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llvm-mirror/unittests/Analysis/ScalarEvolutionTest.cpp
Sanjoy Das e62cbedf0c Revert "[SCEV] Maintain and use a loop->loop invalidation dependency" 
This reverts commit r315713.  It causes PR34968.

I think I know what the problem is, but I don't think I'll have time to fix it
this week.

llvm-svn: 315962
2017-10-17 01:03:56 +00:00

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//===- 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/ADT/SmallVector.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Support/SourceMgr.h"
#include "gtest/gtest.h"
namespace llvm {
namespace {
// We use this fixture to ensure that we clean up ScalarEvolution before
// deleting the PassManager.
class ScalarEvolutionsTest : public testing::Test {
protected:
LLVMContext Context;
Module M;
TargetLibraryInfoImpl TLII;
TargetLibraryInfo TLI;
std::unique_ptr<AssumptionCache> AC;
std::unique_ptr<DominatorTree> DT;
std::unique_ptr<LoopInfo> LI;
ScalarEvolutionsTest() : M("", Context), TLII(), TLI(TLII) {}
ScalarEvolution buildSE(Function &F) {
AC.reset(new AssumptionCache(F));
DT.reset(new DominatorTree(F));
LI.reset(new LoopInfo(*DT));
return ScalarEvolution(F, TLI, *AC, *DT, *LI);
}
void runWithSE(
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;
ScalarEvolution SE = buildSE(*F);
Test(*F, *LI, SE);
}
};
TEST_F(ScalarEvolutionsTest, SCEVUnknownRAUW) {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context),
std::vector<Type *>(), false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
BasicBlock *BB = BasicBlock::Create(Context, "entry", F);
ReturnInst::Create(Context, nullptr, BB);
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");
ScalarEvolution SE = buildSE(*F);
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);
}
TEST_F(ScalarEvolutionsTest, SimplifiedPHI) {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context),
std::vector<Type *>(), false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
BasicBlock *LoopBB = BasicBlock::Create(Context, "loop", F);
BasicBlock *ExitBB = BasicBlock::Create(Context, "exit", F);
BranchInst::Create(LoopBB, EntryBB);
BranchInst::Create(LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)),
LoopBB);
ReturnInst::Create(Context, nullptr, ExitBB);
auto *Ty = Type::getInt32Ty(Context);
auto *PN = PHINode::Create(Ty, 2, "", &*LoopBB->begin());
PN->addIncoming(Constant::getNullValue(Ty), EntryBB);
PN->addIncoming(UndefValue::get(Ty), LoopBB);
ScalarEvolution SE = buildSE(*F);
auto *S1 = SE.getSCEV(PN);
auto *S2 = SE.getSCEV(PN);
auto *ZeroConst = SE.getConstant(Ty, 0);
// At some point, only the first call to getSCEV returned the simplified
// SCEVConstant and later calls just returned a SCEVUnknown referencing the
// PHI node.
EXPECT_EQ(S1, ZeroConst);
EXPECT_EQ(S1, S2);
}
TEST_F(ScalarEvolutionsTest, ExpandPtrTypeSCEV) {
// It is to test the fix for PR30213. It exercises the branch in scev
// expansion when the value in ValueOffsetPair is a ptr and the offset
// is not divisible by the elem type size of value.
auto *I8Ty = Type::getInt8Ty(Context);
auto *I8PtrTy = Type::getInt8PtrTy(Context);
auto *I32Ty = Type::getInt32Ty(Context);
auto *I32PtrTy = Type::getInt32PtrTy(Context);
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), std::vector<Type *>(), false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
BasicBlock *LoopBB = BasicBlock::Create(Context, "loop", F);
BasicBlock *ExitBB = BasicBlock::Create(Context, "exit", F);
BranchInst::Create(LoopBB, EntryBB);
ReturnInst::Create(Context, nullptr, ExitBB);
// loop: ; preds = %loop, %entry
// %alloca = alloca i32
// %gep0 = getelementptr i32, i32* %alloca, i32 1
// %bitcast1 = bitcast i32* %gep0 to i8*
// %gep1 = getelementptr i8, i8* %bitcast1, i32 1
// %gep2 = getelementptr i8, i8* undef, i32 1
// %cmp = icmp ult i8* undef, %bitcast1
// %select = select i1 %cmp, i8* %gep1, i8* %gep2
// %bitcast2 = bitcast i8* %select to i32*
// br i1 undef, label %loop, label %exit
const DataLayout &DL = F->getParent()->getDataLayout();
BranchInst *Br = BranchInst::Create(
LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)), LoopBB);
AllocaInst *Alloca = new AllocaInst(I32Ty, DL.getAllocaAddrSpace(),
"alloca", Br);
ConstantInt *Ci32 = ConstantInt::get(Context, APInt(32, 1));
GetElementPtrInst *Gep0 =
GetElementPtrInst::Create(I32Ty, Alloca, Ci32, "gep0", Br);
CastInst *CastA =
CastInst::CreateBitOrPointerCast(Gep0, I8PtrTy, "bitcast1", Br);
