llvm/unittests/Analysis/LoopInfoTest.cpp

//===- LoopInfoTest.cpp - LoopInfo unit tests -----------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "llvm/Analysis/LoopInfo.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Dominators.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"

using namespace llvm;

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

// This tests that for a loop with a single latch, we get the loop id from
// its only latch, even in case the loop may not be in a simplified form.
TEST(LoopInfoTest, LoopWithSingleLatch) {
  const char *ModuleStr =
         "target datalayout = \"e-m:o-i64:64-f80:128-n8:16:32:64-S128\"\n"
         "define void @foo(i32 %n) {\n"
         "entry:\n"
         "  br i1 undef, label %for.cond, label %for.end\n"
         "for.cond:\n"
         "  %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.inc ]\n"
         "  %cmp = icmp slt i32 %i.0, %n\n"
         "  br i1 %cmp, label %for.inc, label %for.end\n"
         "for.inc:\n"
         "  %inc = add nsw i32 %i.0, 1\n"
         "  br label %for.cond, !llvm.loop !0\n"
         "for.end:\n"
         "  ret void\n"
         "}\n"
         "!0 = distinct !{!0, !1}\n"
         "!1 = !{!\"llvm.loop.distribute.enable\", i1 true}\n";
  
  // Parse the module.
  LLVMContext Context;
  std::unique_ptr<Module> M = makeLLVMModule(Context, ModuleStr);

  // Build the dominator tree and loop info.
  DominatorTree DT;
  DT.recalculate(*M->begin());
  LoopInfo LI;
  LI.analyze(DT);


  Function &F = *M->begin();
  Function::iterator FI = F.begin();
  FI++; // First basic block is entry - skip it.
  BasicBlock *Header = &*FI++;
  assert(Header->getName() == "for.cond");
  Loop *L = LI.getLoopFor(Header);

  // This loop is not in simplified form.
  EXPECT_FALSE(L->isLoopSimplifyForm());

  // Analyze the loop metadata id.
  bool loopIDFoundAndSet = false;
  // Try to get and set the metadata id for the loop.
  if (MDNode *D = L->getLoopID()) {
    L->setLoopID(D);
    loopIDFoundAndSet = true;
  }

  // We must have successfully found and set the loop id in the
  // only latch the loop has.
  EXPECT_TRUE(loopIDFoundAndSet);
}