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morph.cpp
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morph.cpp
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
/*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XX XX
XX Morph XX
XX XX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
*/
#include "jitpch.h"
#ifdef _MSC_VER
#pragma hdrstop
#endif
#include "allocacheck.h" // for alloca
//-------------------------------------------------------------
// fgMorphInit: prepare for running the morph phases
//
// Returns:
// suitable phase status
//
PhaseStatus Compiler::fgMorphInit()
{
bool madeChanges = false;
// We could allow ESP frames. Just need to reserve space for
// pushing EBP if the method becomes an EBP-frame after an edit.
// Note that requiring a EBP Frame disallows double alignment. Thus if we change this
// we either have to disallow double alignment for E&C some other way or handle it in EETwain.
if (opts.compDbgEnC)
{
codeGen->setFramePointerRequired(true);
// We don't care about localloc right now. If we do support it,
// EECodeManager::FixContextForEnC() needs to handle it smartly
// in case the localloc was actually executed.
//
// compLocallocUsed = true;
}
// Initialize the BlockSet epoch
NewBasicBlockEpoch();
fgAvailableOutgoingArgTemps = hashBv::Create(this);
// Insert call to class constructor as the first basic block if
// we were asked to do so.
if (info.compCompHnd->initClass(nullptr /* field */, nullptr /* method */,
impTokenLookupContextHandle /* context */) &
CORINFO_INITCLASS_USE_HELPER)
{
fgEnsureFirstBBisScratch();
fgNewStmtAtBeg(fgFirstBB, fgInitThisClass());
madeChanges = true;
}
#ifdef DEBUG
if (opts.compGcChecks)
{
for (unsigned i = 0; i < info.compArgsCount; i++)
{
if (lvaGetDesc(i)->TypeGet() == TYP_REF)
{
// confirm that the argument is a GC pointer (for debugging (GC stress))
GenTree* op = gtNewLclvNode(i, TYP_REF);
op = gtNewHelperCallNode(CORINFO_HELP_CHECK_OBJ, TYP_VOID, op);
fgEnsureFirstBBisScratch();
fgNewStmtAtEnd(fgFirstBB, op);
madeChanges = true;
if (verbose)
{
printf("\ncompGcChecks tree:\n");
gtDispTree(op);
}
}
}
}
#endif // DEBUG
#if defined(DEBUG) && defined(TARGET_XARCH)
if (opts.compStackCheckOnRet)
{
lvaReturnSpCheck = lvaGrabTempWithImplicitUse(false DEBUGARG("ReturnSpCheck"));
lvaSetVarDoNotEnregister(lvaReturnSpCheck, DoNotEnregisterReason::ReturnSpCheck);
lvaGetDesc(lvaReturnSpCheck)->lvType = TYP_I_IMPL;
madeChanges = true;
}
#endif // defined(DEBUG) && defined(TARGET_XARCH)
#if defined(DEBUG) && defined(TARGET_X86)
if (opts.compStackCheckOnCall)
{
lvaCallSpCheck = lvaGrabTempWithImplicitUse(false DEBUGARG("CallSpCheck"));
lvaSetVarDoNotEnregister(lvaCallSpCheck, DoNotEnregisterReason::CallSpCheck);
lvaGetDesc(lvaCallSpCheck)->lvType = TYP_I_IMPL;
madeChanges = true;
}
#endif // defined(DEBUG) && defined(TARGET_X86)
return madeChanges ? PhaseStatus::MODIFIED_EVERYTHING : PhaseStatus::MODIFIED_NOTHING;
}
// Convert the given node into a call to the specified helper passing
// the given argument list.
//
// Tries to fold constants and also adds an edge for overflow exception
// returns the morphed tree
GenTree* Compiler::fgMorphCastIntoHelper(GenTree* tree, int helper, GenTree* oper)
{
GenTree* result;
/* If the operand is a constant, we'll try to fold it */
if (oper->OperIsConst())
{
GenTree* oldTree = tree;
tree = gtFoldExprConst(tree); // This may not fold the constant (NaN ...)