GetElementPtrInst *Gep1 =
GetElementPtrInst::Create(I8Ty, CastA, Ci32, "gep1", Br);
GetElementPtrInst *Gep2 = GetElementPtrInst::Create(
I8Ty, UndefValue::get(I8PtrTy), Ci32, "gep2", Br);
CmpInst *Cmp = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_ULT,
UndefValue::get(I8PtrTy), CastA, "cmp", Br);
SelectInst *Sel = SelectInst::Create(Cmp, Gep1, Gep2, "select", Br);
CastInst *CastB =
CastInst::CreateBitOrPointerCast(Sel, I32PtrTy, "bitcast2", Br);
ScalarEvolution SE = buildSE(*F);
auto *S = SE.getSCEV(CastB);
SCEVExpander Exp(SE, M.getDataLayout(), "expander");
Value *V =
Exp.expandCodeFor(cast<SCEVAddExpr>(S)->getOperand(1), nullptr, Br);
// Expect the expansion code contains:
// %0 = bitcast i32* %bitcast2 to i8*
// %uglygep = getelementptr i8, i8* %0, i64 -1
// %1 = bitcast i8* %uglygep to i32*
EXPECT_TRUE(isa<BitCastInst>(V));
Instruction *Gep = cast<Instruction>(V)->getPrevNode();
EXPECT_TRUE(isa<GetElementPtrInst>(Gep));
EXPECT_TRUE(isa<ConstantInt>(Gep->getOperand(1)));
EXPECT_EQ(cast<ConstantInt>(Gep->getOperand(1))->getSExtValue(), -1);
EXPECT_TRUE(isa<BitCastInst>(Gep->getPrevNode()));
}
static Instruction *getInstructionByName(Function &F, StringRef Name) {
for (auto &I : instructions(F))
if (I.getName() == Name)
return &I;
llvm_unreachable("Expected to find instruction!");
}
TEST_F(ScalarEvolutionsTest, CommutativeExprOperandOrder) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"target datalayout = \"e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128\" "
" "
"@var_0 = external global i32, align 4"
"@var_1 = external global i32, align 4"
"@var_2 = external global i32, align 4"
" "
"declare i32 @unknown(i32, i32, i32)"
" "
"define void @f_1(i8* nocapture %arr, i32 %n, i32* %A, i32* %B) "
" local_unnamed_addr { "
"entry: "
" %entrycond = icmp sgt i32 %n, 0 "
" br i1 %entrycond, label %loop.ph, label %for.end "
" "
"loop.ph: "
" %a = load i32, i32* %A, align 4 "
" %b = load i32, i32* %B, align 4 "
" %mul = mul nsw i32 %b, %a "
" %iv0.init = getelementptr inbounds i8, i8* %arr, i32 %mul "
" br label %loop "
" "
"loop: "
" %iv0 = phi i8* [ %iv0.inc, %loop ], [ %iv0.init, %loop.ph ] "
" %iv1 = phi i32 [ %iv1.inc, %loop ], [ 0, %loop.ph ] "
" %conv = trunc i32 %iv1 to i8 "
" store i8 %conv, i8* %iv0, align 1 "
" %iv0.inc = getelementptr inbounds i8, i8* %iv0, i32 %b "
" %iv1.inc = add nuw nsw i32 %iv1, 1 "
" %exitcond = icmp eq i32 %iv1.inc, %n "
" br i1 %exitcond, label %for.end.loopexit, label %loop "
" "
"for.end.loopexit: "
" br label %for.end "
" "
"for.end: "
" ret void "
"} "
" "
"define void @f_2(i32* %X, i32* %Y, i32* %Z) { "
" %x = load i32, i32* %X "
" %y = load i32, i32* %Y "
" %z = load i32, i32* %Z "
" ret void "
"} "
" "
"define void @f_3() { "
" %x = load i32, i32* @var_0"
" %y = load i32, i32* @var_1"
" %z = load i32, i32* @var_2"
" ret void"
"} "
" "
"define void @f_4(i32 %a, i32 %b, i32 %c) { "
" %x = call i32 @unknown(i32 %a, i32 %b, i32 %c)"
" %y = call i32 @unknown(i32 %b, i32 %c, i32 %a)"
" %z = call i32 @unknown(i32 %c, i32 %a, i32 %b)"
" ret void"
"} "
,
Err, C);
assert(M && "Could not parse module?");
assert(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "f_1", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *IV0 = getInstructionByName(F, "iv0");
auto *IV0Inc = getInstructionByName(F, "iv0.inc");
auto *FirstExprForIV0 = SE.getSCEV(IV0);
auto *FirstExprForIV0Inc = SE.getSCEV(IV0Inc);
auto *SecondExprForIV0 = SE.getSCEV(IV0);
EXPECT_TRUE(isa<SCEVAddRecExpr>(FirstExprForIV0));
EXPECT_TRUE(isa<SCEVAddRecExpr>(FirstExprForIV0Inc));
EXPECT_TRUE(isa<SCEVAddRecExpr>(SecondExprForIV0));
});
auto CheckCommutativeMulExprs = [&](ScalarEvolution &SE, const SCEV *A,
const SCEV *B, const SCEV *C) {
EXPECT_EQ(SE.getMulExpr(A, B), SE.getMulExpr(B, A));
EXPECT_EQ(SE.getMulExpr(B, C), SE.getMulExpr(C, B));
EXPECT_EQ(SE.getMulExpr(A, C), SE.getMulExpr(C, A));
SmallVector<const SCEV *, 3> Ops0 = {A, B, C};
SmallVector<const SCEV *, 3> Ops1 = {A, C, B};
SmallVector<const SCEV *, 3> Ops2 = {B, A, C};
SmallVector<const SCEV *, 3> Ops3 = {B, C, A};
SmallVector<const SCEV *, 3> Ops4 = {C, B, A};
SmallVector<const SCEV *, 3> Ops5 = {C, A, B};
auto *Mul0 = SE.getMulExpr(Ops0);
auto *Mul1 = SE.getMulExpr(Ops1);
auto *Mul2 = SE.getMulExpr(Ops2);
auto *Mul3 = SE.getMulExpr(Ops3);
auto *Mul4 = SE.getMulExpr(Ops4);
auto *Mul5 = SE.getMulExpr(Ops5);
EXPECT_EQ(Mul0, Mul1) << "Expected " << *Mul0 << " == " << *Mul1;
