2 files changed, 101 insertions, 0 deletions
diff --git a/llvm/unittests/Analysis/CMakeLists.txt b/llvm/unittests/Analysis/CMakeLists.txt
index 45d31f88911..20b4ae21edb 100644
--- a/llvm/unittests/Analysis/CMakeLists.txt
+++ b/llvm/unittests/Analysis/CMakeLists.txt
@@ -18,6 +18,7 @@ add_llvm_unittest(AnalysisTests
   DivergenceAnalysisTest.cpp
   DomTreeUpdaterTest.cpp
   GlobalsModRefTest.cpp
+  IVDescriptorsTest.cpp
   LazyCallGraphTest.cpp
   LoopInfoTest.cpp
   MemoryBuiltinsTest.cpp
diff --git a/llvm/unittests/Analysis/IVDescriptorsTest.cpp b/llvm/unittests/Analysis/IVDescriptorsTest.cpp
new file mode 100644
index 00000000000..cba45a96e68
--- /dev/null
+++ b/llvm/unittests/Analysis/IVDescriptorsTest.cpp
@@ -0,0 +1,100 @@
+//===- IVDescriptorsTest.cpp - IVDescriptors 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/IVDescriptors.h"
+#include "llvm/Analysis/AssumptionCache.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 loop info and scalar evolution for the function and run the Test.
+static void runWithLoopInfoAndSE(
+    Module &M, StringRef FuncName,
+    function_ref<void(Function &F, LoopInfo &LI, 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);
+
+  Test(*F, LI, SE);
+}
+
+static std::unique_ptr<Module> parseIR(LLVMContext &C, const char *IR) {
+  SMDiagnostic Err;
+  std::unique_ptr<Module> Mod = parseAssemblyString(IR, Err, C);
+  if (!Mod)
+    Err.print("IVDescriptorsTests", errs());
+  return Mod;
+}
+
+// This tests that IVDescriptors can obtain the induction binary operator for
+// integer induction variables. And hasUnsafeAlgebra() and
+// getUnsafeAlgebraInst() correctly return the expected behavior, i.e. no unsafe
+// algebra.
+TEST(IVDescriptorsTest, LoopWithSingleLatch) {
+  // Parse the module.
+  LLVMContext Context;
+
+  std::unique_ptr<Module> M = parseIR(
+    Context,
+    R"(define void @foo(i32* %A, i32 %ub) {
+entry:
+  br label %for.body
+for.body:
+  %i = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  %idxprom = sext i32 %i to i64
+  %arrayidx = getelementptr inbounds i32, i32* %A, i64 %idxprom
+  store i32 %i, i32* %arrayidx, align 4
+  %inc = add nsw i32 %i, 1
+  %cmp = icmp slt i32 %inc, %ub
+  br i1 %cmp, label %for.body, label %for.exit
+for.exit:
+  br label %for.end
+for.end:
+  ret void
+})"
+    );
+
+  runWithLoopInfoAndSE(
+      *M, "foo", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
+        Function::iterator FI = F.begin();
+        // First basic block is entry - skip it.
+        BasicBlock *Header = &*(++FI);
+        assert(Header->getName() == "for.body");
+        Loop *L = LI.getLoopFor(Header);
+        EXPECT_NE(L, nullptr);
+        PHINode *Inst_i = dyn_cast<PHINode>(&Header->front());
+        assert(Inst_i->getName() == "i");
+        InductionDescriptor IndDesc;
+        bool IsInductionPHI =
+            InductionDescriptor::isInductionPHI(Inst_i, L, &SE, IndDesc);
+        EXPECT_TRUE(IsInductionPHI);
+        Instruction *Inst_inc = nullptr;
+        BasicBlock::iterator BBI = Header->begin();
+        do {
+          if ((&*BBI)->getName() == "inc")
+            Inst_inc = &*BBI;
+          ++BBI;
+        } while (!Inst_inc);
+        assert(Inst_inc->getName() == "inc");
+        EXPECT_EQ(IndDesc.getInductionBinOp(), Inst_inc);
+        EXPECT_FALSE(IndDesc.hasUnsafeAlgebra());
+        EXPECT_EQ(IndDesc.getUnsafeAlgebraInst(), nullptr);
+      });
+}