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[SLSR] handle candidate form &B[i * S]

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Summary:
This patch enhances SLSR to handle another candidate form &B[i * S]. If
we found two candidates

S1: X = &B[i * S]
S2: Y = &B[i' * S]

and S1 dominates S2, we can replace S2 with

Y = &X[(i' - i) * S]

Test Plan:
slsr-gep.ll
X86/no-slsr.ll: verify that we do not run SLSR on GEPs that already fit into
an addressing mode

Reviewers: eliben, atrick, meheff, hfinkel

Reviewed By: hfinkel

Subscribers: sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D7459

llvm-svn: 233286
This commit is contained in:
Jingyue Wu 2015-03-26 16:49:24 +00:00
parent b816aeb026
commit 537669aad8
5 changed files with 471 additions and 67 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

395
lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
View File

@ -15,19 +15,30 @@
//
// There are many optimizations we can perform in the domain of SLSR. This file
// for now contains only an initial step. Specifically, we look for strength
// reduction candidate in the form of
// reduction candidates in two forms:
//
// (B + i) * S
// Form 1: (B + i) * S
// Form 2: &B[i * S]
//
// where B and S are integer constants or variables, and i is a constant
// integer. If we found two such candidates
// where S is an integer variable, and i is a constant integer. If we found two
// candidates
//
// S1: X = (B + i) * S S2: Y = (B + i') * S
// S1: X = (B + i) * S
// S2: Y = (B + i') * S
//
// or
//
// S1: X = &B[i * S]
// S2: Y = &B[i' * S]
//
// and S1 dominates S2, we call S1 a basis of S2, and can replace S2 with
//
// Y = X + (i' - i) * S
//
// or
//
// Y = &X[(i' - i) * S]
//
// where (i' - i) * S is folded to the extent possible. When S2 has multiple
// bases, we pick the one that is closest to S2, or S2's "immediate" basis.
//
@ -35,8 +46,6 @@
//
// - Handle candidates in the form of B + i * S
//
// - Handle candidates in the form of pointer arithmetics. e.g., B[i * S]
//
// - Floating point arithmetics when fast math is enabled.
//
// - SLSR may decrease ILP at the architecture level. Targets that are very
@ -45,6 +54,10 @@
#include <vector>
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
@ -58,14 +71,30 @@ using namespace PatternMatch;
namespace {
class StraightLineStrengthReduce : public FunctionPass {
public:
public:
// SLSR candidate. Such a candidate must be in the form of
// (Base + Index) * Stride
// or
// Base[..][Index * Stride][..]
struct Candidate : public ilist_node<Candidate> {
Candidate(Value *B = nullptr, ConstantInt *Idx = nullptr,
Value *S = nullptr, Instruction *I = nullptr)
: Base(B), Index(Idx), Stride(S), Ins(I), Basis(nullptr) {}
Value *Base;
enum Kind {
Invalid, // reserved for the default constructor
Mul, // (B + i) * S
GEP, // &B[..][i * S][..]
};
Candidate()
: CandidateKind(Invalid), Base(nullptr), Index(nullptr),
Stride(nullptr), Ins(nullptr), Basis(nullptr) {}
Candidate(Kind CT, const SCEV *B, ConstantInt *Idx, Value *S,
Instruction *I)
: CandidateKind(CT), Base(B), Index(Idx), Stride(S), Ins(I),
Basis(nullptr) {}
Kind CandidateKind;
const SCEV *Base;
// Note that Index and Stride of a GEP candidate may not have the same
// integer type. In that case, during rewriting, Stride will be
// sign-extended or truncated to Index's type.
ConstantInt *Index;
Value *Stride;
// The instruction this candidate corresponds to. It helps us to rewrite a
@ -90,33 +119,70 @@ class StraightLineStrengthReduce : public FunctionPass {
static char ID;
StraightLineStrengthReduce() : FunctionPass(ID), DT(nullptr) {
StraightLineStrengthReduce()
: FunctionPass(ID), DL(nullptr), DT(nullptr), TTI(nullptr) {
initializeStraightLineStrengthReducePass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<ScalarEvolution>();
