forked from OSchip/llvm-project
1795 lines
70 KiB
C++
1795 lines
70 KiB
C++
//===- MemoryDependenceAnalysis.cpp - Mem Deps Implementation -------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements an analysis that determines, for a given memory
|
|
// operation, what preceding memory operations it depends on. It builds on
|
|
// alias analysis information, and tries to provide a lazy, caching interface to
|
|
// a common kind of alias information query.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
|
|
#include "llvm/ADT/DenseMap.h"
|
|
#include "llvm/ADT/STLExtras.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/ADT/SmallVector.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/Analysis/AliasAnalysis.h"
|
|
#include "llvm/Analysis/AssumptionCache.h"
|
|
#include "llvm/Analysis/MemoryBuiltins.h"
|
|
#include "llvm/Analysis/MemoryLocation.h"
|
|
#include "llvm/Analysis/OrderedBasicBlock.h"
|
|
#include "llvm/Analysis/PHITransAddr.h"
|
|
#include "llvm/Analysis/TargetLibraryInfo.h"
|
|
#include "llvm/Analysis/ValueTracking.h"
|
|
#include "llvm/IR/Attributes.h"
|
|
#include "llvm/IR/BasicBlock.h"
|
|
#include "llvm/IR/CallSite.h"
|
|
#include "llvm/IR/Constants.h"
|
|
#include "llvm/IR/DataLayout.h"
|
|
#include "llvm/IR/DerivedTypes.h"
|
|
#include "llvm/IR/Dominators.h"
|
|
#include "llvm/IR/Function.h"
|
|
#include "llvm/IR/InstrTypes.h"
|
|
#include "llvm/IR/Instruction.h"
|
|
#include "llvm/IR/Instructions.h"
|
|
#include "llvm/IR/IntrinsicInst.h"
|
|
#include "llvm/IR/LLVMContext.h"
|
|
#include "llvm/IR/Metadata.h"
|
|
#include "llvm/IR/Module.h"
|
|
#include "llvm/IR/PredIteratorCache.h"
|
|
#include "llvm/IR/Type.h"
|
|
#include "llvm/IR/Use.h"
|
|
#include "llvm/IR/User.h"
|
|
#include "llvm/IR/Value.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/Support/AtomicOrdering.h"
|
|
#include "llvm/Support/Casting.h"
|
|
#include "llvm/Support/CommandLine.h"
|
|
#include "llvm/Support/Compiler.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/MathExtras.h"
|
|
#include <algorithm>
|
|
#include <cassert>
|
|
#include <cstdint>
|
|
#include <iterator>
|
|
#include <utility>
|
|
|
|
using namespace llvm;
|
|
|
|
#define DEBUG_TYPE "memdep"
|
|
|
|
STATISTIC(NumCacheNonLocal, "Number of fully cached non-local responses");
|
|
STATISTIC(NumCacheDirtyNonLocal, "Number of dirty cached non-local responses");
|
|
STATISTIC(NumUncacheNonLocal, "Number of uncached non-local responses");
|
|
|
|
STATISTIC(NumCacheNonLocalPtr,
|
|
"Number of fully cached non-local ptr responses");
|
|
STATISTIC(NumCacheDirtyNonLocalPtr,
|
|
"Number of cached, but dirty, non-local ptr responses");
|
|
STATISTIC(NumUncacheNonLocalPtr, "Number of uncached non-local ptr responses");
|
|
STATISTIC(NumCacheCompleteNonLocalPtr,
|
|
"Number of block queries that were completely cached");
|
|
|
|
// Limit for the number of instructions to scan in a block.
|
|
|
|
static cl::opt<unsigned> BlockScanLimit(
|
|
"memdep-block-scan-limit", cl::Hidden, cl::init(100),
|
|
cl::desc("The number of instructions to scan in a block in memory "
|
|
"dependency analysis (default = 100)"));
|
|
|
|
static cl::opt<unsigned>
|
|
BlockNumberLimit("memdep-block-number-limit", cl::Hidden, cl::init(1000),
|
|
cl::desc("The number of blocks to scan during memory "
|
|
"dependency analysis (default = 1000)"));
|
|
|
|
// Limit on the number of memdep results to process.
|
|
static const unsigned int NumResultsLimit = 100;
|
|
|
|
/// This is a helper function that removes Val from 'Inst's set in ReverseMap.
|
|
///
|
|
/// If the set becomes empty, remove Inst's entry.
|
|
template <typename KeyTy>
|
|
static void
|
|
RemoveFromReverseMap(DenseMap<Instruction *, SmallPtrSet<KeyTy, 4>> &ReverseMap,
|
|
Instruction *Inst, KeyTy Val) {
|
|
typename DenseMap<Instruction *, SmallPtrSet<KeyTy, 4>>::iterator InstIt =
|
|
ReverseMap.find(Inst);
|
|
assert(InstIt != ReverseMap.end() && "Reverse map out of sync?");
|
|
bool Found = InstIt->second.erase(Val);
|
|
assert(Found && "Invalid reverse map!");
|
|
(void)Found;
|
|
if (InstIt->second.empty())
|
|
ReverseMap.erase(InstIt);
|
|
}
|
|
|
|
/// If the given instruction references a specific memory location, fill in Loc
|
|
/// with the details, otherwise set Loc.Ptr to null.
|
|
///
|
|
/// Returns a ModRefInfo value describing the general behavior of the
|
|
/// instruction.
|
|
static ModRefInfo GetLocation(const Instruction *Inst, MemoryLocation &Loc,
|
|
const TargetLibraryInfo &TLI) {
|
|
if (const LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
|
|
if (LI->isUnordered()) {
|
|
Loc = MemoryLocation::get(LI);
|
|
return ModRefInfo::Ref;
|
|
}
|
|
if (LI->getOrdering() == AtomicOrdering::Monotonic) {
|
|
Loc = MemoryLocation::get(LI);
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
Loc = MemoryLocation();
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
if (const StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
|
if (SI->isUnordered()) {
|
|
Loc = MemoryLocation::get(SI);
|
|
return ModRefInfo::Mod;
|
|
}
|
|
if (SI->getOrdering() == AtomicOrdering::Monotonic) {
|
|
Loc = MemoryLocation::get(SI);
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
Loc = MemoryLocation();
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
if (const VAArgInst *V = dyn_cast<VAArgInst>(Inst)) {
|
|
Loc = MemoryLocation::get(V);
|
|
return ModRefInfo::ModRef;
|
|
}
|
|
|
|
if (const CallInst *CI = isFreeCall(Inst, &TLI)) {
|
|
// calls to free() deallocate the entire structure
|
|
Loc = MemoryLocation(CI->getArgOperand(0));
|
|
return ModRefInfo::Mod;
|
|
}
|
|
|
|
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
|
|
switch (II->getIntrinsicID()) {
|
|
case Intrinsic::lifetime_start:
|
|
case Intrinsic::lifetime_end:
|
|
case Intrinsic::invariant_start:
|
|
Loc = MemoryLocation::getForArgument(II, 1, TLI);
|
|
// These intrinsics don't really modify the memory, but returning Mod
|
|
// will allow them to be handled conservatively.
|
|
return ModRefInfo::Mod;
|
|
case Intrinsic::invariant_end:
|
|
Loc = MemoryLocation::getForArgument(II, 2, TLI);
|
|
// These intrinsics don't really modify the memory, but returning Mod
|
|
// will allow them to be handled conservatively.
|
|
return ModRefInfo::Mod;
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Otherwise, just do the coarse-grained thing that always works.
|
|
if (Inst->mayWriteToMemory())
|
|
return ModRefInfo::ModRef;
|
|
if (Inst->mayReadFromMemory())
|
|
return ModRefInfo::Ref;
|
|
return ModRefInfo::NoModRef;
|
|
}
|
|
|
|
/// Private helper for finding the local dependencies of a call site.
|
|
MemDepResult MemoryDependenceResults::getCallSiteDependencyFrom(
|
|
CallSite CS, bool isReadOnlyCall, BasicBlock::iterator ScanIt,
|
|
BasicBlock *BB) {
|
|
unsigned Limit = BlockScanLimit;
|
|
|
|
// Walk backwards through the block, looking for dependencies.
|
|
while (ScanIt != BB->begin()) {
|
|
Instruction *Inst = &*--ScanIt;
|
|
// Debug intrinsics don't cause dependences and should not affect Limit
|
|
if (isa<DbgInfoIntrinsic>(Inst))
|
|
continue;
|
|
|
|
// Limit the amount of scanning we do so we don't end up with quadratic
|
|
// running time on extreme testcases.
|
|
--Limit;
|
|
if (!Limit)
|
|
return MemDepResult::getUnknown();
|
|
|
|
// If this inst is a memory op, get the pointer it accessed
|
|
MemoryLocation Loc;
|
|
ModRefInfo MR = GetLocation(Inst, Loc, TLI);
|
|
if (Loc.Ptr) {
|
|
// A simple instruction.
|
|
if (isModOrRefSet(AA.getModRefInfo(CS, Loc)))
|
|
return MemDepResult::getClobber(Inst);
|
|
continue;
|
|
}
|
|
|
|
if (auto InstCS = CallSite(Inst)) {
|
|
// If these two calls do not interfere, look past it.
|
|
if (isNoModRef(AA.getModRefInfo(CS, InstCS))) {
|
|
// If the two calls are the same, return InstCS as a Def, so that
|
|
// CS can be found redundant and eliminated.
|
|
if (isReadOnlyCall && !isModSet(MR) &&
|
|
CS.getInstruction()->isIdenticalToWhenDefined(Inst))
|
|
return MemDepResult::getDef(Inst);
|
|
|
|
// Otherwise if the two calls don't interact (e.g. InstCS is readnone)
|
|
// keep scanning.
|
|
continue;
|
|
} else
|
|
return MemDepResult::getClobber(Inst);
|
|
}
|
|
|
|
// If we could not obtain a pointer for the instruction and the instruction
|
|
// touches memory then assume that this is a dependency.
|
|
if (isModOrRefSet(MR))
|
|
return MemDepResult::getClobber(Inst);
|
|
}
|
|
|
|
// No dependence found. If this is the entry block of the function, it is
|
|
// unknown, otherwise it is non-local.
|
|
if (BB != &BB->getParent()->getEntryBlock())
|
|
return MemDepResult::getNonLocal();
|
|
return MemDepResult::getNonFuncLocal();
|
|
}
|
|
|
|
unsigned MemoryDependenceResults::getLoadLoadClobberFullWidthSize(
|
|
const Value *MemLocBase, int64_t MemLocOffs, unsigned MemLocSize,
|
|
const LoadInst *LI) {
|
|
// We can only extend simple integer loads.
