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

[Philip Reames via Phabricator via llvm-commits]

reames accepted this revision.
reames added a comment.
This revision is now accepted and ready to land.

LGTM w/minor comments.



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Comment at: llvm/lib/Transforms/Scalar/GVN.cpp:1467
+  // We plan to hoist the load to preheader without introducing a new fault.
+  // In irder to do it, we need to prove that we cannot side-exit the loop
+  // once loop header is first entered before execution of the load.
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Type: In order


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Comment at: llvm/lib/Transforms/Scalar/GVN.cpp:1511
+  Value *LoadPtr = Load->getPointerOperand();
+  if (LoadPtr->canBeFreed())
+    return false;
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In a follow up, please generalize by using stripping bitcasts and inbounds geps before calling canBeFreed.  Please don't do this in the change being lgtmed now.  


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Comment at: llvm/test/Transforms/GVN/PRE/pre-loop-load.ll:10
 
-; TODO: We can PRE the load from gc-managed memory away from the hot path.
 define i32 @test_load_on_cold_path_gc(i32 addrspace(1)* %p) gc "statepoint-example" personality i32 ()* @"personality_function" {
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Please add a positive test (analogous to this one), but using an alloca.  


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

https://reviews.llvm.org/D99926