void Rationalizer::RewriteAssignment(LIR::Use& use)
{
assert(use.IsInitialized());
GenTreeOp* assignment = use.Def()->AsOp();
assert(assignment->OperGet() == GT_ASG);
GenTree* location = assignment->gtGetOp1();
GenTree* value = assignment->gtGetOp2();
genTreeOps locationOp = location->OperGet();
if (assignment->OperIsBlkOp())
{
#ifdef FEATURE_SIMD
if (varTypeIsSIMD(location) && assignment->OperIsInitBlkOp())
{
if (location->OperGet() == GT_LCL_VAR)
{
var_types simdType = location->TypeGet();
GenTree* initVal = assignment->gtOp.gtOp2;
var_types baseType = comp->getBaseTypeOfSIMDLocal(location);
if (baseType != TYP_UNKNOWN)
{
GenTreeSIMD* simdTree = new (comp, GT_SIMD)
GenTreeSIMD(simdType, initVal, SIMDIntrinsicInit, baseType, genTypeSize(simdType));
assignment->gtOp.gtOp2 = simdTree;
value = simdTree;
initVal->gtNext = simdTree;
simdTree->gtPrev = initVal;
simdTree->gtNext = location;
location->gtPrev = simdTree;
}
}
}
#endif // FEATURE_SIMD
if ((location->TypeGet() == TYP_STRUCT) && !assignment->IsPhiDefn() && !value->IsMultiRegCall())
{
if ((location->OperGet() == GT_LCL_VAR))
{
// We need to construct a block node for the location.
// Modify lcl to be the address form.
location->SetOper(addrForm(locationOp));
LclVarDsc* varDsc = &(comp->lvaTable[location->AsLclVarCommon()->gtLclNum]);
location->gtType = TYP_BYREF;
GenTreeBlk* storeBlk = nullptr;
unsigned int size = varDsc->lvExactSize;
if (varDsc->lvStructGcCount != 0)
{
CORINFO_CLASS_HANDLE structHnd = varDsc->lvVerTypeInfo.GetClassHandle();
GenTreeObj* objNode = comp->gtNewObjNode(structHnd, location)->AsObj();
unsigned int slots = (unsigned)(roundUp(size, TARGET_POINTER_SIZE) / TARGET_POINTER_SIZE);
objNode->SetGCInfo(varDsc->lvGcLayout, varDsc->lvStructGcCount, slots);
objNode->ChangeOper(GT_STORE_OBJ);
objNode->SetData(value);
comp->fgMorphUnsafeBlk(objNode);
storeBlk = objNode;
}
else
{
storeBlk = new (comp, GT_STORE_BLK) GenTreeBlk(GT_STORE_BLK, TYP_STRUCT, location, value, size);
}
storeBlk->gtFlags |= (GTF_REVERSE_OPS | GTF_ASG);
storeBlk->gtFlags |= ((location->gtFlags | value->gtFlags) & GTF_ALL_EFFECT);
GenTree* insertionPoint = location->gtNext;
BlockRange().InsertBefore(insertionPoint, storeBlk);
use.ReplaceWith(comp, storeBlk);
BlockRange().Remove(assignment);
JITDUMP("After transforming local struct assignment into a block op:\n");
DISPTREERANGE(BlockRange(), use.Def());
JITDUMP("\n");
return;
}
else
{
assert(location->OperIsBlk());
}
}
}
switch (locationOp)
{
case GT_LCL_VAR:
case GT_LCL_FLD:
case GT_REG_VAR:
case GT_PHI_ARG:
RewriteAssignmentIntoStoreLclCore(assignment, location, value, locationOp);
BlockRange().Remove(location);
break;
case GT_IND:
{
GenTreeStoreInd* store =
new (comp, GT_STOREIND) GenTreeStoreInd(location->TypeGet(), location->gtGetOp1(), value);
copyFlags(store, assignment, GTF_ALL_EFFECT);
copyFlags(store, location, GTF_IND_FLAGS);
if (assignment->IsReverseOp())
{
store->gtFlags |= GTF_REVERSE_OPS;
}
// TODO: JIT dump
// Remove the GT_IND node and replace the assignment node with the store
BlockRange().Remove(location);
BlockRange().InsertBefore(assignment, store);