EXPECT_EQ(Mul1, Mul2) << "Expected " << *Mul1 << " == " << *Mul2;
EXPECT_EQ(Mul2, Mul3) << "Expected " << *Mul2 << " == " << *Mul3;
EXPECT_EQ(Mul3, Mul4) << "Expected " << *Mul3 << " == " << *Mul4;
EXPECT_EQ(Mul4, Mul5) << "Expected " << *Mul4 << " == " << *Mul5;
};
for (StringRef FuncName : {"f_2", "f_3", "f_4"})
runWithSE(
*M, FuncName, [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
CheckCommutativeMulExprs(SE, SE.getSCEV(getInstructionByName(F, "x")),
SE.getSCEV(getInstructionByName(F, "y")),
SE.getSCEV(getInstructionByName(F, "z")));
});
}
TEST_F(ScalarEvolutionsTest, CompareSCEVComplexity) {
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), std::vector<Type *>(), false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
BasicBlock *LoopBB = BasicBlock::Create(Context, "bb1", F);
BranchInst::Create(LoopBB, EntryBB);
auto *Ty = Type::getInt32Ty(Context);
SmallVector<Instruction*, 8> Muls(8), Acc(8), NextAcc(8);
Acc[0] = PHINode::Create(Ty, 2, "", LoopBB);
Acc[1] = PHINode::Create(Ty, 2, "", LoopBB);
Acc[2] = PHINode::Create(Ty, 2, "", LoopBB);
Acc[3] = PHINode::Create(Ty, 2, "", LoopBB);
Acc[4] = PHINode::Create(Ty, 2, "", LoopBB);
Acc[5] = PHINode::Create(Ty, 2, "", LoopBB);
Acc[6] = PHINode::Create(Ty, 2, "", LoopBB);
Acc[7] = PHINode::Create(Ty, 2, "", LoopBB);
for (int i = 0; i < 20; i++) {
Muls[0] = BinaryOperator::CreateMul(Acc[0], Acc[0], "", LoopBB);
NextAcc[0] = BinaryOperator::CreateAdd(Muls[0], Acc[4], "", LoopBB);
Muls[1] = BinaryOperator::CreateMul(Acc[1], Acc[1], "", LoopBB);
NextAcc[1] = BinaryOperator::CreateAdd(Muls[1], Acc[5], "", LoopBB);
Muls[2] = BinaryOperator::CreateMul(Acc[2], Acc[2], "", LoopBB);
NextAcc[2] = BinaryOperator::CreateAdd(Muls[2], Acc[6], "", LoopBB);
Muls[3] = BinaryOperator::CreateMul(Acc[3], Acc[3], "", LoopBB);
NextAcc[3] = BinaryOperator::CreateAdd(Muls[3], Acc[7], "", LoopBB);
Muls[4] = BinaryOperator::CreateMul(Acc[4], Acc[4], "", LoopBB);
NextAcc[4] = BinaryOperator::CreateAdd(Muls[4], Acc[0], "", LoopBB);
Muls[5] = BinaryOperator::CreateMul(Acc[5], Acc[5], "", LoopBB);
NextAcc[5] = BinaryOperator::CreateAdd(Muls[5], Acc[1], "", LoopBB);
Muls[6] = BinaryOperator::CreateMul(Acc[6], Acc[6], "", LoopBB);
NextAcc[6] = BinaryOperator::CreateAdd(Muls[6], Acc[2], "", LoopBB);
Muls[7] = BinaryOperator::CreateMul(Acc[7], Acc[7], "", LoopBB);
NextAcc[7] = BinaryOperator::CreateAdd(Muls[7], Acc[3], "", LoopBB);
Acc = NextAcc;
}
auto II = LoopBB->begin();
for (int i = 0; i < 8; i++) {
PHINode *Phi = cast<PHINode>(&*II++);
Phi->addIncoming(Acc[i], LoopBB);
Phi->addIncoming(UndefValue::get(Ty), EntryBB);
}
BasicBlock *ExitBB = BasicBlock::Create(Context, "bb2", F);
BranchInst::Create(LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)),
LoopBB);
Acc[0] = BinaryOperator::CreateAdd(Acc[0], Acc[1], "", ExitBB);
Acc[1] = BinaryOperator::CreateAdd(Acc[2], Acc[3], "", ExitBB);
Acc[2] = BinaryOperator::CreateAdd(Acc[4], Acc[5], "", ExitBB);
Acc[3] = BinaryOperator::CreateAdd(Acc[6], Acc[7], "", ExitBB);
Acc[0] = BinaryOperator::CreateAdd(Acc[0], Acc[1], "", ExitBB);
Acc[1] = BinaryOperator::CreateAdd(Acc[2], Acc[3], "", ExitBB);
Acc[0] = BinaryOperator::CreateAdd(Acc[0], Acc[1], "", ExitBB);
ReturnInst::Create(Context, nullptr, ExitBB);
ScalarEvolution SE = buildSE(*F);
EXPECT_NE(nullptr, SE.getSCEV(Acc[0]));
}
TEST_F(ScalarEvolutionsTest, CompareValueComplexity) {
IntegerType *IntPtrTy = M.getDataLayout().getIntPtrType(Context);
PointerType *IntPtrPtrTy = IntPtrTy->getPointerTo();
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), {IntPtrTy, IntPtrTy}, false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
Value *X = &*F->arg_begin();
Value *Y = &*std::next(F->arg_begin());
const int ValueDepth = 10;
for (int i = 0; i < ValueDepth; i++) {
X = new LoadInst(new IntToPtrInst(X, IntPtrPtrTy, "", EntryBB), "",
/*isVolatile*/ false, EntryBB);
Y = new LoadInst(new IntToPtrInst(Y, IntPtrPtrTy, "", EntryBB), "",
/*isVolatile*/ false, EntryBB);
}
auto *MulA = BinaryOperator::CreateMul(X, Y, "", EntryBB);
auto *MulB = BinaryOperator::CreateMul(Y, X, "", EntryBB);
ReturnInst::Create(Context, nullptr, EntryBB);
// This test isn't checking for correctness. Today making A and B resolve to
// the same SCEV would require deeper searching in CompareValueComplexity,
// which will slow down compilation. However, this test can fail (with LLVM's
// behavior still being correct) if we ever have a smarter
// CompareValueComplexity that is both fast and more accurate.
