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block.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 BasicBlock XX
XX XX
XX XX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
*/
#include "jitpch.h"
#ifdef _MSC_VER
#pragma hdrstop
#endif
#include "jitstd/algorithm.h"
#if MEASURE_BLOCK_SIZE
/* static */
size_t BasicBlock::s_Size;
/* static */
size_t BasicBlock::s_Count;
#endif // MEASURE_BLOCK_SIZE
#ifdef DEBUG
// The max # of tree nodes in any BB
/* static */
unsigned BasicBlock::s_nMaxTrees;
#endif // DEBUG
#ifdef DEBUG
FlowEdge* ShuffleHelper(unsigned hash, FlowEdge* res)
{
FlowEdge* head = res;
for (FlowEdge *prev = nullptr; res != nullptr; prev = res, res = res->getNextPredEdge())
{
unsigned blkHash = (hash ^ (res->getSourceBlock()->bbNum << 16) ^ res->getSourceBlock()->bbNum);
if (((blkHash % 1879) & 1) && prev != nullptr)
{
// Swap res with head.
prev->setNextPredEdge(head);
FlowEdge* const resNext = res->getNextPredEdge();
FlowEdge* const headNext = head->getNextPredEdge();
head->setNextPredEdge(resNext);
res->setNextPredEdge(headNext);
std::swap(head, res);
}
}
return head;
}
unsigned SsaStressHashHelper()
{
// hash = 0: turned off, hash = 1: use method hash, hash = *: use custom hash.
unsigned hash = JitConfig.JitSsaStress();
if (hash == 0)
{
return hash;
}
if (hash == 1)
{
return JitTls::GetCompiler()->info.compMethodHash();
}
return ((hash >> 16) == 0) ? ((hash << 16) | hash) : hash;
}
#endif
//------------------------------------------------------------------------
// AllSuccessorEnumerator: Construct an instance of the enumerator.
//
// Arguments:
// comp - Compiler instance
// block - The block whose successors are to be iterated
//
AllSuccessorEnumerator::AllSuccessorEnumerator(Compiler* comp, BasicBlock* block) : m_block(block)
{
m_numSuccs = 0;
block->VisitAllSuccs(comp, [this](BasicBlock* succ) {
if (m_numSuccs < ArrLen(m_successors))
{
m_successors[m_numSuccs] = succ;
}
m_numSuccs++;
return BasicBlockVisit::Continue;
});
if (m_numSuccs > ArrLen(m_successors))
{
m_pSuccessors = new (comp, CMK_BasicBlock) BasicBlock*[m_numSuccs];
unsigned numSuccs = 0;
block->VisitAllSuccs(comp, [this, &numSuccs](BasicBlock* succ) {
assert(numSuccs < m_numSuccs);
m_pSuccessors[numSuccs++] = succ;
return BasicBlockVisit::Continue;
});
assert(numSuccs == m_numSuccs);
}
}
//------------------------------------------------------------------------
// BlockPredsWithEH:
// Return list of predecessors, including due to EH flow. This is logically
// the opposite of BasicBlock::VisitAllSuccs.
//
// Arguments:
// blk - Block to get predecessors for.
//
// Returns:
// List of edges.
//
FlowEdge* Compiler::BlockPredsWithEH(BasicBlock* blk)
{
if (!bbIsHandlerBeg(blk))
{
return blk->bbPreds;
}
BlockToFlowEdgeMap* ehPreds = GetBlockToEHPreds();
FlowEdge* res;
if (ehPreds->Lookup(blk, &res))
{
return res;
}
res = blk->bbPreds;
unsigned tryIndex = blk->getHndIndex();
// Add all blocks handled by this handler (except for second blocks of BBJ_CALLFINALLY/BBJ_CALLFINALLYRET pairs;
// these cannot cause transfer to the handler...)
// TODO-Throughput: It would be nice if we could iterate just over the blocks in the try, via
// something like:
// for (BasicBlock* bb = ehblk->ebdTryBeg; bb != ehblk->ebdTryLast->Next(); bb = bb->Next())
// (plus adding in any filter blocks outside the try whose exceptions are handled here).
