From 9259de217e608ae965d12531e06e10805072a212 Mon Sep 17 00:00:00 2001
From: Nirav Dave <niravd@google.com>
Date: Fri, 29 Mar 2019 14:09:47 +0000
Subject: [PATCH] [DAGCombine] Improve Lifetime node chains.

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

llvm-svn: 357256
---
 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 30 +++++++++++++++++++++++++++
 llvm/test/CodeGen/X86/swap.ll                 |  3 ---
 llvm/test/DebugInfo/COFF/lexicalblock.ll      | 13 ------------
 3 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 5dccaf5..5c4f98e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -384,6 +384,10 @@ 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);
@@ -1604,6 +1608,7 @@ 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);
@@ -15654,7 +15659,32 @@ 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) {
+    SDNode *N2 = DAG.UpdateNodeOperands(N, NewChain, N->getOperand(1));
+    // Make sure users of new N still depend on Chain
+    auto TF = DAG.getNode(ISD::TokenFactor, SDLoc(N2), MVT::Other, Chain,
+                          SDValue(N2, 0));
+    DAG.ReplaceAllUsesOfValueWith(SDValue(N2, 0), TF);
+    AddToWorklist(DAG.UpdateNodeOperands(TF.getNode(), Chain, SDValue(N2, 0)));
+    AddToWorklist(N2);
+    return SDValue(N, 0);
+  }
+  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 7a8edbb..08166d8 100644
--- a/llvm/test/CodeGen/X86/swap.ll
+++ b/llvm/test/CodeGen/X86/swap.ll
@@ -94,7 +94,6 @@ 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:
@@ -125,7 +124,6 @@ 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:
@@ -155,7 +153,6 @@ 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 970aae2..646f13b 100644
--- a/llvm/test/DebugInfo/COFF/lexicalblock.ll
+++ b/llvm/test/DebugInfo/COFF/lexicalblock.ll
@@ -80,19 +80,6 @@
 ; 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