[llvm] Revert "[RegAlloc] Strengthen asserts in LiveRangeEdit::scanRemattable [nfc]" (PR #160897)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-regalloc

Author: Philip Reames (preames)

<details>
<summary>Changes</summary>

Reverts llvm/llvm-project#<!-- -->160765.  Failures on buildbot indicate second assertion does not in fact hold.

---
Full diff: https://github.com/llvm/llvm-project/pull/160897.diff


1 Files Affected:

- (modified) llvm/lib/CodeGen/LiveRangeEdit.cpp (+3-3) 


``````````diff
diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index 4aeacc332476d..59bc82dc267b5 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -75,11 +75,11 @@ void LiveRangeEdit::scanRemattable() {
     Register Original = VRM->getOriginal(getReg());
     LiveInterval &OrigLI = LIS.getInterval(Original);
     VNInfo *OrigVNI = OrigLI.getVNInfoAt(VNI->def);
-    assert(OrigVNI && "Corrupt interval mapping?");
-    if (OrigVNI->isPHIDef())
+    if (!OrigVNI)
       continue;
     MachineInstr *DefMI = LIS.getInstructionFromIndex(OrigVNI->def);
-    assert(DefMI && "Missing instruction for def slot");
+    if (!DefMI)
+      continue;
     if (TII.isReMaterializable(*DefMI))
       Remattable.insert(OrigVNI);
   }

``````````

</details>


https://github.com/llvm/llvm-project/pull/160897