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AdjointGenerator.h
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AdjointGenerator.h
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//===- AdjointGenerator.h - Implementation of Adjoint's of instructions --===//
//
// Enzyme Project
//
// Part of the Enzyme Project, under the Apache License v2.0 with LLVM
// Exceptions. See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
// If using this code in an academic setting, please cite the following:
// @incollection{enzymeNeurips,
// title = {Instead of Rewriting Foreign Code for Machine Learning,
// Automatically Synthesize Fast Gradients},
// author = {Moses, William S. and Churavy, Valentin},
// booktitle = {Advances in Neural Information Processing Systems 33},
// year = {2020},
// note = {To appear in},
// }
//
//===----------------------------------------------------------------------===//
//
// This file contains an instruction visitor AdjointGenerator that generates
// the corresponding augmented forward pass code, and adjoints for all
// LLVM instructions.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Value.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "DiffeGradientUtils.h"
#include "DifferentialUseAnalysis.h"
#include "EnzymeLogic.h"
#include "FunctionUtils.h"
#include "GradientUtils.h"
#include "LibraryFuncs.h"
#include "TraceUtils.h"
#include "TypeAnalysis/TBAA.h"
#define DEBUG_TYPE "enzyme"
// Helper instruction visitor that generates adjoints
template <class AugmentedReturnType = AugmentedReturn *>
class AdjointGenerator
: public llvm::InstVisitor<AdjointGenerator<AugmentedReturnType>> {
private:
// Type of code being generated (forward, reverse, or both)
const DerivativeMode Mode;
GradientUtils *const gutils;
llvm::ArrayRef<DIFFE_TYPE> constant_args;
DIFFE_TYPE retType;
TypeResults &TR = gutils->TR;
std::function<unsigned(llvm::Instruction *, CacheType)> getIndex;
const std::map<llvm::CallInst *, const std::vector<bool>>
overwritten_args_map;
const llvm::SmallPtrSetImpl<llvm::Instruction *> *returnuses;
AugmentedReturnType augmentedReturn;
const std::map<llvm::ReturnInst *, llvm::StoreInst *> *replacedReturns;
const llvm::SmallPtrSetImpl<const llvm::Value *> &unnecessaryValues;
const llvm::SmallPtrSetImpl<const llvm::Instruction *>
&unnecessaryInstructions;
const llvm::SmallPtrSetImpl<const llvm::Instruction *> &unnecessaryStores;
const llvm::SmallPtrSetImpl<llvm::BasicBlock *> &oldUnreachable;
llvm::AllocaInst *dretAlloca;
public:
AdjointGenerator(
DerivativeMode Mode, GradientUtils *gutils,
llvm::ArrayRef<DIFFE_TYPE> constant_args, DIFFE_TYPE retType,
std::function<unsigned(llvm::Instruction *, CacheType)> getIndex,
const std::map<llvm::CallInst *, const std::vector<bool>>
overwritten_args_map,
const llvm::SmallPtrSetImpl<llvm::Instruction *> *returnuses,
AugmentedReturnType augmentedReturn,
const std::map<llvm::ReturnInst *, llvm::StoreInst *> *replacedReturns,
const llvm::SmallPtrSetImpl<const llvm::Value *> &unnecessaryValues,
const llvm::SmallPtrSetImpl<const llvm::Instruction *>
&unnecessaryInstructions,
const llvm::SmallPtrSetImpl<const llvm::Instruction *> &unnecessaryStores,
const llvm::SmallPtrSetImpl<llvm::BasicBlock *> &oldUnreachable,
llvm::AllocaInst *dretAlloca)
: Mode(Mode), gutils(gutils), constant_args(constant_args),
retType(retType), getIndex(getIndex),
overwritten_args_map(overwritten_args_map), returnuses(returnuses),
augmentedReturn(augmentedReturn), replacedReturns(replacedReturns),
unnecessaryValues(unnecessaryValues),
unnecessaryInstructions(unnecessaryInstructions),
unnecessaryStores(unnecessaryStores), oldUnreachable(oldUnreachable),
dretAlloca(dretAlloca) {
using namespace llvm;
assert(TR.getFunction() == gutils->oldFunc);
for (auto &pair : TR.analyzer.analysis) {
if (auto in = dyn_cast<Instruction>(pair.first)) {
if (in->getParent()->getParent() != gutils->oldFunc) {
llvm::errs() << "inf: " << *in->getParent()->getParent() << "\n";