AU.addRequired<TargetTransformInfoWrapperPass>();
// We do not modify the shape of the CFG.
AU.setPreservesCFG();
}
bool doInitialization(Module &M) override {
DL = &M.getDataLayout();
return false;
}
bool runOnFunction(Function &F) override;
private:
private:
// Returns true if Basis is a basis for C, i.e., Basis dominates C and they
// share the same base and stride.
bool isBasisFor(const Candidate &Basis, const Candidate &C);
// Checks whether I is in a candidate form. If so, adds all the matching forms
// to Candidates, and tries to find the immediate basis for each of them.
void allocateCandidateAndFindBasis(Instruction *I);
// Given that I is in the form of "(B + Idx) * S", adds this form to
// Candidates, and finds its immediate basis.
void allocateCandidateAndFindBasis(Value *B, ConstantInt *Idx, Value *S,
// Allocate candidates and find bases for Mul instructions.
void allocateCandidateAndFindBasisForMul(Instruction *I);
// Splits LHS into Base + Index and, if succeeds, calls
// allocateCandidateAndFindBasis.
void allocateCandidateAndFindBasisForMul(Value *LHS, Value *RHS,
Instruction *I);
// Allocate candidates and find bases for GetElementPtr instructions.
void allocateCandidateAndFindBasisForGEP(GetElementPtrInst *GEP);
// A helper function that scales Idx with ElementSize before invoking
// allocateCandidateAndFindBasis.
void allocateCandidateAndFindBasisForGEP(const SCEV *B, ConstantInt *Idx,
Value *S, uint64_t ElementSize,
Instruction *I);
// Adds the given form <CT, B, Idx, S> to Candidates, and finds its immediate
// basis.
void allocateCandidateAndFindBasis(Candidate::Kind CT, const SCEV *B,
ConstantInt *Idx, Value *S,
Instruction *I);
// Rewrites candidate C with respect to Basis.
void rewriteCandidateWithBasis(const Candidate &C, const Candidate &Basis);
// A helper function that factors ArrayIdx to a product of a stride and a
// constant index, and invokes allocateCandidateAndFindBasis with the
// factorings.
void factorArrayIndex(Value *ArrayIdx, const SCEV *Base, uint64_t ElementSize,
GetElementPtrInst *GEP);
// Emit code that computes the "bump" from Basis to C. If the candidate is a
// GEP and the bump is not divisible by the element size of the GEP, this
// function sets the BumpWithUglyGEP flag to notify its caller to bump the
// basis using an ugly GEP.
static Value *emitBump(const Candidate &Basis, const Candidate &C,
IRBuilder<> &Builder, const DataLayout *DL,
bool &BumpWithUglyGEP);
const DataLayout *DL;
DominatorTree *DT;
ScalarEvolution *SE;
TargetTransformInfo *TTI;
ilist<Candidate> Candidates;
// Temporarily holds all instructions that are unlinked (but not deleted) by
// rewriteCandidateWithBasis. These instructions will be actually removed
@ -129,6 +195,8 @@ char StraightLineStrengthReduce::ID = 0;
INITIALIZE_PASS_BEGIN(StraightLineStrengthReduce, "slsr",
"Straight line strength reduction", false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_END(StraightLineStrengthReduce, "slsr",
"Straight line strength reduction", false, false)
@ -141,9 +209,47 @@ bool StraightLineStrengthReduce::isBasisFor(const Candidate &Basis,
return (Basis.Ins != C.Ins && // skip the same instruction
// Basis must dominate C in order to rewrite C with respect to Basis.
DT->dominates(Basis.Ins->getParent(), C.Ins->getParent()) &&
// They share the same base and stride.
// They share the same base, stride, and candidate kind.
Basis.Base == C.Base &&
Basis.Stride == C.Stride);
Basis.Stride == C.Stride &&
Basis.CandidateKind == C.CandidateKind);
}
static bool isCompletelyFoldable(GetElementPtrInst *GEP,
const TargetTransformInfo *TTI,
const DataLayout *DL) {
GlobalVariable *BaseGV = nullptr;
int64_t BaseOffset = 0;
bool HasBaseReg = false;
int64_t Scale = 0;
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getPointerOperand()))
BaseGV = GV;
else
HasBaseReg = true;