ScalarEvolution SE = buildSE(*F);
auto *A = SE.getSCEV(MulA);
auto *B = SE.getSCEV(MulB);
EXPECT_NE(A, B);
}
TEST_F(ScalarEvolutionsTest, SCEVAddExpr) {
Type *Ty32 = Type::getInt32Ty(Context);
Type *ArgTys[] = {Type::getInt64Ty(Context), Ty32};
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), ArgTys, false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
Argument *A1 = &*F->arg_begin();
Argument *A2 = &*(std::next(F->arg_begin()));
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
Instruction *Trunc = CastInst::CreateTruncOrBitCast(A1, Ty32, "", EntryBB);
Instruction *Mul1 = BinaryOperator::CreateMul(Trunc, A2, "", EntryBB);
Instruction *Add1 = BinaryOperator::CreateAdd(Mul1, Trunc, "", EntryBB);
Mul1 = BinaryOperator::CreateMul(Add1, Trunc, "", EntryBB);
Instruction *Add2 = BinaryOperator::CreateAdd(Mul1, Add1, "", EntryBB);
// FIXME: The size of this is arbitrary and doesn't seem to change the
// result, but SCEV will do quadratic work for these so a large number here
// will be extremely slow. We should revisit what and how this is testing
// SCEV.
for (int i = 0; i < 10; i++) {
Mul1 = BinaryOperator::CreateMul(Add2, Add1, "", EntryBB);
Add1 = Add2;
Add2 = BinaryOperator::CreateAdd(Mul1, Add1, "", EntryBB);
}
ReturnInst::Create(Context, nullptr, EntryBB);
ScalarEvolution SE = buildSE(*F);
EXPECT_NE(nullptr, SE.getSCEV(Mul1));
}
static Instruction &GetInstByName(Function &F, StringRef Name) {
for (auto &I : instructions(F))
if (I.getName() == Name)
return I;
llvm_unreachable("Could not find instructions!");
}
TEST_F(ScalarEvolutionsTest, SCEVNormalization) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"target datalayout = \"e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128\" "
" "
"@var_0 = external global i32, align 4"
"@var_1 = external global i32, align 4"
"@var_2 = external global i32, align 4"
" "
"declare i32 @unknown(i32, i32, i32)"
" "
"define void @f_1(i8* nocapture %arr, i32 %n, i32* %A, i32* %B) "
" local_unnamed_addr { "
"entry: "
" br label %loop.ph "
" "
"loop.ph: "
" br label %loop "
" "
"loop: "
" %iv0 = phi i32 [ %iv0.inc, %loop ], [ 0, %loop.ph ] "
" %iv1 = phi i32 [ %iv1.inc, %loop ], [ -2147483648, %loop.ph ] "
" %iv0.inc = add i32 %iv0, 1 "
" %iv1.inc = add i32 %iv1, 3 "
" br i1 undef, label %for.end.loopexit, label %loop "
" "
"for.end.loopexit: "
" ret void "
"} "
" "
"define void @f_2(i32 %a, i32 %b, i32 %c, i32 %d) "
" local_unnamed_addr { "
"entry: "
" br label %loop_0 "
" "
"loop_0: "
" br i1 undef, label %loop_0, label %loop_1 "
" "
"loop_1: "
" br i1 undef, label %loop_2, label %loop_1 "
" "
" "
"loop_2: "
" br i1 undef, label %end, label %loop_2 "
" "
"end: "
" ret void "
"} "
,
Err, C);
assert(M && "Could not parse module?");
assert(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "f_1", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto &I0 = GetInstByName(F, "iv0");
auto &I1 = *I0.getNextNode();
auto *S0 = cast<SCEVAddRecExpr>(SE.getSCEV(&I0));
PostIncLoopSet Loops;
Loops.insert(S0->getLoop());
auto *N0 = normalizeForPostIncUse(S0, Loops, SE);
auto *D0 = denormalizeForPostIncUse(N0, Loops, SE);
EXPECT_EQ(S0, D0) << *S0 << " " << *D0;
auto *S1 = cast<SCEVAddRecExpr>(SE.getSCEV(&I1));
Loops.clear();
Loops.insert(S1->getLoop());
auto *N1 = normalizeForPostIncUse(S1, Loops, SE);
auto *D1 = denormalizeForPostIncUse(N1, Loops, SE);
EXPECT_EQ(S1, D1) << *S1 << " " << *D1;
});
runWithSE(*M, "f_2", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *L2 = *LI.begin();
auto *L1 = *std::next(LI.begin());
auto *L0 = *std::next(LI.begin(), 2);
auto GetAddRec = [&SE](const Loop *L, std::initializer_list<const SCEV *> Ops) {
SmallVector<const SCEV *, 4> OpsCopy(Ops);
return SE.getAddRecExpr(OpsCopy, L, SCEV::FlagAnyWrap);
};
auto GetAdd = [&SE](std::initializer_list<const SCEV *> Ops) {
SmallVector<const SCEV *, 4> OpsCopy(Ops);
return SE.getAddExpr(OpsCopy, SCEV::FlagAnyWrap);
};
// We first populate the AddRecs vector with a few "interesting" SCEV
// expressions, and then we go through the list and assert that each
// expression in it has an invertible normalization.