|
|
if (!isa<IntegerType>(LI->getType()) || !LI->isSimple())
|
|
return 0;
|
|
|
|
// Load widening is hostile to ThreadSanitizer: it may cause false positives
|
|
// or make the reports more cryptic (access sizes are wrong).
|
|
if (LI->getParent()->getParent()->hasFnAttribute(Attribute::SanitizeThread))
|
|
return 0;
|
|
|
|
const DataLayout &DL = LI->getModule()->getDataLayout();
|
|
|
|
// Get the base of this load.
|
|
int64_t LIOffs = 0;
|
|
const Value *LIBase =
|
|
GetPointerBaseWithConstantOffset(LI->getPointerOperand(), LIOffs, DL);
|
|
|
|
// If the two pointers are not based on the same pointer, we can't tell that
|
|
// they are related.
|
|
if (LIBase != MemLocBase)
|
|
return 0;
|
|
|
|
// Okay, the two values are based on the same pointer, but returned as
|
|
// no-alias. This happens when we have things like two byte loads at "P+1"
|
|
// and "P+3". Check to see if increasing the size of the "LI" load up to its
|
|
// alignment (or the largest native integer type) will allow us to load all
|
|
// the bits required by MemLoc.
|
|
|
|
// If MemLoc is before LI, then no widening of LI will help us out.
|
|
if (MemLocOffs < LIOffs)
|
|
return 0;
|
|
|
|
// Get the alignment of the load in bytes. We assume that it is safe to load
|
|
// any legal integer up to this size without a problem. For example, if we're
|
|
// looking at an i8 load on x86-32 that is known 1024 byte aligned, we can
|
|
// widen it up to an i32 load. If it is known 2-byte aligned, we can widen it
|
|
// to i16.
|
|
unsigned LoadAlign = LI->getAlignment();
|
|
|
|
int64_t MemLocEnd = MemLocOffs + MemLocSize;
|
|
|
|
// If no amount of rounding up will let MemLoc fit into LI, then bail out.
|
|
if (LIOffs + LoadAlign < MemLocEnd)
|
|
return 0;
|
|
|
|
// This is the size of the load to try. Start with the next larger power of
|
|
// two.
|
|
unsigned NewLoadByteSize = LI->getType()->getPrimitiveSizeInBits() / 8U;
|
|
NewLoadByteSize = NextPowerOf2(NewLoadByteSize);
|
|
|
|
while (true) {
|
|
// If this load size is bigger than our known alignment or would not fit
|
|
// into a native integer register, then we fail.
|
|
if (NewLoadByteSize > LoadAlign ||
|
|
!DL.fitsInLegalInteger(NewLoadByteSize * 8))
|
|
return 0;
|
|
|
|
if (LIOffs + NewLoadByteSize > MemLocEnd &&
|
|
(LI->getParent()->getParent()->hasFnAttribute(
|
|
Attribute::SanitizeAddress) ||
|
|
LI->getParent()->getParent()->hasFnAttribute(
|
|
Attribute::SanitizeHWAddress)))
|
|
// We will be reading past the location accessed by the original program.
|
|
// While this is safe in a regular build, Address Safety analysis tools
|
|
// may start reporting false warnings. So, don't do widening.
|
|
return 0;
|
|
|
|
// If a load of this width would include all of MemLoc, then we succeed.
|
|
if (LIOffs + NewLoadByteSize >= MemLocEnd)
|
|
return NewLoadByteSize;
|
|
|
|
NewLoadByteSize <<= 1;
|
|
}
|
|
}
|
|
|
|
static bool isVolatile(Instruction *Inst) {
|
|
if (auto *LI = dyn_cast<LoadInst>(Inst))
|
|
return LI->isVolatile();
|
|
if (auto *SI = dyn_cast<StoreInst>(Inst))
|
|
return SI->isVolatile();
|
|
if (auto *AI = dyn_cast<AtomicCmpXchgInst>(Inst))
|
|
return AI->isVolatile();
|
|
return false;
|
|
}
|
|
|
|
MemDepResult MemoryDependenceResults::getPointerDependencyFrom(
|
|
const MemoryLocation &MemLoc, bool isLoad, BasicBlock::iterator ScanIt,
|
|
BasicBlock *BB, Instruction *QueryInst, unsigned *Limit) {
|
|
MemDepResult InvariantGroupDependency = MemDepResult::getUnknown();
|
|
if (QueryInst != nullptr) {
|
|
if (auto *LI = dyn_cast<LoadInst>(QueryInst)) {
|
|
InvariantGroupDependency = getInvariantGroupPointerDependency(LI, BB);
|
|
|
|
if (InvariantGroupDependency.isDef())
|
|
return InvariantGroupDependency;
|
|
}
|
|
}
|
|
MemDepResult SimpleDep = getSimplePointerDependencyFrom(
|
|
MemLoc, isLoad, ScanIt, BB, QueryInst, Limit);
|
|
if (SimpleDep.isDef())
|
|
return SimpleDep;
|
|
// Non-local invariant group dependency indicates there is non local Def
|
|
// (it only returns nonLocal if it finds nonLocal def), which is better than
|
|
// local clobber and everything else.
|
|
if (InvariantGroupDependency.isNonLocal())
|
|
return InvariantGroupDependency;
|
|
|
|
assert(InvariantGroupDependency.isUnknown() &&
|
|
"InvariantGroupDependency should be only unknown at this point");
|
|
return SimpleDep;
|
|
}
|
|
|
|
MemDepResult
|
|
MemoryDependenceResults::getInvariantGroupPointerDependency(LoadInst *LI,
|
|
BasicBlock *BB) {
|
|
|
|
if (!LI->getMetadata(LLVMContext::MD_invariant_group))
|
|
return MemDepResult::getUnknown();
|
|
|
|
// Take the ptr operand after all casts and geps 0. This way we can search
|
|
// cast graph down only.
|
|
Value *LoadOperand = LI->getPointerOperand()->stripPointerCasts();
|
|
|
|
// It's is not safe to walk the use list of global value, because function
|
|
// passes aren't allowed to look outside their functions.
|
|
// FIXME: this could be fixed by filtering instructions from outside
|
|
// of current function.
|
|
if (isa<GlobalValue>(LoadOperand))
|
|
return MemDepResult::getUnknown();
|
|
|
|
// Queue to process all pointers that are equivalent to load operand.
|
|
SmallVector<const Value *, 8> LoadOperandsQueue;
|
|
LoadOperandsQueue.push_back(LoadOperand);
|
|
|
|
Instruction *ClosestDependency = nullptr;
|
|
// Order of instructions in uses list is unpredictible. In order to always
|
|
// get the same result, we will look for the closest dominance.
|
|
auto GetClosestDependency = [this](Instruction *Best, Instruction *Other) {
|
|
assert(Other && "Must call it with not null instruction");
|
|
if (Best == nullptr || DT.dominates(Best, Other))
|
|
return Other;
|
|
return Best;
|
|
};
|
|
|
|
// FIXME: This loop is O(N^2) because dominates can be O(n) and in worst case
|
|
// we will see all the instructions. This should be fixed in MSSA.
|
|
while (!LoadOperandsQueue.empty()) {
|
|
const Value *Ptr = LoadOperandsQueue.pop_back_val();
|
|
assert(Ptr && !isa<GlobalValue>(Ptr) &&
|
|
"Null or GlobalValue should not be inserted");
|
|
|
|
for (const Use &Us : Ptr->uses()) {
|
|
auto *U = dyn_cast<Instruction>(Us.getUser());
|
|
if (!U || U == LI || !DT.dominates(U, LI))
|
|
continue;
|
|
|
|
// Bitcast or gep with zeros are using Ptr. Add to queue to check it's
|
|
// users. U = bitcast Ptr
|
|
if (isa<BitCastInst>(U)) {
|
|
LoadOperandsQueue.push_back(U);
|
|
continue;
|
|
}
|
|
// Gep with zeros is equivalent to bitcast.
|
|
// FIXME: we are not sure if some bitcast should be canonicalized to gep 0
|
|
// or gep 0 to bitcast because of SROA, so there are 2 forms. When
|
|
// typeless pointers will be ready then both cases will be gone
|
|
// (and this BFS also won't be needed).
|
|
if (auto *GEP = dyn_cast<GetElementPtrInst>(U))
|
|
if (GEP->hasAllZeroIndices()) {
|
|
LoadOperandsQueue.push_back(U);
|
|
continue;
|
|
}
|
|
|
|
// If we hit load/store with the same invariant.group metadata (and the
|
|
// same pointer operand) we can assume that value pointed by pointer
|
|
// operand didn't change.
|
|
if ((isa<LoadInst>(U) || isa<StoreInst>(U)) &&
|
|
U->getMetadata(LLVMContext::MD_invariant_group) != nullptr)
|
|
ClosestDependency = GetClosestDependency(ClosestDependency, U);
|
|
}
|
|
}
|
|
|
|
if (!ClosestDependency)
|
|
return MemDepResult::getUnknown();
|
|
if (ClosestDependency->getParent() == BB)
|
|
return MemDepResult::getDef(ClosestDependency);
|
|
// Def(U) can't be returned here because it is non-local. If local
|
|
// dependency won't be found then return nonLocal counting that the
|
|
// user will call getNonLocalPointerDependency, which will return cached
|
|
// result.
|
|
NonLocalDefsCache.try_emplace(
|
|
LI, NonLocalDepResult(ClosestDependency->getParent(),
|
|
MemDepResult::getDef(ClosestDependency), nullptr));
|
|
ReverseNonLocalDefsCache[ClosestDependency].insert(LI);
|
|
return MemDepResult::getNonLocal();
|
|
}
|
|
|
|
MemDepResult MemoryDependenceResults::getSimplePointerDependencyFrom(
|
|
const MemoryLocation &MemLoc, bool isLoad, BasicBlock::iterator ScanIt,
|
|
BasicBlock *BB, Instruction *QueryInst, unsigned *Limit) {
|
|
bool isInvariantLoad = false;
|
|
|
|
if (!Limit) {
|
|
unsigned DefaultLimit = BlockScanLimit;
|
|
return getSimplePointerDependencyFrom(MemLoc, isLoad, ScanIt, BB, QueryInst,
|
|
&DefaultLimit);
|
|
}
|
|
|
|
// We must be careful with atomic accesses, as they may allow another thread
|
|
// to touch this location, clobbering it. We are conservative: if the
|
|
// QueryInst is not a simple (non-atomic) memory access, we automatically
|
|
// return getClobber.