llvm::errs() << "gutils->oldFunc: " << *gutils->oldFunc << "\n";
llvm::errs() << "in: " << *in << "\n";
}
assert(in->getParent()->getParent() == gutils->oldFunc);
}
}
}
void eraseIfUnused(llvm::Instruction &I, bool erase = true,
bool check = true) {
using namespace llvm;
bool used =
unnecessaryInstructions.find(&I) == unnecessaryInstructions.end();
if (!used) {
// if decided to cache a value, preserve it here for later
// replacement in EnzymeLogic
auto found = gutils->knownRecomputeHeuristic.find(&I);
if (found != gutils->knownRecomputeHeuristic.end() && !found->second)
used = true;
}
auto iload = gutils->getNewFromOriginal((llvm::Value *)&I);
if (used && check)
return;
if (auto newi = dyn_cast<Instruction>(iload))
gutils->eraseWithPlaceholder(newi, &I, "_replacementA", erase);
}
llvm::Value *MPI_TYPE_SIZE(llvm::Value *DT, llvm::IRBuilder<> &B,
llvm::Type *intType) {
using namespace llvm;
if (DT->getType()->isIntegerTy())
DT = B.CreateIntToPtr(DT, Type::getInt8PtrTy(DT->getContext()));
if (Constant *C = dyn_cast<Constant>(DT)) {
while (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
C = CE->getOperand(0);
}
if (auto GV = dyn_cast<GlobalVariable>(C)) {
if (GV->getName() == "ompi_mpi_double") {
return ConstantInt::get(intType, 8, false);
} else if (GV->getName() == "ompi_mpi_float") {
return ConstantInt::get(intType, 4, false);
}
}
}
Type *pargs[] = {Type::getInt8PtrTy(DT->getContext()),
PointerType::getUnqual(intType)};
auto FT = FunctionType::get(intType, pargs, false);
auto alloc = IRBuilder<>(gutils->inversionAllocs).CreateAlloca(intType);
llvm::Value *args[] = {DT, alloc};
if (DT->getType() != pargs[0])
args[0] = B.CreateBitCast(args[0], pargs[0]);
AttributeList AL;
AL = AL.addParamAttribute(DT->getContext(), 0,
Attribute::AttrKind::ReadOnly);
AL = AL.addParamAttribute(DT->getContext(), 0,
Attribute::AttrKind::NoCapture);
AL =
AL.addParamAttribute(DT->getContext(), 0, Attribute::AttrKind::NoAlias);
AL =
AL.addParamAttribute(DT->getContext(), 0, Attribute::AttrKind::NonNull);
AL = AL.addParamAttribute(DT->getContext(), 1,
Attribute::AttrKind::WriteOnly);
AL = AL.addParamAttribute(DT->getContext(), 1,
Attribute::AttrKind::NoCapture);
AL =
AL.addParamAttribute(DT->getContext(), 1, Attribute::AttrKind::NoAlias);
AL =
AL.addParamAttribute(DT->getContext(), 1, Attribute::AttrKind::NonNull);
#if LLVM_VERSION_MAJOR >= 14
AL = AL.addAttributeAtIndex(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::NoUnwind);
AL = AL.addAttributeAtIndex(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::NoFree);
AL = AL.addAttributeAtIndex(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::NoSync);
AL = AL.addAttributeAtIndex(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::WillReturn);
#else
AL = AL.addAttribute(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::NoFree);
AL = AL.addAttribute(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::NoSync);
AL = AL.addAttribute(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::WillReturn);
#endif
#if LLVM_VERSION_MAJOR < 14
AL = AL.addAttribute(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::ArgMemOnly);
AL = AL.addAttribute(DT->getContext(), AttributeList::FunctionIndex,
Attribute::AttrKind::NoUnwind);
#endif
auto CI = B.CreateCall(
B.GetInsertBlock()->getParent()->getParent()->getOrInsertFunction(
"MPI_Type_size", FT, AL),
args);
#if LLVM_VERSION_MAJOR >= 16
CI->setOnlyAccessesArgMemory();
#else
#if LLVM_VERSION_MAJOR >= 14
CI->addAttributeAtIndex(AttributeList::FunctionIndex,
Attribute::ArgMemOnly);
#else
CI->addAttribute(AttributeList::FunctionIndex, Attribute::ArgMemOnly);
#endif
#endif
return B.CreateLoad(intType, alloc);
}
// To be double-checked against the functionality needed and the respective
// implementation in Adjoint-MPI
llvm::Value *MPI_COMM_RANK(llvm::Value *comm, llvm::IRBuilder<> &B,
llvm::Type *rankTy) {
using namespace llvm;
Type *pargs[] = {comm->getType(), PointerType::getUnqual(rankTy)};
auto FT = FunctionType::get(rankTy, pargs, false);
