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llvm-mirror/unittests/Analysis/ScalarEvolutionTest.cpp
Philip Reames a74c4e37ae [unittest] Exercise SCEV's udiv and udiv ceiling routines 
The ceiling variant was recently added (due to the work towards D105216), and we're spending a lot of time trying to find optimizations for the expression. This patch brute forces the space of i8 unsigned divides and checks that we get a correct (well consistent with APInt) result for both udiv and udiv ceiling.

(This is basically what I've been doing locally in a hand rolled C++ program, and I realized there no good reason not to check it in as a unit test which directly exercises the logic on constants.)

Differential Revision: https://reviews.llvm.org/D106083
2021-07-15 11:55:00 -07:00

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//===- ScalarEvolutionsTest.cpp - ScalarEvolution 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/ADT/SmallVector.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ScalarEvolutionNormalization.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 {
// 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);
}
static Optional<APInt> computeConstantDifference(ScalarEvolution &SE,
const SCEV *LHS,
const SCEV *RHS) {
return SE.computeConstantDifference(LHS, RHS);
}
static bool matchURem(ScalarEvolution &SE, const SCEV *Expr, const SCEV *&LHS,
const SCEV *&RHS) {
return SE.matchURem(Expr, LHS, RHS);
}
static bool isImpliedCond(
ScalarEvolution &SE, ICmpInst::Predicate Pred, const SCEV *LHS,
const SCEV *RHS, ICmpInst::Predicate FoundPred, const SCEV *FoundLHS,
const SCEV *FoundRHS) {
return SE.isImpliedCond(Pred, LHS, RHS, FoundPred, FoundLHS, FoundRHS);
}
};
TEST_F(ScalarEvolutionsTest, SCEVUnknownRAUW) {
FunctionType *FTy = FunctionType::get(Type::getVoidTy(Context),
std::vector<Type *>(), false);
Function *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
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, SE.getConstant(S0->getType(), 2));
const SCEV *P1 = SE.getAddExpr(S1, SE.getConstant(S0->getType(), 2));
const SCEV *P2 = SE.getAddExpr(S2, SE.getConstant(S0->getType(), 2));
auto *M0 = cast<SCEVAddExpr>(P0);
auto *M1 = cast<SCEVAddExpr>(P1);
auto *M2 = cast<SCEVAddExpr>(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 = Function::Create(FTy, Function::ExternalLinkage, "f", M);
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);
}
static Instruction *getInstructionByName(Function &F, StringRef Name) {
for (auto &I : instructions(F))
if (I.getName() == Name)
return &I;
llvm_unreachable("Expected to find instruction!");
}
static Value *getArgByName(Function &F, StringRef Name) {
for (auto &Arg : F.args())
if (Arg.getName() == Name)
return &Arg;
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 = Function::Create(FTy, Function::ExternalLinkage, "f", M);
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 = Function::Create(FTy, Function::ExternalLinkage, "f", M);
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(IntPtrTy, new IntToPtrInst(X, IntPtrPtrTy, "", EntryBB),
"",
/*isVolatile*/ false, EntryBB);
Y = new LoadInst(IntPtrTy, 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, Ty32, Ty32, Ty32, Ty32};
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), ArgTys, false);
Function *F = Function::Create(FTy, Function::ExternalLinkage, "f", M);
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));
Argument *A3 = &*(std::next(F->arg_begin(), 2));
Argument *A4 = &*(std::next(F->arg_begin(), 3));
Argument *A5 = &*(std::next(F->arg_begin(), 4));
Argument *A6 = &*(std::next(F->arg_begin(), 5));
auto *AddWithNUW = cast<SCEVAddExpr>(SE.getAddExpr(
