[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

llvm-svn: 302612

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp b/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
index 75359fe..7392c83 100644
--- a/llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
+++ b/llvm/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;