[PATCH] D99926: [GVN] Introduce loop load PRE

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/lib/Transforms/Scalar/GVN.cpp:1517
+  AvailableLoads[LoopBlock] = LoadPtr;
+  AvailableLoads[Preheader] = LoadPtr;
+
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Where do we check that LoadPtr is loop invariant (and thus available in preheader)?


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Comment at: llvm/test/Transforms/GVN/PRE/pre-loop-load.ll:164
 ; CHECK:       loop:
 ; CHECK-NEXT:    br i1 undef, label [[HOT_PATH:%.*]], label [[COLD_PATH:%.*]]
 ; CHECK:       hot_path:
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This test looks broken. I think for it to do something useful you'll want to pass %p to may_free_memory (or another function). Otherwise the load is just undef and there is no clobber in the loop either.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D99926/new/

https://reviews.llvm.org/D99926