[PATCH] D65047: [DAGCombine] matchBinOpReduction - add partial reduction matching

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: include/llvm/CodeGen/SelectionDAG.h:1586-1593
   /// Match a binop + shuffle pyramid that represents a horizontal reduction
   /// over the elements of a vector starting from the EXTRACT_VECTOR_ELT node /p
   /// Extract. The reduction must use one of the opcodes listed in /p
   /// CandidateBinOps and on success /p BinOp will contain the matching opcode.
   /// Returns the vector that is being reduced on, or SDValue() if a reduction
-  /// was not matched.
+  /// was not matched. If /p AllowPartials is set then in the case of a
+  /// reduction pattern that only matches the first few stages, the extracted
----------------
Aren't slashes wrong here, should it be `\p` ?


================
Comment at: lib/CodeGen/SelectionDAG/SelectionDAG.cpp:9055-9056
+  SDValue PrevOp;
   for (unsigned i = 0; i < Stages; ++i) {
+    unsigned MaskEnd = (1 << i);
+
----------------
This might warrant a comment/assertion that we do know that i is always less than 31.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65047/new/

https://reviews.llvm.org/D65047