|
|
// If it is simple, we know based on the results of
|
|
// "Compiler testing via a theory of sound optimisations in the C11/C++11
|
|
// memory model" in PLDI 2013, that a non-atomic location can only be
|
|
// clobbered between a pair of a release and an acquire action, with no
|
|
// access to the location in between.
|
|
// Here is an example for giving the general intuition behind this rule.
|
|
// In the following code:
|
|
// store x 0;
|
|
// release action; [1]
|
|
// acquire action; [4]
|
|
// %val = load x;
|
|
// It is unsafe to replace %val by 0 because another thread may be running:
|
|
// acquire action; [2]
|
|
// store x 42;
|
|
// release action; [3]
|
|
// with synchronization from 1 to 2 and from 3 to 4, resulting in %val
|
|
// being 42. A key property of this program however is that if either
|
|
// 1 or 4 were missing, there would be a race between the store of 42
|
|
// either the store of 0 or the load (making the whole program racy).
|
|
// The paper mentioned above shows that the same property is respected
|
|
// by every program that can detect any optimization of that kind: either
|
|
// it is racy (undefined) or there is a release followed by an acquire
|
|
// between the pair of accesses under consideration.
|
|
|
|
// If the load is invariant, we "know" that it doesn't alias *any* write. We
|
|
// do want to respect mustalias results since defs are useful for value
|
|
// forwarding, but any mayalias write can be assumed to be noalias.
|
|
// Arguably, this logic should be pushed inside AliasAnalysis itself.
|
|
if (isLoad && QueryInst) {
|
|
LoadInst *LI = dyn_cast<LoadInst>(QueryInst);
|
|
if (LI && LI->getMetadata(LLVMContext::MD_invariant_load) != nullptr)
|
|
isInvariantLoad = true;
|
|
}
|
|
|
|
const DataLayout &DL = BB->getModule()->getDataLayout();
|
|
|
|
// Create a numbered basic block to lazily compute and cache instruction
|
|
// positions inside a BB. This is used to provide fast queries for relative
|
|
// position between two instructions in a BB and can be used by
|
|
// AliasAnalysis::callCapturesBefore.
|
|
OrderedBasicBlock OBB(BB);
|
|
|
|
// Return "true" if and only if the instruction I is either a non-simple
|
|
// load or a non-simple store.
|
|
auto isNonSimpleLoadOrStore = [](Instruction *I) -> bool {
|
|
if (auto *LI = dyn_cast<LoadInst>(I))
|
|
return !LI->isSimple();
|
|
if (auto *SI = dyn_cast<StoreInst>(I))
|
|
return !SI->isSimple();
|
|
return false;
|
|
};
|
|
|
|
// Return "true" if I is not a load and not a store, but it does access
|
|
// memory.
|
|
auto isOtherMemAccess = [](Instruction *I) -> bool {
|
|
return !isa<LoadInst>(I) && !isa<StoreInst>(I) && I->mayReadOrWriteMemory();
|
|
};
|
|
|
|
// Walk backwards through the basic block, looking for dependencies.
|
|
while (ScanIt != BB->begin()) {
|
|
Instruction *Inst = &*--ScanIt;
|
|
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst))
|
|
// Debug intrinsics don't (and can't) cause dependencies.
|
|
if (isa<DbgInfoIntrinsic>(II))
|
|
continue;
|
|
|
|
// Limit the amount of scanning we do so we don't end up with quadratic
|
|
// running time on extreme testcases.
|
|
--*Limit;
|
|
if (!*Limit)
|
|
return MemDepResult::getUnknown();
|
|
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
|
|
// If we reach a lifetime begin or end marker, then the query ends here
|
|
// because the value is undefined.
|
|
if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
|
|
// FIXME: This only considers queries directly on the invariant-tagged
|
|
// pointer, not on query pointers that are indexed off of them. It'd
|
|
// be nice to handle that at some point (the right approach is to use
|
|
// GetPointerBaseWithConstantOffset).
|
|
if (AA.isMustAlias(MemoryLocation(II->getArgOperand(1)), MemLoc))
|
|
return MemDepResult::getDef(II);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Values depend on loads if the pointers are must aliased. This means
|
|
// that a load depends on another must aliased load from the same value.
|
|
// One exception is atomic loads: a value can depend on an atomic load that
|
|
// it does not alias with when this atomic load indicates that another
|
|
// thread may be accessing the location.
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
|
|
// While volatile access cannot be eliminated, they do not have to clobber
|
|
// non-aliasing locations, as normal accesses, for example, can be safely
|
|
// reordered with volatile accesses.
|
|
if (LI->isVolatile()) {
|
|
if (!QueryInst)
|
|
// Original QueryInst *may* be volatile
|
|
return MemDepResult::getClobber(LI);
|
|
if (isVolatile(QueryInst))
|
|
// Ordering required if QueryInst is itself volatile
|
|
return MemDepResult::getClobber(LI);
|
|
// Otherwise, volatile doesn't imply any special ordering
|
|
}
|
|
|
|
// Atomic loads have complications involved.
|
|
// A Monotonic (or higher) load is OK if the query inst is itself not
|
|
// atomic.
|
|
// FIXME: This is overly conservative.
|
|
if (LI->isAtomic() && isStrongerThanUnordered(LI->getOrdering())) {
|
|
if (!QueryInst || isNonSimpleLoadOrStore(QueryInst) ||
|
|
isOtherMemAccess(QueryInst))
|
|
return MemDepResult::getClobber(LI);
|
|
if (LI->getOrdering() != AtomicOrdering::Monotonic)
|
|
return MemDepResult::getClobber(LI);
|
|
}
|
|
|
|
MemoryLocation LoadLoc = MemoryLocation::get(LI);
|
|
|
|
// If we found a pointer, check if it could be the same as our pointer.
|
|
AliasResult R = AA.alias(LoadLoc, MemLoc);
|
|
|
|
if (isLoad) {
|
|
if (R == NoAlias)
|
|
continue;
|
|
|
|
// Must aliased loads are defs of each other.
|
|
if (R == MustAlias)
|
|
return MemDepResult::getDef(Inst);
|
|
|
|
#if 0 // FIXME: Temporarily disabled. GVN is cleverly rewriting loads
|
|
// in terms of clobbering loads, but since it does this by looking
|
|
// at the clobbering load directly, it doesn't know about any
|
|
// phi translation that may have happened along the way.
|
|
|
|
// If we have a partial alias, then return this as a clobber for the
|
|
// client to handle.
|
|
if (R == PartialAlias)
|
|
return MemDepResult::getClobber(Inst);
|
|
#endif
|
|
|
|
// Random may-alias loads don't depend on each other without a
|
|
// dependence.
|
|
continue;
|
|
}
|
|
|
|
// Stores don't depend on other no-aliased accesses.
|
|
if (R == NoAlias)
|
|
continue;
|
|
|
|
// Stores don't alias loads from read-only memory.
|
|
if (AA.pointsToConstantMemory(LoadLoc))
|
|
continue;
|
|
|
|
// Stores depend on may/must aliased loads.
|
|
return MemDepResult::getDef(Inst);
|
|
}
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
|
// Atomic stores have complications involved.
|
|
// A Monotonic store is OK if the query inst is itself not atomic.
|
|
// FIXME: This is overly conservative.
|
|
if (!SI->isUnordered() && SI->isAtomic()) {
|
|
if (!QueryInst || isNonSimpleLoadOrStore(QueryInst) ||
|
|
isOtherMemAccess(QueryInst))
|
|
return MemDepResult::getClobber(SI);
|
|
if (SI->getOrdering() != AtomicOrdering::Monotonic)
|
|
return MemDepResult::getClobber(SI);
|
|
}
|
|
|
|
// FIXME: this is overly conservative.
|
|
// While volatile access cannot be eliminated, they do not have to clobber
|
|
// non-aliasing locations, as normal accesses can for example be reordered
|
|
// with volatile accesses.
|
|
if (SI->isVolatile())
|
|
if (!QueryInst || isNonSimpleLoadOrStore(QueryInst) ||
|
|
isOtherMemAccess(QueryInst))
|
|
return MemDepResult::getClobber(SI);
|
|
|
|
// If alias analysis can tell that this store is guaranteed to not modify
|
|
// the query pointer, ignore it. Use getModRefInfo to handle cases where
|
|
// the query pointer points to constant memory etc.
|
|
if (!isModOrRefSet(AA.getModRefInfo(SI, MemLoc)))
|
|
continue;
|
|
|
|
// Ok, this store might clobber the query pointer. Check to see if it is
|
|
// a must alias: in this case, we want to return this as a def.
|
|
// FIXME: Use ModRefInfo::Must bit from getModRefInfo call above.
|
|
MemoryLocation StoreLoc = MemoryLocation::get(SI);
|
|
|
|
// If we found a pointer, check if it could be the same as our pointer.
|
|
AliasResult R = AA.alias(StoreLoc, MemLoc);
|
|
|
|
if (R == NoAlias)
|
|
continue;
|
|
if (R == MustAlias)
|
|
return MemDepResult::getDef(Inst);
|
|
if (isInvariantLoad)
|
|
continue;
|
|
return MemDepResult::getClobber(Inst);
|
|
}
|
|
|
|
// If this is an allocation, and if we know that the accessed pointer is to
|
|
// the allocation, return Def. This means that there is no dependence and
|
|
// the access can be optimized based on that. For example, a load could
|
|
// turn into undef. Note that we can bypass the allocation itself when
|
|
// looking for a clobber in many cases; that's an alias property and is
|
|
// handled by BasicAA.
|
|
if (isa<AllocaInst>(Inst) || isNoAliasFn(Inst, &TLI)) {
|
|
const Value *AccessPtr = GetUnderlyingObject(MemLoc.Ptr, DL);
|
|
if (AccessPtr == Inst || AA.isMustAlias(Inst, AccessPtr))
|
|
return MemDepResult::getDef(Inst);
|
|
}
|
|
|
|
if (isInvariantLoad)
|
|
continue;
|
|
|
|
// A release fence requires that all stores complete before it, but does
|
|
// not prevent the reordering of following loads or stores 'before' the
|
|
// fence. As a result, we look past it when finding a dependency for
|
|
// loads. DSE uses this to find preceeding stores to delete and thus we
|
|
// can't bypass the fence if the query instruction is a store.
|
|
if (FenceInst *FI = dyn_cast<FenceInst>(Inst))
|
|
if (isLoad && FI->getOrdering() == AtomicOrdering::Release)
|
|
continue;
|
|
|
|
// See if this instruction (e.g. a call or vaarg) mod/ref's the pointer.