use.ReplaceWith(comp, store);
BlockRange().Remove(assignment);
}
break;
case GT_CLS_VAR:
{
location->SetOper(GT_CLS_VAR_ADDR);
location->gtType = TYP_BYREF;
assignment->SetOper(GT_STOREIND);
// TODO: JIT dump
}
break;
case GT_BLK:
case GT_OBJ:
case GT_DYN_BLK:
{
assert(varTypeIsStruct(location));
GenTreeBlk* storeBlk = location->AsBlk();
genTreeOps storeOper;
switch (location->gtOper)
{
case GT_BLK:
storeOper = GT_STORE_BLK;
break;
case GT_OBJ:
storeOper = GT_STORE_OBJ;
break;
case GT_DYN_BLK:
storeOper = GT_STORE_DYN_BLK;
break;
default:
unreached();
}
JITDUMP("Rewriting GT_ASG(%s(X), Y) to %s(X,Y):\n", GenTree::NodeName(location->gtOper),
GenTree::NodeName(storeOper));
storeBlk->SetOperRaw(storeOper);
storeBlk->gtFlags &= ~GTF_DONT_CSE;
storeBlk->gtFlags |= (assignment->gtFlags & (GTF_ALL_EFFECT | GTF_REVERSE_OPS | GTF_BLK_VOLATILE |
GTF_BLK_UNALIGNED | GTF_DONT_CSE));
storeBlk->gtBlk.Data() = value;
// Replace the assignment node with the store
use.ReplaceWith(comp, storeBlk);
BlockRange().Remove(assignment);
DISPTREERANGE(BlockRange(), use.Def());
JITDUMP("\n");
}
break;
default:
unreached();
break;
}
}
Compiler::fgWalkResult Rationalizer::RewriteNode(GenTree** useEdge, ArrayStack<GenTree*>& parentStack)
{
assert(useEdge != nullptr);
GenTree* node = *useEdge;
assert(node != nullptr);
#ifdef DEBUG
const bool isLateArg = (node->gtFlags & GTF_LATE_ARG) != 0;
#endif
// First, remove any preceeding list nodes, which are not otherwise visited by the tree walk.
//
// NOTE: GT_FIELD_LIST head nodes, and GT_LIST nodes used by phi nodes will in fact be visited.
for (GenTree* prev = node->gtPrev; prev != nullptr && prev->OperIsAnyList() && !(prev->OperIsFieldListHead());
prev = node->gtPrev)
{
BlockRange().Remove(prev);
}
// In addition, remove the current node if it is a GT_LIST node that is not an aggregate.
if (node->OperIsAnyList())
{
GenTreeArgList* list = node->AsArgList();
if (!list->OperIsFieldListHead())
{
BlockRange().Remove(list);
}
return Compiler::WALK_CONTINUE;
}
LIR::Use use;
if (parentStack.Height() < 2)
{
use = LIR::Use::GetDummyUse(BlockRange(), *useEdge);
}
else
{
use = LIR::Use(BlockRange(), useEdge, parentStack.Index(1));
}
assert(node == use.Def());
switch (node->OperGet())
{
case GT_ASG:
RewriteAssignment(use);
break;
case GT_BOX:
// GT_BOX at this level just passes through so get rid of it
use.ReplaceWith(comp, node->gtGetOp1());
BlockRange().Remove(node);
break;
case GT_ADDR:
RewriteAddress(use);
break;
case GT_IND:
// Clear the `GTF_IND_ASG_LHS` flag, which overlaps with `GTF_IND_REQ_ADDR_IN_REG`.
node->gtFlags &= ~GTF_IND_ASG_LHS;
if (varTypeIsSIMD(node))
{
RewriteSIMDOperand(use, false);
}
else
{
// Due to promotion of structs containing fields of type struct with a
// single scalar type field, we could potentially see IR nodes of the
// form GT_IND(GT_ADD(lclvarAddr, 0)) where 0 is an offset representing
// a field-seq. These get folded here.
//
// TODO: This code can be removed once JIT implements recursive struct
// promotion instead of lying about the type of struct field as the type
// of its single scalar field.