SE.getAddExpr(SE.getSCEV(A2), SE.getSCEV(A3), SCEV::FlagNUW),
SE.getConstant(APInt(/*numBits=*/32, 5)), SCEV::FlagNUW));
EXPECT_EQ(AddWithNUW->getNumOperands(), 3u);
EXPECT_EQ(AddWithNUW->getNoWrapFlags(), SCEV::FlagNUW);
auto *AddWithAnyWrap =
SE.getAddExpr(SE.getSCEV(A3), SE.getSCEV(A4), SCEV::FlagAnyWrap);
auto *AddWithAnyWrapNUW = cast<SCEVAddExpr>(
SE.getAddExpr(AddWithAnyWrap, SE.getSCEV(A5), SCEV::FlagNUW));
EXPECT_EQ(AddWithAnyWrapNUW->getNumOperands(), 3u);
EXPECT_EQ(AddWithAnyWrapNUW->getNoWrapFlags(), SCEV::FlagAnyWrap);
auto *AddWithNSW = SE.getAddExpr(
SE.getSCEV(A2), SE.getConstant(APInt(32, 99)), SCEV::FlagNSW);
auto *AddWithNSW_NUW = cast<SCEVAddExpr>(
SE.getAddExpr(AddWithNSW, SE.getSCEV(A5), SCEV::FlagNUW));
EXPECT_EQ(AddWithNSW_NUW->getNumOperands(), 3u);
EXPECT_EQ(AddWithNSW_NUW->getNoWrapFlags(), SCEV::FlagAnyWrap);
auto *AddWithNSWNUW =
SE.getAddExpr(SE.getSCEV(A2), SE.getSCEV(A4),
ScalarEvolution::setFlags(SCEV::FlagNUW, SCEV::FlagNSW));
auto *AddWithNSWNUW_NUW = cast<SCEVAddExpr>(
SE.getAddExpr(AddWithNSWNUW, SE.getSCEV(A5), SCEV::FlagNUW));
EXPECT_EQ(AddWithNSWNUW_NUW->getNumOperands(), 3u);
EXPECT_EQ(AddWithNSWNUW_NUW->getNoWrapFlags(), SCEV::FlagNUW);
auto *AddWithNSW_NSWNUW = cast<SCEVAddExpr>(
SE.getAddExpr(AddWithNSW, SE.getSCEV(A6),
ScalarEvolution::setFlags(SCEV::FlagNUW, SCEV::FlagNSW)));
EXPECT_EQ(AddWithNSW_NSWNUW->getNumOperands(), 3u);
EXPECT_EQ(AddWithNSW_NSWNUW->getNoWrapFlags(), SCEV::FlagAnyWrap);
}
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 = Function::Create(FTy, Function::ExternalLinkage, "foo", M);
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, PN, "gep", EndBB);
PrevBB = CondBB;
CondBB = NextBB;
}
ReturnInst::Create(Context, nullptr, EndBB);
ScalarEvolution SE = buildSE(*F);
const SCEV *S = SE.getSCEV(Accum);
S = SE.getLosslessPtrToIntExpr(S);
Type *I128Ty = Type::getInt128Ty(Context);
SE.getZeroExtendExpr(S, I128Ty);
}
// 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 = Function::Create(FTy, Function::ExternalLinkage, "foo", NIM);
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 = Function::Create(FTy, Function::ExternalLinkage, "foo", NIM);
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 =
Function::Create(FTy, Function::ExternalLinkage, "addrecphitest", M);
/*
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 =
Function::Create(FTy, Function::ExternalLinkage, "addrecphitest", M);
/*
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 = Function::Create(FTy, Function::ExternalLinkage, "f", M);
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);
}
// Check logic of SCEV expression size computation.
TEST_F(ScalarEvolutionsTest, SCEVComputeExpressionSize) {
/*
* Create the following code:
* void func(i64 %a, i64 %b)
* entry:
* %s1 = add i64 %a, 1
* %s2 = udiv i64 %s1, %b
* br label %exit
* exit:
* ret
*/
// Create a module.
Module M("SCEVComputeExpressionSize", Context);
Type *T_int64 = Type::getInt64Ty(Context);
FunctionType *FTy =
FunctionType::get(Type::getVoidTy(Context), { T_int64, T_int64 }, false);
Function *F = Function::Create(FTy, Function::ExternalLinkage, "func", M);
Argument *A = &*F->arg_begin();
Argument *B = &*std::next(F->arg_begin());
ConstantInt *C = ConstantInt::get(Context, APInt(64, 1));
BasicBlock *Entry = BasicBlock::Create(Context, "entry", F);
BasicBlock *Exit = BasicBlock::Create(Context, "exit", F);
IRBuilder<> Builder(Entry);
auto *S1 = cast<Instruction>(Builder.CreateAdd(A, C, "s1"));
auto *S2 = cast<Instruction>(Builder.CreateUDiv(S1, B, "s2"));
Builder.CreateBr(Exit);
Builder.SetInsertPoint(Exit);
Builder.CreateRetVoid();
ScalarEvolution SE = buildSE(*F);
// Get S2 first to move it to cache.
