Factor out some of the code for updating old SCEVUnknown values, and

extend it to handle the case where multiple RAUWs affect a single
SCEVUnknown.

Add a ScalarEvolution unittest to test for this situation.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109705 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 78 insertions, 0 deletions

diff --git a/unittests/Analysis/ScalarEvolutionTest.cpp b/unittests/Analysis/ScalarEvolutionTest.cpp
new file mode 100644
index 0000000000..19bf90f073
--- /dev/null
+++ b/unittests/Analysis/ScalarEvolutionTest.cpp
@@ -0,0 +1,78 @@
+//===- ScalarEvolutionsTest.cpp - ScalarEvolution 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/ScalarEvolutionExpressions.h>
+#include <llvm/GlobalVariable.h>
+#include <llvm/Constants.h>
+#include <llvm/LLVMContext.h>
+#include <llvm/Module.h>
+#include <llvm/PassManager.h>
+#include "gtest/gtest.h"
+
+namespace llvm {
+namespace {
+
+TEST(ScalarEvolutionsTest, ReturnInst) {
+  LLVMContext Context;
+  Module M("world", Context);
+
+  const FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context),
+                                              std::vector<const Type *>(), false);
+  Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
+  BasicBlock *BB = BasicBlock::Create(Context, "entry", F);
+  ReturnInst::Create(Context, 0, BB);
+
+  const Type *Ty = Type::getInt1Ty(Context);
+  Constant *Init = Constant::getNullValue(Ty);
+  Value *V0 = new GlobalVariable(M, Ty, false, GlobalValue::ExternalLinkage, Init, "V0");
+  Value *V1 = new GlobalVariable(M, Ty, false, GlobalValue::ExternalLinkage, Init, "V1");
+  Value *V2 = new GlobalVariable(M, Ty, false, GlobalValue::ExternalLinkage, Init, "V2");
+
+  // Create a ScalarEvolution and "run" it so that it gets initialized.
+  PassManager PM;
+  ScalarEvolution &SE = *new ScalarEvolution();
+  PM.add(&SE);
+  PM.run(M);
+
+  const SCEV *S0 = SE.getSCEV(V0);
+  const SCEV *S1 = SE.getSCEV(V1);
+  const SCEV *S2 = SE.getSCEV(V2);
+
+  const SCEV *P0 = SE.getAddExpr(S0, S0);
+  const SCEV *P1 = SE.getAddExpr(S1, S1);
+  const SCEV *P2 = SE.getAddExpr(S2, S2);
+
+  const SCEVMulExpr *M0 = cast<SCEVMulExpr>(P0);
+  const SCEVMulExpr *M1 = cast<SCEVMulExpr>(P1);
+  const SCEVMulExpr *M2 = cast<SCEVMulExpr>(P2);
+
+  EXPECT_EQ(cast<SCEVConstant>(M0->getOperand(0))->getValue()->getZExtValue(),
+            2u);
+  EXPECT_EQ(cast<SCEVConstant>(M1->getOperand(0))->getValue()->getZExtValue(),
+            2u);
+  EXPECT_EQ(cast<SCEVConstant>(M2->getOperand(0))->getValue()->getZExtValue(),
+            2u);
+
+  // Before the RAUWs, these are all pointing to separate values.
+  EXPECT_EQ(cast<SCEVUnknown>(M0->getOperand(1))->getValue(), V0);
+  EXPECT_EQ(cast<SCEVUnknown>(M1->getOperand(1))->getValue(), V1);
+  EXPECT_EQ(cast<SCEVUnknown>(M2->getOperand(1))->getValue(), V2);
+
+  // Do some RAUWs.
+  V2->replaceAllUsesWith(V1);
+  V1->replaceAllUsesWith(V0);
+
+  // After the RAUWs, these should all be pointing to V0.
+  EXPECT_EQ(cast<SCEVUnknown>(M0->getOperand(1))->getValue(), V0);
+  EXPECT_EQ(cast<SCEVUnknown>(M1->getOperand(1))->getValue(), V0);
+  EXPECT_EQ(cast<SCEVUnknown>(M2->getOperand(1))->getValue(), V0);
+}
+
+}  // end anonymous namespace
+}  // end namespace llvm