if (tree != oldTree)
{
return fgMorphTree(tree);
}
else if (tree->OperIsConst())
{
return fgMorphConst(tree);
}
// assert that oper is unchanged and that it is still a GT_CAST node
noway_assert(tree->AsCast()->CastOp() == oper);
noway_assert(tree->gtOper == GT_CAST);
}
result = fgMorphIntoHelperCall(tree, helper, true /* morphArgs */, oper);
assert(result == tree);
return result;
}
class SharedTempsScope
{
Compiler* m_comp;
ArrayStack<unsigned> m_usedSharedTemps;
ArrayStack<unsigned>* m_prevUsedSharedTemps;
public:
SharedTempsScope(Compiler* comp)
: m_comp(comp)
, m_usedSharedTemps(comp->getAllocator(CMK_CallArgs))
, m_prevUsedSharedTemps(comp->fgUsedSharedTemps)
{
comp->fgUsedSharedTemps = &m_usedSharedTemps;
}
~SharedTempsScope()
{
m_comp->fgUsedSharedTemps = m_prevUsedSharedTemps;
for (int i = 0; i < m_usedSharedTemps.Height(); i++)
{
m_comp->fgAvailableOutgoingArgTemps->setBit((indexType)m_usedSharedTemps.Top(i));
}
}
};
//------------------------------------------------------------------------
// fgMorphIntoHelperCall:
// Morph a node into a helper call, specifying up to two args and whether to
// call fgMorphArgs after.
//
// Parameters:
// tree - The node that is changed. This must be a large node.
// helper - The helper.
// morphArgs - Whether to call fgMorphArgs after adding the args.
// arg1, arg2 - Optional arguments to add to the call.
//
// Return value:
// The call (which is the same as `tree`).
//
GenTree* Compiler::fgMorphIntoHelperCall(GenTree* tree, int helper, bool morphArgs, GenTree* arg1, GenTree* arg2)
{
// The helper call ought to be semantically equivalent to the original node, so preserve its VN.
tree->ChangeOper(GT_CALL, GenTree::PRESERVE_VN);
GenTreeCall* call = tree->AsCall();
// Args are cleared by ChangeOper above
call->gtCallType = CT_HELPER;
call->gtReturnType = tree->TypeGet();
call->gtCallMethHnd = eeFindHelper(helper);
call->gtRetClsHnd = nullptr;
call->gtCallMoreFlags = GTF_CALL_M_EMPTY;
INDEBUG(call->gtCallDebugFlags = GTF_CALL_MD_EMPTY);
call->gtControlExpr = nullptr;
call->ClearInlineInfo();
#ifdef UNIX_X86_ABI
call->gtFlags |= GTF_CALL_POP_ARGS;
#endif // UNIX_X86_ABI
#if DEBUG
// Helper calls are never candidates.
call->gtInlineObservation = InlineObservation::CALLSITE_IS_CALL_TO_HELPER;
call->callSig = nullptr;
#endif // DEBUG
#ifdef FEATURE_READYTORUN
call->gtEntryPoint.addr = nullptr;
call->gtEntryPoint.accessType = IAT_VALUE;
#endif
#if FEATURE_MULTIREG_RET
call->ResetReturnType();
call->ClearOtherRegs();
call->ClearOtherRegFlags();
#ifndef TARGET_64BIT
if (varTypeIsLong(tree))
{
call->InitializeLongReturnType();
}
#endif // !TARGET_64BIT
#endif // FEATURE_MULTIREG_RET
if (call->OperMayThrow(this))
{
call->gtFlags |= GTF_EXCEPT;
}
else
{
call->gtFlags &= ~GTF_EXCEPT;
}
call->gtFlags |= GTF_CALL;
if (arg2 != nullptr)
{
call->gtArgs.PushFront(this, NewCallArg::Primitive(arg2));
call->gtFlags |= arg2->gtFlags & GTF_ALL_EFFECT;
}
if (arg1 != nullptr)
{
call->gtArgs.PushFront(this, NewCallArg::Primitive(arg1));
call->gtFlags |= arg1->gtFlags & GTF_ALL_EFFECT;
}
// Perform the morphing
if (morphArgs)
{
SharedTempsScope scope(this);
tree = fgMorphArgs(call);
}
return tree;
}
//------------------------------------------------------------------------
// fgMorphExpandCast: Performs the pre-order (required) morphing for a cast.
//
// Performs a rich variety of pre-order transformations (and some optimizations).
//
// Notably:
// 1. Splits long -> small type casts into long -> int -> small type
// for 32 bit targets. Does the same for float/double -> small type
// casts for all targets.
// 2. Morphs casts not supported by the target directly into helpers.
// These mostly have to do with casts from and to floating point
// types, especially checked ones. Refer to the implementation for
// what specific casts need to be handled - it is a complex matrix.