// That doesn't work, however: funclets have caused us to sometimes split the body of a try into
// more than one sequence of contiguous blocks. We need to find a better way to do this.
for (BasicBlock* const bb : Blocks())
{
if (bbInExnFlowRegions(tryIndex, bb) && !bb->isBBCallFinallyPairTail())
{
res = new (this, CMK_FlowEdge) FlowEdge(bb, res);
#if MEASURE_BLOCK_SIZE
genFlowNodeCnt += 1;
genFlowNodeSize += sizeof(FlowEdge);
#endif // MEASURE_BLOCK_SIZE
}
}
EHblkDsc* ehblk = ehGetDsc(tryIndex);
if (ehblk->HasFinallyOrFaultHandler() && (ehblk->ebdHndBeg == blk))
{
// block is a finally or fault handler; all enclosing filters are predecessors
unsigned enclosing = ehblk->ebdEnclosingTryIndex;
while (enclosing != EHblkDsc::NO_ENCLOSING_INDEX)
{
EHblkDsc* enclosingDsc = ehGetDsc(enclosing);
if (enclosingDsc->HasFilter())
{
for (BasicBlock* filterBlk = enclosingDsc->ebdFilter; filterBlk != enclosingDsc->ebdHndBeg;
filterBlk = filterBlk->Next())
{
res = new (this, CMK_FlowEdge) FlowEdge(filterBlk, res);
assert(filterBlk->VisitEHEnclosedHandlerSecondPassSuccs(this, [blk](BasicBlock* succ) {
return succ == blk ? BasicBlockVisit::Abort : BasicBlockVisit::Continue;
}) == BasicBlockVisit::Abort);
}
}
enclosing = enclosingDsc->ebdEnclosingTryIndex;
}
}
#ifdef DEBUG
unsigned hash = SsaStressHashHelper();
if (hash != 0)
{
res = ShuffleHelper(hash, res);
}
#endif // DEBUG
ehPreds->Set(blk, res);
return res;
}
//------------------------------------------------------------------------
// BlockDominancePreds:
// Return list of dominance predecessors. This is the set that we know for
// sure contains a block that was fully executed before control reached
// 'blk'.
//
// Arguments:
// blk - Block to get dominance predecessors for.
//
// Returns:
// List of edges.
//
// Remarks:
// Differs from BlockPredsWithEH only in the treatment of handler blocks;
// enclosed blocks are never dominance preds, while all predecessors of
// blocks in the 'try' are (currently only the first try block expected).
//
FlowEdge* Compiler::BlockDominancePreds(BasicBlock* blk)
{
if (!bbIsHandlerBeg(blk))
{
return blk->bbPreds;
}
EHblkDsc* ehblk = ehGetBlockHndDsc(blk);
if (!ehblk->HasFinallyOrFaultHandler() || (ehblk->ebdHndBeg != blk))
{
return ehblk->ebdTryBeg->bbPreds;
}
// Finally/fault handlers can be preceded by enclosing filters due to 2
// pass EH, so add those and keep them cached.
