[PATCH] D106875: [DebugInfo] Attempt to preserve more information during tail duplication

[Stephen Tozer via Phabricator via llvm-commits]

StephenTozer added inline comments.


================
Comment at: llvm/lib/CodeGen/TailDuplicator.cpp:233-242
+      UI = MRI->use_begin(VReg);
+      while (UI != MRI->use_end()) {
+        MachineOperand &UseMO = *UI;
+        MachineInstr *UseMI = UseMO.getParent();
+        ++UI;
+        if (!UseMI->isDebugValue())
+          continue;
----------------
jmorse wrote:
> Performance opinion: better to store debug uses and re-visit rather than enumerate all the uses again, it'll preserve the same performance characteristics as before this patch.
> 
> Also: will not UseMO.setReg invalidate the vreg use list?
The vreg use list is (as far as I'm aware) a linked list, so calling `setReg` after iterating to the next use will not cause any issues.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106875/new/

https://reviews.llvm.org/D106875