From 94b867dc7c202162f587fd3345eccdb09bff2a77 Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Wed, 3 Apr 2019 07:41:58 +0000
Subject: [PATCH] Revert r357256 "[DAGCombine] Improve Lifetime node chains."

As it caused a pathological compile-time regressionin V8, see PR41352.

> Improve both start and end lifetime nodes chain dependencies.
>
> Reviewers: courbet
>
> Reviewed By: courbet
>
> Subscribers: hiraditya, llvm-commits
>
> Tags: #llvm
>
> Differential Revision: https://reviews.llvm.org/D59795

This also reverts the follow-up r357309:

> [DAGCombiner] Rewrite ImproveLifetimeNodeChain to avoid DAG loop.
>
> Avoid EXPENSIVE_CHECK failure. NFCI.

llvm-svn: 357563
---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 31 ---------------------------
 llvm/test/CodeGen/X86/swap.ll                 |  3 +++
 llvm/test/DebugInfo/COFF/lexicalblock.ll      | 13 +++++++++++
 3 files changed, 16 insertions(+), 31 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 15044d1..e58e835 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -427,10 +427,6 @@ namespace {
     SDValue replaceStoreOfFPConstant(StoreSDNode *ST);
 
     SDValue visitSTORE(SDNode *N);
-
-    SDValue ImproveLifetimeNodeChain(SDNode *N);
-
-    SDValue visitLIFETIME_START(SDNode *N);
     SDValue visitLIFETIME_END(SDNode *N);
     SDValue visitINSERT_VECTOR_ELT(SDNode *N);
     SDValue visitEXTRACT_VECTOR_ELT(SDNode *N);
@@ -1654,7 +1650,6 @@ SDValue DAGCombiner::visit(SDNode *N) {
   case ISD::MLOAD:              return visitMLOAD(N);
   case ISD::MSCATTER:           return visitMSCATTER(N);
   case ISD::MSTORE:             return visitMSTORE(N);
-  case ISD::LIFETIME_START:     return visitLIFETIME_START(N);
   case ISD::LIFETIME_END:       return visitLIFETIME_END(N);
   case ISD::FP_TO_FP16:         return visitFP_TO_FP16(N);
   case ISD::FP16_TO_FP:         return visitFP16_TO_FP(N);
@@ -15705,33 +15700,7 @@ SDValue DAGCombiner::visitSTORE(SDNode *N) {
   return ReduceLoadOpStoreWidth(N);
 }
 
-SDValue DAGCombiner::ImproveLifetimeNodeChain(SDNode *N) {
-  auto Chain = N->getOperand(0);
-  auto NewChain = FindBetterChain(N, Chain);
-  if (NewChain != Chain) {
-    LifetimeSDNode *LN = cast<LifetimeSDNode>(N);
-    // Create New Node to prevent loop in CombineTo.
-    SDValue NewN = DAG.getLifetimeNode(N->getOpcode() == ISD::LIFETIME_START,
-                                       SDLoc(N), NewChain, LN->getFrameIndex(),
-                                       LN->hasOffset() ? LN->getSize() : -1,
-                                       LN->hasOffset() ? LN->getOffset() : -1);
-    AddToWorklist(NewN.getNode());
-    auto TF = DAG.getNode(ISD::TokenFactor, SDLoc(N), MVT::Other, Chain, NewN);
-    return CombineTo(N, TF);
-  }
-  return SDValue();
-}
-
-SDValue DAGCombiner::visitLIFETIME_START(SDNode *N) {
-  if (SDValue V = ImproveLifetimeNodeChain(N))
-    return V;
-  return SDValue();
-}
-
 SDValue DAGCombiner::visitLIFETIME_END(SDNode *N) {
-  if (SDValue V = ImproveLifetimeNodeChain(N))
-    return V;
-
   const auto *LifetimeEnd = cast<LifetimeSDNode>(N);
   if (!LifetimeEnd->hasOffset())
     return SDValue();
diff --git a/llvm/test/CodeGen/X86/swap.ll b/llvm/test/CodeGen/X86/swap.ll
index 08166d8..7a8edbb 100644
--- a/llvm/test/CodeGen/X86/swap.ll
+++ b/llvm/test/CodeGen/X86/swap.ll
@@ -94,6 +94,7 @@ define dso_local void @twoallocs(i8* nocapture %a, i8* nocapture %b) local_unnam
 ; AA-LABEL: twoallocs:
 ; AA:       # %bb.0: # %entry
 ; AA-NEXT:    vmovups (%rdi), %xmm0
+; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups %xmm0, (%rsi)
 ; AA-NEXT:    retq
 entry:
@@ -124,6 +125,7 @@ define dso_local void @onealloc_readback_1(i8* nocapture %a, i8* nocapture %b) l
 ; AA-LABEL: onealloc_readback_1:
 ; AA:       # %bb.0: # %entry
 ; AA-NEXT:    vmovups (%rsi), %xmm0
+; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups %xmm0, (%rdi)
 ; AA-NEXT:    retq
 entry:
@@ -153,6 +155,7 @@ define dso_local void @onealloc_readback_2(i8* nocapture %a, i8* nocapture %b) l
 ; AA-LABEL: onealloc_readback_2:
 ; AA:       # %bb.0: # %entry
 ; AA-NEXT:    vmovups (%rsi), %xmm0
+; AA-NEXT:    vmovaps %xmm0, -{{[0-9]+}}(%rsp)
 ; AA-NEXT:    vmovups %xmm0, (%rdi)
 ; AA-NEXT:    retq
 entry:
diff --git a/llvm/test/DebugInfo/COFF/lexicalblock.ll b/llvm/test/DebugInfo/COFF/lexicalblock.ll
index 646f13b..970aae2 100644
--- a/llvm/test/DebugInfo/COFF/lexicalblock.ll
+++ b/llvm/test/DebugInfo/COFF/lexicalblock.ll
@@ -80,6 +80,19 @@
 ; CHECK: ScopeEndSym {
 ; CHECK:   Kind: S_END {{.*}}
 ; CHECK: }
+; CHECK: BlockSym {
+; CHECK:   Kind: S_BLOCK32 {{.*}}
+; CHECK:   BlockName: 
+; CHECK: }
+; CHECK: ScopeEndSym {
+; CHECK: }
+; CHECK: BlockSym {
+; CHECK:   Kind: S_BLOCK32 {{.*}}
+; CHECK:   BlockName: 
+; CHECK: }
+; CHECK: ScopeEndSym {
+; CHECK:   Kind: S_END {{.*}}
+; CHECK: }
 ; CHECK: ProcEnd {
 ; CHECK: }
 ;
-- 
2.7.4