auto &context = comm->getContext();
auto alloc = IRBuilder<>(gutils->inversionAllocs).CreateAlloca(rankTy);
AttributeList AL;
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::ReadOnly);
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::NoCapture);
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::NoAlias);
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::NonNull);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::WriteOnly);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::NoCapture);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::NoAlias);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::NonNull);
#if LLVM_VERSION_MAJOR >= 14
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoUnwind);
#else
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoUnwind);
#endif
#if LLVM_VERSION_MAJOR >= 14
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoFree);
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoSync);
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::WillReturn);
#else
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoFree);
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoSync);
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::WillReturn);
#endif
llvm::Value *args[] = {comm, alloc};
B.CreateCall(
B.GetInsertBlock()->getParent()->getParent()->getOrInsertFunction(
"MPI_Comm_rank", FT, AL),
args);
return B.CreateLoad(rankTy, alloc);
}
llvm::Value *MPI_COMM_SIZE(llvm::Value *comm, llvm::IRBuilder<> &B,
llvm::Type *rankTy) {
using namespace llvm;
Type *pargs[] = {comm->getType(), PointerType::getUnqual(rankTy)};
auto FT = FunctionType::get(rankTy, pargs, false);
auto &context = comm->getContext();
auto alloc = IRBuilder<>(gutils->inversionAllocs).CreateAlloca(rankTy);
AttributeList AL;
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::ReadOnly);
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::NoCapture);
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::NoAlias);
AL = AL.addParamAttribute(context, 0, Attribute::AttrKind::NonNull);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::WriteOnly);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::NoCapture);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::NoAlias);
AL = AL.addParamAttribute(context, 1, Attribute::AttrKind::NonNull);
#if LLVM_VERSION_MAJOR >= 14
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoUnwind);
#else
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoUnwind);
#endif
#if LLVM_VERSION_MAJOR >= 14
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoFree);
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoSync);
AL = AL.addAttributeAtIndex(context, AttributeList::FunctionIndex,
Attribute::AttrKind::WillReturn);
#else
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoFree);
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::NoSync);
AL = AL.addAttribute(context, AttributeList::FunctionIndex,
Attribute::AttrKind::WillReturn);
#endif
llvm::Value *args[] = {comm, alloc};
B.CreateCall(
B.GetInsertBlock()->getParent()->getParent()->getOrInsertFunction(
"MPI_Comm_size", FT, AL),
args);
return B.CreateLoad(rankTy, alloc);
}
void visitInstruction(llvm::Instruction &inst) {
using namespace llvm;
// TODO explicitly handle all instructions rather than using the catch all
// below
switch (inst.getOpcode()) {
#include "InstructionDerivatives.inc"
default:
break;
}
std::string s;
llvm::raw_string_ostream ss(s);
ss << *gutils->oldFunc << "\n";
ss << *gutils->newFunc << "\n";
ss << "in Mode: " << to_string(Mode) << "\n";
ss << "cannot handle unknown instruction\n" << inst;
if (CustomErrorHandler) {
IRBuilder<> Builder2(&inst);
getForwardBuilder(Builder2);
CustomErrorHandler(ss.str().c_str(), wrap(&inst), ErrorType::NoDerivative,
gutils, nullptr, wrap(&Builder2));
return;
} else {
EmitFailure("NoDerivative", inst.getDebugLoc(), &inst, ss.str());
return;
}
}
// Common function for falling back to the implementation
// of dual propagation, as available in invertPointerM.
