[PATCH] D80128: [IR] Revert r2694 in BasicBlock::removePredecessor

[Jay Foad via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGbdd8c111fc0d: [IR] Revert r2694 in BasicBlock::removePredecessor (authored by foad).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D80128/new/

https://reviews.llvm.org/D80128

Files:
  llvm/lib/IR/BasicBlock.cpp


Index: llvm/lib/IR/BasicBlock.cpp
===================================================================
--- llvm/lib/IR/BasicBlock.cpp
+++ llvm/lib/IR/BasicBlock.cpp
@@ -334,25 +334,9 @@
   if (!APN) return;   // Quick exit.
 
   // If there are exactly two predecessors, then we want to nuke the PHI nodes
-  // altogether.  However, we cannot do this, if this in this case:
-  //
-  //  Loop:
-  //    %x = phi [X, Loop]
-  //    %x2 = add %x, 1         ;; This would become %x2 = add %x2, 1
-  //    br Loop                 ;; %x2 does not dominate all uses
-  //
-  // This is because the PHI node input is actually taken from the predecessor
-  // basic block.  The only case this can happen is with a self loop, so we
-  // check for this case explicitly now.
-  //
+  // altogether.
   unsigned max_idx = APN->getNumIncomingValues();
   assert(max_idx != 0 && "PHI Node in block with 0 predecessors!?!?!");
-  if (max_idx == 2) {
-    BasicBlock *Other = APN->getIncomingBlock(APN->getIncomingBlock(0) == Pred);
-
-    // Disable PHI elimination!
-    if (this == Other) max_idx = 3;
-  }
 
   // <= Two predecessors BEFORE I remove one?
   if (max_idx <= 2 && !KeepOneInputPHIs) {


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