std::vector<const SCEV *> Exprs;
{
const SCEV *V0 = SE.getSCEV(&*F.arg_begin());
const SCEV *V1 = SE.getSCEV(&*std::next(F.arg_begin(), 1));
const SCEV *V2 = SE.getSCEV(&*std::next(F.arg_begin(), 2));
const SCEV *V3 = SE.getSCEV(&*std::next(F.arg_begin(), 3));
Exprs.push_back(GetAddRec(L0, {V0})); // 0
Exprs.push_back(GetAddRec(L0, {V0, V1})); // 1
Exprs.push_back(GetAddRec(L0, {V0, V1, V2})); // 2
Exprs.push_back(GetAddRec(L0, {V0, V1, V2, V3})); // 3
Exprs.push_back(
GetAddRec(L1, {Exprs[1], Exprs[2], Exprs[3], Exprs[0]})); // 4
Exprs.push_back(
GetAddRec(L1, {Exprs[1], Exprs[2], Exprs[0], Exprs[3]})); // 5
Exprs.push_back(
GetAddRec(L1, {Exprs[1], Exprs[3], Exprs[3], Exprs[1]})); // 6
Exprs.push_back(GetAdd({Exprs[6], Exprs[3], V2})); // 7
Exprs.push_back(
GetAddRec(L2, {Exprs[4], Exprs[3], Exprs[3], Exprs[5]})); // 8
Exprs.push_back(
GetAddRec(L2, {Exprs[4], Exprs[6], Exprs[7], Exprs[3], V0})); // 9
}
std::vector<PostIncLoopSet> LoopSets;
for (int i = 0; i < 8; i++) {
LoopSets.emplace_back();
if (i & 1)
LoopSets.back().insert(L0);
if (i & 2)
LoopSets.back().insert(L1);
if (i & 4)
LoopSets.back().insert(L2);
}
for (const auto &LoopSet : LoopSets)
for (auto *S : Exprs) {
{
auto *N = llvm::normalizeForPostIncUse(S, LoopSet, SE);
auto *D = llvm::denormalizeForPostIncUse(N, LoopSet, SE);
// Normalization and then denormalizing better give us back the same
// value.
EXPECT_EQ(S, D) << "S = " << *S << " D = " << *D << " N = " << *N;
}
{
auto *D = llvm::denormalizeForPostIncUse(S, LoopSet, SE);
auto *N = llvm::normalizeForPostIncUse(D, LoopSet, SE);
// Denormalization and then normalizing better give us back the same
// value.
EXPECT_EQ(S, N) << "S = " << *S << " N = " << *N;
}
}
});
}
// Expect the call of getZeroExtendExpr will not cost exponential time.
TEST_F(ScalarEvolutionsTest, SCEVZeroExtendExpr) {
LLVMContext C;
SMDiagnostic Err;
// Generate a function like below:
// define void @foo() {
// entry:
// br label %for.cond
//
// for.cond:
// %0 = phi i64 [ 100, %entry ], [ %dec, %for.inc ]
// %cmp = icmp sgt i64 %0, 90
// br i1 %cmp, label %for.inc, label %for.cond1
//
// for.inc:
// %dec = add nsw i64 %0, -1
// br label %for.cond
//
// for.cond1:
// %1 = phi i64 [ 100, %for.cond ], [ %dec5, %for.inc2 ]
// %cmp3 = icmp sgt i64 %1, 90
// br i1 %cmp3, label %for.inc2, label %for.cond4
//
// for.inc2:
// %dec5 = add nsw i64 %1, -1
// br label %for.cond1
//
// ......
//
// for.cond89:
// %19 = phi i64 [ 100, %for.cond84 ], [ %dec94, %for.inc92 ]
// %cmp93 = icmp sgt i64 %19, 90
// br i1 %cmp93, label %for.inc92, label %for.end
//
// for.inc92:
// %dec94 = add nsw i64 %19, -1
// br label %for.cond89
//
// for.end:
// %gep = getelementptr i8, i8* null, i64 %dec
// %gep6 = getelementptr i8, i8* %gep, i64 %dec5
// ......
// %gep95 = getelementptr i8, i8* %gep91, i64 %dec94
// ret void
// }
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context), {}, false);
Function *F = cast<Function>(M.getOrInsertFunction("foo", FTy));
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
BasicBlock *CondBB = BasicBlock::Create(Context, "for.cond", F);
BasicBlock *EndBB = BasicBlock::Create(Context, "for.end", F);
BranchInst::Create(CondBB, EntryBB);
BasicBlock *PrevBB = EntryBB;
Type *I64Ty = Type::getInt64Ty(Context);
Type *I8Ty = Type::getInt8Ty(Context);
Type *I8PtrTy = Type::getInt8PtrTy(Context);
Value *Accum = Constant::getNullValue(I8PtrTy);
int Iters = 20;
for (int i = 0; i < Iters; i++) {
BasicBlock *IncBB = BasicBlock::Create(Context, "for.inc", F, EndBB);
auto *PN = PHINode::Create(I64Ty, 2, "", CondBB);
PN->addIncoming(ConstantInt::get(Context, APInt(64, 100)), PrevBB);
auto *Cmp = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_SGT, PN,
ConstantInt::get(Context, APInt(64, 90)), "cmp",
CondBB);
BasicBlock *NextBB;
if (i != Iters - 1)
NextBB = BasicBlock::Create(Context, "for.cond", F, EndBB);
else
NextBB = EndBB;
BranchInst::Create(IncBB, NextBB, Cmp, CondBB);
auto *Dec = BinaryOperator::CreateNSWAdd(
PN, ConstantInt::get(Context, APInt(64, -1)), "dec", IncBB);
PN->addIncoming(Dec, IncBB);
BranchInst::Create(CondBB, IncBB);
Accum = GetElementPtrInst::Create(I8Ty, Accum, Dec, "gep", EndBB);
PrevBB = CondBB;
CondBB = NextBB;
}
ReturnInst::Create(Context, nullptr, EndBB);
ScalarEvolution SE = buildSE(*F);
const SCEV *S = SE.getSCEV(Accum);
Type *I128Ty = Type::getInt128Ty(Context);
SE.getZeroExtendExpr(S, I128Ty);
}
// Make sure that SCEV doesn't introduce illegal ptrtoint/inttoptr instructions
TEST_F(ScalarEvolutionsTest, SCEVZeroExtendExprNonIntegral) {
/*
* Create the following code:
* func(i64 addrspace(10)* %arg)
* top:
* br label %L.ph
* L.ph:
* br label %L
* L:
* %phi = phi i64 [i64 0, %L.ph], [ %add, %L2 ]
* %add = add i64 %phi2, 1
* br i1 undef, label %post, label %L2
* post:
* %gepbase = getelementptr i64 addrspace(10)* %arg, i64 1
* #= %gep = getelementptr i64 addrspace(10)* %gepbase, i64 %add =#
* ret void
*
* We will create the appropriate SCEV expression for %gep and expand it,
* then check that no inttoptr/ptrtoint instructions got inserted.