void forwardModeInvertedPointerFallback(llvm::Instruction &I) {
using namespace llvm;
if (gutils->isConstantValue(&I))
return;
auto found = gutils->invertedPointers.find(&I);
assert(found != gutils->invertedPointers.end());
auto placeholder = cast<PHINode>(&*found->second);
gutils->invertedPointers.erase(found);
if (!DifferentialUseAnalysis::is_value_needed_in_reverse<ValueType::Shadow>(
gutils, &I, Mode, oldUnreachable)) {
gutils->erase(placeholder);
return;
}
IRBuilder<> Builder2(&I);
getForwardBuilder(Builder2);
auto toset = gutils->invertPointerM(&I, Builder2, /*nullShadow*/ true);
gutils->replaceAWithB(placeholder, toset);
placeholder->replaceAllUsesWith(toset);
gutils->erase(placeholder);
gutils->invertedPointers.insert(
std::make_pair((const Value *)&I, InvertedPointerVH(gutils, toset)));
return;
}
void visitAllocaInst(llvm::AllocaInst &I) {
eraseIfUnused(I);
switch (Mode) {
case DerivativeMode::ForwardModeSplit:
case DerivativeMode::ForwardMode: {
forwardModeInvertedPointerFallback(I);
return;
}
default:
return;
}
}
void visitICmpInst(llvm::ICmpInst &I) { eraseIfUnused(I); }
void visitFCmpInst(llvm::FCmpInst &I) { eraseIfUnused(I); }
void visitLoadLike(llvm::Instruction &I, llvm::MaybeAlign alignment,
bool constantval, llvm::Value *mask = nullptr,
llvm::Value *orig_maskInit = nullptr) {
using namespace llvm;
auto &DL = gutils->newFunc->getParent()->getDataLayout();
auto LoadSize = (DL.getTypeSizeInBits(I.getType()) + 1) / 8;
assert(Mode == DerivativeMode::ForwardMode || gutils->can_modref_map);
assert(Mode == DerivativeMode::ForwardMode ||
gutils->can_modref_map->find(&I) != gutils->can_modref_map->end());
bool can_modref = Mode == DerivativeMode::ForwardMode
? false
: gutils->can_modref_map->find(&I)->second;
constantval |= gutils->isConstantValue(&I);
BasicBlock *parent = I.getParent();
Type *type = gutils->getShadowType(I.getType());
auto *newi = dyn_cast<Instruction>(gutils->getNewFromOriginal(&I));
SmallVector<Metadata *, 1> scopeMD = {
gutils->getDerivativeAliasScope(I.getOperand(0), -1)};
if (auto prev = I.getMetadata(LLVMContext::MD_alias_scope)) {
for (auto &M : cast<MDNode>(prev)->operands()) {
scopeMD.push_back(M);
}
}
auto scope = MDNode::get(I.getContext(), scopeMD);
newi->setMetadata(LLVMContext::MD_alias_scope, scope);
SmallVector<Metadata *, 1> MDs;
for (size_t j = 0; j < gutils->getWidth(); j++) {
MDs.push_back(gutils->getDerivativeAliasScope(I.getOperand(0), j));
}
if (auto prev = I.getMetadata(LLVMContext::MD_noalias)) {
for (auto &M : cast<MDNode>(prev)->operands()) {
MDs.push_back(M);
}
}
auto noscope = MDNode::get(I.getContext(), MDs);
newi->setMetadata(LLVMContext::MD_noalias, noscope);
auto vd = TR.query(&I);
IRBuilder<> BuilderZ(newi);
if (!vd.isKnown()) {
auto ET = I.getType();
if (looseTypeAnalysis || true) {
vd = defaultTypeTreeForLLVM(ET, &I);
EmitWarning("CannotDeduceType", I, "failed to deduce type of load ", I);
goto known;
}
if (CustomErrorHandler) {
std::string str;
raw_string_ostream ss(str);
ss << "Cannot deduce type of load " << I;
CustomErrorHandler(str.c_str(), wrap(&I), ErrorType::NoType,
&TR.analyzer, nullptr, wrap(&BuilderZ));
} else {
EmitFailure("CannotDeduceType", I.getDebugLoc(), &I,
"failed to deduce type of load ", I);
TR.intType(LoadSize, &I, /*errifnotfound*/ true,
/*pointerIntSame*/ true);
llvm_unreachable("bad mti");
}
known:;
}
if (Mode == DerivativeMode::ForwardMode ||
Mode == DerivativeMode::ForwardModeSplit) {
if (!constantval) {
auto found = gutils->invertedPointers.find(&I);
assert(found != gutils->invertedPointers.end());
Instruction *placeholder = cast<Instruction>(&*found->second);
assert(placeholder->getType() == type);
gutils->invertedPointers.erase(found);
// only make shadow where caching needed
if (!DifferentialUseAnalysis::is_value_needed_in_reverse<
ValueType::Shadow>(gutils, &I, Mode, oldUnreachable)) {
