[PATCH] D60715: [ISEL] Collect argument's forwarding regs when lowering calls

[Nikola Prica via Phabricator via llvm-commits]

NikolaPrica added a comment.

Thanks for the comments! I've addressed most of them. This patch will be split on 3 parts once we decide how to address comment about updating call site in `TargetInstrInfo`.



================
Comment at: lib/CodeGen/TargetInstrInfo.cpp:145
+    ++Tail;
+    MBB->erase(MI);
+  }
----------------
aprantl wrote:
> I'd prefer writing two loops (or even better two std::algorithms) for updating and erasing and let the optimizer merge them.
I've tried with std::remove_if and llvm::remove_if but they require deleted MachineInstr copy assignment operator. So I came up with two solutions:

`Solution 1`
```
// Update call site info and remove all the dead instructions
 // from the end of MBB.
 while (Tail != MBB->end()) {
   auto MI = Tail++;
   if (MI->isCall())
     MBB->getParent()->updateCallSiteInfo(&*MI);
   MBB->erase(MI);
 }
```

Or 

 `Solution 2`
```
// Update call site info.
 for (auto It = Tail; It != MBB->end(); ++It)
   if (It->isCall())
     MBB->getParent()->updateCallSiteInfo(&*It)

 // Remove all the dead instructions from the end of MBB.
 for (auto It = Tail; It != MBB->end();) {
   auto MI = It++;
   MBB->erase(MI);
 }
```

@aprantl First example seams better than existing one. I'm wondering whether second with two loops is what you aimed to?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D60715/new/

https://reviews.llvm.org/D60715