llvm/unittests/Transforms/Scalar/LICMTest.cpp

   1 //===- LICMTest.cpp - LICM unit tests -------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Analysis/ScalarEvolution.h"
  10 #include "llvm/AsmParser/Parser.h"
  11 #include "llvm/IR/Module.h"
  12 #include "llvm/Passes/PassBuilder.h"
  13 #include "llvm/Support/SourceMgr.h"
  14 #include "llvm/Testing/Support/Error.h"
  15 #include "llvm/Transforms/Scalar/LICM.h"
  16 #include "gtest/gtest.h"
  17
  18 namespace llvm {
  19
  20 TEST(LICMTest, TestSCEVInvalidationOnHoisting) {
  21   LLVMContext Ctx;
  22   ModulePassManager MPM;
  23   PassBuilder PB;
  24   LoopAnalysisManager LAM;
  25   FunctionAnalysisManager FAM;
  26   CGSCCAnalysisManager CGAM;
  27   ModuleAnalysisManager MAM;
  28
  29   PB.registerModuleAnalyses(MAM);
  30   PB.registerCGSCCAnalyses(CGAM);
  31   PB.registerFunctionAnalyses(FAM);
  32   PB.registerLoopAnalyses(LAM);
  33   PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
  34
  35   StringRef PipelineStr = "require<opt-remark-emit>,loop-mssa(licm)";
  36   ASSERT_THAT_ERROR(PB.parsePassPipeline(MPM, PipelineStr), Succeeded());
  37
  38   SMDiagnostic Error;
  39   StringRef Text = R"(
  40     define void @foo(i64* %ptr) {
  41     entry:
  42       br label %loop
  43
  44     loop:
  45       %iv = phi i64 [ 0, %entry ], [ %iv.inc, %loop ]
  46       %n = load i64, i64* %ptr, !invariant.load !0
  47       %iv.inc = add i64 %iv, 1
  48       %cmp = icmp ult i64 %iv.inc, %n
  49       br i1 %cmp, label %loop, label %exit
  50
  51     exit:
  52       ret void
  53     }
  54
  55     !0 = !{}
  56   )";
  57
  58   std::unique_ptr<Module> M = parseAssemblyString(Text, Error, Ctx);
  59   ASSERT_TRUE(M);
  60   Function *F = M->getFunction("foo");
  61   ScalarEvolution &SE = FAM.getResult<ScalarEvolutionAnalysis>(*F);
  62   BasicBlock &EntryBB = F->getEntryBlock();
  63   BasicBlock *LoopBB = EntryBB.getUniqueSuccessor();
  64
  65   // Select `load i64, i64* %ptr`.
  66   Instruction *IBefore = LoopBB->getFirstNonPHI();
  67   // Make sure the right instruction was selected.
  68   ASSERT_TRUE(isa<LoadInst>(IBefore));
  69   // Upon this query SCEV caches disposition of <load i64, i64* %ptr> SCEV.
  70   ASSERT_EQ(SE.getBlockDisposition(SE.getSCEV(IBefore), LoopBB),
  71             ScalarEvolution::BlockDisposition::DominatesBlock);
  72
  73   MPM.run(*M, MAM);
  74
  75   // Select `load i64, i64* %ptr` after it was hoisted.
  76   Instruction *IAfter = EntryBB.getFirstNonPHI();
  77   // Make sure the right instruction was selected.
  78   ASSERT_TRUE(isa<LoadInst>(IAfter));
  79
  80   ScalarEvolution::BlockDisposition DispositionBeforeInvalidation =
  81       SE.getBlockDisposition(SE.getSCEV(IAfter), LoopBB);
  82   SE.forgetValue(IAfter);
  83   ScalarEvolution::BlockDisposition DispositionAfterInvalidation =
  84       SE.getBlockDisposition(SE.getSCEV(IAfter), LoopBB);
  85
  86   // If LICM have properly invalidated SCEV,
  87   //   1. SCEV of <load i64, i64* %ptr> should properly dominate the "loop" BB,
  88   //   2. extra invalidation shouldn't change result of the query.
  89   EXPECT_EQ(DispositionBeforeInvalidation,
  90             ScalarEvolution::BlockDisposition::ProperlyDominatesBlock);
  91   EXPECT_EQ(DispositionBeforeInvalidation, DispositionAfterInvalidation);
  92 }
  93 }