Revert "[LSR] Create fewer redundant instructions."

This reverts commit r263644.  Investigating bootstrap failures.

llvm-svn: 263655

1 files changed, 20 insertions, 22 deletions

diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 3b0fccc..acfdec4 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -4331,28 +4331,7 @@ BasicBlock::iterator
 LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,
                                  const SmallVectorImpl<Instruction *> &Inputs)
                                                                          const {
-  Instruction *Tentative = &*IP;
   for (;;) {
-    bool AllDominate = true;
-    Instruction *BetterPos = nullptr;
-    for (Instruction *Inst : Inputs) {
-      if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {
-        AllDominate = false;
-        break;
-      }
-      // Attempt to find an insert position in the middle of the block,
-      // instead of at the end, so that it can be used for other expansions.
-      if (Tentative->getParent() == Inst->getParent() &&
-          (!BetterPos || !DT.dominates(Inst, BetterPos)))
-        BetterPos = &*std::next(BasicBlock::iterator(Inst));
-    }
-    if (!AllDominate)
-      break;
-    if (BetterPos)
-      IP = BetterPos->getIterator();
-    else
-      IP = Tentative->getIterator();
-
     const Loop *IPLoop = LI.getLoopFor(IP->getParent());
     unsigned IPLoopDepth = IPLoop ? IPLoop->getLoopDepth() : 0;
 
@@ -4371,7 +4350,26 @@ LSRInstance::HoistInsertPosition(BasicBlock::iterator IP,
         break;
     }
 
-    Tentative = IDom->getTerminator();
+    bool AllDominate = true;
+    Instruction *BetterPos = nullptr;
+    Instruction *Tentative = IDom->getTerminator();
+    for (Instruction *Inst : Inputs) {
+      if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {
+        AllDominate = false;
+        break;
+      }
+      // Attempt to find an insert position in the middle of the block,
+      // instead of at the end, so that it can be used for other expansions.
+      if (IDom == Inst->getParent() &&
+          (!BetterPos || !DT.dominates(Inst, BetterPos)))
+        BetterPos = &*std::next(BasicBlock::iterator(Inst));
+    }
+    if (!AllDominate)
+      break;
+    if (BetterPos)
+      IP = BetterPos->getIterator();
+    else
+      IP = Tentative->getIterator();
   }
 
   return IP;