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/ScalarEvolution.h"
12 #include "llvm/AsmParser/Parser.h"
13 #include "llvm/IR/Dominators.h"
14 #include "llvm/Support/SourceMgr.h"
15 #include "gtest/gtest.h"
16 
17 using namespace llvm;
18 
19 static std::unique_ptr<Module> parseIR(LLVMContext &C, const char *IR) {
20   SMDiagnostic Err;
21   std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
22   if (!Mod)
23     Err.print("LoopUtilsTests", errs());
24   return Mod;
25 }
26 
27 static void run(Module &M, StringRef FuncName,
28                 function_ref<void(Function &F, DominatorTree &DT,
29                                   ScalarEvolution &SE, LoopInfo &LI)>
30                     Test) {
31   Function *F = M.getFunction(FuncName);
32   DominatorTree DT(*F);
33   TargetLibraryInfoImpl TLII;
34   TargetLibraryInfo TLI(TLII);
35   AssumptionCache AC(*F);
36   LoopInfo LI(DT);
37   ScalarEvolution SE(*F, TLI, AC, DT, LI);
38   Test(*F, DT, SE, LI);
39 }
40 
41 TEST(LoopUtils, DeleteDeadLoopNest) {
42   LLVMContext C;
43   std::unique_ptr<Module> M =
44       parseIR(C, "define void @foo() {\n"
45                  "entry:\n"
46                  "  br label %for.i\n"
47                  "for.i:\n"
48                  "  %i = phi i64 [ 0, %entry ], [ %inc.i, %for.i.latch ]\n"
49                  "  br label %for.j\n"
50                  "for.j:\n"
51                  "  %j = phi i64 [ 0, %for.i ], [ %inc.j, %for.j ]\n"
52                  "  %inc.j = add nsw i64 %j, 1\n"
53                  "  %cmp.j = icmp slt i64 %inc.j, 100\n"
54                  "  br i1 %cmp.j, label %for.j, label %for.k.preheader\n"
55                  "for.k.preheader:\n"
56                  "  br label %for.k\n"
57                  "for.k:\n"
58                  "  %k = phi i64 [ %inc.k, %for.k ], [ 0, %for.k.preheader ]\n"
59                  "  %inc.k = add nsw i64 %k, 1\n"
60                  "  %cmp.k = icmp slt i64 %inc.k, 100\n"
61                  "  br i1 %cmp.k, label %for.k, label %for.i.latch\n"
62                  "for.i.latch:\n"
63                  "  %inc.i = add nsw i64 %i, 1\n"
64                  "  %cmp.i = icmp slt i64 %inc.i, 100\n"
65                  "  br i1 %cmp.i, label %for.i, label %for.end\n"
66                  "for.end:\n"
67                  "  ret void\n"
68                  "}\n");
69 
70   run(*M, "foo",
71       [&](Function &F, DominatorTree &DT, ScalarEvolution &SE, LoopInfo &LI) {
72         assert(LI.begin() != LI.end() && "Expecting loops in function F");
73         Loop *L = *LI.begin();
74         assert(L && L->getName() == "for.i" && "Expecting loop for.i");
75 
76         deleteDeadLoop(L, &DT, &SE, &LI);
77 
78         assert(DT.verify(DominatorTree::VerificationLevel::Fast) &&
79                "Expecting valid dominator tree");
80         LI.verify(DT);
81         assert(LI.begin() == LI.end() &&
82                "Expecting no loops left in function F");
83         SE.verify();
84 
85         Function::iterator FI = F.begin();
86         BasicBlock *Entry = &*(FI++);
87         assert(Entry->getName() == "entry" && "Expecting BasicBlock entry");
88         const BranchInst *BI = dyn_cast<BranchInst>(Entry->getTerminator());
89         assert(BI && "Expecting valid branch instruction");
90         EXPECT_EQ(BI->getNumSuccessors(), (unsigned)1);
91         EXPECT_EQ(BI->getSuccessor(0)->getName(), "for.end");
92       });
93 }
94