[CodeExtractor] Allowing for caller to access final inputs and outputs.

[AndrewLitteken]

Summary

The Code Extractor does not provide an easy mechanism for determining the inputs and outputs after extraction has occurred, this patch gives the ability to pass in empty SetVectors to be filled with the inputs and outputs if they need to be analyzed.

[paquette]

Add a testcase to unittests/Transforms/Utils/CodeExtractorTest.cpp?

[AndrewLitteken]

Adding a test and clang-format issues.

[paquette]

LGTM with documentation nit.

llvm/include/llvm/Transforms/Utils/CodeExtractor.h

142

Can you add documentation for Inputs and Outputs explaining that they are out-params?

[paquette]

llvm/unittests/Transforms/Utils/CodeExtractorTest.cpp

118

Can all of these use EXPECT_EQ?

[AndrewLitteken]

Updating for nits

[paquette]

LGTM with one more nit

llvm/include/llvm/Transforms/Utils/CodeExtractor.h

147

maybe just say "filled with input values to the outlined function"?

even though this is a typedef of SetVector, it's a little confusing when looking at this locally.

(similar nit with Outputs)

llvm/include/llvm/Transforms/Utils/CodeExtractor.h

CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs = false,
                   std::string Suffix = "");
 
     /// Perform the extraction, returning the new function.
     ///
     /// Returns zero when called on a CodeExtractor instance where isEligible
     /// returns false.
     Function *extractCodeRegion(const CodeExtractorAnalysisCache &CEAC);
 
+    Function *extractCodeRegion(const CodeExtractorAnalysisCache &CEAC,
+                                ValueSet &Inputs, ValueSet &Outputs);
+
     /// Verify that assumption cache isn't stale after a region is extracted.
     /// Returns true when verifier finds errors. AssumptionCache is passed as
     /// parameter to make this function stateless.
     static bool verifyAssumptionCache(const Function &OldFunc,
                                       const Function &NewFunc,
                                       AssumptionCache *AC);
 
     /// Test whether this code extractor is eligible.
     ///
     /// Based on the blocks used when constructing the code extractor,
     /// determine whether it is eligible for extraction.

llvm/lib/Transforms/Utils/CodeExtractor.cpp

static void fixupDebugInfoPostExtraction(Function &OldFunc, Function &NewFunc,
   if (!TheCall.getDebugLoc())
     TheCall.setDebugLoc(DILocation::get(Ctx, 0, 0, OldSP));
 
   eraseDebugIntrinsicsWithNonLocalRefs(NewFunc);
 }
 
 Function *
 CodeExtractor::extractCodeRegion(const CodeExtractorAnalysisCache &CEAC) {
+  ValueSet Inputs, Outputs;
+  return extractCodeRegion(CEAC, Inputs, Outputs);
+}
+
+Function *
+CodeExtractor::extractCodeRegion(const CodeExtractorAnalysisCache &CEAC,
+                                 ValueSet &inputs, ValueSet &outputs) {
   if (!isEligible())
     return nullptr;
 
   // Assumption: this is a single-entry code region, and the header is the first
   // block in the region.
   BasicBlock *header = *Blocks.begin();
   Function *oldFunction = header->getParent();
 
   // Calculate the entry frequency of the new function before we change the root
any_of(Blocks, [&BranchI](const BasicBlock *BB) {
           return false;
         BranchI->setDebugLoc(I.getDebugLoc());
         return true;
       });
     });
   }
   newFuncRoot->getInstList().push_back(BranchI);
 
-  ValueSet inputs, outputs, SinkingCands, HoistingCands;
+  ValueSet SinkingCands, HoistingCands;
   BasicBlock *CommonExit = nullptr;
   findAllocas(CEAC, SinkingCands, HoistingCands, CommonExit);
   assert(HoistingCands.empty() || CommonExit);
 
   // Find inputs to, outputs from the code region.
   findInputsOutputs(inputs, outputs, SinkingCands);
 
   // Now sink all instructions which only have non-phi uses inside the region.

llvm/unittests/Transforms/Utils/CodeExtractorTest.cpp

TEST(CodeExtractor, ExitStub) {
   EXPECT_TRUE(Exit && cast<PHINode>(Exit->front()).getNumIncomingValues() == 1);
   // Ensure that there is a PHI in outlined function with 2 incoming values.
   EXPECT_TRUE(ExitSplit &&
               cast<PHINode>(ExitSplit->front()).getNumIncomingValues() == 2);
   EXPECT_FALSE(verifyFunction(*Outlined));
   EXPECT_FALSE(verifyFunction(*Func));
 }
 
+TEST(CodeExtractor, InputOutputMonitoring) {
+  LLVMContext Ctx;
+  SMDiagnostic Err;
+  std::unique_ptr<Module> M(parseAssemblyString(R"invalid(
+    define i32 @foo(i32 %x, i32 %y, i32 %z) {
+    header:
+      %0 = icmp ugt i32 %x, %y
+      br i1 %0, label %body1, label %body2
+
+    body1:
+      %1 = add i32 %z, 2
+      br label %notExtracted
+
+    body2:
+      %2 = mul i32 %z, 7
+      br label %notExtracted
+
+    notExtracted:
+      %3 = phi i32 [ %1, %body1 ], [ %2, %body2 ]
+      %4 = add i32 %3, %x
+      ret i32 %4
+    }
+  )invalid",
+                                                Err, Ctx));
+
+  Function *Func = M->getFunction("foo");
+  SmallVector<BasicBlock *, 3> Candidates{ getBlockByName(Func, "header"),
+                                           getBlockByName(Func, "body1"),
+                                           getBlockByName(Func, "body2") };
+
+  CodeExtractor CE(Candidates);
+  EXPECT_TRUE(CE.isEligible());
+
+  CodeExtractorAnalysisCache CEAC(*Func);
+  SetVector<Value *> Inputs, Outputs;
+  Function *Outlined = CE.extractCodeRegion(CEAC, Inputs, Outputs);
+  EXPECT_TRUE(Outlined);
+
+  EXPECT_TRUE(Inputs.size() == 3);
+  EXPECT_TRUE(Inputs[0] == Func->getArg(2));
+  EXPECT_TRUE(Inputs[1] == Func->getArg(0));
+  EXPECT_TRUE(Inputs[2] == Func->getArg(1));
+  EXPECT_TRUE(Outputs.size() == 1);
+  StoreInst *SI = cast<StoreInst>(Outlined->getArg(3)->user_back());
+  Value *OutputVal = SI->getValueOperand();
+  EXPECT_TRUE(Outputs[0] == OutputVal);
+  BasicBlock *Exit = getBlockByName(Func, "notExtracted");
+  BasicBlock *ExitSplit = getBlockByName(Outlined, "notExtracted.split");
+  // Ensure that PHI in exit block has only one incoming value (from code
+  // replacer block).
+  EXPECT_TRUE(Exit && cast<PHINode>(Exit->front()).getNumIncomingValues() == 1);
+  // Ensure that there is a PHI in outlined function with 2 incoming values.
+  EXPECT_TRUE(ExitSplit &&
+              cast<PHINode>(ExitSplit->front()).getNumIncomingValues() == 2);
+  EXPECT_FALSE(verifyFunction(*Outlined));
+  EXPECT_FALSE(verifyFunction(*Func));
+}
+
 TEST(CodeExtractor, ExitPHIOnePredFromRegion) {
   LLVMContext Ctx;
   SMDiagnostic Err;
   std::unique_ptr<Module> M(parseAssemblyString(R"invalid(
     define i32 @foo() {
     header:
       br i1 undef, label %extracted1, label %pred