[PATCH] D63444: [ThinLTO] Optimize write-only globals out

[Eugene Leviant via Phabricator via llvm-commits]

evgeny777 marked an inline comment as done.
evgeny777 added a comment.

> Is the global storage (from the other module) also eliminated in this case? If so, can you add a testcase for that?

Yes, optimized variable is internalized in both source and destination module. I'll add test case for that



================
Comment at: include/llvm/IR/ModuleSummaryIndex.h:165
 struct ValueInfo {
-  PointerIntPair<const GlobalValueSummaryMapTy::value_type *, 2, int>
+  enum Flags { HaveGV = 1, ReadOnly = 2, WriteOnly = 4 };
+  PointerIntPair<const GlobalValueSummaryMapTy::value_type *, 3, int>
----------------
steven_wu wrote:
> Would it be cleaner if you create a new enum bitfield for access specifier?
> ```
> enum Access { ReadWrite = 0, ReadOnly = 1, WriteOnly =2, Invalid =3 };
> ```
> This should make all the method below a bit cleaner. 
I'm not sure if this would make it cleaner. There is also a HaveGV flag in `PointerIntPair`, so to manipulate access bits as suggested you'll have to do something like this:
```
bool isValidAccessSpecifier() const {
    return (RefAndFlags.getInt() &  (Invalid << 1)) !=  (Invalid << 1);
}
void setWriteOnly() {
    assert(isValidAccessSpecifier());
    RefAndFlags.setInt(RefAndFlags.getInt() | (WriteOnly << 1));
 }
```
so technically almost the same as before


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https://reviews.llvm.org/D63444