[PATCH] D124050: llvm-reduce: Fix not removing first instruction in MachineBasicBlock

[Matt Arsenault via Phabricator via llvm-commits]

arsenm added inline comments.


================
Comment at: llvm/tools/llvm-reduce/deltas/ReduceInstructionsMIR.cpp:111
+        unsigned ImpDef = IsGeneric ? TargetOpcode::G_IMPLICIT_DEF
+                                    : TargetOpcode::IMPLICIT_DEF;
+        BuildMI(*EntryMBB, EntryInsPt, DebugLoc(), TII->get(ImpDef))
----------------
markus wrote:
> When I originally decided to just slap a implicit-def to the first MI in the entry block instead of building a new instruction I thought it would be unsafe for the delta debugging algorithm to add instructions here. I did not dig deep into that though so maybe it is of no concern.
It’s not unsafe, but gives suboptimal results. D124049 tries to address this problem 


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D124050/new/

https://reviews.llvm.org/D124050