[llvm-branch-commits] [llvm] [3/3][RegAlloc][LiveRegMatrix] Added validity check between VRM and LRM. (PR #197778)

[Valery Pykhtin via llvm-branch-commits]

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@@ -324,7 +324,51 @@ bool LiveRegMatrix::isValid() const {
       }
     }
   }
-  return NumDanglingPointers == 0;
+
+  // Reverse check: every VRM-assigned vreg with a non-empty live interval
+  // must have its segments present in the Matrix for its assigned phys reg.
+  unsigned NumMissing = 0;
+  for (unsigned RegIdx = 0, NumRegs = VRM->getRegInfo().getNumVirtRegs();
+       RegIdx < NumRegs; ++RegIdx) {
+    Register VReg = Register::index2VirtReg(RegIdx);
+    if (!VRM->hasPhys(VReg) || !LIS->hasInterval(VReg))
+      continue;
+    const LiveInterval &LI = LIS->getInterval(VReg);
+    if (LI.empty())
+      continue;
+    MCRegister PhysReg = VRM->getPhys(VReg);
+    // Check that the first segment of LI is present in the LiveUnion for
+    // at least one reg unit of PhysReg.
+    SlotIndex FirstStart = LI.beginIndex();
+    bool Found = false;
+    for (MCRegUnit Unit : TRI->regunits(PhysReg)) {
+      auto It = Matrix[Unit].find(FirstStart);
+      if (It.valid() && It.start() == FirstStart && It.value() == &LI) {
+        Found = true;
+        break;
+      }
+    }
+    if (!Found) {
+      ++NumMissing;
+      dbgs() << "ERROR: VirtReg " << printReg(VReg, TRI) << " assigned to "
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vpykhtin wrote:

right, this method was assumed to be called like `assert(isValid());`

https://github.com/llvm/llvm-project/pull/197778