[llvm] bba9172 - [RegAlloc] Strengthen asserts in LiveRangeEdit::scanRemattable [nfc] (#160765)

[via llvm-commits]

Author: Philip Reames
Date: 2025-09-26T06:55:07-07:00
New Revision: bba91727789bed302758dac282107a44c7b33504

URL: https://github.com/llvm/llvm-project/commit/bba91727789bed302758dac282107a44c7b33504
DIFF: https://github.com/llvm/llvm-project/commit/bba91727789bed302758dac282107a44c7b33504.diff

LOG: [RegAlloc] Strengthen asserts in LiveRangeEdit::scanRemattable [nfc] (#160765)

We should always be able to find the VNInfo in the original live
interval which corresponds to the subset we're trying to spill, and the
only cases where we have a VNInfo without a definition instruction are
if the vni is unused, or corresponds to a phi. Adjust the code structure
to explicitly check for PHIDef, and assert the stronger conditions.

Added: 
    

Modified: 
    llvm/lib/CodeGen/LiveRangeEdit.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index 59bc82dc267b5..4aeacc332476d 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);
-    if (!OrigVNI)
+    assert(OrigVNI && "Corrupt interval mapping?");
+    if (OrigVNI->isPHIDef())
       continue;
     MachineInstr *DefMI = LIS.getInstructionFromIndex(OrigVNI->def);
-    if (!DefMI)
-      continue;
+    assert(DefMI && "Missing instruction for def slot");
     if (TII.isReMaterializable(*DefMI))
       Remattable.insert(OrigVNI);
   }