const SCEV *AS = SE.getSCEV(A);
const SCEV *BS = SE.getSCEV(B);
const SCEV *CS = SE.getSCEV(C);
const SCEV *S1S = SE.getSCEV(S1);
const SCEV *S2S = SE.getSCEV(S2);
EXPECT_EQ(AS->getExpressionSize(), 1u);
EXPECT_EQ(BS->getExpressionSize(), 1u);
EXPECT_EQ(CS->getExpressionSize(), 1u);
EXPECT_EQ(S1S->getExpressionSize(), 3u);
EXPECT_EQ(S2S->getExpressionSize(), 5u);
}
TEST_F(ScalarEvolutionsTest, SCEVLoopDecIntrinsic) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define void @foo(i32 %N) { "
"entry: "
" %cmp3 = icmp sgt i32 %N, 0 "
" br i1 %cmp3, label %for.body, label %for.cond.cleanup "
"for.cond.cleanup: "
" ret void "
"for.body: "
" %i.04 = phi i32 [ %inc, %for.body ], [ 100, %entry ] "
" %inc = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %i.04, i32 1) "
" %exitcond = icmp ne i32 %inc, 0 "
" br i1 %exitcond, label %for.cond.cleanup, label %for.body "
"} "
"declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32) ",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *ScevInc = SE.getSCEV(getInstructionByName(F, "inc"));
EXPECT_TRUE(isa<SCEVAddRecExpr>(ScevInc));
});
}
TEST_F(ScalarEvolutionsTest, SCEVComputeConstantDifference) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define void @foo(i32 %sz, i32 %pp) { "
"entry: "
" %v0 = add i32 %pp, 0 "
" %v3 = add i32 %pp, 3 "
" br label %loop.body "
"loop.body: "
" %iv = phi i32 [ %iv.next, %loop.body ], [ 0, %entry ] "
" %xa = add nsw i32 %iv, %v0 "
" %yy = add nsw i32 %iv, %v3 "
" %xb = sub nsw i32 %yy, 3 "
" %iv.next = add nsw i32 %iv, 1 "
" %cmp = icmp sle i32 %iv.next, %sz "
" br i1 %cmp, label %loop.body, label %exit "
"exit: "
" ret void "
"} ",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *ScevV0 = SE.getSCEV(getInstructionByName(F, "v0")); // %pp
auto *ScevV3 = SE.getSCEV(getInstructionByName(F, "v3")); // (3 + %pp)
auto *ScevIV = SE.getSCEV(getInstructionByName(F, "iv")); // {0,+,1}
auto *ScevXA = SE.getSCEV(getInstructionByName(F, "xa")); // {%pp,+,1}
auto *ScevYY = SE.getSCEV(getInstructionByName(F, "yy")); // {(3 + %pp),+,1}
auto *ScevXB = SE.getSCEV(getInstructionByName(F, "xb")); // {%pp,+,1}
auto *ScevIVNext = SE.getSCEV(getInstructionByName(F, "iv.next")); // {1,+,1}
auto diff = [&SE](const SCEV *LHS, const SCEV *RHS) -> Optional<int> {
auto ConstantDiffOrNone = computeConstantDifference(SE, LHS, RHS);
if (!ConstantDiffOrNone)
return None;
auto ExtDiff = ConstantDiffOrNone->getSExtValue();
int Diff = ExtDiff;
assert(Diff == ExtDiff && "Integer overflow");
return Diff;
};
EXPECT_EQ(diff(ScevV3, ScevV0), 3);
EXPECT_EQ(diff(ScevV0, ScevV3), -3);
EXPECT_EQ(diff(ScevV0, ScevV0), 0);
EXPECT_EQ(diff(ScevV3, ScevV3), 0);
EXPECT_EQ(diff(ScevIV, ScevIV), 0);
EXPECT_EQ(diff(ScevXA, ScevXB), 0);
EXPECT_EQ(diff(ScevXA, ScevYY), -3);
EXPECT_EQ(diff(ScevYY, ScevXB), 3);
EXPECT_EQ(diff(ScevIV, ScevIVNext), -1);
EXPECT_EQ(diff(ScevIVNext, ScevIV), 1);
EXPECT_EQ(diff(ScevIVNext, ScevIVNext), 0);
EXPECT_EQ(diff(ScevV0, ScevIV), None);
EXPECT_EQ(diff(ScevIVNext, ScevV3), None);
EXPECT_EQ(diff(ScevYY, ScevV3), None);
});
}