// 3. "Casts away" the GC-ness of a tree (for CAST(nint <- byref)) via
// storing the GC tree to an inline non-GC temporary.
// 3. "Pushes down" truncating long -> int casts for some operations:
// CAST(int <- MUL(long, long)) => MUL(CAST(int <- long), CAST(int <- long)).
// The purpose of this is to allow "optNarrowTree" in the post-order
// traversal to fold the tree into a TYP_INT one, which helps 32 bit
// targets (and AMD64 too since 32 bit instructions are more compact).
// TODO-Arm64-CQ: Re-evaluate the value of this optimization for ARM64.
//
// Arguments:
// tree - the cast tree to morph
//
// Return Value:
// The fully morphed tree, or "nullptr" if it needs further morphing,
// in which case the cast may be transformed into an unchecked one
// and its operand changed (the cast "expanded" into two).
//
GenTree* Compiler::fgMorphExpandCast(GenTreeCast* tree)
{
GenTree* oper = tree->CastOp();
var_types srcType = genActualType(oper);
var_types dstType = tree->CastToType();
unsigned dstSize = genTypeSize(dstType);
#if defined(TARGET_AMD64)
// If AVX512 is present, we have intrinsic available to convert
// ulong directly to float. Hence, we need to combine the 2 nodes
// GT_CAST(GT_CAST(TYP_ULONG, TYP_DOUBLE), TYP_FLOAT) into a single
// node i.e. GT_CAST(TYP_ULONG, TYP_FLOAT). At this point, we already
// have the 2 GT_CAST nodes in the tree and we are combining them below.
if (oper->OperIs(GT_CAST))
{
GenTreeCast* innerCast = oper->AsCast();
if (innerCast->IsUnsigned())
{
GenTree* innerOper = innerCast->CastOp();
var_types innerSrcType = genActualType(innerOper);
var_types innerDstType = innerCast->CastToType();
unsigned innerDstSize = genTypeSize(innerDstType);
innerSrcType = varTypeToUnsigned(innerSrcType);
// Check if we are going from ulong->double->float
if ((innerSrcType == TYP_ULONG) && (innerDstType == TYP_DOUBLE) && (dstType == TYP_FLOAT))
{
if (canUseEvexEncoding())
{
// One optimized (combined) cast here
tree = gtNewCastNode(TYP_FLOAT, innerOper, true, TYP_FLOAT);
return fgMorphTree(tree);
}
}
}
}
#endif // TARGET_AMD64
// See if the cast has to be done in two steps. R -> I
if (varTypeIsFloating(srcType) && varTypeIsIntegral(dstType))
{
if (srcType == TYP_FLOAT
#if defined(TARGET_ARM64) || defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
// Arm64: src = float, dst is overflow conversion.
// This goes through helper and hence src needs to be converted to double.
&& tree->gtOverflow()
#elif defined(TARGET_AMD64)
// Amd64: src = float, dst = uint64 or overflow conversion.
// src needs to be converted to double except for the following cases
// dstType = int/uint/ulong for AVX512F
// dstType = int for SSE41
// For pre-SSE41, the all src is converted to TYP_DOUBLE
// and goes through helpers.
&& (tree->gtOverflow() || (dstType == TYP_LONG) ||
!(canUseEvexEncoding() || (dstType == TYP_INT && compOpportunisticallyDependsOn(InstructionSet_SSE41))))
#elif defined(TARGET_ARM)
// Arm: src = float, dst = int64/uint64 or overflow conversion.
&& (tree->gtOverflow() || varTypeIsLong(dstType))
#else
// x86: src = float, dst = uint32/int64/uint64 or overflow conversion.
&& (tree->gtOverflow() || varTypeIsIntegral(dstType))
#endif
)
{
oper = gtNewCastNode(TYP_DOUBLE, oper, false, TYP_DOUBLE);
}
// Do we need to do it in two steps R -> I -> smallType?
if (dstSize < genTypeSize(TYP_INT))
{
oper = gtNewCastNodeL(TYP_INT, oper, /* fromUnsigned */ false, TYP_INT);
oper->gtFlags |= (tree->gtFlags & (GTF_OVERFLOW | GTF_EXCEPT));
tree->AsCast()->CastOp() = oper;
// We must not mistreat the original cast, which was from a floating point type,
// as from an unsigned type, since we now have a TYP_INT node for the source and
// CAST_OVF(BYTE <- INT) != CAST_OVF(BYTE <- UINT).
