revert r280432:

r280432 | dehao | 2016-09-01 16:51:37 -0700 (Thu, 01 Sep 2016) | 9 lines

Explicitly require DominatorTreeAnalysis pass for instsimplify pass.

Summary: DominatorTreeAnalysis is always required by instsimplify.
llvm-svn: 280452

1 files changed, 5 insertions, 6 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp b/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
index 0be0b65..3099c49 100644
--- a/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyInstructions.cpp
@@ -90,7 +90,6 @@ namespace {
 
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.setPreservesCFG();
-      AU.addRequired<DominatorTreeWrapperPass>();
       AU.addRequired<AssumptionCacheTracker>();
       AU.addRequired<TargetLibraryInfoWrapperPass>();
     }
@@ -100,8 +99,9 @@ namespace {
       if (skipFunction(F))
         return false;
 
-      const DominatorTree *DT =
-          &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+      const DominatorTreeWrapperPass *DTWP =
+          getAnalysisIfAvailable<DominatorTreeWrapperPass>();
+      const DominatorTree *DT = DTWP ? &DTWP->getDomTree() : nullptr;
       const TargetLibraryInfo *TLI =
           &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
       AssumptionCache *AC =
@@ -115,7 +115,6 @@ char InstSimplifier::ID = 0;
 INITIALIZE_PASS_BEGIN(InstSimplifier, "instsimplify",
                       "Remove redundant instructions", false, false)
 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
-INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 INITIALIZE_PASS_END(InstSimplifier, "instsimplify",
                     "Remove redundant instructions", false, false)
@@ -128,10 +127,10 @@ FunctionPass *llvm::createInstructionSimplifierPass() {
 
 PreservedAnalyses InstSimplifierPass::run(Function &F,
                                       FunctionAnalysisManager &AM) {
-  auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
+  auto *DT = AM.getCachedResult<DominatorTreeAnalysis>(F);
   auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
   auto &AC = AM.getResult<AssumptionAnalysis>(F);
-  bool Changed = runImpl(F, &DT, &TLI, &AC);
+  bool Changed = runImpl(F, DT, &TLI, &AC);
   if (!Changed)
     return PreservedAnalyses::all();
   // FIXME: This should also 'preserve the CFG'.