|
|
ModRefInfo MR = AA.getModRefInfo(Inst, MemLoc);
|
|
// If necessary, perform additional analysis.
|
|
if (isModAndRefSet(MR))
|
|
MR = AA.callCapturesBefore(Inst, MemLoc, &DT, &OBB);
|
|
switch (clearMust(MR)) {
|
|
case ModRefInfo::NoModRef:
|
|
// If the call has no effect on the queried pointer, just ignore it.
|
|
continue;
|
|
case ModRefInfo::Mod:
|
|
return MemDepResult::getClobber(Inst);
|
|
case ModRefInfo::Ref:
|
|
// If the call is known to never store to the pointer, and if this is a
|
|
// load query, we can safely ignore it (scan past it).
|
|
if (isLoad)
|
|
continue;
|
|
LLVM_FALLTHROUGH;
|
|
default:
|
|
// Otherwise, there is a potential dependence. Return a clobber.
|
|
return MemDepResult::getClobber(Inst);
|
|
}
|
|
}
|
|
|
|
// No dependence found. If this is the entry block of the function, it is
|
|
// unknown, otherwise it is non-local.
|
|
if (BB != &BB->getParent()->getEntryBlock())
|
|
return MemDepResult::getNonLocal();
|
|
return MemDepResult::getNonFuncLocal();
|
|
}
|
|
|
|
MemDepResult MemoryDependenceResults::getDependency(Instruction *QueryInst) {
|
|
Instruction *ScanPos = QueryInst;
|
|
|
|
// Check for a cached result
|
|
MemDepResult &LocalCache = LocalDeps[QueryInst];
|
|
|
|
// If the cached entry is non-dirty, just return it. Note that this depends
|
|
// on MemDepResult's default constructing to 'dirty'.
|
|
if (!LocalCache.isDirty())
|
|
return LocalCache;
|
|
|
|
// Otherwise, if we have a dirty entry, we know we can start the scan at that
|
|
// instruction, which may save us some work.
|
|
if (Instruction *Inst = LocalCache.getInst()) {
|
|
ScanPos = Inst;
|
|
|
|
RemoveFromReverseMap(ReverseLocalDeps, Inst, QueryInst);
|
|
}
|
|
|
|
BasicBlock *QueryParent = QueryInst->getParent();
|
|
|
|
// Do the scan.
|
|
if (BasicBlock::iterator(QueryInst) == QueryParent->begin()) {
|
|
// No dependence found. If this is the entry block of the function, it is
|
|
// unknown, otherwise it is non-local.
|
|
if (QueryParent != &QueryParent->getParent()->getEntryBlock())
|
|
LocalCache = MemDepResult::getNonLocal();
|
|
else
|
|
LocalCache = MemDepResult::getNonFuncLocal();
|
|
} else {
|
|
MemoryLocation MemLoc;
|
|
ModRefInfo MR = GetLocation(QueryInst, MemLoc, TLI);
|
|
if (MemLoc.Ptr) {
|
|
// If we can do a pointer scan, make it happen.
|
|
bool isLoad = !isModSet(MR);
|
|
if (auto *II = dyn_cast<IntrinsicInst>(QueryInst))
|
|
isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_start;
|
|
|
|
LocalCache = getPointerDependencyFrom(
|
|
MemLoc, isLoad, ScanPos->getIterator(), QueryParent, QueryInst);
|
|
} else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) {
|
|
CallSite QueryCS(QueryInst);
|
|
bool isReadOnly = AA.onlyReadsMemory(QueryCS);
|
|
LocalCache = getCallSiteDependencyFrom(
|
|
QueryCS, isReadOnly, ScanPos->getIterator(), QueryParent);
|
|
} else
|
|
// Non-memory instruction.
|
|
LocalCache = MemDepResult::getUnknown();
|
|
}
|
|
|
|
// Remember the result!
|
|
if (Instruction *I = LocalCache.getInst())
|
|
ReverseLocalDeps[I].insert(QueryInst);
|
|
|
|
return LocalCache;
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
/// This method is used when -debug is specified to verify that cache arrays
|
|
/// are properly kept sorted.
|
|
static void AssertSorted(MemoryDependenceResults::NonLocalDepInfo &Cache,
|
|
int Count = -1) {
|
|
if (Count == -1)
|
|
Count = Cache.size();
|
|
assert(std::is_sorted(Cache.begin(), Cache.begin() + Count) &&
|
|
"Cache isn't sorted!");
|
|
}
|
|
#endif
|
|
|
|
const MemoryDependenceResults::NonLocalDepInfo &
|
|
MemoryDependenceResults::getNonLocalCallDependency(CallSite QueryCS) {
|
|
assert(getDependency(QueryCS.getInstruction()).isNonLocal() &&
|
|
"getNonLocalCallDependency should only be used on calls with "
|
|
"non-local deps!");
|
|
PerInstNLInfo &CacheP = NonLocalDeps[QueryCS.getInstruction()];
|
|
NonLocalDepInfo &Cache = CacheP.first;
|
|
|
|
// This is the set of blocks that need to be recomputed. In the cached case,
|
|
// this can happen due to instructions being deleted etc. In the uncached
|
|
// case, this starts out as the set of predecessors we care about.
|
|
SmallVector<BasicBlock *, 32> DirtyBlocks;
|
|
|
|
if (!Cache.empty()) {
|
|
// Okay, we have a cache entry. If we know it is not dirty, just return it
|
|
// with no computation.
|
|
if (!CacheP.second) {
|
|
++NumCacheNonLocal;
|
|
return Cache;
|
|
}
|
|
|
|
// If we already have a partially computed set of results, scan them to
|
|
// determine what is dirty, seeding our initial DirtyBlocks worklist.
|
|
for (auto &Entry : Cache)
|
|
if (Entry.getResult().isDirty())
|
|
DirtyBlocks.push_back(Entry.getBB());
|
|
|
|
// Sort the cache so that we can do fast binary search lookups below.
|
|
llvm::sort(Cache.begin(), Cache.end());
|
|
|
|
++NumCacheDirtyNonLocal;
|
|
// cerr << "CACHED CASE: " << DirtyBlocks.size() << " dirty: "
|
|
// << Cache.size() << " cached: " << *QueryInst;
|
|
} else {
|
|
// Seed DirtyBlocks with each of the preds of QueryInst's block.
|
|
BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
|
|
for (BasicBlock *Pred : PredCache.get(QueryBB))
|
|
DirtyBlocks.push_back(Pred);
|
|
++NumUncacheNonLocal;
|
|
}
|
|
|
|
// isReadonlyCall - If this is a read-only call, we can be more aggressive.
|
|
bool isReadonlyCall = AA.onlyReadsMemory(QueryCS);
|
|
|
|
SmallPtrSet<BasicBlock *, 32> Visited;
|
|
|
|
unsigned NumSortedEntries = Cache.size();
|
|
LLVM_DEBUG(AssertSorted(Cache));
|
|
|
|
// Iterate while we still have blocks to update.
|
|
while (!DirtyBlocks.empty()) {
|
|
BasicBlock *DirtyBB = DirtyBlocks.back();
|
|
DirtyBlocks.pop_back();
|
|
|
|
// Already processed this block?
|
|
if (!Visited.insert(DirtyBB).second)
|
|
continue;
|
|
|
|
// Do a binary search to see if we already have an entry for this block in
|
|
// the cache set. If so, find it.
|
|
LLVM_DEBUG(AssertSorted(Cache, NumSortedEntries));
|
|
NonLocalDepInfo::iterator Entry =
|
|
std::upper_bound(Cache.begin(), Cache.begin() + NumSortedEntries,
|
|
NonLocalDepEntry(DirtyBB));
|
|
if (Entry != Cache.begin() && std::prev(Entry)->getBB() == DirtyBB)
|
|
--Entry;
|
|
|
|
NonLocalDepEntry *ExistingResult = nullptr;
|
|
if (Entry != Cache.begin() + NumSortedEntries &&
|
|
Entry->getBB() == DirtyBB) {
|
|
// If we already have an entry, and if it isn't already dirty, the block
|
|
// is done.
|
|
if (!Entry->getResult().isDirty())
|
|
continue;
|
|
|
|
// Otherwise, remember this slot so we can update the value.
|
|
ExistingResult = &*Entry;
|
|
}
|
|
|
|
// If the dirty entry has a pointer, start scanning from it so we don't have
|
|
// to rescan the entire block.
|
|
BasicBlock::iterator ScanPos = DirtyBB->end();
|
|
if (ExistingResult) {
|
|
if (Instruction *Inst = ExistingResult->getResult().getInst()) {
|
|
ScanPos = Inst->getIterator();
|
|
// We're removing QueryInst's use of Inst.
|
|
RemoveFromReverseMap(ReverseNonLocalDeps, Inst,
|
|
QueryCS.getInstruction());
|
|
}
|
|
}
|
|
|
|
// Find out if this block has a local dependency for QueryInst.
|
|
MemDepResult Dep;
|
|
|
|
if (ScanPos != DirtyBB->begin()) {
|
|
Dep =
|
|
getCallSiteDependencyFrom(QueryCS, isReadonlyCall, ScanPos, DirtyBB);
|
|
} else if (DirtyBB != &DirtyBB->getParent()->getEntryBlock()) {
|
|
// No dependence found. If this is the entry block of the function, it is
|
|
// a clobber, otherwise it is unknown.
|
|
Dep = MemDepResult::getNonLocal();
|
|
} else {
|
|
Dep = MemDepResult::getNonFuncLocal();
|
|
}
|
|
|
|
// If we had a dirty entry for the block, update it. Otherwise, just add
|
|
// a new entry.
|
|
if (ExistingResult)
|
|
ExistingResult->setResult(Dep);
|
|
else
|
|
Cache.push_back(NonLocalDepEntry(DirtyBB, Dep));
|
|
|
|
// If the block has a dependency (i.e. it isn't completely transparent to
|
|
// the value), remember the association!
|
|
if (!Dep.isNonLocal()) {
|
|
// Keep the ReverseNonLocalDeps map up to date so we can efficiently
|
|
// update this when we remove instructions.
|
|
if (Instruction *Inst = Dep.getInst())
|
|
ReverseNonLocalDeps[Inst].insert(QueryCS.getInstruction());
|
|
} else {
|
|
|
|
// If the block *is* completely transparent to the load, we need to check
|
|
// the predecessors of this block. Add them to our worklist.