gutils->erase(placeholder);
return;
}
if (can_modref) {
if (vd[{-1}].isPossiblePointer()) {
Value *newip = gutils->cacheForReverse(
BuilderZ, placeholder, getIndex(&I, CacheType::Shadow));
assert(newip->getType() == type);
gutils->invertedPointers.insert(std::make_pair(
(const Value *)&I, InvertedPointerVH(gutils, newip)));
} else {
gutils->erase(placeholder);
}
} else {
Value *newip = gutils->invertPointerM(&I, BuilderZ);
if (EnzymeRuntimeActivityCheck && vd[{-1}].isFloat()) {
// TODO handle mask
assert(!mask);
auto rule = [&](Value *inop, Value *newip) -> Value * {
Value *shadow = BuilderZ.CreateICmpNE(
gutils->getNewFromOriginal(I.getOperand(0)), inop);
newip = CreateSelect(BuilderZ, shadow, newip,
Constant::getNullValue(newip->getType()));
return newip;
};
newip = applyChainRule(
I.getType(), BuilderZ, rule,
gutils->invertPointerM(I.getOperand(0), BuilderZ), newip);
}
assert(newip->getType() == type);
placeholder->replaceAllUsesWith(newip);
gutils->erase(placeholder);
gutils->invertedPointers.erase(&I);
gutils->invertedPointers.insert(std::make_pair(
(const Value *)&I, InvertedPointerVH(gutils, newip)));
}
}
return;
}
//! Store inverted pointer loads that need to be cached for use in reverse
//! pass
if (vd[{-1}].isPossiblePointer()) {
auto found = gutils->invertedPointers.find(&I);
if (found != gutils->invertedPointers.end()) {
Instruction *placeholder = cast<Instruction>(&*found->second);
assert(placeholder->getType() == type);
gutils->invertedPointers.erase(found);
if (!constantval) {
Value *newip = nullptr;
// TODO: In the case of fwd mode this should be true if the loaded
// value itself is used as a pointer.
bool needShadow = DifferentialUseAnalysis::is_value_needed_in_reverse<
ValueType::Shadow>(gutils, &I, Mode, oldUnreachable);
switch (Mode) {
case DerivativeMode::ReverseModePrimal:
case DerivativeMode::ReverseModeCombined: {
if (!needShadow) {
gutils->erase(placeholder);
} else {
newip = gutils->invertPointerM(&I, BuilderZ);
assert(newip->getType() == type);
if (Mode == DerivativeMode::ReverseModePrimal && can_modref &&
DifferentialUseAnalysis::is_value_needed_in_reverse<
ValueType::Shadow>(gutils, &I,
DerivativeMode::ReverseModeGradient,
oldUnreachable)) {
gutils->cacheForReverse(BuilderZ, newip,
getIndex(&I, CacheType::Shadow));
}
placeholder->replaceAllUsesWith(newip);
gutils->erase(placeholder);
gutils->invertedPointers.insert(std::make_pair(
(const Value *)&I, InvertedPointerVH(gutils, newip)));
}
break;
}
case DerivativeMode::ForwardModeSplit:
case DerivativeMode::ForwardMode: {
assert(0 && "impossible branch");
return;
}
case DerivativeMode::ReverseModeGradient: {
if (!needShadow) {
gutils->erase(placeholder);
} else {
// only make shadow where caching needed
if (can_modref) {
newip = gutils->cacheForReverse(
BuilderZ, placeholder, getIndex(&I, CacheType::Shadow));
assert(newip->getType() == type);
gutils->invertedPointers.insert(std::make_pair(
(const Value *)&I, InvertedPointerVH(gutils, newip)));
} else {
newip = gutils->invertPointerM(&I, BuilderZ);
assert(newip->getType() == type);
placeholder->replaceAllUsesWith(newip);
gutils->erase(placeholder);
gutils->invertedPointers.insert(std::make_pair(
(const Value *)&I, InvertedPointerVH(gutils, newip)));
}
}
break;
}
}
} else {
gutils->erase(placeholder);
}
}
}
Value *inst = newi;
//! Store loads that need to be cached for use in reverse pass
// Only cache value here if caching decision isn't precomputed.
// Otherwise caching will be done inside EnzymeLogic.cpp at
// the end of the function jointly.
if (Mode != DerivativeMode::ForwardMode &&
!gutils->knownRecomputeHeuristic.count(&I) && can_modref &&
!gutils->unnecessaryIntermediates.count(&I)) {
// we can pre initialize all the knownRecomputeHeuristic values to false
// (not needing) as we may assume that minCutCache already preserves
// everything it requires.