*/
// Create a module with non-integral pointers in it's datalayout
Module NIM("nonintegral", Context);
std::string DataLayout = M.getDataLayoutStr();
if (!DataLayout.empty())
DataLayout += "-";
DataLayout += "ni:10";
NIM.setDataLayout(DataLayout);
Type *T_int1 = Type::getInt1Ty(Context);
Type *T_int64 = Type::getInt64Ty(Context);
Type *T_pint64 = T_int64->getPointerTo(10);
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), {T_pint64}, false);
Function *F = cast<Function>(NIM.getOrInsertFunction("foo", FTy));
Argument *Arg = &*F->arg_begin();
BasicBlock *Top = BasicBlock::Create(Context, "top", F);
BasicBlock *LPh = BasicBlock::Create(Context, "L.ph", F);
BasicBlock *L = BasicBlock::Create(Context, "L", F);
BasicBlock *Post = BasicBlock::Create(Context, "post", F);
IRBuilder<> Builder(Top);
Builder.CreateBr(LPh);
Builder.SetInsertPoint(LPh);
Builder.CreateBr(L);
Builder.SetInsertPoint(L);
PHINode *Phi = Builder.CreatePHI(T_int64, 2);
Value *Add = Builder.CreateAdd(Phi, ConstantInt::get(T_int64, 1), "add");
Builder.CreateCondBr(UndefValue::get(T_int1), L, Post);
Phi->addIncoming(ConstantInt::get(T_int64, 0), LPh);
Phi->addIncoming(Add, L);
Builder.SetInsertPoint(Post);
Value *GepBase = Builder.CreateGEP(Arg, ConstantInt::get(T_int64, 1));
Instruction *Ret = Builder.CreateRetVoid();
ScalarEvolution SE = buildSE(*F);
auto *AddRec =
SE.getAddRecExpr(SE.getUnknown(GepBase), SE.getConstant(T_int64, 1),
LI->getLoopFor(L), SCEV::FlagNUW);
SCEVExpander Exp(SE, NIM.getDataLayout(), "expander");
Exp.disableCanonicalMode();
Exp.expandCodeFor(AddRec, T_pint64, Ret);
// Make sure none of the instructions inserted were inttoptr/ptrtoint.
// The verifier will check this.
EXPECT_FALSE(verifyFunction(*F, &errs()));
}
// Make sure that SCEV invalidates exit limits after invalidating the values it
// depends on when we forget a loop.
TEST_F(ScalarEvolutionsTest, SCEVExitLimitForgetLoop) {
/*
* Create the following code:
* func(i64 addrspace(10)* %arg)
* top:
* br label %L.ph
* L.ph:
* br label %L
* L:
* %phi = phi i64 [i64 0, %L.ph], [ %add, %L2 ]
* %add = add i64 %phi2, 1
* %cond = icmp slt i64 %add, 1000; then becomes 2000.
* br i1 %cond, label %post, label %L2
* post:
* ret void
*
*/
// Create a module with non-integral pointers in it's datalayout
Module NIM("nonintegral", Context);
std::string DataLayout = M.getDataLayoutStr();
if (!DataLayout.empty())
DataLayout += "-";
DataLayout += "ni:10";
NIM.setDataLayout(DataLayout);
Type *T_int64 = Type::getInt64Ty(Context);
Type *T_pint64 = T_int64->getPointerTo(10);
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), {T_pint64}, false);
Function *F = cast<Function>(NIM.getOrInsertFunction("foo", FTy));
BasicBlock *Top = BasicBlock::Create(Context, "top", F);
BasicBlock *LPh = BasicBlock::Create(Context, "L.ph", F);
BasicBlock *L = BasicBlock::Create(Context, "L", F);
BasicBlock *Post = BasicBlock::Create(Context, "post", F);
IRBuilder<> Builder(Top);
Builder.CreateBr(LPh);
Builder.SetInsertPoint(LPh);
Builder.CreateBr(L);
Builder.SetInsertPoint(L);
PHINode *Phi = Builder.CreatePHI(T_int64, 2);
auto *Add = cast<Instruction>(
Builder.CreateAdd(Phi, ConstantInt::get(T_int64, 1), "add"));
auto *Limit = ConstantInt::get(T_int64, 1000);
auto *Cond = cast<Instruction>(
Builder.CreateICmp(ICmpInst::ICMP_SLT, Add, Limit, "cond"));
auto *Br = cast<Instruction>(Builder.CreateCondBr(Cond, L, Post));
Phi->addIncoming(ConstantInt::get(T_int64, 0), LPh);
Phi->addIncoming(Add, L);
Builder.SetInsertPoint(Post);
Builder.CreateRetVoid();
ScalarEvolution SE = buildSE(*F);
auto *Loop = LI->getLoopFor(L);
const SCEV *EC = SE.getBackedgeTakenCount(Loop);
EXPECT_FALSE(isa<SCEVCouldNotCompute>(EC));
EXPECT_TRUE(isa<SCEVConstant>(EC));
EXPECT_EQ(cast<SCEVConstant>(EC)->getAPInt().getLimitedValue(), 999u);
// The add recurrence {5,+,1} does not correspond to any PHI in the IR, and
// that is relevant to this test.
