[PATCH] D132657: [DSE] Eliminate noop store even through has clobbering between LoadI and StoreI

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp:1872
+              if (auto *CurrentStoreI =
+                      dyn_cast<StoreInst>(CurrentDef->getMemoryInst()))
+                // Check alignment to ensure load or store does not access at an
----------------
This should use dyn_cast_or_null to account for liveOnEntry defs. Please add a test case like this, that currently crashes:
```
define void @test(i1 %c, ptr %p, ptr noalias %q) {
entry:
  br i1 %c, label %if, label %join

if:
  store i8 0, ptr %q, align 1
  br label %join

join:
  %v = load i8, ptr %q, align 1
  store i8 0, ptr %p, align 1
  store i8 %v, ptr %q, align 1
  ret void
}
```


================
Comment at: llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp:1875
+                // offset.
+                if (CurrentStoreI->getOperand(0) == LoadI &&
+                    std::min(CurrentStoreI->getAlign(), LoadI->getAlign()) >=
----------------
nit: Prefer `getValueOperand()`.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D132657/new/

https://reviews.llvm.org/D132657