std::map<UsageKey, bool> Seen;
bool primalNeededInReverse = false;
for (auto pair : gutils->knownRecomputeHeuristic)
if (!pair.second) {
Seen[UsageKey(pair.first, ValueType::Primal)] = false;
if (pair.first == &I)
primalNeededInReverse = true;
}
primalNeededInReverse |=
DifferentialUseAnalysis::is_value_needed_in_reverse<
ValueType::Primal>(gutils, &I, Mode, Seen, oldUnreachable);
if (primalNeededInReverse) {
inst = gutils->cacheForReverse(BuilderZ, newi,
getIndex(&I, CacheType::Self));
assert(inst->getType() == type);
if (Mode == DerivativeMode::ReverseModeGradient ||
Mode == DerivativeMode::ForwardModeSplit) {
assert(inst != newi);
} else {
assert(inst == newi);
}
}
}
if (Mode == DerivativeMode::ReverseModePrimal)
return;
if (constantval)
return;
if (nonmarkedglobals_inactiveloads) {
// Assume that non enzyme_shadow globals are inactive
// If we ever store to a global variable, we will error if it doesn't
// have a shadow This allows functions who only read global memory to
// have their derivative computed Note that this is too aggressive for
// general programs as if the global aliases with an argument something
// that is written to, then we will have a logical error
if (auto arg = dyn_cast<GlobalVariable>(I.getOperand(0))) {
if (!hasMetadata(arg, "enzyme_shadow")) {
return;
}
}
}
// Only propagate if instruction is active. The value can be active and not
// the instruction if the value is a potential pointer. This may not be
// caught by type analysis is the result does not have a known type.
if (!gutils->isConstantInstruction(&I)) {
switch (Mode) {
case DerivativeMode::ForwardModeSplit:
case DerivativeMode::ForwardMode: {
assert(0 && "impossible branch");
return;
}
case DerivativeMode::ReverseModeGradient:
case DerivativeMode::ReverseModeCombined: {
IRBuilder<> Builder2(&I);
getReverseBuilder(Builder2);
Value *prediff = nullptr;
for (ssize_t i = -1; i < (ssize_t)LoadSize; ++i) {
if (vd[{(int)i}].isFloat()) {
prediff = diffe(&I, Builder2);
break;
}
}
Value *premask = nullptr;
if (prediff && mask &&
(!gutils->isConstantValue(I.getOperand(0)) ||
!gutils->isConstantValue(orig_maskInit))) {
premask = lookup(mask, Builder2);
}
if (prediff)
((DiffeGradientUtils *)gutils)
->addToInvertedPtrDiffe(&I, &I, vd, LoadSize, I.getOperand(0),
prediff, Builder2, alignment, premask);
unsigned start = 0;
unsigned size = LoadSize;
while (1) {
unsigned nextStart = size;
auto dt = vd[{-1}];
for (size_t i = start; i < size; ++i) {
bool Legal = true;
dt.checkedOrIn(vd[{(int)i}], /*PointerIntSame*/ true, Legal);
if (!Legal) {
nextStart = i;
break;
}
}
if (!dt.isKnown()) {
TR.dump();
llvm::errs() << " vd:" << vd.str() << " start:" << start
<< " size: " << size << " dt:" << dt.str() << "\n";
}
assert(dt.isKnown());
if (Type *isfloat = dt.isFloat()) {
if (premask && !gutils->isConstantValue(orig_maskInit)) {
// Masked partial type is unhanled.
if (premask)
assert(start == 0 && nextStart == LoadSize);
addToDiffe(orig_maskInit, prediff, Builder2, isfloat,
Builder2.CreateNot(premask));
}
}
if (nextStart == size)
break;
start = nextStart;
}
break;
}
case DerivativeMode::ReverseModePrimal:
break;
}
}
}
void visitLoadInst(llvm::LoadInst &LI) {
using namespace llvm;
// If a load of an omp init argument, don't cache for reverse
// and don't do any adjoint propagation (assumed integral)
for (auto U : LI.getPointerOperand()->users()) {
if (auto CI = dyn_cast<CallInst>(U)) {
if (auto F = CI->getCalledFunction()) {
if (F->getName() == "__kmpc_for_static_init_4" ||
F->getName() == "__kmpc_for_static_init_4u" ||
F->getName() == "__kmpc_for_static_init_8" ||