assert(!tree->IsUnsigned());
}
else
{
if (!tree->gtOverflow())
{
// ARM64 and LoongArch64 optimize all non-overflow checking conversions
#if defined(TARGET_ARM64) || defined(TARGET_LOONGARCH64) || defined(TARGET_RISCV64)
return nullptr;
#else
#if defined(TARGET_AMD64)
// Following nodes are handled when lowering the nodes
// float -> ulong/uint/int for AVX512F
// double -> ulong/uint/long/int for AVX512F
// float -> int for SSE41
// double -> int/uint/long for SSE41
// For all other conversions, we use helper functions.
if (canUseEvexEncoding() ||
((dstType != TYP_ULONG) && compOpportunisticallyDependsOn(InstructionSet_SSE41)))
{
if (tree->CastOp() != oper)
{
tree->CastOp() = oper;
}
return nullptr;
}
#endif // TARGET_AMD64
switch (dstType)
{
case TYP_INT:
#ifdef TARGET_XARCH
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2INT, oper);
#endif // TARGET_XARCH
return nullptr;
case TYP_UINT:
#if defined(TARGET_ARM)
return nullptr;
#endif
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2UINT, oper);
case TYP_LONG:
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2LNG, oper);
case TYP_ULONG:
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2ULNG, oper);
default:
unreached();
}
#endif // TARGET_ARM64 || TARGET_LOONGARCH64 || TARGET_RISCV64
}
else
{
switch (dstType)
{
case TYP_INT:
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2INT_OVF, oper);
case TYP_UINT:
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2UINT_OVF, oper);
case TYP_LONG:
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2LNG_OVF, oper);
case TYP_ULONG:
return fgMorphCastIntoHelper(tree, CORINFO_HELP_DBL2ULNG_OVF, oper);
default:
unreached();
}
}
}
}
#ifndef TARGET_64BIT
// The code generation phase (for x86 & ARM32) does not handle casts
// directly from [u]long to anything other than [u]int. Insert an
// intermediate cast to native int.
else if (varTypeIsLong(srcType) && varTypeIsSmall(dstType))
{
oper = gtNewCastNode(TYP_I_IMPL, oper, tree->IsUnsigned(), TYP_I_IMPL);
oper->gtFlags |= (tree->gtFlags & (GTF_OVERFLOW | GTF_EXCEPT));
tree->ClearUnsigned();
tree->AsCast()->CastOp() = oper;
}
#endif //! TARGET_64BIT
#ifdef TARGET_ARMARCH
// AArch, unlike x86/amd64, has instructions that can cast directly from
// all integers (except for longs on AArch32 of course) to floats.
// Because there is no IL instruction conv.r4.un, uint/ulong -> float
// casts are always imported as CAST(float <- CAST(double <- uint/ulong)).
// We can eliminate the redundant intermediate cast as an optimization.
else if ((dstType == TYP_FLOAT) && (srcType == TYP_DOUBLE) && oper->OperIs(GT_CAST) &&
!gtIsActiveCSE_Candidate(tree)
#ifdef TARGET_ARM
&& !varTypeIsLong(oper->AsCast()->CastOp())
#endif
)
{
oper->gtType = TYP_FLOAT;
oper->CastToType() = TYP_FLOAT;
return fgMorphTree(oper);
}
#endif // TARGET_ARMARCH
#ifdef TARGET_ARM
// converts long/ulong --> float/double casts into helper calls.
else if (varTypeIsFloating(dstType) && varTypeIsLong(srcType))
{
if (dstType == TYP_FLOAT)
{
// there is only a double helper, so we
// - change the dsttype to double
// - insert a cast from double to float
// - recurse into the resulting tree
tree->CastToType() = TYP_DOUBLE;
tree->gtType = TYP_DOUBLE;
tree = gtNewCastNode(TYP_FLOAT, tree, false, TYP_FLOAT);
return fgMorphTree(tree);
}
if (tree->gtFlags & GTF_UNSIGNED)
return fgMorphCastIntoHelper(tree, CORINFO_HELP_ULNG2DBL, oper);
return fgMorphCastIntoHelper(tree, CORINFO_HELP_LNG2DBL, oper);
}
#endif // TARGET_ARM
#ifdef TARGET_AMD64
// Do we have to do two step U4/8 -> R4/8 ?
