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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.
#include "jitpch.h"
#include "ssaconfig.h"
#include "ssarenamestate.h"
//------------------------------------------------------------------------
// SsaRenameState: Initialize SsaRenameState
//
// Arguments:
// alloc - A memory allocator
// lvaCount - The number of local variables
//
SsaRenameState::SsaRenameState(CompAllocator alloc, unsigned lvaCount)
: m_alloc(alloc), m_lvaCount(lvaCount), m_stacks(nullptr), m_stackListTail(nullptr)
{
}
//------------------------------------------------------------------------
// EnsureStacks: Allocate memory for the stacks array.
//
void SsaRenameState::EnsureStacks()
{
if (m_stacks == nullptr)
{
m_stacks = new (m_alloc) Stack[m_lvaCount]();
}
}
//------------------------------------------------------------------------
// Top: Get the SSA number at the top of the stack for the specified variable.
//
// Arguments:
// lclNum - The local variable number
//
// Return Value:
// The SSA number.
//
// Notes:
// The stack must not be empty. Method parameters and local variables that are live in at
// the start of the first block must have associated SSA definitions and their SSA numbers
// must have been pushed first.
//
unsigned SsaRenameState::Top(unsigned lclNum)
{
DBG_SSA_JITDUMP("[SsaRenameState::Top] V%02u\n", lclNum);
noway_assert(m_stacks != nullptr);
StackNode* top = m_stacks[lclNum].Top();
noway_assert(top != nullptr);
return top->m_ssaNum;
}
//------------------------------------------------------------------------
// Push: Push a SSA number onto the stack for the specified variable.
//
// Arguments:
// block - The block where the SSA definition occurs
// lclNum - The local variable number
// ssaNum - The SSA number
//
void SsaRenameState::Push(BasicBlock* block, unsigned lclNum, unsigned ssaNum)
{
DBG_SSA_JITDUMP("[SsaRenameState::Push] " FMT_BB ", V%02u, count = %d\n", block->bbNum, lclNum, ssaNum);
EnsureStacks();
Push(&m_stacks[lclNum], block, ssaNum);
}
//------------------------------------------------------------------------
// Push: Push a SSA number onto a stack
//
// Arguments:
// stack - The stack to push to
// block - The block where the SSA definition occurs
// ssaNum - The SSA number
//
void SsaRenameState::Push(Stack* stack, BasicBlock* block, unsigned ssaNum)
{
StackNode* top = stack->Top();
if ((top == nullptr) || (top->m_block != block))
{
stack->Push(AllocStackNode(m_stackListTail, block, ssaNum));
// Append the stack to the stack list. The stack list allows PopBlockStacks
// to easily find stacks that need popping.
m_stackListTail = stack;
}
else
{
// If we already have a stack node for this block then simply update
// update the SSA number, the previous one is no longer needed.
top->m_ssaNum = ssaNum;
}
INDEBUG(DumpStack(stack));
}
void SsaRenameState::PopBlockStacks(BasicBlock* block)
{
DBG_SSA_JITDUMP("[SsaRenameState::PopBlockStacks] " FMT_BB "\n", block->bbNum);
while ((m_stackListTail != nullptr) && (m_stackListTail->Top()->m_block == block))
{
StackNode* top = m_stackListTail->Pop();
INDEBUG(DumpStack(m_stackListTail));
m_stackListTail = top->m_listPrev;
m_freeStack.Push(top);
}
#ifdef DEBUG
if (m_stacks != nullptr)
{
// It should now be the case that no stack in stacks has an entry for "block" on top --
// the loop above popped them all.
for (unsigned i = 0; i < m_lvaCount; ++i)
{
if (m_stacks[i].Top() != nullptr)
{
assert(m_stacks[i].Top()->m_block != block);
}
}
}
#endif // DEBUG
}
#ifdef DEBUG
//------------------------------------------------------------------------
// DumpStack: Print the specified stack.
//
// Arguments:
// stack - The stack to print
//
void SsaRenameState::DumpStack(Stack* stack)
{
if (JitTls::GetCompiler()->verboseSsa)
{
if (stack == &m_memoryStack[ByrefExposed])
{
printf("ByrefExposed: ");
}
else if (stack == &m_memoryStack[GcHeap])
{
printf("GcHeap: ");
}
else
{
printf("V%02u: ", stack - m_stacks);
}
for (StackNode* i = stack->Top(); i != nullptr; i = i->m_stackPrev)
{
printf("%s<" FMT_BB ", %u>", (i == stack->Top()) ? "" : ", ", i->m_block->bbNum, i->m_ssaNum);
}
printf("\n");
}
}
#endif // DEBUG
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