gep_type_iterator GTI = gep_type_begin(GEP);
for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I, ++GTI) {
if (isa<SequentialType>(*GTI)) {
int64_t ElementSize = DL->getTypeAllocSize(GTI.getIndexedType());
if (ConstantInt *ConstIdx = dyn_cast<ConstantInt>(*I)) {
BaseOffset += ConstIdx->getSExtValue() * ElementSize;
} else {
// Needs scale register.
if (Scale != 0) {
// No addressing mode takes two scale registers.
return false;
}
Scale = ElementSize;
}
} else {
StructType *STy = cast<StructType>(*GTI);
uint64_t Field = cast<ConstantInt>(*I)->getZExtValue();
BaseOffset += DL->getStructLayout(STy)->getElementOffset(Field);
}
}
return TTI->isLegalAddressingMode(GEP->getType()->getElementType(), BaseGV,
BaseOffset, HasBaseReg, Scale);
}
// TODO: We currently implement an algorithm whose time complexity is linear to
@ -153,11 +259,17 @@ bool StraightLineStrengthReduce::isBasisFor(const Candidate &Basis,
// table is indexed by the base and the stride of a candidate. Therefore,
// finding the immediate basis of a candidate boils down to one hash-table look
// up.
void StraightLineStrengthReduce::allocateCandidateAndFindBasis(Value *B,
ConstantInt *Idx,
Value *S,
Instruction *I) {
Candidate C(B, Idx, S, I);
void StraightLineStrengthReduce::allocateCandidateAndFindBasis(
Candidate::Kind CT, const SCEV *B, ConstantInt *Idx, Value *S,
Instruction *I) {
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
// If &B[Idx * S] fits into an addressing mode, do not turn it into
// non-free computation.
if (isCompletelyFoldable(GEP, TTI, DL))
return;
}
Candidate C(CT, B, Idx, S, I);
// Try to compute the immediate basis of C.
unsigned NumIterations = 0;
// Limit the scan radius to avoid running forever.
@ -176,60 +288,209 @@ void StraightLineStrengthReduce::allocateCandidateAndFindBasis(Value *B,
}
void StraightLineStrengthReduce::allocateCandidateAndFindBasis(Instruction *I) {
switch (I->getOpcode()) {
case Instruction::Mul:
allocateCandidateAndFindBasisForMul(I);
break;
case Instruction::GetElementPtr:
allocateCandidateAndFindBasisForGEP(cast<GetElementPtrInst>(I));
break;
}
}
void StraightLineStrengthReduce::allocateCandidateAndFindBasisForMul(
Value *LHS, Value *RHS, Instruction *I) {
Value *B = nullptr;
ConstantInt *Idx = nullptr;
// "(Base + Index) * Stride" must be a Mul instruction at the first hand.
if (I->getOpcode() == Instruction::Mul) {
if (IntegerType *ITy = dyn_cast<IntegerType>(I->getType())) {
Value *LHS = I->getOperand(0), *RHS = I->getOperand(1);
for (unsigned Swapped = 0; Swapped < 2; ++Swapped) {
// Only handle the canonical operand ordering.
if (match(LHS, m_Add(m_Value(B), m_ConstantInt(Idx)))) {
// If LHS is in the form of "Base + Index", then I is in the form of
// "(Base + Index) * RHS".
allocateCandidateAndFindBasis(B, Idx, RHS, I);
} else {
// Otherwise, at least try the form (LHS + 0) * RHS.
allocateCandidateAndFindBasis(LHS, ConstantInt::get(ITy, 0), RHS, I);
}
// Swap LHS and RHS so that we also cover the cases where LHS is the
// stride.
if (LHS == RHS)
break;
std::swap(LHS, RHS);
}
}
// Only handle the canonical operand ordering.
if (match(LHS, m_Add(m_Value(B), m_ConstantInt(Idx)))) {
// If LHS is in the form of "Base + Index", then I is in the form of
// "(Base + Index) * RHS".
allocateCandidateAndFindBasis(Candidate::Mul, SE->getSCEV(B), Idx, RHS, I);
} else {
// Otherwise, at least try the form (LHS + 0) * RHS.
ConstantInt *Zero = ConstantInt::get(cast<IntegerType>(I->getType()), 0);
allocateCandidateAndFindBasis(Candidate::Mul, SE->getSCEV(LHS), Zero, RHS,
I);
}
}
void StraightLineStrengthReduce::allocateCandidateAndFindBasisForMul(
Instruction *I) {
// Try matching (B + i) * S.
// TODO: we could extend SLSR to float and vector types.
if (!isa<IntegerType>(I->getType()))
return;
Value *LHS = I->getOperand(0), *RHS = I->getOperand(1);
