// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/compiler/backend/inliner.h"

#include "vm/compiler/backend/il.h"
#include "vm/compiler/backend/il_printer.h"
#include "vm/compiler/backend/il_test_helper.h"
#include "vm/compiler/compiler_pass.h"
#include "vm/object.h"
#include "vm/unit_test.h"

namespace dart {

// Test that the redefinition for an inlined polymorphic function used with
// multiple receiver cids does not have a concrete type.
ISOLATE_UNIT_TEST_CASE(Inliner_PolyInliningRedefinition) {
  const char* kScript = R"(
    abstract class A {
      String toInline() { return "A"; }
    }

    class B extends A {}
    class C extends A {
      @override
      String toInline() { return "C";}
    }
    class D extends A {}

    testInlining(A arg) {
      arg.toInline();
    }

    main() {
      for (var i = 0; i < 10; i++) {
        testInlining(B());
        testInlining(C());
        testInlining(D());
      }
    }
  )";

  const auto& root_library = Library::Handle(LoadTestScript(kScript));
  const auto& function =
      Function::Handle(GetFunction(root_library, "testInlining"));

  Invoke(root_library, "main");

  TestPipeline pipeline(function, CompilerPass::kJIT);
  FlowGraph* flow_graph = pipeline.RunPasses({
      CompilerPass::kComputeSSA,
      CompilerPass::kApplyICData,
      CompilerPass::kTryOptimizePatterns,
      CompilerPass::kSetOuterInliningId,
      CompilerPass::kTypePropagation,
      CompilerPass::kApplyClassIds,
      CompilerPass::kInlining,
  });

  auto entry = flow_graph->graph_entry()->normal_entry();
  EXPECT(entry != nullptr);

  EXPECT(entry->initial_definitions()->length() == 1);
  EXPECT(entry->initial_definitions()->At(0)->IsParameter());
  ParameterInstr* param = entry->initial_definitions()->At(0)->AsParameter();

  // First we find the start of the prelude for the inlined instruction,
  // and also keep a reference to the LoadClassId instruction for later.
  LoadClassIdInstr* lcid = nullptr;
  BranchInstr* prelude = nullptr;

  ILMatcher cursor(flow_graph, entry);
  RELEASE_ASSERT(cursor.TryMatch(
      {
          {kMatchLoadClassId, &lcid},
          {kMatchBranch, &prelude},
      },
      /*insert_before=*/kMoveGlob));

  const Class& cls = Class::Handle(
      root_library.LookupLocalClass(String::Handle(Symbols::New(thread, "B"))));

  Definition* cid_B = flow_graph->GetConstant(Smi::Handle(Smi::New(cls.id())));
  Instruction* current = prelude;

  // We walk false branches until we either reach a branch instruction that uses
  // B's cid for comparison to the value returned from the LCID instruction
  // above, or a default case if there was no branch instruction for B's cid.
  while (true) {
    EXPECT(current->IsBranch());
    const ComparisonInstr* check = current->AsBranch()->comparison();
    EXPECT(check->left()->definition() == lcid);
    if (check->right()->definition() == cid_B) break;
    current = current->SuccessorAt(1);
    // By following false paths, we should be walking a series of blocks that
    // looks like:
    // B#[target]:#
    //   Branch if <check on class ID>
    // If we end up not finding a branch, then we're in a default case
    // that contains a class check.
    current = current->next();
    if (!current->IsBranch()) {
      break;
    }
  }
  // If we found a branch that checks against the class ID, we follow the true
  // branch to a block that contains only a goto to the desired join block.
  if (current->IsBranch()) {
    current = current->SuccessorAt(0);
  } else {
    // We're in the default case, which will check the class ID to make sure
    // it's the one expected for the fallthrough. That check will be followed
    // by a goto to the desired join block.
    EXPECT(current->IsRedefinition());
    const auto redef = current->AsRedefinition();
    EXPECT(redef->value()->definition() == lcid);
    current = current->next();
    EXPECT(current->IsCheckClassId());
    EXPECT(current->AsCheckClassId()->value()->definition() == redef);
  }
  current = current->next();
  EXPECT(current->IsGoto());
  current = current->AsGoto()->successor();
  // Now we should be at a block that starts like:
  // BY[join]:# pred(...)
  //    vW <- Redefinition(vV)
  //
  // where vV is a reference to the function parameter (the receiver of
  // the inlined function).
  current = current->next();
  EXPECT(current->IsRedefinition());
  EXPECT(current->AsRedefinition()->value()->definition() == param);
  EXPECT(current->AsRedefinition()->Type()->ToCid() == kDynamicCid);
}

}  // namespace dart