[PATCH] D90328: Eliminates dead store of an exisiting value

[Daniel McCrevan via Phabricator via llvm-commits]

dmccrevan added a comment.

So I tried to build the `check-llvm-transforms-deadstoreelimination` target, but it seems that 4 tests are failing:

  ********************
  ********************
  Failed Tests (4):
    LLVM :: Transforms/DeadStoreElimination/MSSA/multiblock-loops.ll
    LLVM :: Transforms/DeadStoreElimination/MSSA/multiblock-memoryphis.ll
    LLVM :: Transforms/DeadStoreElimination/MSSA/multiblock-simple.ll
    LLVM :: Transforms/DeadStoreElimination/MSSA/simple.ll

I am not too sure how to interpret the test results, but I am attaching a file to this comment with the build output.

I also have my current implementation below incase you want to comment on anything you see to have issues

  /// Eliminates writes to variables where the value that is being written
  /// is already stored in the variable
  bool eliminateDeadStoresOfExisitingValues() {
    bool MadeChange = false;
    LLVM_DEBUG(dbgs() << "Trying to eliminate MemoryDefs that write the "
                         "already exisiting value\n");
    for (int I = MemDefs.size() - 1; I >= 0; I--) {
      MemoryDef *Def = MemDefs[I];
      if (SkipStores.find(Def) != SkipStores.end() ||
          !isRemovable(Def->getMemoryInst()))
        continue;
      MemoryAccess *DefAccess = dyn_cast<MemoryAccess>(Def);
      if (!DefAccess || isa<MemoryPhi>(DefAccess))
        continue;
      Instruction *DefInst = cast<MemoryUseOrDef>(DefAccess)->getMemoryInst();
      if (!DefInst)
        continue;
      for (auto UI = DefAccess->use_begin(), IE = DefAccess->use_end();
           UI != IE;) {
        MemoryAccess *UseAccess = cast<MemoryAccess>((UI++)->getUser());
        if (MemoryDef *UseDef = dyn_cast_or_null<MemoryDef>(UseAccess)) {
          Instruction *UseInst = UseDef->getMemoryInst();
          if (!UseInst)
            continue;
          if (UseInst->isIdenticalTo(DefInst)) {
            deleteDeadInstruction(UseInst);
            MadeChange = true;
          }
        }
      }
    }
    return MadeChange;
  }

F14485702: buildoutput.txt <https://reviews.llvm.org/F14485702>


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D90328/new/

https://reviews.llvm.org/D90328