|
|
for (BasicBlock *Pred : PredCache.get(DirtyBB))
|
|
DirtyBlocks.push_back(Pred);
|
|
}
|
|
}
|
|
|
|
return Cache;
|
|
}
|
|
|
|
void MemoryDependenceResults::getNonLocalPointerDependency(
|
|
Instruction *QueryInst, SmallVectorImpl<NonLocalDepResult> &Result) {
|
|
const MemoryLocation Loc = MemoryLocation::get(QueryInst);
|
|
bool isLoad = isa<LoadInst>(QueryInst);
|
|
BasicBlock *FromBB = QueryInst->getParent();
|
|
assert(FromBB);
|
|
|
|
assert(Loc.Ptr->getType()->isPointerTy() &&
|
|
"Can't get pointer deps of a non-pointer!");
|
|
Result.clear();
|
|
{
|
|
// Check if there is cached Def with invariant.group.
|
|
auto NonLocalDefIt = NonLocalDefsCache.find(QueryInst);
|
|
if (NonLocalDefIt != NonLocalDefsCache.end()) {
|
|
Result.push_back(NonLocalDefIt->second);
|
|
ReverseNonLocalDefsCache[NonLocalDefIt->second.getResult().getInst()]
|
|
.erase(QueryInst);
|
|
NonLocalDefsCache.erase(NonLocalDefIt);
|
|
return;
|
|
}
|
|
}
|
|
// This routine does not expect to deal with volatile instructions.
|
|
// Doing so would require piping through the QueryInst all the way through.
|
|
// TODO: volatiles can't be elided, but they can be reordered with other
|
|
// non-volatile accesses.
|
|
|
|
// We currently give up on any instruction which is ordered, but we do handle
|
|
// atomic instructions which are unordered.
|
|
// TODO: Handle ordered instructions
|
|
auto isOrdered = [](Instruction *Inst) {
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
|
|
return !LI->isUnordered();
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
|
return !SI->isUnordered();
|
|
}
|
|
return false;
|
|
};
|
|
if (isVolatile(QueryInst) || isOrdered(QueryInst)) {
|
|
Result.push_back(NonLocalDepResult(FromBB, MemDepResult::getUnknown(),
|
|
const_cast<Value *>(Loc.Ptr)));
|
|
return;
|
|
}
|
|
const DataLayout &DL = FromBB->getModule()->getDataLayout();
|
|
PHITransAddr Address(const_cast<Value *>(Loc.Ptr), DL, &AC);
|
|
|
|
// This is the set of blocks we've inspected, and the pointer we consider in
|
|
// each block. Because of critical edges, we currently bail out if querying
|
|
// a block with multiple different pointers. This can happen during PHI
|
|
// translation.
|
|
DenseMap<BasicBlock *, Value *> Visited;
|
|
if (getNonLocalPointerDepFromBB(QueryInst, Address, Loc, isLoad, FromBB,
|
|
Result, Visited, true))
|
|
return;
|
|
Result.clear();
|
|
Result.push_back(NonLocalDepResult(FromBB, MemDepResult::getUnknown(),
|
|
const_cast<Value *>(Loc.Ptr)));
|
|
}
|
|
|
|
/// Compute the memdep value for BB with Pointer/PointeeSize using either
|
|
/// cached information in Cache or by doing a lookup (which may use dirty cache
|
|
/// info if available).
|
|
///
|
|
/// If we do a lookup, add the result to the cache.
|
|
MemDepResult MemoryDependenceResults::GetNonLocalInfoForBlock(
|
|
Instruction *QueryInst, const MemoryLocation &Loc, bool isLoad,
|
|
BasicBlock *BB, NonLocalDepInfo *Cache, unsigned NumSortedEntries) {
|
|
|
|
// Do a binary search to see if we already have an entry for this block in
|
|
// the cache set. If so, find it.
|
|
NonLocalDepInfo::iterator Entry = std::upper_bound(
|
|
Cache->begin(), Cache->begin() + NumSortedEntries, NonLocalDepEntry(BB));
|
|
if (Entry != Cache->begin() && (Entry - 1)->getBB() == BB)
|
|
--Entry;
|
|
|
|
NonLocalDepEntry *ExistingResult = nullptr;
|
|
if (Entry != Cache->begin() + NumSortedEntries && Entry->getBB() == BB)
|
|
ExistingResult = &*Entry;
|
|
|
|
// If we have a cached entry, and it is non-dirty, use it as the value for
|
|
// this dependency.
|
|
if (ExistingResult && !ExistingResult->getResult().isDirty()) {
|
|
++NumCacheNonLocalPtr;
|
|
return ExistingResult->getResult();
|
|
}
|
|
|
|
// Otherwise, we have to scan for the value. If we have a dirty cache
|
|
// entry, start scanning from its position, otherwise we scan from the end
|
|
// of the block.
|
|
BasicBlock::iterator ScanPos = BB->end();
|
|
if (ExistingResult && ExistingResult->getResult().getInst()) {
|
|
assert(ExistingResult->getResult().getInst()->getParent() == BB &&
|
|
"Instruction invalidated?");
|
|
++NumCacheDirtyNonLocalPtr;
|
|
ScanPos = ExistingResult->getResult().getInst()->getIterator();
|
|
|
|
// Eliminating the dirty entry from 'Cache', so update the reverse info.
|
|
ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, &*ScanPos, CacheKey);
|
|
} else {
|
|
++NumUncacheNonLocalPtr;
|
|
}
|
|
|
|
// Scan the block for the dependency.
|
|
MemDepResult Dep =
|
|
getPointerDependencyFrom(Loc, isLoad, ScanPos, BB, QueryInst);
|
|
|
|
// If we had a dirty entry for the block, update it. Otherwise, just add
|
|
// a new entry.
|
|
if (ExistingResult)
|
|
ExistingResult->setResult(Dep);
|
|
else
|
|
Cache->push_back(NonLocalDepEntry(BB, Dep));
|
|
|
|
// If the block has a dependency (i.e. it isn't completely transparent to
|
|
// the value), remember the reverse association because we just added it
|
|
// to Cache!
|
|
if (!Dep.isDef() && !Dep.isClobber())
|
|
return Dep;
|
|
|
|
// Keep the ReverseNonLocalPtrDeps map up to date so we can efficiently
|
|
// update MemDep when we remove instructions.
|
|
Instruction *Inst = Dep.getInst();
|
|
assert(Inst && "Didn't depend on anything?");
|
|
ValueIsLoadPair CacheKey(Loc.Ptr, isLoad);
|
|
ReverseNonLocalPtrDeps[Inst].insert(CacheKey);
|
|
return Dep;
|
|
}
|
|
|
|
/// Sort the NonLocalDepInfo cache, given a certain number of elements in the
|
|
/// array that are already properly ordered.
|
|
///
|
|
/// This is optimized for the case when only a few entries are added.
|
|
static void
|
|
SortNonLocalDepInfoCache(MemoryDependenceResults::NonLocalDepInfo &Cache,
|
|
unsigned NumSortedEntries) {
|
|
switch (Cache.size() - NumSortedEntries) {
|
|
case 0:
|
|
// done, no new entries.
|
|
break;
|
|
case 2: {
|
|
// Two new entries, insert the last one into place.
|
|
NonLocalDepEntry Val = Cache.back();
|
|
Cache.pop_back();
|
|
MemoryDependenceResults::NonLocalDepInfo::iterator Entry =
|
|
std::upper_bound(Cache.begin(), Cache.end() - 1, Val);
|
|
Cache.insert(Entry, Val);
|
|
LLVM_FALLTHROUGH;
|
|
}
|
|
case 1:
|
|
// One new entry, Just insert the new value at the appropriate position.
|
|
if (Cache.size() != 1) {
|
|
NonLocalDepEntry Val = Cache.back();
|
|
Cache.pop_back();
|
|
MemoryDependenceResults::NonLocalDepInfo::iterator Entry =
|
|
std::upper_bound(Cache.begin(), Cache.end(), Val);
|
|
Cache.insert(Entry, Val);
|
|
}
|
|
break;
|
|
default:
|
|
// Added many values, do a full scale sort.
|
|
llvm::sort(Cache.begin(), Cache.end());
|
|
break;
|
|
}
|
|
}
|
|
|
|
/// Perform a dependency query based on pointer/pointeesize starting at the end
|
|
/// of StartBB.
|
|
///
|
|
/// Add any clobber/def results to the results vector and keep track of which
|
|
/// blocks are visited in 'Visited'.
|
|
///
|
|
/// This has special behavior for the first block queries (when SkipFirstBlock
|
|
/// is true). In this special case, it ignores the contents of the specified
|
|
/// block and starts returning dependence info for its predecessors.
|
|
///
|
|
/// This function returns true on success, or false to indicate that it could
|
|
/// not compute dependence information for some reason. This should be treated
|
|
/// as a clobber dependence on the first instruction in the predecessor block.
|
|
bool MemoryDependenceResults::getNonLocalPointerDepFromBB(
|
|
Instruction *QueryInst, const PHITransAddr &Pointer,
|
|
const MemoryLocation &Loc, bool isLoad, BasicBlock *StartBB,
|
|
SmallVectorImpl<NonLocalDepResult> &Result,
|
|
DenseMap<BasicBlock *, Value *> &Visited, bool SkipFirstBlock) {
|
|
// Look up the cached info for Pointer.
|
|
ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad);
|
|
|
|
// Set up a temporary NLPI value. If the map doesn't yet have an entry for
|
|
// CacheKey, this value will be inserted as the associated value. Otherwise,
|
|
// it'll be ignored, and we'll have to check to see if the cached size and
|
|
// aa tags are consistent with the current query.
|
|
NonLocalPointerInfo InitialNLPI;
|
|
InitialNLPI.Size = Loc.Size;
|
|
InitialNLPI.AATags = Loc.AATags;
|
|
|
|
// Get the NLPI for CacheKey, inserting one into the map if it doesn't
|
|
// already have one.
|
|
std::pair<CachedNonLocalPointerInfo::iterator, bool> Pair =
|
|
NonLocalPointerDeps.insert(std::make_pair(CacheKey, InitialNLPI));
|
|
NonLocalPointerInfo *CacheInfo = &Pair.first->second;
|
|
|
|
// If we already have a cache entry for this CacheKey, we may need to do some
|
|
// work to reconcile the cache entry and the current query.
|
|
if (!Pair.second) {
|
|
if (CacheInfo->Size < Loc.Size) {
|
|
// The query's Size is greater than the cached one. Throw out the
|
|
// cached data and proceed with the query at the greater size.
