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9cb64b47cf
llvm-mirror/unittests/Analysis/ScalarEvolutionTest.cpp
Sanjoy Das 9cb64b47cf [SCEV] Maintain loop use lists, and use them in forgetLoop 
Summary:
Currently we do not correctly invalidate memoized results for add recurrences
that were created directly (i.e. they were not created from a `Value`).  This
change fixes this by keeping loop use lists and using the loop use lists to
determine which SCEV expressions to invalidate.

Here are some statistics on the number of uses of in the use lists of all loops
on a clang bootstrap (config: release, no asserts):

     Count: 731310
       Min: 1
      Mean: 8.555150
50th %time: 4
95th %tile: 25
99th %tile: 53
       Max: 433

Reviewers: atrick, sunfish, mkazantsev

Subscribers: mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D38434

llvm-svn: 315672
2017-10-13 05:50:52 +00:00

1118 lines
40 KiB
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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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