auto *Five = SE.getConstant(APInt(/*numBits=*/64, 5));
auto *AR =
SE.getAddRecExpr(Five, SE.getOne(T_int64), Loop, SCEV::FlagAnyWrap);
const SCEV *ARAtLoopExit = SE.getSCEVAtScope(AR, nullptr);
EXPECT_FALSE(isa<SCEVCouldNotCompute>(ARAtLoopExit));
EXPECT_TRUE(isa<SCEVConstant>(ARAtLoopExit));
EXPECT_EQ(cast<SCEVConstant>(ARAtLoopExit)->getAPInt().getLimitedValue(),
1004u);
SE.forgetLoop(Loop);
Br->eraseFromParent();
Cond->eraseFromParent();
Builder.SetInsertPoint(L);
auto *NewCond = Builder.CreateICmp(
ICmpInst::ICMP_SLT, Add, ConstantInt::get(T_int64, 2000), "new.cond");
Builder.CreateCondBr(NewCond, L, Post);
const SCEV *NewEC = SE.getBackedgeTakenCount(Loop);
EXPECT_FALSE(isa<SCEVCouldNotCompute>(NewEC));
EXPECT_TRUE(isa<SCEVConstant>(NewEC));
EXPECT_EQ(cast<SCEVConstant>(NewEC)->getAPInt().getLimitedValue(), 1999u);
const SCEV *NewARAtLoopExit = SE.getSCEVAtScope(AR, nullptr);
EXPECT_FALSE(isa<SCEVCouldNotCompute>(NewARAtLoopExit));
EXPECT_TRUE(isa<SCEVConstant>(NewARAtLoopExit));
EXPECT_EQ(cast<SCEVConstant>(NewARAtLoopExit)->getAPInt().getLimitedValue(),
2004u);
}
// Make sure that SCEV invalidates exit limits after invalidating the values it
// depends on when we forget a value.
TEST_F(ScalarEvolutionsTest, SCEVExitLimitForgetValue) {
/*
* Create the following code:
* func(i64 addrspace(10)* %arg)
* top:
* br label %L.ph
* L.ph:
* %load = load i64 addrspace(10)* %arg
* br label %L
* L:
* %phi = phi i64 [i64 0, %L.ph], [ %add, %L2 ]
* %add = add i64 %phi2, 1
* %cond = icmp slt i64 %add, %load ; then becomes 2000.
* br i1 %cond, label %post, label %L2
* post:
* ret void
*
*/
// Create a module with non-integral pointers in it's datalayout
Module NIM("nonintegral", Context);
std::string DataLayout = M.getDataLayoutStr();
if (!DataLayout.empty())
DataLayout += "-";
DataLayout += "ni:10";
NIM.setDataLayout(DataLayout);
Type *T_int64 = Type::getInt64Ty(Context);
Type *T_pint64 = T_int64->getPointerTo(10);
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), {T_pint64}, false);
Function *F = cast<Function>(NIM.getOrInsertFunction("foo", FTy));
Argument *Arg = &*F->arg_begin();
BasicBlock *Top = BasicBlock::Create(Context, "top", F);
BasicBlock *LPh = BasicBlock::Create(Context, "L.ph", F);
BasicBlock *L = BasicBlock::Create(Context, "L", F);
BasicBlock *Post = BasicBlock::Create(Context, "post", F);
IRBuilder<> Builder(Top);
Builder.CreateBr(LPh);
Builder.SetInsertPoint(LPh);
auto *Load = cast<Instruction>(Builder.CreateLoad(T_int64, Arg, "load"));
Builder.CreateBr(L);
Builder.SetInsertPoint(L);
PHINode *Phi = Builder.CreatePHI(T_int64, 2);
auto *Add = cast<Instruction>(
Builder.CreateAdd(Phi, ConstantInt::get(T_int64, 1), "add"));
auto *Cond = cast<Instruction>(
Builder.CreateICmp(ICmpInst::ICMP_SLT, Add, Load, "cond"));
auto *Br = cast<Instruction>(Builder.CreateCondBr(Cond, L, Post));
Phi->addIncoming(ConstantInt::get(T_int64, 0), LPh);
Phi->addIncoming(Add, L);
Builder.SetInsertPoint(Post);
Builder.CreateRetVoid();
ScalarEvolution SE = buildSE(*F);
auto *Loop = LI->getLoopFor(L);
const SCEV *EC = SE.getBackedgeTakenCount(Loop);
EXPECT_FALSE(isa<SCEVCouldNotCompute>(EC));
EXPECT_FALSE(isa<SCEVConstant>(EC));
SE.forgetValue(Load);
Br->eraseFromParent();
Cond->eraseFromParent();
Load->eraseFromParent();
Builder.SetInsertPoint(L);
auto *NewCond = Builder.CreateICmp(
ICmpInst::ICMP_SLT, Add, ConstantInt::get(T_int64, 2000), "new.cond");
Builder.CreateCondBr(NewCond, L, Post);
const SCEV *NewEC = SE.getBackedgeTakenCount(Loop);
EXPECT_FALSE(isa<SCEVCouldNotCompute>(NewEC));
EXPECT_TRUE(isa<SCEVConstant>(NewEC));
EXPECT_EQ(cast<SCEVConstant>(NewEC)->getAPInt().getLimitedValue(), 1999u);
}
TEST_F(ScalarEvolutionsTest, SCEVAddRecFromPHIwithLargeConstants) {
// Reference: https://reviews.llvm.org/D37265
// Make sure that SCEV does not blow up when constructing an AddRec
// with predicates for a phi with the update pattern:
// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
// when either the initial value of the Phi or the InvariantAccum are
// constants that are too large to fit in an ix but are zero when truncated to
// ix.
