vendor/llvm/llvm-trunk-r304460

2 files changed, 36 insertions, 7 deletions

diff --git a/lib/Transforms/IPO/PartialInlining.cpp b/lib/Transforms/IPO/PartialInlining.cpp
index 4c417f1c55eb..bc0967448cdd 100644
--- a/lib/Transforms/IPO/PartialInlining.cpp
+++ b/lib/Transforms/IPO/PartialInlining.cpp
@@ -652,12 +652,21 @@ Function *PartialInlinerImpl::unswitchFunction(Function *F) {
   // only split block when necessary:
   PHINode *FirstPhi = getFirstPHI(PreReturn);
   unsigned NumPredsFromEntries = OI->ReturnBlockPreds.size();
+  auto IsTrivialPhi = [](PHINode *PN) -> Value * {
+    Value *CommonValue = PN->getIncomingValue(0);
+    if (all_of(PN->incoming_values(),
+               [&](Value *V) { return V == CommonValue; }))
+      return CommonValue;
+    return nullptr;
+  };
+
   if (FirstPhi && FirstPhi->getNumIncomingValues() > NumPredsFromEntries + 1) {
 
     NewReturnBlock = NewReturnBlock->splitBasicBlock(
         NewReturnBlock->getFirstNonPHI()->getIterator());
     BasicBlock::iterator I = PreReturn->begin();
     Instruction *Ins = &NewReturnBlock->front();
+    SmallVector<Instruction *, 4> DeadPhis;
     while (I != PreReturn->end()) {
       PHINode *OldPhi = dyn_cast<PHINode>(I);
       if (!OldPhi)
@@ -674,8 +683,22 @@ Function *PartialInlinerImpl::unswitchFunction(Function *F) {
         RetPhi->addIncoming(OldPhi->getIncomingValueForBlock(NewE), NewE);
         OldPhi->removeIncomingValue(NewE);
       }
+
+      // After incoming values splitting, the old phi may become trivial.
+      // Keeping the trivial phi can introduce definition inside the outline
+      // region which is live-out, causing necessary overhead (load, store
+      // arg passing etc).
+      if (auto *OldPhiVal = IsTrivialPhi(OldPhi)) {
+        OldPhi->replaceAllUsesWith(OldPhiVal);
+        DeadPhis.push_back(OldPhi);
+      }
+
       ++I;
     }
+
+    for (auto *DP : DeadPhis)
+      DP->eraseFromParent();
+
     for (auto E : OI->ReturnBlockPreds) {
       BasicBlock *NewE = cast<BasicBlock>(VMap[E]);
       NewE->getTerminator()->replaceUsesOfWith(PreReturn, NewReturnBlock);
diff --git a/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp b/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
index 659cb9df00a2..9dede4cedd1d 100644
--- a/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
+++ b/lib/Transforms/IPO/ThinLTOBitcodeWriter.cpp
@@ -6,14 +6,8 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This pass prepares a module containing type metadata for ThinLTO by splitting
-// it into regular and thin LTO parts if possible, and writing both parts to
-// a multi-module bitcode file. Modules that do not contain type metadata are
-// written unmodified as a single module.
-//
-//===----------------------------------------------------------------------===//
 
+#include "llvm/Transforms/IPO/ThinLTOBitcodeWriter.h"
 #include "llvm/Analysis/BasicAliasAnalysis.h"
 #include "llvm/Analysis/ModuleSummaryAnalysis.h"
 #include "llvm/Analysis/ProfileSummaryInfo.h"
@@ -436,3 +430,15 @@ ModulePass *llvm::createWriteThinLTOBitcodePass(raw_ostream &Str,
                                                 raw_ostream *ThinLinkOS) {
   return new WriteThinLTOBitcode(Str, ThinLinkOS);
 }
+
+PreservedAnalyses
+llvm::ThinLTOBitcodeWriterPass::run(Module &M, ModuleAnalysisManager &AM) {
+  FunctionAnalysisManager &FAM =
+      AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
+  writeThinLTOBitcode(OS, ThinLinkOS,
+                      [&FAM](Function &F) -> AAResults & {
+                        return FAM.getResult<AAManager>(F);
+                      },
+                      M, &AM.getResult<ModuleSummaryIndexAnalysis>(M));
+  return PreservedAnalyses::all();
+}