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
CacheInfo->Size = Loc.Size;
|
|
for (auto &Entry : CacheInfo->NonLocalDeps)
|
|
if (Instruction *Inst = Entry.getResult().getInst())
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
|
|
CacheInfo->NonLocalDeps.clear();
|
|
} else if (CacheInfo->Size > Loc.Size) {
|
|
// This query's Size is less than the cached one. Conservatively restart
|
|
// the query using the greater size.
|
|
return getNonLocalPointerDepFromBB(
|
|
QueryInst, Pointer, Loc.getWithNewSize(CacheInfo->Size), isLoad,
|
|
StartBB, Result, Visited, SkipFirstBlock);
|
|
}
|
|
|
|
// If the query's AATags are inconsistent with the cached one,
|
|
// conservatively throw out the cached data and restart the query with
|
|
// no tag if needed.
|
|
if (CacheInfo->AATags != Loc.AATags) {
|
|
if (CacheInfo->AATags) {
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
CacheInfo->AATags = AAMDNodes();
|
|
for (auto &Entry : CacheInfo->NonLocalDeps)
|
|
if (Instruction *Inst = Entry.getResult().getInst())
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Inst, CacheKey);
|
|
CacheInfo->NonLocalDeps.clear();
|
|
}
|
|
if (Loc.AATags)
|
|
return getNonLocalPointerDepFromBB(
|
|
QueryInst, Pointer, Loc.getWithoutAATags(), isLoad, StartBB, Result,
|
|
Visited, SkipFirstBlock);
|
|
}
|
|
}
|
|
|
|
NonLocalDepInfo *Cache = &CacheInfo->NonLocalDeps;
|
|
|
|
// If we have valid cached information for exactly the block we are
|
|
// investigating, just return it with no recomputation.
|
|
if (CacheInfo->Pair == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
|
|
// We have a fully cached result for this query then we can just return the
|
|
// cached results and populate the visited set. However, we have to verify
|
|
// that we don't already have conflicting results for these blocks. Check
|
|
// to ensure that if a block in the results set is in the visited set that
|
|
// it was for the same pointer query.
|
|
if (!Visited.empty()) {
|
|
for (auto &Entry : *Cache) {
|
|
DenseMap<BasicBlock *, Value *>::iterator VI =
|
|
Visited.find(Entry.getBB());
|
|
if (VI == Visited.end() || VI->second == Pointer.getAddr())
|
|
continue;
|
|
|
|
// We have a pointer mismatch in a block. Just return false, saying
|
|
// that something was clobbered in this result. We could also do a
|
|
// non-fully cached query, but there is little point in doing this.
|
|
return false;
|
|
}
|
|
}
|
|
|
|
Value *Addr = Pointer.getAddr();
|
|
for (auto &Entry : *Cache) {
|
|
Visited.insert(std::make_pair(Entry.getBB(), Addr));
|
|
if (Entry.getResult().isNonLocal()) {
|
|
continue;
|
|
}
|
|
|
|
if (DT.isReachableFromEntry(Entry.getBB())) {
|
|
Result.push_back(
|
|
NonLocalDepResult(Entry.getBB(), Entry.getResult(), Addr));
|
|
}
|
|
}
|
|
++NumCacheCompleteNonLocalPtr;
|
|
return true;
|
|
}
|
|
|
|
// Otherwise, either this is a new block, a block with an invalid cache
|
|
// pointer or one that we're about to invalidate by putting more info into it
|
|
// than its valid cache info. If empty, the result will be valid cache info,
|
|
// otherwise it isn't.
|
|
if (Cache->empty())
|
|
CacheInfo->Pair = BBSkipFirstBlockPair(StartBB, SkipFirstBlock);
|
|
else
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
|
|
SmallVector<BasicBlock *, 32> Worklist;
|
|
Worklist.push_back(StartBB);
|
|
|
|
// PredList used inside loop.
|
|
SmallVector<std::pair<BasicBlock *, PHITransAddr>, 16> PredList;
|
|
|
|
// Keep track of the entries that we know are sorted. Previously cached
|
|
// entries will all be sorted. The entries we add we only sort on demand (we
|
|
// don't insert every element into its sorted position). We know that we
|
|
// won't get any reuse from currently inserted values, because we don't
|
|
// revisit blocks after we insert info for them.
|
|
unsigned NumSortedEntries = Cache->size();
|
|
unsigned WorklistEntries = BlockNumberLimit;
|
|
bool GotWorklistLimit = false;
|
|
LLVM_DEBUG(AssertSorted(*Cache));
|
|
|
|
while (!Worklist.empty()) {
|
|
BasicBlock *BB = Worklist.pop_back_val();
|
|
|
|
// If we do process a large number of blocks it becomes very expensive and
|
|
// likely it isn't worth worrying about
|
|
if (Result.size() > NumResultsLimit) {
|
|
Worklist.clear();
|
|
// Sort it now (if needed) so that recursive invocations of
|
|
// getNonLocalPointerDepFromBB and other routines that could reuse the
|
|
// cache value will only see properly sorted cache arrays.
|
|
if (Cache && NumSortedEntries != Cache->size()) {
|
|
SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
|
|
}
|
|
// Since we bail out, the "Cache" set won't contain all of the
|
|
// results for the query. This is ok (we can still use it to accelerate
|
|
// specific block queries) but we can't do the fastpath "return all
|
|
// results from the set". Clear out the indicator for this.
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
return false;
|
|
}
|
|
|
|
// Skip the first block if we have it.
|
|
if (!SkipFirstBlock) {
|
|
// Analyze the dependency of *Pointer in FromBB. See if we already have
|
|
// been here.
|
|
assert(Visited.count(BB) && "Should check 'visited' before adding to WL");
|
|
|
|
// Get the dependency info for Pointer in BB. If we have cached
|
|
// information, we will use it, otherwise we compute it.
|
|
LLVM_DEBUG(AssertSorted(*Cache, NumSortedEntries));
|
|
MemDepResult Dep = GetNonLocalInfoForBlock(QueryInst, Loc, isLoad, BB,
|
|
Cache, NumSortedEntries);
|
|
|
|
// If we got a Def or Clobber, add this to the list of results.
|
|
if (!Dep.isNonLocal()) {
|
|
if (DT.isReachableFromEntry(BB)) {
|
|
Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr()));
|
|
continue;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If 'Pointer' is an instruction defined in this block, then we need to do
|
|
// phi translation to change it into a value live in the predecessor block.
|
|
// If not, we just add the predecessors to the worklist and scan them with
|
|
// the same Pointer.
|
|
if (!Pointer.NeedsPHITranslationFromBlock(BB)) {
|
|
SkipFirstBlock = false;
|
|
SmallVector<BasicBlock *, 16> NewBlocks;
|
|
for (BasicBlock *Pred : PredCache.get(BB)) {
|
|
// Verify that we haven't looked at this block yet.
|
|
std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> InsertRes =
|
|
Visited.insert(std::make_pair(Pred, Pointer.getAddr()));
|
|
if (InsertRes.second) {
|
|
// First time we've looked at *PI.
|
|
NewBlocks.push_back(Pred);
|
|
continue;
|
|
}
|
|
|
|
// If we have seen this block before, but it was with a different
|
|
// pointer then we have a phi translation failure and we have to treat
|
|
// this as a clobber.
|
|
if (InsertRes.first->second != Pointer.getAddr()) {
|
|
// Make sure to clean up the Visited map before continuing on to
|
|
// PredTranslationFailure.
|
|
for (unsigned i = 0; i < NewBlocks.size(); i++)
|
|
Visited.erase(NewBlocks[i]);
|
|
goto PredTranslationFailure;
|
|
}
|
|
}
|
|
if (NewBlocks.size() > WorklistEntries) {
|
|
// Make sure to clean up the Visited map before continuing on to
|
|
// PredTranslationFailure.
|
|
for (unsigned i = 0; i < NewBlocks.size(); i++)
|
|
Visited.erase(NewBlocks[i]);
|
|
GotWorklistLimit = true;
|
|
goto PredTranslationFailure;
|
|
}
|
|
WorklistEntries -= NewBlocks.size();
|
|
Worklist.append(NewBlocks.begin(), NewBlocks.end());
|
|
continue;
|
|
}
|
|
|
|
// We do need to do phi translation, if we know ahead of time we can't phi
|
|
// translate this value, don't even try.
|
|
if (!Pointer.IsPotentiallyPHITranslatable())
|
|
goto PredTranslationFailure;
|
|
|
|
// We may have added values to the cache list before this PHI translation.
|
|
// If so, we haven't done anything to ensure that the cache remains sorted.
|
|
// Sort it now (if needed) so that recursive invocations of
|
|
// getNonLocalPointerDepFromBB and other routines that could reuse the cache
|
|
// value will only see properly sorted cache arrays.
|
|
if (Cache && NumSortedEntries != Cache->size()) {
|
|
SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
|
|
NumSortedEntries = Cache->size();
|
|
}
|
|
Cache = nullptr;
|
|
|
|
PredList.clear();
|
|
for (BasicBlock *Pred : PredCache.get(BB)) {
|
|
PredList.push_back(std::make_pair(Pred, Pointer));
|
|
|
|
// Get the PHI translated pointer in this predecessor. This can fail if
|
|
// not translatable, in which case the getAddr() returns null.
|
|
PHITransAddr &PredPointer = PredList.back().second;
|
|
PredPointer.PHITranslateValue(BB, Pred, &DT, /*MustDominate=*/false);
|
|
Value *PredPtrVal = PredPointer.getAddr();
|
|
|
|
// Check to see if we have already visited this pred block with another
|
|
// pointer. If so, we can't do this lookup. This failure can occur
|
|
// with PHI translation when a critical edge exists and the PHI node in
|
|
// the successor translates to a pointer value different than the
|
|
// pointer the block was first analyzed with.
|
|
std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> InsertRes =
|
|
Visited.insert(std::make_pair(Pred, PredPtrVal));
|
|
|
|
if (!InsertRes.second) {
|
|
// We found the pred; take it off the list of preds to visit.
|
|
PredList.pop_back();
|
|
|
|
// If the predecessor was visited with PredPtr, then we already did
|
|
// the analysis and can ignore it.
|
|
if (InsertRes.first->second == PredPtrVal)
|
|
continue;
|
|
|
|
// Otherwise, the block was previously analyzed with a different
|
|
// pointer. We can't represent the result of this case, so we just
|
|
// treat this as a phi translation failure.
|
|
|
|
// Make sure to clean up the Visited map before continuing on to
|
|
// PredTranslationFailure.