TEST_F(ScalarEvolutionsTest, SCEVrewriteUnknowns) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define void @foo(i32 %i) { "
"entry: "
" %cmp3 = icmp ult i32 %i, 16 "
" br i1 %cmp3, label %loop.body, label %exit "
"loop.body: "
" %iv = phi i32 [ %iv.next, %loop.body ], [ %i, %entry ] "
" %iv.next = add nsw i32 %iv, 1 "
" %cmp = icmp eq i32 %iv.next, 16 "
" br i1 %cmp, label %exit, label %loop.body "
"exit: "
" ret void "
"} ",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *ScevIV = SE.getSCEV(getInstructionByName(F, "iv")); // {0,+,1}
auto *ScevI = SE.getSCEV(getArgByName(F, "i")); // {0,+,1}
ValueToSCEVMapTy RewriteMap;
RewriteMap[cast<SCEVUnknown>(ScevI)->getValue()] =
SE.getUMinExpr(ScevI, SE.getConstant(ScevI->getType(), 17));
auto *WithUMin = SCEVParameterRewriter::rewrite(ScevIV, SE, RewriteMap);
EXPECT_NE(WithUMin, ScevIV);
auto *AR = dyn_cast<SCEVAddRecExpr>(WithUMin);
EXPECT_TRUE(AR);
EXPECT_EQ(AR->getStart(),
SE.getUMinExpr(ScevI, SE.getConstant(ScevI->getType(), 17)));
EXPECT_EQ(AR->getStepRecurrence(SE),
cast<SCEVAddRecExpr>(ScevIV)->getStepRecurrence(SE));
});
}
TEST_F(ScalarEvolutionsTest, SCEVAddNUW) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString("define void @foo(i32 %x) { "
" ret void "
"} ",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *X = SE.getSCEV(getArgByName(F, "x"));
auto *One = SE.getOne(X->getType());
auto *Sum = SE.getAddExpr(X, One, SCEV::FlagNUW);
EXPECT_TRUE(SE.isKnownPredicate(ICmpInst::ICMP_UGE, Sum, X));
EXPECT_TRUE(SE.isKnownPredicate(ICmpInst::ICMP_UGT, Sum, X));
});
}
TEST_F(ScalarEvolutionsTest, SCEVgetRanges) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define void @foo(i32 %i) { "
"entry: "
" br label %loop.body "
"loop.body: "
" %iv = phi i32 [ %iv.next, %loop.body ], [ 0, %entry ] "
" %iv.next = add nsw i32 %iv, 1 "
" %cmp = icmp eq i32 %iv.next, 16 "
" br i1 %cmp, label %exit, label %loop.body "
"exit: "
" ret void "
"} ",
Err, C);
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *ScevIV = SE.getSCEV(getInstructionByName(F, "iv")); // {0,+,1}
auto *ScevI = SE.getSCEV(getArgByName(F, "i"));
EXPECT_EQ(SE.getUnsignedRange(ScevIV).getLower(), 0);
EXPECT_EQ(SE.getUnsignedRange(ScevIV).getUpper(), 16);
auto *Add = SE.getAddExpr(ScevI, ScevIV);
ValueToSCEVMapTy RewriteMap;
RewriteMap[cast<SCEVUnknown>(ScevI)->getValue()] =
SE.getUMinExpr(ScevI, SE.getConstant(ScevI->getType(), 17));
auto *AddWithUMin = SCEVParameterRewriter::rewrite(Add, SE, RewriteMap);
EXPECT_EQ(SE.getUnsignedRange(AddWithUMin).getLower(), 0);
EXPECT_EQ(SE.getUnsignedRange(AddWithUMin).getUpper(), 33);
});
}
TEST_F(ScalarEvolutionsTest, SCEVgetExitLimitForGuardedLoop) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define void @foo(i32 %i) { "
"entry: "
" %cmp3 = icmp ult i32 %i, 16 "
" br i1 %cmp3, label %loop.body, label %exit "
"loop.body: "
" %iv = phi i32 [ %iv.next, %loop.body ], [ %i, %entry ] "
" %iv.next = add nsw i32 %iv, 1 "
" %cmp = icmp eq i32 %iv.next, 16 "
" br i1 %cmp, label %exit, label %loop.body "
"exit: "
" ret void "
"} ",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *ScevIV = SE.getSCEV(getInstructionByName(F, "iv")); // {0,+,1}