// Codegen supports the following conversion as one-step operation
// a) Long -> R4/R8
// b) U8 -> R8
//
// The following conversions are performed as two-step operations using above.
// U4 -> R4/8 = U4-> Long -> R4/8
// U8 -> R4 = U8 -> R8 -> R4
else if (tree->IsUnsigned() && varTypeIsFloating(dstType))
{
srcType = varTypeToUnsigned(srcType);
if (srcType == TYP_ULONG && !canUseEvexEncoding())
{
if (dstType == TYP_FLOAT)
{
// Codegen can handle U8 -> R8 conversion.
// U8 -> R4 = U8 -> R8 -> R4
// - change the dsttype to double
// - insert a cast from double to float
// - recurse into the resulting tree
tree->CastToType() = TYP_DOUBLE;
tree->gtType = TYP_DOUBLE;
tree = gtNewCastNode(TYP_FLOAT, tree, false, TYP_FLOAT);
return fgMorphTree(tree);
}
}
else if (srcType == TYP_UINT)
{
oper = gtNewCastNode(TYP_LONG, oper, true, TYP_LONG);
oper->gtFlags |= (tree->gtFlags & (GTF_OVERFLOW | GTF_EXCEPT));
tree->ClearUnsigned();
tree->CastOp() = oper;
}
}
#endif // TARGET_AMD64
#ifdef TARGET_X86
// Do we have to do two step U4/8 -> R4/8 ?
else if (tree->IsUnsigned() && varTypeIsFloating(dstType))
{
srcType = varTypeToUnsigned(srcType);
if (srcType == TYP_ULONG)
{
return fgMorphCastIntoHelper(tree, CORINFO_HELP_ULNG2DBL, oper);
}
else if (srcType == TYP_UINT)
{
oper = gtNewCastNode(TYP_LONG, oper, true, TYP_LONG);
oper->gtFlags |= (tree->gtFlags & (GTF_OVERFLOW | GTF_EXCEPT));
tree->gtFlags &= ~GTF_UNSIGNED;
return fgMorphCastIntoHelper(tree, CORINFO_HELP_LNG2DBL, oper);
}
}
else if (((tree->gtFlags & GTF_UNSIGNED) == 0) && (srcType == TYP_LONG) && varTypeIsFloating(dstType))
{
oper = fgMorphCastIntoHelper(tree, CORINFO_HELP_LNG2DBL, oper);
// Since we don't have a Jit Helper that converts to a TYP_FLOAT
// we just use the one that converts to a TYP_DOUBLE
// and then add a cast to TYP_FLOAT
//
if ((dstType == TYP_FLOAT) && (oper->OperGet() == GT_CALL))
{
// Fix the return type to be TYP_DOUBLE
//
oper->gtType = TYP_DOUBLE;
// Add a Cast to TYP_FLOAT
//
tree = gtNewCastNode(TYP_FLOAT, oper, false, TYP_FLOAT);
INDEBUG(tree->gtDebugFlags |= GTF_DEBUG_NODE_MORPHED);
return tree;
}
else
{
return oper;
}
}
#endif // TARGET_X86
else if (varTypeIsGC(srcType) != varTypeIsGC(dstType))
{
// We are casting away GC information. we would like to just
// change the type to int, however this gives the emitter fits because
// it believes the variable is a GC variable at the beginning of the
// instruction group, but is not turned non-gc by the code generator
// we fix this by copying the GC pointer to a non-gc pointer temp.
noway_assert(!varTypeIsGC(dstType) && "How can we have a cast to a GCRef here?");
// We generate a store to an int and then do the cast from an int. With this we avoid
// the gc problem and we allow casts to bytes, longs, etc...
unsigned lclNum = lvaGrabTemp(true DEBUGARG("Cast away GC"));
oper->gtType = TYP_I_IMPL;
GenTree* store = gtNewTempStore(lclNum, oper);
oper->gtType = srcType;
// do the real cast
GenTree* cast = gtNewCastNode(tree->TypeGet(), gtNewLclvNode(lclNum, TYP_I_IMPL), false, dstType);
// Generate the comma tree
oper = gtNewOperNode(GT_COMMA, tree->TypeGet(), store, cast);
return fgMorphTree(oper);
}
// Look for narrowing casts ([u]long -> [u]int) and try to push them
// down into the operand before morphing it.
//
// It doesn't matter if this is cast is from ulong or long (i.e. if
// GTF_UNSIGNED is set) because the transformation is only applied to
// overflow-insensitive narrowing casts, which always silently truncate.