allocateCandidateAndFindBasisForMul(LHS, RHS, I);
if (LHS != RHS) {
// Symmetrically, try to split RHS to Base + Index.
allocateCandidateAndFindBasisForMul(RHS, LHS, I);
}
}
void StraightLineStrengthReduce::allocateCandidateAndFindBasisForGEP(
const SCEV *B, ConstantInt *Idx, Value *S, uint64_t ElementSize,
Instruction *I) {
// I = B + sext(Idx *nsw S) *nsw ElementSize
// = B + (sext(Idx) * ElementSize) * sext(S)
// Casting to IntegerType is safe because we skipped vector GEPs.
IntegerType *IntPtrTy = cast<IntegerType>(DL->getIntPtrType(I->getType()));
ConstantInt *ScaledIdx = ConstantInt::get(
IntPtrTy, Idx->getSExtValue() * (int64_t)ElementSize, true);
allocateCandidateAndFindBasis(Candidate::GEP, B, ScaledIdx, S, I);
}
void StraightLineStrengthReduce::factorArrayIndex(Value *ArrayIdx,
const SCEV *Base,
uint64_t ElementSize,
GetElementPtrInst *GEP) {
// At least, ArrayIdx = ArrayIdx *s 1.
allocateCandidateAndFindBasisForGEP(
Base, ConstantInt::get(cast<IntegerType>(ArrayIdx->getType()), 1),
ArrayIdx, ElementSize, GEP);
Value *LHS = nullptr;
ConstantInt *RHS = nullptr;
// TODO: handle shl. e.g., we could treat (S << 2) as (S * 4).
//
// One alternative is matching the SCEV of ArrayIdx instead of ArrayIdx
// itself. This would allow us to handle the shl case for free. However,
// matching SCEVs has two issues:
//
// 1. this would complicate rewriting because the rewriting procedure
// would have to translate SCEVs back to IR instructions. This translation
// is difficult when LHS is further evaluated to a composite SCEV.
//
// 2. ScalarEvolution is designed to be control-flow oblivious. It tends
// to strip nsw/nuw flags which are critical for SLSR to trace into
// sext'ed multiplication.
if (match(ArrayIdx, m_NSWMul(m_Value(LHS), m_ConstantInt(RHS)))) {
// SLSR is currently unsafe if i * S may overflow.
// GEP = Base + sext(LHS *nsw RHS) *nsw ElementSize
allocateCandidateAndFindBasisForGEP(Base, RHS, LHS, ElementSize, GEP);
}
}
void StraightLineStrengthReduce::allocateCandidateAndFindBasisForGEP(
GetElementPtrInst *GEP) {
// TODO: handle vector GEPs
if (GEP->getType()->isVectorTy())
return;
const SCEV *GEPExpr = SE->getSCEV(GEP);
Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
gep_type_iterator GTI = gep_type_begin(GEP);
for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I) {
if (!isa<SequentialType>(*GTI++))
continue;
Value *ArrayIdx = *I;
// Compute the byte offset of this index.
uint64_t ElementSize = DL->getTypeAllocSize(*GTI);
const SCEV *ElementSizeExpr = SE->getSizeOfExpr(IntPtrTy, *GTI);
const SCEV *ArrayIdxExpr = SE->getSCEV(ArrayIdx);
ArrayIdxExpr = SE->getTruncateOrSignExtend(ArrayIdxExpr, IntPtrTy);
const SCEV *LocalOffset =
SE->getMulExpr(ArrayIdxExpr, ElementSizeExpr, SCEV::FlagNSW);
// The base of this candidate equals GEPExpr less the byte offset of this
// index.
const SCEV *Base = SE->getMinusSCEV(GEPExpr, LocalOffset);
factorArrayIndex(ArrayIdx, Base, ElementSize, GEP);
// When ArrayIdx is the sext of a value, we try to factor that value as
// well. Handling this case is important because array indices are
// typically sign-extended to the pointer size.
Value *TruncatedArrayIdx = nullptr;
if (match(ArrayIdx, m_SExt(m_Value(TruncatedArrayIdx))))
factorArrayIndex(TruncatedArrayIdx, Base, ElementSize, GEP);
}
}
// A helper function that unifies the bitwidth of A and B.
static void unifyBitWidth(APInt &A, APInt &B) {
if (A.getBitWidth() < B.getBitWidth())
A = A.sext(B.getBitWidth());
else if (A.getBitWidth() > B.getBitWidth())
B = B.sext(A.getBitWidth());
}
Value *StraightLineStrengthReduce::emitBump(const Candidate &Basis,
const Candidate &C,
IRBuilder<> &Builder,
const DataLayout *DL,
bool &BumpWithUglyGEP) {
APInt Idx = C.Index->getValue(), BasisIdx = Basis.Index->getValue();
unifyBitWidth(Idx, BasisIdx);
APInt IndexOffset = Idx - BasisIdx;
