[llvm] r263655 - Revert "[LSR] Create fewer redundant instructions."

[Geoff Berry via llvm-commits]

Author: gberry
Date: Wed Mar 16 14:21:47 2016
New Revision: 263655

URL: http://llvm.org/viewvc/llvm-project?rev=263655&view=rev
Log:
Revert "[LSR] Create fewer redundant instructions."

This reverts commit r263644.  Investigating bootstrap failures.

Removed:
    llvm/trunk/test/Transforms/LoopStrengthReduce/AArch64/lsr-reuse.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=263655&r1=263654&r2=263655&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Wed Mar 16 14:21:47 2016
@@ -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(BasicBl
         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;

Removed: llvm/trunk/test/Transforms/LoopStrengthReduce/AArch64/lsr-reuse.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/AArch64/lsr-reuse.ll?rev=263654&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/AArch64/lsr-reuse.ll (original)
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/AArch64/lsr-reuse.ll (removed)
@@ -1,34 +0,0 @@
-; RUN: llc -mtriple=arm64-unknown-unknown -print-lsr-output < %s 2>&1 | FileCheck %s
-
-declare void @foo(i64)
-
-; Verify that redundant adds aren't inserted by LSR.
-; CHECK-LABEL: @bar(
-define void @bar(double* %A) {
-entry:
-  br label %while.cond
-
-while.cond:
-; CHECK-LABEL: while.cond:
-; CHECK: add i64 %lsr.iv, 1
-; CHECK-NOT: add i64 %lsr.iv, 1
-; CHECK-LABEL: land.rhs:
-  %indvars.iv28 = phi i64 [ %indvars.iv.next29, %land.rhs ], [ 50, %entry ]
-  %cmp = icmp sgt i64 %indvars.iv28, 0
-  br i1 %cmp, label %land.rhs, label %while.end
-
-land.rhs:
-  %indvars.iv.next29 = add nsw i64 %indvars.iv28, -1
-  %arrayidx = getelementptr inbounds double, double* %A, i64 %indvars.iv.next29
-  %Aload = load double, double* %arrayidx, align 8
-  %cmp1 = fcmp oeq double %Aload, 0.000000e+00
-  br i1 %cmp1, label %while.cond, label %if.end
-
-while.end:
-  %indvars.iv28.lcssa = phi i64 [ %indvars.iv28, %while.cond ]
-  tail call void @foo(i64 %indvars.iv28.lcssa)
-  br label %if.end
-
-if.end:
-  ret void
-}