[PATCH] D107579: [Attributor]Fix PR51249: Stores from memory intrinsics incorrectly being replaced by undef

[Joseph Huber via Phabricator via llvm-commits]

jhuber6 created this revision.
jhuber6 added reviewers: jdoerfert, ye-luo, ggeorgakoudis.
Herald added subscribers: ormris, okura, kuter, uenoku, hiraditya.
Herald added a reviewer: uenoku.
Herald added a reviewer: homerdin.
jhuber6 requested review of this revision.
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This patch fixes a bug observed in OpenMP reductions that occured when the
Attributor would attempt to simplify loads. The attributor would incorrectly
think that the memory intrinsic did not write to memory, and would then replace
the associated load with `undef` which would be turned to `NaN` in the final
output. This behaviour is observed in https://godbolt.org/z/j531848dv on line

314. This patch fixes https://bugs.llvm.org/show_bug.cgi?id=48607.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D107579

Files:
  llvm/lib/Transforms/IPO/AttributorAttributes.cpp


Index: llvm/lib/Transforms/IPO/AttributorAttributes.cpp
===================================================================
--- llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -1344,8 +1344,8 @@
         handleAccess(A, *MI, Ptr, nullptr, AccessKind::AK_WRITE, 0, Changed,
                      nullptr, LengthVal);
       } else if (ArgNo == 1) {
-        handleAccess(A, *MI, Ptr, nullptr, AccessKind::AK_READ, 0, Changed,
-                     nullptr, LengthVal);
+        handleAccess(A, *MI, Ptr, nullptr, AccessKind::AK_READ_WRITE, 0,
+                     Changed, nullptr, LengthVal);
       } else {
         LLVM_DEBUG(dbgs() << "[AAPointerInfo] Unhandled memory intrinsic "
                           << *MI << "\n");


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