Revert "[Dominator] Add findNearestCommonDominator() for Instructions (NFC)"

This reverts commit 7f0de9573f758f5f9108795850337a5acbd17eef.

This is missing handling for !isReachableFromEntry() blocks, which
may be relevant for some callers. Revert for now.

1 files changed, 18 insertions, 3 deletions

diff --git a/llvm/lib/Analysis/CaptureTracking.cpp b/llvm/lib/Analysis/CaptureTracking.cpp
index 7f3a2b4..f4fd660 100644
--- a/llvm/lib/Analysis/CaptureTracking.cpp
+++ b/llvm/lib/Analysis/CaptureTracking.cpp
@@ -179,10 +179,25 @@ namespace {
       if (EphValues.contains(I))
         return false;
 
-      if (!EarliestCapture)
+      if (!EarliestCapture) {
         EarliestCapture = I;
-      else
-        EarliestCapture = DT.findNearestCommonDominator(EarliestCapture, I);
+      } else if (EarliestCapture->getParent() == I->getParent()) {
+        if (I->comesBefore(EarliestCapture))
+          EarliestCapture = I;
+      } else {
+        BasicBlock *CurrentBB = I->getParent();
+        BasicBlock *EarliestBB = EarliestCapture->getParent();
+        if (DT.dominates(EarliestBB, CurrentBB)) {
+          // EarliestCapture already comes before the current use.
+        } else if (DT.dominates(CurrentBB, EarliestBB)) {
+          EarliestCapture = I;
+        } else {
+          // Otherwise find the nearest common dominator and use its terminator.
+          auto *NearestCommonDom =
+              DT.findNearestCommonDominator(CurrentBB, EarliestBB);
+          EarliestCapture = NearestCommonDom->getTerminator();
+        }
+      }
       Captured = true;
 
       // Return false to continue analysis; we need to see all potential