//
// Note that casts from [u]long to small integer types are handled above.
if ((srcType == TYP_LONG) && ((dstType == TYP_INT) || (dstType == TYP_UINT)))
{
// As a special case, look for overflow-sensitive casts of an AND
// expression, and see if the second operand is a small constant. Since
// the result of an AND is bound by its smaller operand, it may be
// possible to prove that the cast won't overflow, which will in turn
// allow the cast's operand to be transformed.
if (tree->gtOverflow() && (oper->OperGet() == GT_AND))
{
GenTree* andOp2 = oper->AsOp()->gtOp2;
// Look for a constant less than 2^{32} for a cast to uint, or less
// than 2^{31} for a cast to int.
int maxWidth = (dstType == TYP_UINT) ? 32 : 31;
if ((andOp2->OperGet() == GT_CNS_NATIVELONG) && ((andOp2->AsIntConCommon()->LngValue() >> maxWidth) == 0))
{
tree->ClearOverflow();
tree->SetAllEffectsFlags(oper);
}
}
// Only apply this transformation during global morph,
// when neither the cast node nor the oper node may throw an exception
// based on the upper 32 bits.
//
if (fgGlobalMorph && !tree->gtOverflow() && !oper->gtOverflowEx())
{
// For these operations the lower 32 bits of the result only depends
// upon the lower 32 bits of the operands.
//
bool canPushCast = oper->OperIs(GT_ADD, GT_SUB, GT_MUL, GT_AND, GT_OR, GT_XOR, GT_NOT, GT_NEG);
// For long LSH cast to int, there is a discontinuity in behavior
// when the shift amount is 32 or larger.
//
// CAST(INT, LSH(1LL, 31)) == LSH(1, 31)
// LSH(CAST(INT, 1LL), CAST(INT, 31)) == LSH(1, 31)
//
// CAST(INT, LSH(1LL, 32)) == 0
// LSH(CAST(INT, 1LL), CAST(INT, 32)) == LSH(1, 32) == LSH(1, 0) == 1
//
// So some extra validation is needed.
//
if (oper->OperIs(GT_LSH))
{
GenTree* shiftAmount = oper->AsOp()->gtOp2;
// Expose constant value for shift, if possible, to maximize the number
// of cases we can handle.
shiftAmount = gtFoldExpr(shiftAmount);
oper->AsOp()->gtOp2 = shiftAmount;
#if DEBUG
// We may remorph the shift amount tree again later, so clear any morphed flag.
shiftAmount->gtDebugFlags &= ~GTF_DEBUG_NODE_MORPHED;
#endif // DEBUG
if (shiftAmount->IsIntegralConst())
{
const ssize_t shiftAmountValue = shiftAmount->AsIntCon()->IconValue();
if ((shiftAmountValue >= 64) || (shiftAmountValue < 0))
{
// Shift amount is large enough or negative so result is undefined.
// Don't try to optimize.
assert(!canPushCast);
}
else if (shiftAmountValue >= 32)
{
// We know that we have a narrowing cast ([u]long -> [u]int)
// and that we are casting to a 32-bit value, which will result in zero.
//
// Check to see if we have any side-effects that we must keep
//
if ((tree->gtFlags & GTF_ALL_EFFECT) == 0)
{
// Result of the shift is zero.
DEBUG_DESTROY_NODE(tree);
GenTree* zero = gtNewZeroConNode(TYP_INT);
return fgMorphTree(zero);
}
else // We do have a side-effect
{
// We could create a GT_COMMA node here to keep the side-effect and return a zero
// Instead we just don't try to optimize this case.
canPushCast = false;
}
}
else
{
// Shift amount is positive and small enough that we can push the cast through.
canPushCast = true;
}
}
else
{
// Shift amount is unknown. We can't optimize this case.
assert(!canPushCast);
}
}
if (canPushCast)
{
GenTree* op1 = oper->gtGetOp1();
GenTree* op2 = oper->gtGetOp2IfPresent();
canPushCast = !varTypeIsGC(op1) && ((op2 == nullptr) || !varTypeIsGC(op2));
}
if (canPushCast)
{
DEBUG_DESTROY_NODE(tree);
// Insert narrowing casts for op1 and op2.
