[PATCH] D75982: [DAGCombine] Respect the uses when combine FMA for a*b+/-c*d

[qshanz via Phabricator via llvm-commits]

steven.zhang marked an inline comment as done.
steven.zhang added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:11900-11919
   // fold (fsub (fmul x, y), z) -> (fma x, y, (fneg z))
-  if (isContractableFMUL(N0) && (Aggressive || N0->hasOneUse())) {
-    return DAG.getNode(PreferredFusedOpcode, SL, VT,
-                       N0.getOperand(0), N0.getOperand(1),
-                       DAG.getNode(ISD::FNEG, SL, VT, N1), Flags);
-  }
+  auto tryToFoldXYSubZ = [&](SDValue XY, SDValue Z) {
+    if (isContractableFMUL(XY) && (Aggressive || XY->hasOneUse())) {
+      return DAG.getNode(PreferredFusedOpcode, SL, VT, XY.getOperand(0),
+                         XY.getOperand(1), DAG.getNode(ISD::FNEG, SL, VT, Z),
+                         Flags);
+    }
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lebedev.ri wrote:
> I suggest to land this NFC refactoring first, to make the diff more understandable.
ok，I assume that you LGTM with the refactor. So, I won't post another revision review for this NFC.(adding two lambda to do the folding). With that NFC patch landing, I will update this patch. If there is any concern, let me know. Thank you!


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https://reviews.llvm.org/D75982