From bf31cb7a60d340bc12e4cf5a60ea4c9e3e8646f1 Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Wed, 10 May 2017 00:56:00 +0000
Subject: [PATCH] [CodeGen] Don't require AA in TwoAddress at -O0.

This is a follow-up to r302611, which moved an -O0 computation of DT
from SDAGISel to TwoAddress.

Don't use it here either, and avoid computing it completely.  The only
use was forwarding the analysis as an optional argument to utility
functions.

Differential Revision: https://reviews.llvm.org/D32766

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@302612 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/TwoAddressInstructionPass.cpp | 7 +++++--
 test/CodeGen/X86/O0-pipeline.ll           | 3 ---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/CodeGen/TwoAddressInstructionPass.cpp b/lib/CodeGen/TwoAddressInstructionPass.cpp
index 75359fe3c0e..7392c832714 100644
--- a/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/lib/CodeGen/TwoAddressInstructionPass.cpp
@@ -155,7 +155,7 @@ public:
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesCFG();
-    AU.addRequired<AAResultsWrapperPass>();
+    AU.addUsedIfAvailable<AAResultsWrapperPass>();
     AU.addUsedIfAvailable<LiveVariables>();
     AU.addPreserved<LiveVariables>();
     AU.addPreserved<SlotIndexes>();
@@ -1627,7 +1627,10 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &Func) {
   InstrItins = MF->getSubtarget().getInstrItineraryData();
   LV = getAnalysisIfAvailable<LiveVariables>();
   LIS = getAnalysisIfAvailable<LiveIntervals>();
-  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
+  if (auto *AAPass = getAnalysisIfAvailable<AAResultsWrapperPass>())
+    AA = &AAPass->getAAResults();
+  else
+    AA = nullptr;
   OptLevel = TM.getOptLevel();
 
   bool MadeChange = false;
diff --git a/test/CodeGen/X86/O0-pipeline.ll b/test/CodeGen/X86/O0-pipeline.ll
index 0002dbe5c94..12e13f2a4ff 100644
--- a/test/CodeGen/X86/O0-pipeline.ll
+++ b/test/CodeGen/X86/O0-pipeline.ll
@@ -36,9 +36,6 @@
 ; CHECK-NEXT:       Local Stack Slot Allocation
 ; CHECK-NEXT:       X86 WinAlloca Expander
 ; CHECK-NEXT:       Eliminate PHI nodes for register allocation
-; CHECK-NEXT:       Dominator Tree Construction
-; CHECK-NEXT:       Basic Alias Analysis (stateless AA impl)
-; CHECK-NEXT:       Function Alias Analysis Results
 ; CHECK-NEXT:       Two-Address instruction pass
 ; CHECK-NEXT:       Fast Register Allocator
 ; CHECK-NEXT:       Bundle Machine CFG Edges
-- 
2.50.1