F->getName() == "__kmpc_for_static_init_8u") {
eraseIfUnused(LI);
return;
}
}
}
}
auto alignment = LI.getAlign();
auto &DL = gutils->newFunc->getParent()->getDataLayout();
bool constantval = parseTBAA(LI, DL).Inner0().isIntegral();
visitLoadLike(LI, alignment, constantval);
eraseIfUnused(LI);
}
void visitAtomicRMWInst(llvm::AtomicRMWInst &I) {
using namespace llvm;
if (gutils->isConstantInstruction(&I) && gutils->isConstantValue(&I)) {
if (Mode == DerivativeMode::ReverseModeGradient ||
Mode == DerivativeMode::ForwardModeSplit) {
eraseIfUnused(I, /*erase*/ true, /*check*/ false);
} else {
eraseIfUnused(I);
}
return;
}
IRBuilder<> BuilderZ(&I);
getForwardBuilder(BuilderZ);
switch (I.getOperation()) {
case AtomicRMWInst::FAdd:
case AtomicRMWInst::FSub: {
if (Mode == DerivativeMode::ForwardMode ||
Mode == DerivativeMode::ForwardModeSplit) {
auto rule = [&](Value *ptr, Value *dif) -> Value * {
if (dif == nullptr)
dif = Constant::getNullValue(I.getType());
if (!gutils->isConstantInstruction(&I)) {
assert(ptr);
AtomicRMWInst *rmw = nullptr;
#if LLVM_VERSION_MAJOR >= 13
rmw = BuilderZ.CreateAtomicRMW(I.getOperation(), ptr, dif,
I.getAlign(), I.getOrdering(),
I.getSyncScopeID());
#else
rmw = BuilderZ.CreateAtomicRMW(I.getOperation(), ptr, dif,
I.getOrdering(), I.getSyncScopeID());
rmw->setAlignment(I.getAlign());
#endif
rmw->setVolatile(I.isVolatile());
if (gutils->isConstantValue(&I))
return Constant::getNullValue(dif->getType());
else
return rmw;
} else {
assert(gutils->isConstantValue(&I));
return Constant::getNullValue(dif->getType());
}
};
Value *diff = applyChainRule(
I.getType(), BuilderZ, rule,
gutils->isConstantValue(I.getPointerOperand())
? nullptr
: gutils->invertPointerM(I.getPointerOperand(), BuilderZ),
gutils->isConstantValue(I.getValOperand())
? nullptr
: gutils->invertPointerM(I.getValOperand(), BuilderZ));
if (!gutils->isConstantValue(&I))
setDiffe(&I, diff, BuilderZ);
return;
}
if (Mode == DerivativeMode::ReverseModePrimal) {
eraseIfUnused(I);
return;
}
if ((Mode == DerivativeMode::ReverseModeCombined ||
Mode == DerivativeMode::ReverseModeGradient) &&
gutils->isConstantValue(&I)) {
if (!gutils->isConstantValue(I.getValOperand())) {
assert(!gutils->isConstantValue(I.getPointerOperand()));
IRBuilder<> Builder2(&I);
getReverseBuilder(Builder2);
Value *ip = gutils->invertPointerM(I.getPointerOperand(), Builder2);
ip = lookup(ip, Builder2);
auto order = I.getOrdering();
if (order == AtomicOrdering::Release)
order = AtomicOrdering::Monotonic;
else if (order == AtomicOrdering::AcquireRelease)
order = AtomicOrdering::Acquire;
auto rule = [&](Value *ip) -> Value * {
LoadInst *dif1 =
Builder2.CreateLoad(I.getType(), ip, I.isVolatile());
dif1->setAlignment(I.getAlign());
dif1->setOrdering(order);
dif1->setSyncScopeID(I.getSyncScopeID());
return dif1;
};
Value *diff = applyChainRule(I.getType(), Builder2, rule, ip);
addToDiffe(I.getValOperand(), diff, Builder2,
I.getValOperand()->getType()->getScalarType());
}
if (Mode == DerivativeMode::ReverseModeGradient) {
eraseIfUnused(I, /*erase*/ true, /*check*/ false);
} else
eraseIfUnused(I);
return;
}
break;
}
default:
break;
}
if (looseTypeAnalysis) {
auto &DL = gutils->newFunc->getParent()->getDataLayout();
auto valType = I.getValOperand()->getType();
auto storeSize = DL.getTypeSizeInBits(valType) / 8;
auto fp = TR.firstPointer(storeSize, I.getPointerOperand(), &I,
/*errifnotfound*/ false,
/*pointerIntSame*/ true);
if (!fp.isKnown() && valType->isIntOrIntVectorTy()) {
if (Mode == DerivativeMode::ReverseModeGradient ||
Mode == DerivativeMode::ReverseModeGradient) {
