[PATCH] D127095: [llvm][CodeGen] Add a default implementation to check whether two memory accesses are trivially disjoint

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


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Comment at: llvm/lib/CodeGen/MachineInstr.cpp:2414
+  for (auto MMOa : MMOpsA) {
+    for (auto MMOb : MMOpsB) {
+      if (!areMemOperandsTriviallyDisjoint(MMOa, MMOb)) {
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Instead of repeating the loop from MachineInstr::mayAlias, can we make MemOperandsHaveAlias call areMemOperandsTriviallyDisjoint?


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Comment at: llvm/lib/CodeGen/MachineInstr.cpp:1358
 
   return !AA->isNoAlias(
       MemoryLocation(ValA, OverlapA, UseTBAA ? MMOa->getAAInfo() : AAMDNodes()),
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csstormq wrote:
> efriedma wrote:
> > Do we reach this call isNoAlias() for two different intoptr constants?  Does it not handle the case you're trying to deal with?
> > 
> I migrate our backend to the latest main branch. And I tried again. I truly reach this call isNoAlias() for two different intoptr constants using gdb step by step, but it still returns false wrongly.
Maybe worth looking into modifying BasicAAResult::aliasCheck to make this work?  That would also benefit IR-level optimizations.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D127095/new/

https://reviews.llvm.org/D127095