD,
-                               ISD::ZERO_EXTEND))
+  if (SDValue foldedExt = tryToFoldExtOfMaskedLoad(
+          DAG, TLI, VT, N, N0, ISD::ZEXTLOAD, ISD::ZERO_EXTEND))
     return foldedExt;
 
   // fold (zext (load x)) to multiple smaller zextloads.


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