BumpWithUglyGEP = false;
if (Basis.CandidateKind == Candidate::GEP) {
APInt ElementSize(
IndexOffset.getBitWidth(),
DL->getTypeAllocSize(
cast<GetElementPtrInst>(Basis.Ins)->getType()->getElementType()));
APInt Q, R;
APInt::sdivrem(IndexOffset, ElementSize, Q, R);
if (R.getSExtValue() == 0)
IndexOffset = Q;
else
BumpWithUglyGEP = true;
}
// Compute Bump = C - Basis = (i' - i) * S.
// Common case 1: if (i' - i) is 1, Bump = S.
if (IndexOffset.getSExtValue() == 1)
return C.Stride;
// Common case 2: if (i' - i) is -1, Bump = -S.
if (IndexOffset.getSExtValue() == -1)
return Builder.CreateNeg(C.Stride);
// Otherwise, Bump = (i' - i) * sext/trunc(S).
ConstantInt *Delta = ConstantInt::get(Basis.Ins->getContext(), IndexOffset);
Value *ExtendedStride = Builder.CreateSExtOrTrunc(C.Stride, Delta->getType());
return Builder.CreateMul(ExtendedStride, Delta);
}
void StraightLineStrengthReduce::rewriteCandidateWithBasis(
const Candidate &C, const Candidate &Basis) {
assert(C.CandidateKind == Basis.CandidateKind && C.Base == Basis.Base &&
C.Stride == Basis.Stride);
// An instruction can correspond to multiple candidates. Therefore, instead of
// simply deleting an instruction when we rewrite it, we mark its parent as
// nullptr (i.e. unlink it) so that we can skip the candidates whose
// instruction is already rewritten.
if (!C.Ins->getParent())
return;
assert(C.Base == Basis.Base && C.Stride == Basis.Stride);
// Basis = (B + i) * S
// C = (B + i') * S
// ==>
// C = Basis + (i' - i) * S
IRBuilder<> Builder(C.Ins);
ConstantInt *IndexOffset = ConstantInt::get(
C.Ins->getContext(), C.Index->getValue() - Basis.Index->getValue());
Value *Reduced;
// TODO: preserve nsw/nuw in some cases.
if (IndexOffset->isOne()) {
// If (i' - i) is 1, fold C into Basis + S.
Reduced = Builder.CreateAdd(Basis.Ins, C.Stride);
} else if (IndexOffset->isMinusOne()) {
// If (i' - i) is -1, fold C into Basis - S.
Reduced = Builder.CreateSub(Basis.Ins, C.Stride);
} else {
Value *Bump = Builder.CreateMul(C.Stride, IndexOffset);
bool BumpWithUglyGEP;
Value *Bump = emitBump(Basis, C, Builder, DL, BumpWithUglyGEP);
Value *Reduced = nullptr; // equivalent to but weaker than C.Ins
switch (C.CandidateKind) {
case Candidate::Mul:
Reduced = Builder.CreateAdd(Basis.Ins, Bump);
}
break;
case Candidate::GEP:
{
Type *IntPtrTy = DL->getIntPtrType(C.Ins->getType());
if (BumpWithUglyGEP) {
// C = (char *)Basis + Bump
unsigned AS = Basis.Ins->getType()->getPointerAddressSpace();
Type *CharTy = Type::getInt8PtrTy(Basis.Ins->getContext(), AS);
Reduced = Builder.CreateBitCast(Basis.Ins, CharTy);
// We only considered inbounds GEP as candidates.
Reduced = Builder.CreateInBoundsGEP(Reduced, Bump);
Reduced = Builder.CreateBitCast(Reduced, C.Ins->getType());
} else {
// C = gep Basis, Bump
// Canonicalize bump to pointer size.
Bump = Builder.CreateSExtOrTrunc(Bump, IntPtrTy);
Reduced = Builder.CreateInBoundsGEP(Basis.Ins, Bump);
}
}
break;
default:
llvm_unreachable("C.CandidateKind is invalid");
};
Reduced->takeName(C.Ins);
C.Ins->replaceAllUsesWith(Reduced);
C.Ins->dropAllReferences();
@ -243,15 +504,15 @@ bool StraightLineStrengthReduce::runOnFunction(Function &F) {
if (skipOptnoneFunction(F))
return false;
TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
SE = &getAnalysis<ScalarEvolution>();
// Traverse the dominator tree in the depth-first order. This order makes sure
// all bases of a candidate are in Candidates when we process it.
for (auto node = GraphTraits<DominatorTree *>::nodes_begin(DT);
node != GraphTraits<DominatorTree *>::nodes_end(DT); ++node) {
BasicBlock *B = node->getBlock();
for (auto I = B->begin(); I != B->end(); ++I) {
allocateCandidateAndFindBasis(I);
}
for (auto &I : *node->getBlock())
allocateCandidateAndFindBasis(&I);
}
// Rewrite candidates in the reverse depth-first order. This order makes sure

