[llvm] [RISCV] Fold vp.reverse of vp.load through binary ops (PR #205529)

[Luke Lau via llvm-commits]

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@@ -19649,61 +19649,85 @@ static SDValue performReverseEVLCombine(SDNode *N, SelectionDAG &DAG,
   //
   // splice.right(reverse(vp.load(ADDR, REVMASK, EVL)), poison, EVL)
   // -> vp.strided.load(ADDR, -1, MASK, EVL)
-
-  // Check if its first operand is a vp.load.
+  //
+  // vp.reverse(binop(vp.load(ADDR, REVMASK, EVL), splat), EVL)
+  // -> binop(vp.strided.load(ADDR, -1, MASK, EVL), splat)
   using namespace SDPatternMatch;
   SDValue Op, EVL;
-  if (!sd_match(N,
-                m_ReverseEVL(m_OneUse(m_Value(Op, m_SpecificOpc(ISD::VP_LOAD))),
-                             m_Value(EVL))))
+  if (!sd_match(N, m_ReverseEVL(m_Value(Op), m_Value(EVL))))
     return SDValue();
 
-  auto *VPLoad = cast<VPLoadSDNode>(Op);
-
-  EVT LoadVT = VPLoad->getValueType(0);
-  // We do not have a strided_load version for masks, and the evl of vp.reverse
-  // and vp.load should always be the same.
-  if (!LoadVT.getVectorElementType().isByteSized() ||
-      EVL != VPLoad->getVectorLength())
-    return SDValue();
-
-  SDValue LoadMask = VPLoad->getMask();
-  // If Mask is all ones, then load is unmasked and can be reversed.
-  if (!isOneOrOneSplat(LoadMask)) {
-    // If the mask is not all ones, we can reverse the load if the mask was also
-    // reversed by a vp.reverse with the same EVL.
-    SDValue OrigMask;
-    if (!sd_match(LoadMask, m_ReverseEVL(m_Value(OrigMask), m_Specific(EVL))))
+  // Check that all leaves are splats or vp_loads, and collect the latter.
+  SmallVector<SDValue> Worklist = {Op};
+  SmallVector<VPLoadSDNode *> VPLoads;
+  while (!Worklist.empty()) {
+    SDValue X = Worklist.pop_back_val();
+    if (!X->hasOneUse())
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lukel97 wrote:

No, should be fixed in 6ad90b26797491814cf5b246eecc33bf6f800fc4

https://github.com/llvm/llvm-project/pull/205529