|
|
for (unsigned i = 0, n = PredList.size(); i < n; ++i)
|
|
Visited.erase(PredList[i].first);
|
|
|
|
goto PredTranslationFailure;
|
|
}
|
|
}
|
|
|
|
// Actually process results here; this need to be a separate loop to avoid
|
|
// calling getNonLocalPointerDepFromBB for blocks we don't want to return
|
|
// any results for. (getNonLocalPointerDepFromBB will modify our
|
|
// datastructures in ways the code after the PredTranslationFailure label
|
|
// doesn't expect.)
|
|
for (unsigned i = 0, n = PredList.size(); i < n; ++i) {
|
|
BasicBlock *Pred = PredList[i].first;
|
|
PHITransAddr &PredPointer = PredList[i].second;
|
|
Value *PredPtrVal = PredPointer.getAddr();
|
|
|
|
bool CanTranslate = true;
|
|
// If PHI translation was unable to find an available pointer in this
|
|
// predecessor, then we have to assume that the pointer is clobbered in
|
|
// that predecessor. We can still do PRE of the load, which would insert
|
|
// a computation of the pointer in this predecessor.
|
|
if (!PredPtrVal)
|
|
CanTranslate = false;
|
|
|
|
// FIXME: it is entirely possible that PHI translating will end up with
|
|
// the same value. Consider PHI translating something like:
|
|
// X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need*
|
|
// to recurse here, pedantically speaking.
|
|
|
|
// If getNonLocalPointerDepFromBB fails here, that means the cached
|
|
// result conflicted with the Visited list; we have to conservatively
|
|
// assume it is unknown, but this also does not block PRE of the load.
|
|
if (!CanTranslate ||
|
|
!getNonLocalPointerDepFromBB(QueryInst, PredPointer,
|
|
Loc.getWithNewPtr(PredPtrVal), isLoad,
|
|
Pred, Result, Visited)) {
|
|
// Add the entry to the Result list.
|
|
NonLocalDepResult Entry(Pred, MemDepResult::getUnknown(), PredPtrVal);
|
|
Result.push_back(Entry);
|
|
|
|
// Since we had a phi translation failure, the cache for CacheKey won't
|
|
// include all of the entries that we need to immediately satisfy future
|
|
// queries. Mark this in NonLocalPointerDeps by setting the
|
|
// BBSkipFirstBlockPair pointer to null. This requires reuse of the
|
|
// cached value to do more work but not miss the phi trans failure.
|
|
NonLocalPointerInfo &NLPI = NonLocalPointerDeps[CacheKey];
|
|
NLPI.Pair = BBSkipFirstBlockPair();
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Refresh the CacheInfo/Cache pointer so that it isn't invalidated.
|
|
CacheInfo = &NonLocalPointerDeps[CacheKey];
|
|
Cache = &CacheInfo->NonLocalDeps;
|
|
NumSortedEntries = Cache->size();
|
|
|
|
// Since we did phi translation, the "Cache" set won't contain all of the
|
|
// results for the query. This is ok (we can still use it to accelerate
|
|
// specific block queries) but we can't do the fastpath "return all
|
|
// results from the set" Clear out the indicator for this.
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
SkipFirstBlock = false;
|
|
continue;
|
|
|
|
PredTranslationFailure:
|
|
// The following code is "failure"; we can't produce a sane translation
|
|
// for the given block. It assumes that we haven't modified any of
|
|
// our datastructures while processing the current block.
|
|
|
|
if (!Cache) {
|
|
// Refresh the CacheInfo/Cache pointer if it got invalidated.
|
|
CacheInfo = &NonLocalPointerDeps[CacheKey];
|
|
Cache = &CacheInfo->NonLocalDeps;
|
|
NumSortedEntries = Cache->size();
|
|
}
|
|
|
|
// Since we failed phi translation, the "Cache" set won't contain all of the
|
|
// results for the query. This is ok (we can still use it to accelerate
|
|
// specific block queries) but we can't do the fastpath "return all
|
|
// results from the set". Clear out the indicator for this.
|
|
CacheInfo->Pair = BBSkipFirstBlockPair();
|
|
|
|
// If *nothing* works, mark the pointer as unknown.
|
|
//
|
|
// If this is the magic first block, return this as a clobber of the whole
|
|
// incoming value. Since we can't phi translate to one of the predecessors,
|
|
// we have to bail out.
|
|
if (SkipFirstBlock)
|
|
return false;
|
|
|
|
bool foundBlock = false;
|
|
for (NonLocalDepEntry &I : llvm::reverse(*Cache)) {
|
|
if (I.getBB() != BB)
|
|
continue;
|
|
|
|
assert((GotWorklistLimit || I.getResult().isNonLocal() ||
|
|
!DT.isReachableFromEntry(BB)) &&
|
|
"Should only be here with transparent block");
|
|
foundBlock = true;
|
|
I.setResult(MemDepResult::getUnknown());
|
|
Result.push_back(
|
|
NonLocalDepResult(I.getBB(), I.getResult(), Pointer.getAddr()));
|
|
break;
|
|
}
|
|
(void)foundBlock; (void)GotWorklistLimit;
|
|
assert((foundBlock || GotWorklistLimit) && "Current block not in cache?");
|
|
}
|
|
|
|
// Okay, we're done now. If we added new values to the cache, re-sort it.
|
|
SortNonLocalDepInfoCache(*Cache, NumSortedEntries);
|
|
LLVM_DEBUG(AssertSorted(*Cache));
|
|
return true;
|
|
}
|
|
|
|
/// If P exists in CachedNonLocalPointerInfo or NonLocalDefsCache, remove it.
|
|
void MemoryDependenceResults::RemoveCachedNonLocalPointerDependencies(
|
|
ValueIsLoadPair P) {
|
|
|
|
// Most of the time this cache is empty.
|
|
if (!NonLocalDefsCache.empty()) {
|
|
auto it = NonLocalDefsCache.find(P.getPointer());
|
|
if (it != NonLocalDefsCache.end()) {
|
|
RemoveFromReverseMap(ReverseNonLocalDefsCache,
|
|
it->second.getResult().getInst(), P.getPointer());
|
|
NonLocalDefsCache.erase(it);
|
|
}
|
|
|
|
if (auto *I = dyn_cast<Instruction>(P.getPointer())) {
|
|
auto toRemoveIt = ReverseNonLocalDefsCache.find(I);
|
|
if (toRemoveIt != ReverseNonLocalDefsCache.end()) {
|
|
for (const auto &entry : toRemoveIt->second)
|
|
NonLocalDefsCache.erase(entry);
|
|
ReverseNonLocalDefsCache.erase(toRemoveIt);
|
|
}
|
|
}
|
|
}
|
|
|
|
CachedNonLocalPointerInfo::iterator It = NonLocalPointerDeps.find(P);
|
|
if (It == NonLocalPointerDeps.end())
|
|
return;
|
|
|
|
// Remove all of the entries in the BB->val map. This involves removing
|
|
// instructions from the reverse map.
|
|
NonLocalDepInfo &PInfo = It->second.NonLocalDeps;
|
|
|
|
for (unsigned i = 0, e = PInfo.size(); i != e; ++i) {
|
|
Instruction *Target = PInfo[i].getResult().getInst();
|
|
if (!Target)
|
|
continue; // Ignore non-local dep results.
|
|
assert(Target->getParent() == PInfo[i].getBB());
|
|
|
|
// Eliminating the dirty entry from 'Cache', so update the reverse info.
|
|
RemoveFromReverseMap(ReverseNonLocalPtrDeps, Target, P);
|
|
}
|
|
|
|
// Remove P from NonLocalPointerDeps (which deletes NonLocalDepInfo).
|
|
NonLocalPointerDeps.erase(It);
|
|
}
|
|
|
|
void MemoryDependenceResults::invalidateCachedPointerInfo(Value *Ptr) {
|
|
// If Ptr isn't really a pointer, just ignore it.
|
|
if (!Ptr->getType()->isPointerTy())
|
|
return;
|
|
// Flush store info for the pointer.
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
|
|
// Flush load info for the pointer.
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
|
|
}
|
|
|
|
void MemoryDependenceResults::invalidateCachedPredecessors() {
|
|
PredCache.clear();
|
|
}
|
|
|
|
void MemoryDependenceResults::removeInstruction(Instruction *RemInst) {
|
|
// Walk through the Non-local dependencies, removing this one as the value
|
|
// for any cached queries.
|
|
NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
|
|
if (NLDI != NonLocalDeps.end()) {
|
|
NonLocalDepInfo &BlockMap = NLDI->second.first;
|
|
for (auto &Entry : BlockMap)
|
|
if (Instruction *Inst = Entry.getResult().getInst())
|
|
RemoveFromReverseMap(ReverseNonLocalDeps, Inst, RemInst);
|
|
NonLocalDeps.erase(NLDI);
|
|
}
|
|
|
|
// If we have a cached local dependence query for this instruction, remove it.
|
|
LocalDepMapType::iterator LocalDepEntry = LocalDeps.find(RemInst);
|
|
if (LocalDepEntry != LocalDeps.end()) {
|
|
// Remove us from DepInst's reverse set now that the local dep info is gone.
|
|
if (Instruction *Inst = LocalDepEntry->second.getInst())
|
|
RemoveFromReverseMap(ReverseLocalDeps, Inst, RemInst);
|
|
|
|
// Remove this local dependency info.
|
|
LocalDeps.erase(LocalDepEntry);
|
|
}
|
|
|
|
// If we have any cached pointer dependencies on this instruction, remove
|
|
// them. If the instruction has non-pointer type, then it can't be a pointer
|
|
// base.
|
|
|
|
// Remove it from both the load info and the store info. The instruction
|
|
// can't be in either of these maps if it is non-pointer.
|
|
if (RemInst->getType()->isPointerTy()) {
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, false));
|
|
RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(RemInst, true));
|
|
}
|
|
|
|
// Loop over all of the things that depend on the instruction we're removing.
|
|
SmallVector<std::pair<Instruction *, Instruction *>, 8> ReverseDepsToAdd;
|
|
|
|
// If we find RemInst as a clobber or Def in any of the maps for other values,
|
|
// we need to replace its entry with a dirty version of the instruction after
|
|
// it. If RemInst is a terminator, we use a null dirty value.
|
|
//
|
|
// Using a dirty version of the instruction after RemInst saves having to scan
|
|
// the entire block to get to this point.
|
|
MemDepResult NewDirtyVal;
|
|
if (!RemInst->isTerminator())
|
|
NewDirtyVal = MemDepResult::getDirty(&*++RemInst->getIterator());
|
|
|
|
ReverseDepMapType::iterator ReverseDepIt = ReverseLocalDeps.find(RemInst);
|
|
if (ReverseDepIt != ReverseLocalDeps.end()) {
|
|
// RemInst can't be the terminator if it has local stuff depending on it.