2
test/Transforms/StraightLineStrengthReduce/X86/lit.local.cfg Normal file
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@ -0,0 +1,2 @@
if not 'X86' in config.root.targets:
config.unsupported = True

30
test/Transforms/StraightLineStrengthReduce/X86/no-slsr.ll Normal file
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@ -0,0 +1,30 @@
; RUN: opt < %s -slsr -gvn -dce -S | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
; Do not perform SLSR on &input[s] and &input[s * 2] which fit into addressing
; modes of X86.
define i32 @slsr_gep(i32* %input, i64 %s) {
; CHECK-LABEL: @slsr_gep(
; v0 = input[0];
%p0 = getelementptr inbounds i32, i32* %input, i64 0
%v0 = load i32, i32* %p0
; v1 = input[s];
%p1 = getelementptr inbounds i32, i32* %input, i64 %s
; CHECK: %p1 = getelementptr inbounds i32, i32* %input, i64 %s
%v1 = load i32, i32* %p1
; v2 = input[s * 2];
%s2 = mul nsw i64 %s, 2
%p2 = getelementptr inbounds i32, i32* %input, i64 %s2
; CHECK: %p2 = getelementptr inbounds i32, i32* %input, i64 %s2
%v2 = load i32, i32* %p2
; return v0 + v1 + v2;
%1 = add i32 %v0, %v1
%2 = add i32 %1, %v2
ret i32 %2
}

