[PATCH] D72663: [GlobalISel] Change representation of shuffle masks in MachineOperand.

Mon Jan 13 16:32:09 PST 2020

efriedma marked an inline comment as done.
efriedma added inline comments.

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Comment at: llvm/include/llvm/CodeGen/MachineOperand.h:178
     unsigned Pred;           // For MO_Predicate
-    const Constant *ShuffleMask; // For MO_ShuffleMask
+    ArrayRef<int> ShuffleMask; // For MO_ShuffleMask

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arsenm wrote:
> arsenm wrote:
> > Won't this double the size of every MachineOperand? That's an extremely high cost
> I think it's important to avoid increasing the size of MachineOperand at any cost. Whatever goes here should fit in a single pointer to avoid the increase
This patch doesn't make MachineOperand larger. ContentsUnion is at least two pointers wide anyway, for MO_Register etc.  (There's a static_assert in the MachineOperand constructor that checks the size of both ContentsUnion and MachineOperand.)

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D72663/new/

https://reviews.llvm.org/D72663