GenTree* addr = node->AsIndir()->Addr();
if (addr->OperGet() == GT_ADD && addr->gtGetOp1()->OperGet() == GT_LCL_VAR_ADDR &&
addr->gtGetOp2()->IsIntegralConst(0))
{
GenTreeLclVarCommon* lclVarNode = addr->gtGetOp1()->AsLclVarCommon();
unsigned lclNum = lclVarNode->GetLclNum();
LclVarDsc* varDsc = comp->lvaTable + lclNum;
if (node->TypeGet() == varDsc->TypeGet())
{
JITDUMP("Rewriting GT_IND(GT_ADD(LCL_VAR_ADDR,0)) to LCL_VAR\n");
lclVarNode->SetOper(GT_LCL_VAR);
lclVarNode->gtType = node->TypeGet();
use.ReplaceWith(comp, lclVarNode);
BlockRange().Remove(addr);
BlockRange().Remove(addr->gtGetOp2());
BlockRange().Remove(node);
}
}
}
break;
case GT_NOP:
// fgMorph sometimes inserts NOP nodes between defs and uses
// supposedly 'to prevent constant folding'. In this case, remove the
// NOP.
if (node->gtGetOp1() != nullptr)
{
use.ReplaceWith(comp, node->gtGetOp1());
BlockRange().Remove(node);
}
break;
case GT_COMMA:
{
GenTree* op1 = node->gtGetOp1();
if ((op1->gtFlags & GTF_ALL_EFFECT) == 0)
{
// The LHS has no side effects. Remove it.
bool isClosed = false;
unsigned sideEffects = 0;
LIR::ReadOnlyRange lhsRange = BlockRange().GetTreeRange(op1, &isClosed, &sideEffects);
// None of the transforms performed herein violate tree order, so these
// should always be true.
assert(isClosed);
assert((sideEffects & GTF_ALL_EFFECT) == 0);
BlockRange().Delete(comp, m_block, std::move(lhsRange));
}
GenTree* replacement = node->gtGetOp2();
if (!use.IsDummyUse())
{
use.ReplaceWith(comp, replacement);
}
else
{
// This is a top-level comma. If the RHS has no side effects we can remove
// it as well.
if ((replacement->gtFlags & GTF_ALL_EFFECT) == 0)
{
bool isClosed = false;
unsigned sideEffects = 0;
LIR::ReadOnlyRange rhsRange = BlockRange().GetTreeRange(replacement, &isClosed, &sideEffects);
// None of the transforms performed herein violate tree order, so these
// should always be true.
assert(isClosed);
assert((sideEffects & GTF_ALL_EFFECT) == 0);
BlockRange().Delete(comp, m_block, std::move(rhsRange));
}
}
BlockRange().Remove(node);
}
break;
case GT_ARGPLACE:
// Remove argplace and list nodes from the execution order.
//
// TODO: remove phi args and phi nodes as well?
BlockRange().Remove(node);
break;
#if defined(_TARGET_XARCH_) || defined(_TARGET_ARM_)
case GT_CLS_VAR:
{
// Class vars that are the target of an assignment will get rewritten into
// GT_STOREIND(GT_CLS_VAR_ADDR, val) by RewriteAssignment. This check is
// not strictly necessary--the GT_IND(GT_CLS_VAR_ADDR) pattern that would
// otherwise be generated would also be picked up by RewriteAssignment--but
// skipping the rewrite here saves an allocation and a bit of extra work.
const bool isLHSOfAssignment = (use.User()->OperGet() == GT_ASG) && (use.User()->gtGetOp1() == node);
if (!isLHSOfAssignment)
{
GenTree* ind = comp->gtNewOperNode(GT_IND, node->TypeGet(), node);
node->SetOper(GT_CLS_VAR_ADDR);
node->gtType = TYP_BYREF;
BlockRange().InsertAfter(node, ind);
use.ReplaceWith(comp, ind);
// TODO: JIT dump
}
}
break;
#endif // _TARGET_XARCH_
case GT_INTRINSIC:
// Non-target intrinsics should have already been rewritten back into user calls.
assert(Compiler::IsTargetIntrinsic(node->gtIntrinsic.gtIntrinsicId));
break;
#ifdef FEATURE_SIMD
case GT_BLK:
case GT_OBJ:
{
// TODO-1stClassStructs: These should have been transformed to GT_INDs, but in order
// to preserve existing behavior, we will keep this as a block node if this is the
// lhs of a block assignment, and either:
// - It is a "generic" TYP_STRUCT assignment, OR
// - It is an initblk, OR
// - Neither the lhs or rhs are known to be of SIMD type.
