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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"
/**
* Constructor - initialize the stacks and counters maps (lclVar -> stack/counter) map.
*
* @params alloc The allocator class used to allocate jitstd data.
*/
SsaRenameState::SsaRenameState(CompAllocator alloc, unsigned lvaCount, bool byrefStatesMatchGcHeapStates)
: stacks(nullptr)
, definedLocs(alloc)
, memoryStack(alloc)
, lvaCount(lvaCount)
, m_alloc(alloc)
, byrefStatesMatchGcHeapStates(byrefStatesMatchGcHeapStates)
{
}
/**
* Allocates memory for holding pointers to lcl's stacks,
* if not allocated already.
*
*/
void SsaRenameState::EnsureStacks()
{
if (stacks == nullptr)
{
stacks = m_alloc.allocate<Stack*>(lvaCount);
for (unsigned i = 0; i < lvaCount; ++i)
{
stacks[i] = nullptr;
}
}
}
/**
* Returns a SSA count number for a local variable from top of the stack.
*
* @params lclNum The local variable def for which a count has to be returned.
* @return the current variable name for the "use".
*
* @remarks If the stack is empty, then we have an use before a def. To handle this
* special case, we need to initialize the count with 'default+1', so the
* next definition will always use 'default+1' but return 'default' for
* all uses until a definition.
*
*/
unsigned SsaRenameState::CountForUse(unsigned lclNum)
{
EnsureStacks();
DBG_SSA_JITDUMP("[SsaRenameState::CountForUse] V%02u\n", lclNum);
Stack* stack = stacks[lclNum];
noway_assert((stack != nullptr) && !stack->empty());
return stack->back().m_count;
}
/**
* Pushes a count value on the variable stack.
*
* @params lclNum The local variable def whose stack the count needs to be pushed onto.
* @params count The current count value that needs to be pushed on to the stack.
*
* @remarks Usually called when renaming a "def."
* Create stack lazily when needed for the first time.
*/
void SsaRenameState::Push(BasicBlock* bb, unsigned lclNum, unsigned count)
{
EnsureStacks();
// We'll use BB00 here to indicate the "block before any real blocks..."
DBG_SSA_JITDUMP("[SsaRenameState::Push] " FMT_BB ", V%02u, count = %d\n", bb != nullptr ? bb->bbNum : 0, lclNum,
count);
Stack* stack = stacks[lclNum];
if (stack == nullptr)
{
DBG_SSA_JITDUMP("\tCreating a new stack\n");
stack = stacks[lclNum] = new (m_alloc) Stack(m_alloc);
}
if (stack->empty() || stack->back().m_bb != bb)
{
stack->push_back(SsaRenameStateForBlock(bb, count));
// Remember that we've pushed a def for this loc (so we don't have
// to traverse *all* the locs to do the necessary pops later).
definedLocs.push_back(SsaRenameStateLocDef(bb, lclNum));
}
else
{
stack->back().m_count = count;
}
#ifdef DEBUG
if (JitTls::GetCompiler()->verboseSsa)
{
printf("\tContents of the stack: [");
for (Stack::iterator iter2 = stack->begin(); iter2 != stack->end(); iter2++)
{
printf("<" FMT_BB ", %d>", ((*iter2).m_bb != nullptr ? (*iter2).m_bb->bbNum : 0), (*iter2).m_count);
}
printf("]\n");
DumpStacks();
}
#endif
}
void SsaRenameState::PopBlockStacks(BasicBlock* block)
{
DBG_SSA_JITDUMP("[SsaRenameState::PopBlockStacks] " FMT_BB "\n", block->bbNum);
// Iterate over the stacks for all the variables, popping those that have an entry
// for "block" on top.
while (!definedLocs.empty() && definedLocs.back().m_bb == block)
{
unsigned lclNum = definedLocs.back().m_lclNum;
assert(stacks != nullptr); // Cannot be empty because definedLocs is not empty.
Stack* stack = stacks[lclNum];
assert(stack != nullptr);
assert(stack->back().m_bb == block);
stack->pop_back();
definedLocs.pop_back();
}
#ifdef DEBUG
// 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 < lvaCount; ++i)
{
if (stacks != nullptr && stacks[i] != nullptr && !stacks[i]->empty())
{
assert(stacks[i]->back().m_bb != block);
}
}
if (JitTls::GetCompiler()->verboseSsa)
{
DumpStacks();
}
#endif // DEBUG
}
void SsaRenameState::PopBlockMemoryStack(MemoryKind memoryKind, BasicBlock* block)
{
auto& stack = memoryStack[memoryKind];
while (stack.size() > 0 && stack.back().m_bb == block)
{
stack.pop_back();
}
}
#ifdef DEBUG
/**
* Print the stack data for each variable in a loop.
*/
void SsaRenameState::DumpStacks()
{
printf("Dumping stacks:\n-------------------------------\n");
if (lvaCount == 0)
{
printf("None\n");
}
else
{
EnsureStacks();
for (unsigned i = 0; i < lvaCount; ++i)
{
Stack* stack = stacks[i];
printf("V%02u:\t", i);
if (stack != nullptr)
{
for (Stack::iterator iter2 = stack->begin(); iter2 != stack->end(); ++iter2)
{
if (iter2 != stack->begin())
{
printf(", ");
}
printf("<" FMT_BB ", %2d>", ((*iter2).m_bb != nullptr ? (*iter2).m_bb->bbNum : 0),
(*iter2).m_count);
}
}
printf("\n");
}
}
}
#endif // DEBUG
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