oper->AsOp()->gtOp1 = gtNewCastNode(TYP_INT, oper->AsOp()->gtOp1, false, dstType);
if (oper->AsOp()->gtOp2 != nullptr)
{
oper->AsOp()->gtOp2 = gtNewCastNode(TYP_INT, oper->AsOp()->gtOp2, false, dstType);
}
// Clear the GT_MUL_64RSLT if it is set.
if (oper->gtOper == GT_MUL && (oper->gtFlags & GTF_MUL_64RSLT))
{
oper->gtFlags &= ~GTF_MUL_64RSLT;
}
// The operation now produces a 32-bit result.
oper->gtType = TYP_INT;
// Remorph the new tree as the casts that we added may be folded away.
return fgMorphTree(oper);
}
}
}
return nullptr;
}
#ifdef DEBUG
//------------------------------------------------------------------------
// getWellKnownArgName: Get a string representation of a WellKnownArg.
//
const char* getWellKnownArgName(WellKnownArg arg)
{
switch (arg)
{
case WellKnownArg::None:
return "None";
case WellKnownArg::ThisPointer:
return "ThisPointer";
case WellKnownArg::VarArgsCookie:
return "VarArgsCookie";
case WellKnownArg::InstParam:
return "InstParam";
case WellKnownArg::RetBuffer:
return "RetBuffer";
case WellKnownArg::PInvokeFrame:
return "PInvokeFrame";
case WellKnownArg::WrapperDelegateCell:
return "WrapperDelegateCell";
case WellKnownArg::ShiftLow:
return "ShiftLow";
case WellKnownArg::ShiftHigh:
return "ShiftHigh";
case WellKnownArg::VirtualStubCell:
return "VirtualStubCell";
case WellKnownArg::PInvokeCookie:
return "PInvokeCookie";
case WellKnownArg::PInvokeTarget:
return "PInvokeTarget";
case WellKnownArg::R2RIndirectionCell:
return "R2RIndirectionCell";
case WellKnownArg::ValidateIndirectCallTarget:
return "ValidateIndirectCallTarget";
case WellKnownArg::DispatchIndirectCallTarget:
return "DispatchIndirectCallTarget";
case WellKnownArg::SwiftError:
return "SwiftError";
case WellKnownArg::SwiftSelf:
return "SwiftSelf";
case WellKnownArg::X86TailCallSpecialArg:
return "X86TailCallSpecialArg";
}
return "N/A";
}
//------------------------------------------------------------------------
// Dump: Dump information about a CallArg to jitstdout.
//
void CallArg::Dump(Compiler* comp)
{
printf("CallArg[[%06u].%s", comp->dspTreeID(GetNode()), GenTree::OpName(GetNode()->OperGet()));
printf(" %s", varTypeName(m_signatureType));
printf(" (%s)", AbiInfo.PassedByRef ? "By ref" : "By value");
if (AbiInfo.GetRegNum() != REG_STK)
{
printf(", %u reg%s:", AbiInfo.NumRegs, AbiInfo.NumRegs == 1 ? "" : "s");
for (unsigned i = 0; i < AbiInfo.NumRegs; i++)
{
printf(" %s", getRegName(AbiInfo.GetRegNum(i)));
}
}
if (AbiInfo.GetStackByteSize() > 0)
{
printf(", byteSize=%u, byteOffset=%u", AbiInfo.ByteSize, AbiInfo.ByteOffset);
}
if (GetLateNode() != nullptr)
{
printf(", isLate");
}
if (AbiInfo.IsSplit())
{
printf(", isSplit");
}
if (m_needPlace)
{
printf(", needPlace");
}
if (m_processed)
{
printf(", processed");
}
if (AbiInfo.IsHfaRegArg())
{
printf(", isHfa(%s)", varTypeName(AbiInfo.GetHfaType()));
}
if (m_wellKnownArg != WellKnownArg::None)
{
printf(", wellKnown[%s]", getWellKnownArgName(m_wellKnownArg));
}
printf("]\n");
}
#endif
//------------------------------------------------------------------------
// ArgsComplete: Make final decisions on which arguments to evaluate into temporaries.