GenTree* parent = use.User();
bool keepBlk = false;
if ((parent->OperGet() == GT_ASG) && (node == parent->gtGetOp1()))
{
if ((node->TypeGet() == TYP_STRUCT) || parent->OperIsInitBlkOp())
{
keepBlk = true;
}
else if (!comp->isAddrOfSIMDType(node->AsBlk()->Addr()))
{
GenTree* dataSrc = parent->gtGetOp2();
if (!dataSrc->IsLocal() && (dataSrc->OperGet() != GT_SIMD))
{
noway_assert(dataSrc->OperIsIndir());
keepBlk = !comp->isAddrOfSIMDType(dataSrc->AsIndir()->Addr());
}
}
}
RewriteSIMDOperand(use, keepBlk);
}
break;
case GT_LCL_FLD:
case GT_STORE_LCL_FLD:
// TODO-1stClassStructs: Eliminate this.
FixupIfSIMDLocal(node->AsLclVarCommon());
break;
case GT_SIMD:
{
noway_assert(comp->featureSIMD);
GenTreeSIMD* simdNode = node->AsSIMD();
unsigned simdSize = simdNode->gtSIMDSize;
var_types simdType = comp->getSIMDTypeForSize(simdSize);
// TODO-1stClassStructs: This should be handled more generally for enregistered or promoted
// structs that are passed or returned in a different register type than their enregistered
// type(s).
if (simdNode->gtType == TYP_I_IMPL && simdNode->gtSIMDSize == TARGET_POINTER_SIZE)
{
// This happens when it is consumed by a GT_RET_EXPR.
// It can only be a Vector2f or Vector2i.
assert(genTypeSize(simdNode->gtSIMDBaseType) == 4);
simdNode->gtType = TYP_SIMD8;
}
// Certain SIMD trees require rationalizing.
if (simdNode->gtSIMD.gtSIMDIntrinsicID == SIMDIntrinsicInitArray)
{
// Rewrite this as an explicit load.
JITDUMP("Rewriting GT_SIMD array init as an explicit load:\n");
unsigned int baseTypeSize = genTypeSize(simdNode->gtSIMDBaseType);
GenTree* address = new (comp, GT_LEA) GenTreeAddrMode(TYP_BYREF, simdNode->gtOp1, simdNode->gtOp2,
baseTypeSize, offsetof(CORINFO_Array, u1Elems));
GenTree* ind = comp->gtNewOperNode(GT_IND, simdType, address);
BlockRange().InsertBefore(simdNode, address, ind);
use.ReplaceWith(comp, ind);
BlockRange().Remove(simdNode);
DISPTREERANGE(BlockRange(), use.Def());
JITDUMP("\n");
}
else
{
// This code depends on the fact that NONE of the SIMD intrinsics take vector operands
// of a different width. If that assumption changes, we will EITHER have to make these type
// transformations during importation, and plumb the types all the way through the JIT,
// OR add a lot of special handling here.
GenTree* op1 = simdNode->gtGetOp1();
if (op1 != nullptr && op1->gtType == TYP_STRUCT)
{
op1->gtType = simdType;
}
GenTree* op2 = simdNode->gtGetOp2IfPresent();
if (op2 != nullptr && op2->gtType == TYP_STRUCT)
{
op2->gtType = simdType;
}
}
}
break;
#endif // FEATURE_SIMD
default:
// JCC nodes should not be present in HIR.
assert(node->OperGet() != GT_JCC);
break;
}
// Do some extra processing on top-level nodes to remove unused local reads.
if (node->OperIsLocalRead())
{
if (use.IsDummyUse())
{
comp->lvaDecRefCnts(node);
BlockRange().Remove(node);
}
else
{
// Local reads are side-effect-free; clear any flags leftover from frontend transformations.
