[llvm] r263565 - [LV] Preserve LoopInfo when store predication is used

[Adam Nemet via llvm-commits]

Author: anemet
Date: Tue Mar 15 13:06:20 2016
New Revision: 263565

URL: http://llvm.org/viewvc/llvm-project?rev=263565&view=rev
Log:
[LV] Preserve LoopInfo when store predication is used

This was a latent bug that got exposed by the change to add LoopSimplify
as a dependence to LoopLoadElimination.  Since LoopInfo was corrupted
after LV, LoopSimplify mis-compiled nbench in the test-suite (more
details in the PR).

The problem was that when we create the blocks for predicated stores we
didn't add those to any loops.

The original testcase for store predication provides coverage for this
assuming we verify LI on the way out of LV.

Fixes PR26952.

Modified:
    llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
    llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
    llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
    llvm/trunk/test/Transforms/LoopVectorize/if-pred-stores.ll

Modified: llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h?rev=263565&r1=263564&r2=263565&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h (original)
+++ llvm/trunk/include/llvm/Transforms/Utils/BasicBlockUtils.h Tue Mar 15 13:06:20 2016
@@ -259,11 +259,12 @@ ReturnInst *FoldReturnIntoUncondBranch(R
 /// UnreachableInst, otherwise it branches to Tail.
 /// Returns the NewBasicBlock's terminator.
 ///
-/// Updates DT if given.
+/// Updates DT and LI if given.
 TerminatorInst *SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
                                           bool Unreachable,
                                           MDNode *BranchWeights = nullptr,
-                                          DominatorTree *DT = nullptr);
+                                          DominatorTree *DT = nullptr,
+                                          LoopInfo *LI = nullptr);
 
 /// SplitBlockAndInsertIfThenElse is similar to SplitBlockAndInsertIfThen,
 /// but also creates the ElseBlock.

Modified: llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp?rev=263565&r1=263564&r2=263565&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/BasicBlockUtils.cpp Tue Mar 15 13:06:20 2016
@@ -709,11 +709,10 @@ ReturnInst *llvm::FoldReturnIntoUncondBr
 /// UnreachableInst, otherwise it branches to Tail.
 /// Returns the NewBasicBlock's terminator.
 
-TerminatorInst *llvm::SplitBlockAndInsertIfThen(Value *Cond,
-                                                Instruction *SplitBefore,
-                                                bool Unreachable,
-                                                MDNode *BranchWeights,
-                                                DominatorTree *DT) {
+TerminatorInst *
+llvm::SplitBlockAndInsertIfThen(Value *Cond, Instruction *SplitBefore,
+                                bool Unreachable, MDNode *BranchWeights,
+                                DominatorTree *DT, LoopInfo *LI) {
   BasicBlock *Head = SplitBefore->getParent();
   BasicBlock *Tail = Head->splitBasicBlock(SplitBefore->getIterator());
   TerminatorInst *HeadOldTerm = Head->getTerminator();
@@ -743,6 +742,12 @@ TerminatorInst *llvm::SplitBlockAndInser
     }
   }
 
+  if (LI) {
+    Loop *L = LI->getLoopFor(Head);
+    L->addBasicBlockToLoop(ThenBlock, *LI);
+    L->addBasicBlockToLoop(Tail, *LI);
+  }
+
   return CheckTerm;
 }
 

Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp?rev=263565&r1=263564&r2=263565&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorize.cpp Tue Mar 15 13:06:20 2016
@@ -3628,7 +3628,7 @@ void InnerLoopVectorizer::vectorizeLoop(
     BasicBlock::iterator I(KV.first);
     auto *BB = SplitBlock(I->getParent(), &*std::next(I), DT, LI);
     auto *T = SplitBlockAndInsertIfThen(KV.second, &*I, /*Unreachable=*/false,
-                                        /*BranchWeights=*/nullptr, DT);
+                                        /*BranchWeights=*/nullptr, DT, LI);
     I->moveBefore(T);
     I->getParent()->setName("pred.store.if");
     BB->setName("pred.store.continue");

Modified: llvm/trunk/test/Transforms/LoopVectorize/if-pred-stores.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/if-pred-stores.ll?rev=263565&r1=263564&r2=263565&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/if-pred-stores.ll (original)
+++ llvm/trunk/test/Transforms/LoopVectorize/if-pred-stores.ll Tue Mar 15 13:06:20 2016
@@ -1,7 +1,7 @@
-; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=1 -force-vector-interleave=2 -loop-vectorize -simplifycfg < %s | FileCheck %s --check-prefix=UNROLL
-; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=1 -force-vector-interleave=2 -loop-vectorize < %s | FileCheck %s --check-prefix=UNROLL-NOSIMPLIFY
-; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -enable-cond-stores-vec -simplifycfg < %s | FileCheck %s --check-prefix=VEC
-; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -enable-cond-stores-vec -simplifycfg -instcombine < %s | FileCheck %s --check-prefix=VEC-IC
+; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=1 -force-vector-interleave=2 -loop-vectorize -verify-loop-info -simplifycfg < %s | FileCheck %s --check-prefix=UNROLL
+; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=1 -force-vector-interleave=2 -loop-vectorize -verify-loop-info < %s | FileCheck %s --check-prefix=UNROLL-NOSIMPLIFY
+; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -enable-cond-stores-vec -verify-loop-info -simplifycfg < %s | FileCheck %s --check-prefix=VEC
+; RUN: opt -S -vectorize-num-stores-pred=1 -force-vector-width=2 -force-vector-interleave=1 -loop-vectorize -enable-cond-stores-vec -verify-loop-info -simplifycfg -instcombine < %s | FileCheck %s --check-prefix=VEC-IC
 
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.9.0"