|
|
assert(!ReverseDepIt->second.empty() && !isa<TerminatorInst>(RemInst) &&
|
|
"Nothing can locally depend on a terminator");
|
|
|
|
for (Instruction *InstDependingOnRemInst : ReverseDepIt->second) {
|
|
assert(InstDependingOnRemInst != RemInst &&
|
|
"Already removed our local dep info");
|
|
|
|
LocalDeps[InstDependingOnRemInst] = NewDirtyVal;
|
|
|
|
// Make sure to remember that new things depend on NewDepInst.
|
|
assert(NewDirtyVal.getInst() &&
|
|
"There is no way something else can have "
|
|
"a local dep on this if it is a terminator!");
|
|
ReverseDepsToAdd.push_back(
|
|
std::make_pair(NewDirtyVal.getInst(), InstDependingOnRemInst));
|
|
}
|
|
|
|
ReverseLocalDeps.erase(ReverseDepIt);
|
|
|
|
// Add new reverse deps after scanning the set, to avoid invalidating the
|
|
// 'ReverseDeps' reference.
|
|
while (!ReverseDepsToAdd.empty()) {
|
|
ReverseLocalDeps[ReverseDepsToAdd.back().first].insert(
|
|
ReverseDepsToAdd.back().second);
|
|
ReverseDepsToAdd.pop_back();
|
|
}
|
|
}
|
|
|
|
ReverseDepIt = ReverseNonLocalDeps.find(RemInst);
|
|
if (ReverseDepIt != ReverseNonLocalDeps.end()) {
|
|
for (Instruction *I : ReverseDepIt->second) {
|
|
assert(I != RemInst && "Already removed NonLocalDep info for RemInst");
|
|
|
|
PerInstNLInfo &INLD = NonLocalDeps[I];
|
|
// The information is now dirty!
|
|
INLD.second = true;
|
|
|
|
for (auto &Entry : INLD.first) {
|
|
if (Entry.getResult().getInst() != RemInst)
|
|
continue;
|
|
|
|
// Convert to a dirty entry for the subsequent instruction.
|
|
Entry.setResult(NewDirtyVal);
|
|
|
|
if (Instruction *NextI = NewDirtyVal.getInst())
|
|
ReverseDepsToAdd.push_back(std::make_pair(NextI, I));
|
|
}
|
|
}
|
|
|
|
ReverseNonLocalDeps.erase(ReverseDepIt);
|
|
|
|
// Add new reverse deps after scanning the set, to avoid invalidating 'Set'
|
|
while (!ReverseDepsToAdd.empty()) {
|
|
ReverseNonLocalDeps[ReverseDepsToAdd.back().first].insert(
|
|
ReverseDepsToAdd.back().second);
|
|
ReverseDepsToAdd.pop_back();
|
|
}
|
|
}
|
|
|
|
// If the instruction is in ReverseNonLocalPtrDeps then it appears as a
|
|
// value in the NonLocalPointerDeps info.
|
|
ReverseNonLocalPtrDepTy::iterator ReversePtrDepIt =
|
|
ReverseNonLocalPtrDeps.find(RemInst);
|
|
if (ReversePtrDepIt != ReverseNonLocalPtrDeps.end()) {
|
|
SmallVector<std::pair<Instruction *, ValueIsLoadPair>, 8>
|
|
ReversePtrDepsToAdd;
|
|
|
|
for (ValueIsLoadPair P : ReversePtrDepIt->second) {
|
|
assert(P.getPointer() != RemInst &&
|
|
"Already removed NonLocalPointerDeps info for RemInst");
|
|
|
|
NonLocalDepInfo &NLPDI = NonLocalPointerDeps[P].NonLocalDeps;
|
|
|
|
// The cache is not valid for any specific block anymore.
|
|
NonLocalPointerDeps[P].Pair = BBSkipFirstBlockPair();
|
|
|
|
// Update any entries for RemInst to use the instruction after it.
|
|
for (auto &Entry : NLPDI) {
|
|
if (Entry.getResult().getInst() != RemInst)
|
|
continue;
|
|
|
|
// Convert to a dirty entry for the subsequent instruction.
|
|
Entry.setResult(NewDirtyVal);
|
|
|
|
if (Instruction *NewDirtyInst = NewDirtyVal.getInst())
|
|
ReversePtrDepsToAdd.push_back(std::make_pair(NewDirtyInst, P));
|
|
}
|
|
|
|
// Re-sort the NonLocalDepInfo. Changing the dirty entry to its
|
|
// subsequent value may invalidate the sortedness.
|
|
llvm::sort(NLPDI.begin(), NLPDI.end());
|
|
}
|
|
|
|
ReverseNonLocalPtrDeps.erase(ReversePtrDepIt);
|
|
|
|
while (!ReversePtrDepsToAdd.empty()) {
|
|
ReverseNonLocalPtrDeps[ReversePtrDepsToAdd.back().first].insert(
|
|
ReversePtrDepsToAdd.back().second);
|
|
ReversePtrDepsToAdd.pop_back();
|
|
}
|
|
}
|
|
|
|
assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
|
|
LLVM_DEBUG(verifyRemoved(RemInst));
|
|
}
|
|
|
|
/// Verify that the specified instruction does not occur in our internal data
|
|
/// structures.
|
|
///
|
|
/// This function verifies by asserting in debug builds.
|
|
void MemoryDependenceResults::verifyRemoved(Instruction *D) const {
|
|
#ifndef NDEBUG
|
|
for (const auto &DepKV : LocalDeps) {
|
|
assert(DepKV.first != D && "Inst occurs in data structures");
|
|
assert(DepKV.second.getInst() != D && "Inst occurs in data structures");
|
|
}
|
|
|
|
for (const auto &DepKV : NonLocalPointerDeps) {
|
|
assert(DepKV.first.getPointer() != D && "Inst occurs in NLPD map key");
|
|
for (const auto &Entry : DepKV.second.NonLocalDeps)
|
|
assert(Entry.getResult().getInst() != D && "Inst occurs as NLPD value");
|
|
}
|
|
|
|
for (const auto &DepKV : NonLocalDeps) {
|
|
assert(DepKV.first != D && "Inst occurs in data structures");
|
|
const PerInstNLInfo &INLD = DepKV.second;
|
|
for (const auto &Entry : INLD.first)
|
|
assert(Entry.getResult().getInst() != D &&
|
|
"Inst occurs in data structures");
|
|
}
|
|
|
|
for (const auto &DepKV : ReverseLocalDeps) {
|
|
assert(DepKV.first != D && "Inst occurs in data structures");
|
|
for (Instruction *Inst : DepKV.second)
|
|
assert(Inst != D && "Inst occurs in data structures");
|
|
}
|
|
|
|
for (const auto &DepKV : ReverseNonLocalDeps) {
|
|
assert(DepKV.first != D && "Inst occurs in data structures");
|
|
for (Instruction *Inst : DepKV.second)
|
|
assert(Inst != D && "Inst occurs in data structures");
|
|
}
|
|
|
|
for (const auto &DepKV : ReverseNonLocalPtrDeps) {
|
|
assert(DepKV.first != D && "Inst occurs in rev NLPD map");
|
|
|
|
for (ValueIsLoadPair P : DepKV.second)
|
|
assert(P != ValueIsLoadPair(D, false) && P != ValueIsLoadPair(D, true) &&
|
|
"Inst occurs in ReverseNonLocalPtrDeps map");
|
|
}
|
|
#endif
|
|
}
|
|
|
|
AnalysisKey MemoryDependenceAnalysis::Key;
|
|
|
|
MemoryDependenceResults
|
|
MemoryDependenceAnalysis::run(Function &F, FunctionAnalysisManager &AM) {
|
|
auto &AA = AM.getResult<AAManager>(F);
|
|
auto &AC = AM.getResult<AssumptionAnalysis>(F);
|
|
auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
|
|
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
|
|
return MemoryDependenceResults(AA, AC, TLI, DT);
|
|
}
|
|
|
|
char MemoryDependenceWrapperPass::ID = 0;
|
|
|
|
INITIALIZE_PASS_BEGIN(MemoryDependenceWrapperPass, "memdep",
|
|
"Memory Dependence Analysis", false, true)
|
|
INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
|
|
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
|
|
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
|
|
INITIALIZE_PASS_END(MemoryDependenceWrapperPass, "memdep",
|
|
"Memory Dependence Analysis", false, true)
|
|
|
|
MemoryDependenceWrapperPass::MemoryDependenceWrapperPass() : FunctionPass(ID) {
|
|
initializeMemoryDependenceWrapperPassPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
MemoryDependenceWrapperPass::~MemoryDependenceWrapperPass() = default;
|
|
|
|
void MemoryDependenceWrapperPass::releaseMemory() {
|
|
MemDep.reset();
|
|
}
|
|
|
|
void MemoryDependenceWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesAll();
|
|
AU.addRequired<AssumptionCacheTracker>();
|
|
AU.addRequired<DominatorTreeWrapperPass>();
|
|
AU.addRequiredTransitive<AAResultsWrapperPass>();
|
|
AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
|
|
}
|
|
|
|
bool MemoryDependenceResults::invalidate(Function &F, const PreservedAnalyses &PA,
|
|
FunctionAnalysisManager::Invalidator &Inv) {
|
|
// Check whether our analysis is preserved.
|
|
auto PAC = PA.getChecker<MemoryDependenceAnalysis>();
|
|
if (!PAC.preserved() && !PAC.preservedSet<AllAnalysesOn<Function>>())
|
|
// If not, give up now.
|
|
return true;
|
|
|
|
// Check whether the analyses we depend on became invalid for any reason.
|
|
if (Inv.invalidate<AAManager>(F, PA) ||
|
|
Inv.invalidate<AssumptionAnalysis>(F, PA) ||
|
|
Inv.invalidate<DominatorTreeAnalysis>(F, PA))
|
|
return true;
|
|
|
|
// Otherwise this analysis result remains valid.
|
|
return false;
|
|
}
|
|
|
|
unsigned MemoryDependenceResults::getDefaultBlockScanLimit() const {
|
|
return BlockScanLimit;
|
|
}
|
|
|
|
bool MemoryDependenceWrapperPass::runOnFunction(Function &F) {
|
|
auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
|
|
auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
|
|
auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
|
|
auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
|
|
MemDep.emplace(AA, AC, TLI, DT);
|
|
return false;
|
|
}
|