[PATCH] D100109: [RegisterScavenging] Add asserts for better errors

[Sebastian Neubauer via Phabricator via llvm-commits]

sebastian-ne created this revision.
sebastian-ne added reviewers: arsenm, craigblackmore.
Herald added a subscriber: hiraditya.
sebastian-ne requested review of this revision.
Herald added subscribers: llvm-commits, wdng.
Herald added a project: LLVM.

These cases were failing before, but with cryptic asserts.
Add asserts in the RegScavenger that fail earlier with better
messages. NFC


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D100109

Files:
  llvm/lib/CodeGen/RegisterScavenging.cpp


Index: llvm/lib/CodeGen/RegisterScavenging.cpp
===================================================================
--- llvm/lib/CodeGen/RegisterScavenging.cpp
+++ llvm/lib/CodeGen/RegisterScavenging.cpp
@@ -369,6 +369,10 @@
   const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
   LiveRegUnits Used(TRI);
 
+  assert(From->getParent() == To->getParent() &&
+         "Target instruction is in other than current basic block, use "
+         "enterBasicBlockEnd first");
+
   for (MachineBasicBlock::iterator I = From;; --I) {
     const MachineInstr &MI = *I;
 
@@ -423,6 +427,8 @@
       if (I == MBB.begin())
         break;
     }
+    assert(I != MBB.begin() && "Did not find target instruction while "
+                               "iterating backwards");
   }
 
   return std::make_pair(Survivor, Pos);


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