llvm/unittests/Transforms/Utils/LoopUtilsTest.cpp

   1 //===- LoopUtilsTest.cpp - Unit tests for LoopUtils -----------------------===//
   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/Transforms/Utils/LoopUtils.h"
  10 #include "llvm/Analysis/AssumptionCache.h"
  11 #include "llvm/Analysis/LoopInfo.h"
  12 #include "llvm/Analysis/ScalarEvolution.h"
  13 #include "llvm/Analysis/TargetLibraryInfo.h"
  14 #include "llvm/AsmParser/Parser.h"
  15 #include "llvm/IR/Dominators.h"
  16 #include "llvm/IR/Module.h"
  17 #include "llvm/Support/SourceMgr.h"
  18 #include "gtest/gtest.h"
  19
  20 using namespace llvm;
  21
  22 static std::unique_ptr<Module> parseIR(LLVMContext &C, const char *IR) {
  23   SMDiagnostic Err;
  24   std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
  25   if (!Mod)
  26     Err.print("LoopUtilsTests", errs());
  27   return Mod;
  28 }
  29
  30 static void run(Module &M, StringRef FuncName,
  31                 function_ref<void(Function &F, DominatorTree &DT,
  32                                   ScalarEvolution &SE, LoopInfo &LI)>
  33                     Test) {
  34   Function *F = M.getFunction(FuncName);
  35   DominatorTree DT(*F);
  36   TargetLibraryInfoImpl TLII;
  37   TargetLibraryInfo TLI(TLII);
  38   AssumptionCache AC(*F);
  39   LoopInfo LI(DT);
  40   ScalarEvolution SE(*F, TLI, AC, DT, LI);
  41   Test(*F, DT, SE, LI);
  42 }
  43
  44 TEST(LoopUtils, DeleteDeadLoopNest) {
  45   LLVMContext C;
  46   std::unique_ptr<Module> M =
  47       parseIR(C, "define void @foo() {\n"
  48                  "entry:\n"
  49                  "  br label %for.i\n"
  50                  "for.i:\n"
  51                  "  %i = phi i64 [ 0, %entry ], [ %inc.i, %for.i.latch ]\n"
  52                  "  br label %for.j\n"
  53                  "for.j:\n"
  54                  "  %j = phi i64 [ 0, %for.i ], [ %inc.j, %for.j ]\n"
  55                  "  %inc.j = add nsw i64 %j, 1\n"
  56                  "  %cmp.j = icmp slt i64 %inc.j, 100\n"
  57                  "  br i1 %cmp.j, label %for.j, label %for.k.preheader\n"
  58                  "for.k.preheader:\n"
  59                  "  br label %for.k\n"
  60                  "for.k:\n"
  61                  "  %k = phi i64 [ %inc.k, %for.k ], [ 0, %for.k.preheader ]\n"
  62                  "  %inc.k = add nsw i64 %k, 1\n"
  63                  "  %cmp.k = icmp slt i64 %inc.k, 100\n"
  64                  "  br i1 %cmp.k, label %for.k, label %for.i.latch\n"
  65                  "for.i.latch:\n"
  66                  "  %inc.i = add nsw i64 %i, 1\n"
  67                  "  %cmp.i = icmp slt i64 %inc.i, 100\n"
  68                  "  br i1 %cmp.i, label %for.i, label %for.end\n"
  69                  "for.end:\n"
  70                  "  ret void\n"
  71                  "}\n");
  72
  73   run(*M, "foo",
  74       [&](Function &F, DominatorTree &DT, ScalarEvolution &SE, LoopInfo &LI) {
  75         assert(LI.begin() != LI.end() && "Expecting loops in function F");
  76         Loop *L = *LI.begin();
  77         assert(L && L->getName() == "for.i" && "Expecting loop for.i");
  78
  79         deleteDeadLoop(L, &DT, &SE, &LI);
  80
  81         assert(DT.verify(DominatorTree::VerificationLevel::Fast) &&
  82                "Expecting valid dominator tree");
  83         LI.verify(DT);
  84         assert(LI.begin() == LI.end() &&
  85                "Expecting no loops left in function F");
  86         SE.verify();
  87
  88         Function::iterator FI = F.begin();
  89         BasicBlock *Entry = &*(FI++);
  90         assert(Entry->getName() == "entry" && "Expecting BasicBlock entry");
  91         const BranchInst *BI = dyn_cast<BranchInst>(Entry->getTerminator());
  92         assert(BI && "Expecting valid branch instruction");
  93         EXPECT_EQ(BI->getNumSuccessors(), (unsigned)1);
  94         EXPECT_EQ(BI->getSuccessor(0)->getName(), "for.end");
  95       });
  96 }
  97
  98 TEST(LoopUtils, IsKnownPositiveInLoopTest) {
  99   LLVMContext C;
 100   std::unique_ptr<Module> M =
 101       parseIR(C, "define void @foo(i32 %n, i1 %c) {\n"
 102                  "entry:\n"
 103                  "  %is.positive = icmp sgt i32 %n, 0\n"
 104                  "  br i1 %is.positive, label %loop, label %exit\n"
 105                  "loop:\n"
 106                  "  br i1 %c, label %loop, label %exit\n"
 107                  "exit:\n"
 108                  "  ret void\n"
 109                  "}\n");
 110
 111   run(*M, "foo",
 112       [&](Function &F, DominatorTree &DT, ScalarEvolution &SE, LoopInfo &LI) {
 113         assert(LI.begin() != LI.end() && "Expecting loops in function F");
 114         Loop *L = *LI.begin();
 115         assert(L && L->getName() == "loop" && "Expecting loop 'loop'");
 116         auto *Arg = F.getArg(0);
 117         const SCEV *ArgSCEV = SE.getSCEV(Arg);
 118         EXPECT_EQ(isKnownPositiveInLoop(ArgSCEV, L, SE), true);
 119       });
 120 }
 121
 122 TEST(LoopUtils, IsKnownNonPositiveInLoopTest) {
 123   LLVMContext C;
 124   std::unique_ptr<Module> M =
 125       parseIR(C, "define void @foo(i32 %n, i1 %c) {\n"
 126                  "entry:\n"
 127                  "  %is.non.positive = icmp sle i32 %n, 0\n"
 128                  "  br i1 %is.non.positive, label %loop, label %exit\n"
 129                  "loop:\n"
 130                  "  br i1 %c, label %loop, label %exit\n"
 131                  "exit:\n"
 132                  "  ret void\n"
 133                  "}\n");
 134
 135   run(*M, "foo",
 136       [&](Function &F, DominatorTree &DT, ScalarEvolution &SE, LoopInfo &LI) {
 137         assert(LI.begin() != LI.end() && "Expecting loops in function F");
 138         Loop *L = *LI.begin();
 139         assert(L && L->getName() == "loop" && "Expecting loop 'loop'");
 140         auto *Arg = F.getArg(0);
 141         const SCEV *ArgSCEV = SE.getSCEV(Arg);
 142         EXPECT_EQ(isKnownNonPositiveInLoop(ArgSCEV, L, SE), true);
 143       });
 144 }