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), std::vector<Type *>(), false);
Function *F = cast<Function>(M.getOrInsertFunction("addrecphitest", FTy));
/*
Create IR:
entry:
br label %loop
loop:
%0 = phi i64 [-9223372036854775808, %entry], [%3, %loop]
%1 = shl i64 %0, 32
%2 = ashr exact i64 %1, 32
%3 = add i64 %2, -9223372036854775808
br i1 undef, label %exit, label %loop
exit:
ret void
*/
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
BasicBlock *LoopBB = BasicBlock::Create(Context, "loop", F);
BasicBlock *ExitBB = BasicBlock::Create(Context, "exit", F);
// entry:
BranchInst::Create(LoopBB, EntryBB);
// loop:
auto *MinInt64 =
ConstantInt::get(Context, APInt(64, 0x8000000000000000U, true));
auto *Int64_32 = ConstantInt::get(Context, APInt(64, 32));
auto *Br = BranchInst::Create(
LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)), LoopBB);
auto *Phi = PHINode::Create(Type::getInt64Ty(Context), 2, "", Br);
auto *Shl = BinaryOperator::CreateShl(Phi, Int64_32, "", Br);
auto *AShr = BinaryOperator::CreateExactAShr(Shl, Int64_32, "", Br);
auto *Add = BinaryOperator::CreateAdd(AShr, MinInt64, "", Br);
Phi->addIncoming(MinInt64, EntryBB);
Phi->addIncoming(Add, LoopBB);
// exit:
ReturnInst::Create(Context, nullptr, ExitBB);
// Make sure that SCEV doesn't blow up
ScalarEvolution SE = buildSE(*F);
SCEVUnionPredicate Preds;
const SCEV *Expr = SE.getSCEV(Phi);
EXPECT_NE(nullptr, Expr);
EXPECT_TRUE(isa<SCEVUnknown>(Expr));
auto Result = SE.createAddRecFromPHIWithCasts(cast<SCEVUnknown>(Expr));
}
TEST_F(ScalarEvolutionsTest, SCEVAddRecFromPHIwithLargeConstantAccum) {
// Make sure that SCEV does not blow up when constructing an AddRec
// with predicates for a phi with the update pattern:
// (SExt/ZExt ix (Trunc iy (%SymbolicPHI) to ix) to iy) + InvariantAccum
// when the InvariantAccum is a constant that is too large to fit in an
// ix but are zero when truncated to ix, and the initial value of the
// phi is not a constant.
Type *Int32Ty = Type::getInt32Ty(Context);
SmallVector<Type *, 1> Types;
Types.push_back(Int32Ty);
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context), Types, false);
Function *F = cast<Function>(M.getOrInsertFunction("addrecphitest", FTy));
/*
Create IR:
define @addrecphitest(i32)
entry:
br label %loop
loop:
%1 = phi i32 [%0, %entry], [%4, %loop]
%2 = shl i32 %1, 16
%3 = ashr exact i32 %2, 16
%4 = add i32 %3, -2147483648
br i1 undef, label %exit, label %loop
exit:
ret void
*/
BasicBlock *EntryBB = BasicBlock::Create(Context, "entry", F);
BasicBlock *LoopBB = BasicBlock::Create(Context, "loop", F);
BasicBlock *ExitBB = BasicBlock::Create(Context, "exit", F);
// entry:
BranchInst::Create(LoopBB, EntryBB);
// loop:
auto *MinInt32 = ConstantInt::get(Context, APInt(32, 0x80000000U, true));
auto *Int32_16 = ConstantInt::get(Context, APInt(32, 16));
auto *Br = BranchInst::Create(
LoopBB, ExitBB, UndefValue::get(Type::getInt1Ty(Context)), LoopBB);
auto *Phi = PHINode::Create(Int32Ty, 2, "", Br);
auto *Shl = BinaryOperator::CreateShl(Phi, Int32_16, "", Br);
auto *AShr = BinaryOperator::CreateExactAShr(Shl, Int32_16, "", Br);
auto *Add = BinaryOperator::CreateAdd(AShr, MinInt32, "", Br);
auto *Arg = &*(F->arg_begin());
Phi->addIncoming(Arg, EntryBB);
Phi->addIncoming(Add, LoopBB);
// exit:
ReturnInst::Create(Context, nullptr, ExitBB);
// Make sure that SCEV doesn't blow up
ScalarEvolution SE = buildSE(*F);
SCEVUnionPredicate Preds;
const SCEV *Expr = SE.getSCEV(Phi);
EXPECT_NE(nullptr, Expr);
EXPECT_TRUE(isa<SCEVUnknown>(Expr));
auto Result = SE.createAddRecFromPHIWithCasts(cast<SCEVUnknown>(Expr));
}
TEST_F(ScalarEvolutionsTest, SCEVFoldSumOfTruncs) {
// Verify that the following SCEV gets folded to a zero:
// (-1 * (trunc i64 (-1 * %0) to i32)) + (-1 * (trunc i64 %0 to i32)
Type *ArgTy = Type::getInt64Ty(Context);
Type *Int32Ty = Type::getInt32Ty(Context);
SmallVector<Type *, 1> Types;
Types.push_back(ArgTy);
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context), Types, false);
Function *F = cast<Function>(M.getOrInsertFunction("f", FTy));
BasicBlock *BB = BasicBlock::Create(Context, "entry", F);
ReturnInst::Create(Context, nullptr, BB);
ScalarEvolution SE = buildSE(*F);
auto *Arg = &*(F->arg_begin());
const auto *ArgSCEV = SE.getSCEV(Arg);
// Build the SCEV
const auto *A0 = SE.getNegativeSCEV(ArgSCEV);
const auto *A1 = SE.getTruncateExpr(A0, Int32Ty);
const auto *A = SE.getNegativeSCEV(A1);
const auto *B0 = SE.getTruncateExpr(ArgSCEV, Int32Ty);
const auto *B = SE.getNegativeSCEV(B0);
const auto *Expr = SE.getAddExpr(A, B);
// Verify that the SCEV was folded to 0
const auto *ZeroConst = SE.getConstant(Int32Ty, 0);
EXPECT_EQ(Expr, ZeroConst);
}
} // end anonymous namespace
} // end namespace llvm
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