BlockToFlowEdgeMap* domPreds = GetDominancePreds();
FlowEdge* res;
if (domPreds->Lookup(blk, &res))
{
return res;
}
res = ehblk->ebdTryBeg->bbPreds;
if (ehblk->HasFinallyOrFaultHandler() && (ehblk->ebdHndBeg == blk))
{
// block is a finally or fault handler; all enclosing filters are predecessors
unsigned enclosing = ehblk->ebdEnclosingTryIndex;
while (enclosing != EHblkDsc::NO_ENCLOSING_INDEX)
{
EHblkDsc* enclosingDsc = ehGetDsc(enclosing);
if (enclosingDsc->HasFilter())
{
for (BasicBlock* filterBlk = enclosingDsc->ebdFilter; filterBlk != enclosingDsc->ebdHndBeg;
filterBlk = filterBlk->Next())
{
res = new (this, CMK_FlowEdge) FlowEdge(filterBlk, res);
assert(filterBlk->VisitEHEnclosedHandlerSecondPassSuccs(this, [blk](BasicBlock* succ) {
return succ == blk ? BasicBlockVisit::Abort : BasicBlockVisit::Continue;
}) == BasicBlockVisit::Abort);
}
}
enclosing = enclosingDsc->ebdEnclosingTryIndex;
}
}
domPreds->Set(blk, res);
return res;
}
//------------------------------------------------------------------------
// IsLastHotBlock: see if this is the last block before the cold section
//
// Arguments:
// compiler - current compiler instance
//
// Returns:
// true if the next block is fgFirstColdBlock
// (if fgFirstColdBlock is null, this call is equivalent to IsLast())
//
bool BasicBlock::IsLastHotBlock(Compiler* compiler) const
{
return (bbNext == compiler->fgFirstColdBlock);
}
//------------------------------------------------------------------------
// IsFirstColdBlock: see if this is the first block in the cold section
//
// Arguments:
// compiler - current compiler instance
//
// Returns:
// true if this is fgFirstColdBlock
// (fgFirstColdBlock is null if there is no cold code)
//
bool BasicBlock::IsFirstColdBlock(Compiler* compiler) const
{
return (this == compiler->fgFirstColdBlock);
}
//------------------------------------------------------------------------
// CanRemoveJumpToNext: determine if jump to the next block can be omitted
//
// Arguments:
// compiler - current compiler instance
//
// Returns:
// true if block is a BBJ_ALWAYS to the next block that we can fall into
//
bool BasicBlock::CanRemoveJumpToNext(Compiler* compiler) const
{
assert(KindIs(BBJ_ALWAYS));
return JumpsToNext() && !hasAlign() && !compiler->fgInDifferentRegions(this, bbTarget);
}
//------------------------------------------------------------------------
// CanRemoveJumpToTarget: determine if jump to target can be omitted
//
// Arguments:
// target - true/false target of the BBJ_COND block
// compiler - current compiler instance
//
// Returns:
// true if block is a BBJ_COND that can fall into target
//
bool BasicBlock::CanRemoveJumpToTarget(BasicBlock* target, Compiler* compiler) const
{
assert(KindIs(BBJ_COND));
assert(TrueTargetIs(target) || FalseTargetIs(target));
return NextIs(target) && !compiler->fgInDifferentRegions(this, target);
}
//------------------------------------------------------------------------
// checkPredListOrder: see if pred list is properly ordered
//
// Returns:
// false if pred list is not in increasing bbNum order.
//
bool BasicBlock::checkPredListOrder()
{
unsigned lastBBNum = 0;
for (BasicBlock* const predBlock : PredBlocks())
{
const unsigned bbNum = predBlock->bbNum;
if (bbNum <= lastBBNum)
{
assert(bbNum != lastBBNum);
return false;
}
lastBBNum = bbNum;
}
return true;
}
//------------------------------------------------------------------------
// ensurePredListOrder: ensure all pred list entries appear in increasing
// bbNum order.
//
// Arguments:
// compiler - current compiler instance
//
void BasicBlock::ensurePredListOrder(Compiler* compiler)
{
// First, check if list is already in order.
//
if (checkPredListOrder())
{
return;
}
reorderPredList(compiler);
assert(checkPredListOrder());
}
//------------------------------------------------------------------------
// reorderPredList: relink pred list in increasing bbNum order.
//
// Arguments:
// compiler - current compiler instance
//
void BasicBlock::reorderPredList(Compiler* compiler)
{
// Count number or entries.
//
int count = 0;
for (FlowEdge* const pred : PredEdges())
{
count++;
}
// If only 0 or 1 entry, nothing to reorder.
//
if (count < 2)
{
return;
}
// Allocate sort vector if needed.
//
if (compiler->fgPredListSortVector == nullptr)
{
CompAllocator allocator = compiler->getAllocator(CMK_FlowEdge);
compiler->fgPredListSortVector = new (allocator) jitstd::vector<FlowEdge*>(allocator);
}
jitstd::vector<FlowEdge*>* const sortVector = compiler->fgPredListSortVector;
sortVector->clear();
// Fill in the vector from the list.
