[PATCH] D37579: [InstCombine] Fix PR21780 Expansion of 256 bit vector loads fails to fold into shuffles

[Dinar Temirbulatov via Phabricator via llvm-commits]

dtemirbulatov created this revision.

This is a first part of PR21780 fix.

This change allows to keep information about removed Load instruction by InstCombine pass in order to restore those later. Here I am using Intrinsics to keep information in the IR as it was discussed in  http://lists.llvm.org/pipermail/llvm-dev/2017-July/115730.html. Before that, I used metadata for that purpose https://reviews.llvm.org/D35139.

I introduced phantom_mem intrinsic that consist of two parameters the first is pointer and the second is maximum offset for that pointer. In the Instcombine pass, while constructing such intrisics, I try to avoid case if GEP's origin is in a different basic block and GEP itself is in a loop, but it is ok if both GEP and the pointer origin are in the loop and both belong to the same basic block.


https://reviews.llvm.org/D37579

Files:
  include/llvm/IR/Intrinsics.td
  lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
  lib/Transforms/InstCombine/InstCombineInternal.h
  lib/Transforms/InstCombine/InstructionCombining.cpp
  test/Transforms/InstCombine/phantommem.ll

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