const Loop *L = cast<SCEVAddRecExpr>(ScevIV)->getLoop();
const SCEV *BTC = SE.getBackedgeTakenCount(L);
EXPECT_FALSE(isa<SCEVConstant>(BTC));
const SCEV *MaxBTC = SE.getConstantMaxBackedgeTakenCount(L);
EXPECT_EQ(cast<SCEVConstant>(MaxBTC)->getAPInt(), 15);
});
}
TEST_F(ScalarEvolutionsTest, ImpliedViaAddRecStart) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define void @foo(i32* %p) { "
"entry: "
" %x = load i32, i32* %p, !range !0 "
" br label %loop "
"loop: "
" %iv = phi i32 [ %x, %entry], [%iv.next, %backedge] "
" %ne.check = icmp ne i32 %iv, 0 "
" br i1 %ne.check, label %backedge, label %exit "
"backedge: "
" %iv.next = add i32 %iv, -1 "
" br label %loop "
"exit:"
" ret void "
"} "
"!0 = !{i32 0, i32 2147483647}",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *X = SE.getSCEV(getInstructionByName(F, "x"));
auto *Context = getInstructionByName(F, "iv.next");
EXPECT_TRUE(SE.isKnownPredicateAt(ICmpInst::ICMP_NE, X,
SE.getZero(X->getType()), Context));
});
}
TEST_F(ScalarEvolutionsTest, UnsignedIsImpliedViaOperations) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M =
parseAssemblyString("define void @foo(i32* %p1, i32* %p2) { "
"entry: "
" %x = load i32, i32* %p1, !range !0 "
" %cond = icmp ne i32 %x, 0 "
" br i1 %cond, label %guarded, label %exit "
"guarded: "
" %y = add i32 %x, -1 "
" ret void "
"exit: "
" ret void "
"} "
"!0 = !{i32 0, i32 2147483647}",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *X = SE.getSCEV(getInstructionByName(F, "x"));
auto *Y = SE.getSCEV(getInstructionByName(F, "y"));
auto *Guarded = getInstructionByName(F, "y")->getParent();
ASSERT_TRUE(Guarded);
EXPECT_TRUE(
SE.isBasicBlockEntryGuardedByCond(Guarded, ICmpInst::ICMP_ULT, Y, X));
EXPECT_TRUE(
SE.isBasicBlockEntryGuardedByCond(Guarded, ICmpInst::ICMP_UGT, X, Y));
});
}
TEST_F(ScalarEvolutionsTest, ProveImplicationViaNarrowing) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define i32 @foo(i32 %start, i32* %q) { "
"entry: "
" %wide.start = zext i32 %start to i64 "
" br label %loop "
"loop: "
" %wide.iv = phi i64 [%wide.start, %entry], [%wide.iv.next, %backedge] "
" %iv = phi i32 [%start, %entry], [%iv.next, %backedge] "
" %cond = icmp eq i64 %wide.iv, 0 "
" br i1 %cond, label %exit, label %backedge "
"backedge: "
" %iv.next = add i32 %iv, -1 "
" %index = zext i32 %iv.next to i64 "
" %load.addr = getelementptr i32, i32* %q, i64 %index "
" %stop = load i32, i32* %load.addr "
" %loop.cond = icmp eq i32 %stop, 0 "
" %wide.iv.next = add nsw i64 %wide.iv, -1 "
" br i1 %loop.cond, label %loop, label %failure "
"exit: "
" ret i32 0 "
"failure: "
" unreachable "
"} ",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
auto *IV = SE.getSCEV(getInstructionByName(F, "iv"));
auto *Zero = SE.getZero(IV->getType());
auto *Backedge = getInstructionByName(F, "iv.next")->getParent();
ASSERT_TRUE(Backedge);
(void)IV;
(void)Zero;
// FIXME: This can only be proved with turned on option
// scalar-evolution-use-expensive-range-sharpening which is currently off.
// Enable the check once it's switched true by default.