node->gtFlags &= ~GTF_ALL_EFFECT;
}
}
assert(isLateArg == ((use.Def()->gtFlags & GTF_LATE_ARG) != 0));
return Compiler::WALK_CONTINUE;
}
void Rationalizer::RewriteAssignment(LIR::Use& use)
{
assert(use.IsInitialized());
GenTreeOp* assignment = use.Def()->AsOp();
assert(assignment->OperGet() == GT_ASG);
GenTree* location = assignment->gtGetOp1();
GenTree* value = assignment->gtGetOp2();
genTreeOps locationOp = location->OperGet();
#ifdef FEATURE_SIMD
if (varTypeIsSIMD(location) && assignment->OperIsInitBlkOp())
{
if (location->OperGet() == GT_LCL_VAR)
{
var_types simdType = location->TypeGet();
GenTree* initVal = assignment->gtOp.gtOp2;
var_types baseType = comp->getBaseTypeOfSIMDLocal(location);
if (baseType != TYP_UNKNOWN)
{
GenTreeSIMD* simdTree = new (comp, GT_SIMD)
GenTreeSIMD(simdType, initVal, SIMDIntrinsicInit, baseType, genTypeSize(simdType));
assignment->gtOp.gtOp2 = simdTree;
value = simdTree;
initVal->gtNext = simdTree;
simdTree->gtPrev = initVal;
simdTree->gtNext = location;
location->gtPrev = simdTree;
}
}
else
{
assert(location->OperIsBlk());
}
}
#endif // FEATURE_SIMD
switch (locationOp)
{
case GT_LCL_VAR:
case GT_LCL_FLD:
case GT_REG_VAR:
case GT_PHI_ARG:
RewriteAssignmentIntoStoreLclCore(assignment, location, value, locationOp);
BlockRange().Remove(location);
break;
case GT_IND:
{
GenTreeStoreInd* store =
new (comp, GT_STOREIND) GenTreeStoreInd(location->TypeGet(), location->gtGetOp1(), value);
copyFlags(store, assignment, GTF_ALL_EFFECT);
copyFlags(store, location, GTF_IND_FLAGS);
if (assignment->IsReverseOp())
{
store->gtFlags |= GTF_REVERSE_OPS;
}
// TODO: JIT dump
// Remove the GT_IND node and replace the assignment node with the store
BlockRange().Remove(location);
BlockRange().InsertBefore(assignment, store);
use.ReplaceWith(comp, store);
BlockRange().Remove(assignment);
}
break;
case GT_CLS_VAR:
{
location->SetOper(GT_CLS_VAR_ADDR);
location->gtType = TYP_BYREF;
assignment->SetOper(GT_STOREIND);
// TODO: JIT dump
}
break;
case GT_BLK:
case GT_OBJ:
case GT_DYN_BLK:
{
assert(varTypeIsStruct(location));
GenTreeBlk* storeBlk = location->AsBlk();
genTreeOps storeOper;
switch (location->gtOper)
{
case GT_BLK:
storeOper = GT_STORE_BLK;
break;
case GT_OBJ:
storeOper = GT_STORE_OBJ;
break;
case GT_DYN_BLK:
storeOper = GT_STORE_DYN_BLK;
break;
default:
unreached();
}
JITDUMP("Rewriting GT_ASG(%s(X), Y) to %s(X,Y):\n", GenTree::NodeName(location->gtOper),
GenTree::NodeName(storeOper));
storeBlk->SetOperRaw(storeOper);
storeBlk->gtFlags &= ~GTF_DONT_CSE;
storeBlk->gtFlags |= (assignment->gtFlags & (GTF_ALL_EFFECT | GTF_REVERSE_OPS | GTF_BLK_VOLATILE |
GTF_BLK_UNALIGNED | GTF_BLK_INIT | GTF_DONT_CSE));
storeBlk->gtBlk.Data() = value;
// Replace the assignment node with the store
use.ReplaceWith(comp, storeBlk);
BlockRange().Remove(assignment);
DISPTREERANGE(BlockRange(), use.Def());
JITDUMP("\n");
}
break;
default:
unreached();
break;
}
}