eraseIfUnused(I, /*erase*/ true, /*check*/ false);
} else
eraseIfUnused(I);
return;
}
}
std::string s;
llvm::raw_string_ostream ss(s);
ss << *I.getParent()->getParent() << "\n" << I << "\n";
ss << " Active atomic inst not yet handled";
if (CustomErrorHandler) {
CustomErrorHandler(ss.str().c_str(), wrap(&I), ErrorType::NoDerivative,
gutils, nullptr, wrap(&BuilderZ));
return;
} else {
EmitFailure("NoDerivative", I.getDebugLoc(), &I, ss.str());
return;
}
}
void visitStoreInst(llvm::StoreInst &SI) {
using namespace llvm;
// If a store of an omp init argument, don't delete in reverse
// and don't do any adjoint propagation (assumed integral)
for (auto U : SI.getPointerOperand()->users()) {
if (auto CI = dyn_cast<CallInst>(U)) {
if (auto F = CI->getCalledFunction()) {
if (F->getName() == "__kmpc_for_static_init_4" ||
F->getName() == "__kmpc_for_static_init_4u" ||
F->getName() == "__kmpc_for_static_init_8" ||
F->getName() == "__kmpc_for_static_init_8u") {
return;
}
}
}
}
auto align = SI.getAlign();
visitCommonStore(SI, SI.getPointerOperand(), SI.getValueOperand(), align,
SI.isVolatile(), SI.getOrdering(), SI.getSyncScopeID(),
/*mask=*/nullptr);
bool forceErase = false;
if (Mode == DerivativeMode::ReverseModeGradient) {
for (const auto &pair : gutils->rematerializableAllocations) {
if (pair.second.stores.count(&SI) && pair.second.LI) {
forceErase = true;
}
}
}
if (forceErase)
eraseIfUnused(SI, /*erase*/ true, /*check*/ false);
else
eraseIfUnused(SI);
}
void visitCommonStore(llvm::Instruction &I, llvm::Value *orig_ptr,
llvm::Value *orig_val, llvm::MaybeAlign align,
bool isVolatile, llvm::AtomicOrdering ordering,
llvm::SyncScope::ID syncScope, llvm::Value *mask) {
using namespace llvm;
Value *val = gutils->getNewFromOriginal(orig_val);
Type *valType = orig_val->getType();
auto &DL = gutils->newFunc->getParent()->getDataLayout();
if (unnecessaryStores.count(&I)) {
return;
}
if (gutils->isConstantValue(orig_ptr)) {
return;
}
SmallVector<Metadata *, 1> scopeMD = {
gutils->getDerivativeAliasScope(orig_ptr, -1)};
SmallVector<Metadata *, 1> prevScopes;
if (auto prev = I.getMetadata(LLVMContext::MD_alias_scope)) {
for (auto &M : cast<MDNode>(prev)->operands()) {
scopeMD.push_back(M);
prevScopes.push_back(M);
}
}
auto scope = MDNode::get(I.getContext(), scopeMD);
auto NewI = gutils->getNewFromOriginal(&I);
NewI->setMetadata(LLVMContext::MD_alias_scope, scope);
SmallVector<Metadata *, 1> MDs;
SmallVector<Metadata *, 1> prevNoAlias;
for (size_t j = 0; j < gutils->getWidth(); j++) {
MDs.push_back(gutils->getDerivativeAliasScope(orig_ptr, j));
}
if (auto prev = I.getMetadata(LLVMContext::MD_noalias)) {
for (auto &M : cast<MDNode>(prev)->operands()) {
MDs.push_back(M);
prevNoAlias.push_back(M);
}
}
auto noscope = MDNode::get(I.getContext(), MDs);
NewI->setMetadata(LLVMContext::MD_noalias, noscope);
bool constantval = gutils->isConstantValue(orig_val) ||
parseTBAA(I, DL).Inner0().isIntegral();
IRBuilder<> BuilderZ(NewI);
BuilderZ.setFastMathFlags(getFast());
// TODO allow recognition of other types that could contain pointers [e.g.
// {void*, void*} or <2 x i64> ]
auto storeSize = DL.getTypeSizeInBits(valType) / 8;
auto vd = TR.query(orig_ptr).Lookup(storeSize, DL);
if (!vd.isKnown()) {
if (looseTypeAnalysis || true) {
vd = defaultTypeTreeForLLVM(valType, &I);
EmitWarning("CannotDeduceType", I, "failed to deduce type of xtore ",
I);
goto known;
}
if (CustomErrorHandler) {
std::string str;
raw_string_ostream ss(str);
ss << "Cannot deduce type of store " << I;
CustomErrorHandler(str.c_str(), wrap(&I), ErrorType::NoType,