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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.
// See the LICENSE file in the project root for more information.
// ==++==
//
//
//
// ==--==
/*XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XX XX
XX SSA XX
XX XX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
*/
#pragma once
#include "jitstd.h"
// Fixed-size array that can hold elements with no default constructor;
// it will construct them all by forwarding whatever arguments are
// supplied to its constructor.
template <typename T, int N>
class ConstructedArray
{
union {
// Storage that gets used to hold the T objects.
unsigned char bytes[N * sizeof(T)];
#if defined(_MSC_VER) && (_MSC_VER < 1900)
// With MSVC pre-VS2015, the code in the #else branch would hit error C2621,
// so in that case just count on pointer alignment being sufficient
// (currently T is only ever instantiated as jitstd::list<SsaRenameStateForBlock>)
// Unused (except to impart alignment requirement)
void* pointer;
#else
// Unused (except to impart alignment requirement)
T alignedArray[N];
#endif // defined(_MSC_VER) && (_MSC_VER < 1900)
};
public:
T& operator[](size_t i)
{
return *(reinterpret_cast<T*>(bytes + i * sizeof(T)));
}
template <typename... Args>
ConstructedArray(Args&&... args)
{
for (int i = 0; i < N; ++i)
{
new (bytes + i * sizeof(T), jitstd::placement_t()) T(jitstd::forward<Args>(args)...);
}
}
~ConstructedArray()
{
for (int i = 0; i < N; ++i)
{
operator[](i).~T();
}
}
};
struct SsaRenameStateForBlock
{
BasicBlock* m_bb;
unsigned m_count;
SsaRenameStateForBlock(BasicBlock* bb, unsigned count) : m_bb(bb), m_count(count)
{
}
SsaRenameStateForBlock() : m_bb(nullptr), m_count(0)
{
}
};
// A record indicating that local "m_loc" was defined in block "m_bb".
struct SsaRenameStateLocDef
{
BasicBlock* m_bb;
unsigned m_lclNum;
SsaRenameStateLocDef(BasicBlock* bb, unsigned lclNum) : m_bb(bb), m_lclNum(lclNum)
{
}
};
struct SsaRenameState
{
typedef jitstd::list<SsaRenameStateForBlock> Stack;
typedef Stack** Stacks;
typedef unsigned* Counts;
typedef jitstd::list<SsaRenameStateLocDef> DefStack;
SsaRenameState(const jitstd::allocator<int>& allocator, unsigned lvaCount, bool byrefStatesMatchGcHeapStates);
void EnsureCounts();
void EnsureStacks();
// Requires "lclNum" to be a variable number for which a new count corresponding to a
// definition is desired. The method post increments the counter for the "lclNum."
unsigned CountForDef(unsigned lclNum);
// Requires "lclNum" to be a variable number for which an ssa number at the top of the
// stack is required i.e., for variable "uses."
unsigned CountForUse(unsigned lclNum);
// Requires "lclNum" to be a variable number, and requires "count" to represent
// an ssa number, that needs to be pushed on to the stack corresponding to the lclNum.
void Push(BasicBlock* bb, unsigned lclNum, unsigned count);
// Pop all stacks that have an entry for "bb" on top.
void PopBlockStacks(BasicBlock* bb);
// Similar functions for the special implicit memory variable.
unsigned CountForMemoryDef()
{
if (memoryCount == 0)
{
memoryCount = SsaConfig::FIRST_SSA_NUM;
}
unsigned res = memoryCount;
memoryCount++;
return res;
}
unsigned CountForMemoryUse(MemoryKind memoryKind)
{
if ((memoryKind == GcHeap) && byrefStatesMatchGcHeapStates)
{
// Share rename stacks in this configuration.
memoryKind = ByrefExposed;
}
return memoryStack[memoryKind].back().m_count;
}
void PushMemory(MemoryKind memoryKind, BasicBlock* bb, unsigned count)
{
if ((memoryKind == GcHeap) && byrefStatesMatchGcHeapStates)
{
// Share rename stacks in this configuration.
memoryKind = ByrefExposed;
}
memoryStack[memoryKind].push_back(SsaRenameStateForBlock(bb, count));
}
void PopBlockMemoryStack(MemoryKind memoryKind, BasicBlock* bb);
unsigned MemoryCount()
{
return memoryCount;
}
#ifdef DEBUG
// Debug interface
void DumpStacks();
#endif
private:
// Map of lclNum -> count.
Counts counts;
// Map of lclNum -> SsaRenameStateForBlock.
Stacks stacks;
// This list represents the set of locals defined in the current block.
DefStack definedLocs;
// Same state for the special implicit memory variables.
ConstructedArray<Stack, MemoryKindCount> memoryStack;
unsigned memoryCount;
// Number of stacks/counts to allocate.
unsigned lvaCount;
// Allocator to allocate stacks.
jitstd::allocator<void> m_alloc;
// Indicates whether GcHeap and ByrefExposed use the same state.
bool byrefStatesMatchGcHeapStates;
};
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