llvm/unittests/Analysis/DDGTest.cpp

//===- DDGTest.cpp - DDGAnalysis unit tests -------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm/Analysis/DDG.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/BasicAliasAnalysis.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Dominators.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"

using namespace llvm;

/// Build the DDG analysis for a loop and run the given test \p Test.
static void runTest(Module &M, StringRef FuncName,
                    function_ref<void(Function &F, LoopInfo &LI,
                                      DependenceInfo &DI, ScalarEvolution &SE)>
                        Test) {
  auto *F = M.getFunction(FuncName);
  ASSERT_NE(F, nullptr) << "Could not find " << FuncName;

  TargetLibraryInfoImpl TLII;
  TargetLibraryInfo TLI(TLII);
  AssumptionCache AC(*F);
  DominatorTree DT(*F);
  LoopInfo LI(DT);
  ScalarEvolution SE(*F, TLI, AC, DT, LI);
  AAResults AA(TLI);
  DependenceInfo DI(F, &AA, &SE, &LI);
  Test(*F, LI, DI, SE);
}

static std::unique_ptr<Module> makeLLVMModule(LLVMContext &Context,
                                              const char *ModuleStr) {
  SMDiagnostic Err;
  return parseAssemblyString(ModuleStr, Err, Context);
}

TEST(DDGTest, getDependencies) {
  const char *ModuleStr =
      "target datalayout = \"e-m:e-i64:64-n32:64\"\n"
      "target triple = \"powerpc64le-unknown-linux-gnu\"\n"
      "\n"
      "define dso_local void @foo(i32 signext %n, i32* noalias %A, i32* "
      "noalias %B) {\n"
      "entry:\n"
      "   %cmp1 = icmp sgt i32 %n, 0\n"
      "   br i1 %cmp1, label %for.body.preheader, label %for.end\n"
      "\n"
      "for.body.preheader:\n"
      "   %wide.trip.count = zext i32 %n to i64\n"
      "   br label %for.body\n"
      " \n"
      " for.body:\n"
      "   %indvars.iv = phi i64 [ 0, %for.body.preheader ], [ "
      "%indvars.iv.next, %for.body ]\n"
      "   %arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv\n"
      "  %0 = trunc i64 %indvars.iv to i32\n"
      "  store i32 %0, i32* %arrayidx, align 4\n"
      "  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1\n"
      "  %arrayidx2 = getelementptr inbounds i32, i32* %A, i64 "
      "%indvars.iv.next\n"
      "  %1 = load i32, i32* %arrayidx2, align 4\n"
      "  %add3 = add nsw i32 %1, 1\n"
      "  %arrayidx5 = getelementptr inbounds i32, i32* %B, i64 %indvars.iv\n"
      "  store i32 %add3, i32* %arrayidx5, align 4\n"
      "  %exitcond = icmp ne i64 %indvars.iv.next, %wide.trip.count\n"
      "  br i1 %exitcond, label %for.body, label %for.end.loopexit\n"
      "\n"
      "for.end.loopexit:\n"
      "  br label %for.end\n"
      "\n"
      "for.end:\n"
      "  ret void\n"
      "}\n";

  LLVMContext Context;
  std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr);

  runTest(
      *M, "foo",
      [&](Function &F, LoopInfo &LI, DependenceInfo &DI, ScalarEvolution &SE) {
        Loop *L = *LI.begin();
        assert(L && "expected the loop to be identified.");

        DataDependenceGraph DDG(*L, LI, DI);

        // Collect all the nodes that have an outgoing memory edge
        // while collecting all memory edges as well. There should
        // only be one node with an outgoing memory edge and there
        // should only be one memory edge in the entire graph.
        std::vector<DDGNode *> DependenceSourceNodes;
        std::vector<DDGEdge *> MemoryEdges;
        for (DDGNode *N : DDG) {
          for (DDGEdge *E : *N) {
            bool SourceAdded = false;
            if (E->isMemoryDependence()) {
              MemoryEdges.push_back(E);
              if (!SourceAdded) {
                DependenceSourceNodes.push_back(N);
                SourceAdded = true;
              }
            }
          }
        }

        EXPECT_EQ(DependenceSourceNodes.size(), 1ull);
        EXPECT_EQ(MemoryEdges.size(), 1ull);

        DataDependenceGraph::DependenceList DL;
        DDG.getDependencies(*DependenceSourceNodes.back(),
                            MemoryEdges.back()->getTargetNode(), DL);

        EXPECT_EQ(DL.size(), 1ull);
        EXPECT_TRUE(DL.back()->isAnti());
        EXPECT_EQ(DL.back()->getLevels(), 1u);
        EXPECT_NE(DL.back()->getDistance(1), nullptr);
        EXPECT_EQ(DL.back()->getDistance(1),
                  SE.getOne(DL.back()->getDistance(1)->getType()));
      });
}