//
void CallArgs::ArgsComplete(Compiler* comp, GenTreeCall* call)
{
unsigned argCount = CountArgs();
// Previous argument with GTF_EXCEPT
GenTree* prevExceptionTree = nullptr;
// Exceptions previous tree with GTF_EXCEPT may throw (computed lazily, may
// be empty)
ExceptionSetFlags prevExceptionFlags = ExceptionSetFlags::None;
for (CallArg& arg : Args())
{
GenTree* argx = arg.GetEarlyNode();
assert(argx != nullptr);
bool canEvalToTemp = true;
if (arg.AbiInfo.GetRegNum() == REG_STK)
{
assert(m_hasStackArgs);
#if !FEATURE_FIXED_OUT_ARGS
// Non-register arguments are evaluated and pushed in order; they
// should never go in the late arg list.
canEvalToTemp = false;
#endif
}
#if FEATURE_ARG_SPLIT
else if (arg.AbiInfo.IsSplit())
{
assert(m_hasStackArgs);
}
#endif // FEATURE_ARG_SPLIT
// If the argument tree contains a store (GTF_ASG) then the argument and
// and every earlier argument (except constants) must be evaluated into temps
// since there may be other arguments that follow and they may use the value being defined.
//
// EXAMPLE: ArgTab is "a, a=5, a"
// -> when we see the second arg "a=5"
// we know the first two arguments "a, a=5" have to be evaluated into temps
//
if ((argx->gtFlags & GTF_ASG) != 0)
{
// fgMakeOutgoingStructArgCopy can have introduced a temp already,
// in which case it will have created a setup node in the early
// node.
if (!argx->IsValue())
{
assert(arg.m_needTmp);
}
else if (canEvalToTemp && (argCount > 1))
{
SetNeedsTemp(&arg);
}
// For all previous arguments that may interfere with the store we
// require that they be evaluated into temps.
for (CallArg& prevArg : Args())
{
if (&prevArg == &arg)
{
break;
}
#if !FEATURE_FIXED_OUT_ARGS
if (prevArg.AbiInfo.GetRegNum() == REG_STK)
{
// All stack args are already evaluated and placed in order
// in this case.
continue;
}
#endif
if ((prevArg.GetEarlyNode() == nullptr) || prevArg.m_needTmp)
{
continue;
}
if (((prevArg.GetEarlyNode()->gtFlags & GTF_ALL_EFFECT) != 0) ||
comp->gtMayHaveStoreInterference(argx, prevArg.GetEarlyNode()))
{
SetNeedsTemp(&prevArg);
}
}
}
bool treatLikeCall = ((argx->gtFlags & GTF_CALL) != 0);
ExceptionSetFlags exceptionFlags = ExceptionSetFlags::None;
#if FEATURE_FIXED_OUT_ARGS
// Like calls, if this argument has a tree that will do an inline throw,
// a call to a jit helper, then we need to treat it like a call (but only
// if there are/were any stack args).
// This means unnesting, sorting, etc. Technically this is overly
// conservative, but I want to avoid as much special-case debug-only code
// as possible, so leveraging the GTF_CALL flag is the easiest.
//
if (!treatLikeCall && (argx->gtFlags & GTF_EXCEPT) && (argCount > 1) && comp->opts.compDbgCode)
{
exceptionFlags = comp->gtCollectExceptions(argx);
if ((exceptionFlags & (ExceptionSetFlags::IndexOutOfRangeException |
ExceptionSetFlags::OverflowException)) != ExceptionSetFlags::None)
{
for (CallArg& otherArg : Args())
{
if (&otherArg == &arg)
{
continue;
}
if (otherArg.AbiInfo.GetRegNum() == REG_STK)
{
treatLikeCall = true;
break;
}
}
}
}
#endif // FEATURE_FIXED_OUT_ARGS
// If it contains a call (GTF_CALL) then itself and everything before the call
// with a GLOB_EFFECT must eval to temp (this is because everything with SIDE_EFFECT
// has to be kept in the right order since we will move the call to the first position)
// For calls we don't have to be quite as conservative as we are with stores
// since the call won't be modifying any non-address taken LclVars.
if (treatLikeCall)
{
if (canEvalToTemp)
{
if (argCount > 1) // If this is not the only argument
{
SetNeedsTemp(&arg);
}
else if (varTypeIsFloating(argx->TypeGet()) && (argx->OperGet() == GT_CALL))
{
// Spill all arguments that are floating point calls
SetNeedsTemp(&arg);
}
}
// All previous arguments may need to be evaluated into temps
for (CallArg& prevArg : Args())
{
if (&prevArg == &arg)
{
break;
}
#if !FEATURE_FIXED_OUT_ARGS
if (prevArg.AbiInfo.GetRegNum() == REG_STK)
{
// All stack args are already evaluated and placed in order