109
test/Transforms/StraightLineStrengthReduce/slsr-gep.ll Normal file
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@ -0,0 +1,109 @@
; RUN: opt < %s -slsr -gvn -dce -S | FileCheck %s
target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
define i32 @slsr_gep(i32* %input, i64 %s) {
; CHECK-LABEL: @slsr_gep(
; v0 = input[0];
%p0 = getelementptr inbounds i32, i32* %input, i64 0
%v0 = load i32, i32* %p0
; v1 = input[s];
%p1 = getelementptr inbounds i32, i32* %input, i64 %s
; CHECK: %p1 = getelementptr inbounds i32, i32* %input, i64 %s
%v1 = load i32, i32* %p1
; v2 = input[s * 2];
%s2 = mul nsw i64 %s, 2
%p2 = getelementptr inbounds i32, i32* %input, i64 %s2
; CHECK: %p2 = getelementptr inbounds i32, i32* %p1, i64 %s
%v2 = load i32, i32* %p2
; return v0 + v1 + v2;
%1 = add i32 %v0, %v1
%2 = add i32 %1, %v2
ret i32 %2
}
define i32 @slsr_gep_sext(i32* %input, i32 %s) {
; CHECK-LABEL: @slsr_gep_sext(
; v0 = input[0];
%p0 = getelementptr inbounds i32, i32* %input, i64 0
%v0 = load i32, i32* %p0
; v1 = input[(long)s];
%t = sext i32 %s to i64
%p1 = getelementptr inbounds i32, i32* %input, i64 %t
; CHECK: %p1 = getelementptr inbounds i32, i32* %input, i64 %t
%v1 = load i32, i32* %p1
; v2 = input[(long)(s * 2)];
%s2 = mul nsw i32 %s, 2
%t2 = sext i32 %s2 to i64
%p2 = getelementptr inbounds i32, i32* %input, i64 %t2
; CHECK: %p2 = getelementptr inbounds i32, i32* %p1, i64 %t
%v2 = load i32, i32* %p2
; return v0 + v1 + v2;
%1 = add i32 %v0, %v1
%2 = add i32 %1, %v2
ret i32 %2
}
define i32 @slsr_gep_2d([10 x [5 x i32]]* %input, i64 %s, i64 %t) {
; CHECK-LABEL: @slsr_gep_2d(
; v0 = input[s][t];
%p0 = getelementptr inbounds [10 x [5 x i32]], [10 x [5 x i32]]* %input, i64 0, i64 %s, i64 %t
%v0 = load i32, i32* %p0
; v1 = input[s * 2][t];
%s2 = mul nsw i64 %s, 2
; CHECK: [[BUMP:%[a-zA-Z0-9]+]] = mul i64 %s, 5
%p1 = getelementptr inbounds [10 x [5 x i32]], [10 x [5 x i32]]* %input, i64 0, i64 %s2, i64 %t
; CHECK: %p1 = getelementptr inbounds i32, i32* %p0, i64 [[BUMP]]
%v1 = load i32, i32* %p1
; v2 = input[s * 3][t];
%s3 = mul nsw i64 %s, 3
%p2 = getelementptr inbounds [10 x [5 x i32]], [10 x [5 x i32]]* %input, i64 0, i64 %s3, i64 %t
; CHECK: %p2 = getelementptr inbounds i32, i32* %p1, i64 [[BUMP]]
%v2 = load i32, i32* %p2
; return v0 + v1 + v2;
%1 = add i32 %v0, %v1
%2 = add i32 %1, %v2
ret i32 %2
}
%struct.S = type <{ i64, i32 }>
; In this case, the bump
; = (char *)&input[s * 2][t].f1 - (char *)&input[s][t].f1
; = 60 * s
; which may not be divisible by typeof(input[s][t].f1) = 8. Therefore, we
; rewrite the candidates using byte offset instead of index offset as in
; @slsr_gep_2d.
define i64 @slsr_gep_uglygep([10 x [5 x %struct.S]]* %input, i64 %s, i64 %t) {
; CHECK-LABEL: @slsr_gep_uglygep(
; v0 = input[s][t].f1;
%p0 = getelementptr inbounds [10 x [5 x %struct.S]], [10 x [5 x %struct.S]]* %input, i64 0, i64 %s, i64 %t, i32 0
%v0 = load i64, i64* %p0
; v1 = input[s * 2][t].f1;
%s2 = mul nsw i64 %s, 2
; CHECK: [[BUMP:%[a-zA-Z0-9]+]] = mul i64 %s, 60
%p1 = getelementptr inbounds [10 x [5 x %struct.S]], [10 x [5 x %struct.S]]* %input, i64 0, i64 %s2, i64 %t, i32 0
; CHECK: getelementptr inbounds i8, i8* %{{[0-9]+}}, i64 [[BUMP]]
%v1 = load i64, i64* %p1
; v2 = input[s * 3][t].f1;
%s3 = mul nsw i64 %s, 3
%p2 = getelementptr inbounds [10 x [5 x %struct.S]], [10 x [5 x %struct.S]]* %input, i64 0, i64 %s3, i64 %t, i32 0
; CHECK: getelementptr inbounds i8, i8* %{{[0-9]+}}, i64 [[BUMP]]
%v2 = load i64, i64* %p2
; return v0 + v1 + v2;
%1 = add i64 %v0, %v1
%2 = add i64 %1, %v2
ret i64 %2
}

2
test/Transforms/StraightLineStrengthReduce/slsr.ll → test/Transforms/StraightLineStrengthReduce/slsr-mul.ll
View File

@ -1,5 +1,7 @@
; RUN: opt < %s -slsr -gvn -dce -S | FileCheck %s
target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
declare i32 @foo(i32 %a)
define i32 @slsr1(i32 %b, i32 %s) {