// EXPECT_TRUE(SE.isBasicBlockEntryGuardedByCond(Backedge,
// ICmpInst::ICMP_UGT,
// IV, Zero));
});
}
TEST_F(ScalarEvolutionsTest, ImpliedCond) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString(
"define void @foo(i32 %len) { "
"entry: "
" br label %loop "
"loop: "
" %iv = phi i32 [ 0, %entry], [%iv.next, %loop] "
" %iv.next = add nsw i32 %iv, 1 "
" %cmp = icmp slt i32 %iv, %len "
" br i1 %cmp, label %loop, label %exit "
"exit:"
" ret void "
"}",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
Instruction *IV = getInstructionByName(F, "iv");
Type *Ty = IV->getType();
const SCEV *Zero = SE.getZero(Ty);
const SCEV *MinusOne = SE.getMinusOne(Ty);
// {0,+,1}<nuw><nsw>
const SCEV *AddRec_0_1 = SE.getSCEV(IV);
// {0,+,-1}<nw>
const SCEV *AddRec_0_N1 = SE.getNegativeSCEV(AddRec_0_1);
// {0,+,1}<nuw><nsw> > 0 -> {0,+,-1}<nw> < 0
EXPECT_TRUE(isImpliedCond(SE, ICmpInst::ICMP_SLT, AddRec_0_N1, Zero,
ICmpInst::ICMP_SGT, AddRec_0_1, Zero));
// {0,+,-1}<nw> < -1 -> {0,+,1}<nuw><nsw> > 0
EXPECT_TRUE(isImpliedCond(SE, ICmpInst::ICMP_SGT, AddRec_0_1, Zero,
ICmpInst::ICMP_SLT, AddRec_0_N1, MinusOne));
});
}
TEST_F(ScalarEvolutionsTest, MatchURem) {
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\" "
" "
"define void @test(i32 %a, i32 %b, i16 %c, i64 %d) {"
"entry: "
" %rem1 = urem i32 %a, 2"
" %rem2 = urem i32 %a, 5"
" %rem3 = urem i32 %a, %b"
" %c.ext = zext i16 %c to i32"
" %rem4 = urem i32 %c.ext, 2"
" %ext = zext i32 %rem4 to i64"
" %rem5 = urem i64 %d, 17179869184"
" ret void "
"} ",
Err, C);
assert(M && "Could not parse module?");
assert(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "test", [&](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
for (auto *N : {"rem1", "rem2", "rem3", "rem5"}) {
auto *URemI = getInstructionByName(F, N);
auto *S = SE.getSCEV(URemI);
const SCEV *LHS, *RHS;
EXPECT_TRUE(matchURem(SE, S, LHS, RHS));
EXPECT_EQ(LHS, SE.getSCEV(URemI->getOperand(0)));
EXPECT_EQ(RHS, SE.getSCEV(URemI->getOperand(1)));
EXPECT_EQ(LHS->getType(), S->getType());
EXPECT_EQ(RHS->getType(), S->getType());
}
// Check the case where the urem operand is zero-extended. Make sure the
// match results are extended to the size of the input expression.
auto *Ext = getInstructionByName(F, "ext");
auto *URem1 = getInstructionByName(F, "rem4");
auto *S = SE.getSCEV(Ext);
const SCEV *LHS, *RHS;
EXPECT_TRUE(matchURem(SE, S, LHS, RHS));
EXPECT_NE(LHS, SE.getSCEV(URem1->getOperand(0)));
// RHS and URem1->getOperand(1) have different widths, so compare the
// integer values.
EXPECT_EQ(cast<SCEVConstant>(RHS)->getValue()->getZExtValue(),
cast<SCEVConstant>(SE.getSCEV(URem1->getOperand(1)))
->getValue()
->getZExtValue());
EXPECT_EQ(LHS->getType(), S->getType());
EXPECT_EQ(RHS->getType(), S->getType());
});
}
TEST_F(ScalarEvolutionsTest, SCEVUDivFloorCeiling) {
LLVMContext C;
SMDiagnostic Err;
std::unique_ptr<Module> M = parseAssemblyString("define void @foo() { "
" ret void "
"} ",
Err, C);
ASSERT_TRUE(M && "Could not parse module?");
ASSERT_TRUE(!verifyModule(*M) && "Must have been well formed!");
runWithSE(*M, "foo", [](Function &F, LoopInfo &LI, ScalarEvolution &SE) {
// Check that SCEV's udiv and uceil handling produce the correct results
// for all 8 bit options. Div-by-zero is deliberately excluded.
for (unsigned N = 0; N < 256; N++)
for (unsigned D = 1; D < 256; D++) {
APInt NInt(8, N);
APInt DInt(8, D);
using namespace llvm::APIntOps;
APInt FloorInt = RoundingUDiv(NInt, DInt, APInt::Rounding::DOWN);
APInt CeilingInt = RoundingUDiv(NInt, DInt, APInt::Rounding::UP);
auto *NS = SE.getConstant(NInt);
auto *DS = SE.getConstant(DInt);
auto *FloorS = cast<SCEVConstant>(SE.getUDivExpr(NS, DS));
auto *CeilingS = cast<SCEVConstant>(SE.getUDivCeilSCEV(NS, DS));
ASSERT_TRUE(FloorS->getAPInt() == FloorInt);
ASSERT_TRUE(CeilingS->getAPInt() == CeilingInt);
}
});
}
} // end namespace llvm
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