//
for (FlowEdge* const pred : PredEdges())
{
sortVector->push_back(pred);
}
// Sort by increasing bbNum
//
struct FlowEdgeBBNumCmp
{
bool operator()(const FlowEdge* f1, const FlowEdge* f2)
{
return f1->getSourceBlock()->bbNum < f2->getSourceBlock()->bbNum;
}
};
jitstd::sort(sortVector->begin(), sortVector->end(), FlowEdgeBBNumCmp());
// Rethread the list.
//
FlowEdge* last = nullptr;
for (FlowEdge* current : *sortVector)
{
if (last == nullptr)
{
bbPreds = current;
}
else
{
last->setNextPredEdge(current);
}
last = current;
}
last->setNextPredEdge(nullptr);
// Note bbLastPred is only used transiently, during
// initial pred list construction.
//
if (!compiler->fgPredsComputed)
{
bbLastPred = last;
}
}
#ifdef DEBUG
//------------------------------------------------------------------------
// dspBlockILRange(): Display the block's IL range as [XXX...YYY), where XXX and YYY might be "???" for BAD_IL_OFFSET.
//
void BasicBlock::dspBlockILRange() const
{
if (bbCodeOffs != BAD_IL_OFFSET)
{
printf("[%03X..", bbCodeOffs);
}
else
{
printf("[???"
"..");
}
if (bbCodeOffsEnd != BAD_IL_OFFSET)
{
// brace-matching editor workaround for following line: (
printf("%03X)", bbCodeOffsEnd);
}
else
{
// brace-matching editor workaround for following line: (
printf("???"
")");
}
}
//------------------------------------------------------------------------
// dspFlags: Print out the block's flags
//
void BasicBlock::dspFlags() const
{
static const struct
{
const BasicBlockFlags flag;
const char* const displayString;
} bbFlagDisplay[] = {
{BBF_IMPORTED, "i"},
{BBF_IS_LIR, "LIR"},
{BBF_PROF_WEIGHT, "IBC"},
{BBF_RUN_RARELY, "rare"},
{BBF_MARKED, "m"},
{BBF_REMOVED, "del"},
{BBF_DONT_REMOVE, "keep"},
{BBF_INTERNAL, "internal"},
{BBF_FAILED_VERIFICATION, "failV"},
{BBF_HAS_SUPPRESSGC_CALL, "sup-gc"},
{BBF_LOOP_HEAD, "loophead"},
{BBF_HAS_LABEL, "label"},
{BBF_HAS_JMP, "jmp"},
{BBF_HAS_CALL, "hascall"},
{BBF_DOMINATED_BY_EXCEPTIONAL_ENTRY, "xentry"},
{BBF_GC_SAFE_POINT, "gcsafe"},
{BBF_FUNCLET_BEG, "flet"},
{BBF_HAS_IDX_LEN, "idxlen"},
{BBF_HAS_MD_IDX_LEN, "mdidxlen"},
{BBF_HAS_NEWOBJ, "newobj"},
{BBF_HAS_NULLCHECK, "nullcheck"},
{BBF_BACKWARD_JUMP, "bwd"},
{BBF_BACKWARD_JUMP_TARGET, "bwd-target"},
{BBF_BACKWARD_JUMP_SOURCE, "bwd-src"},
{BBF_PATCHPOINT, "ppoint"},
{BBF_PARTIAL_COMPILATION_PATCHPOINT, "pc-ppoint"},
{BBF_HAS_HISTOGRAM_PROFILE, "hist"},
{BBF_TAILCALL_SUCCESSOR, "tail-succ"},
{BBF_RECURSIVE_TAILCALL, "r-tail"},
{BBF_NO_CSE_IN, "no-cse"},
{BBF_CAN_ADD_PRED, "add-pred"},
{BBF_RETLESS_CALL, "retless"},
{BBF_COLD, "cold"},
{BBF_KEEP_BBJ_ALWAYS, "KEEP"},
{BBF_CLONED_FINALLY_BEGIN, "cfb"},
{BBF_CLONED_FINALLY_END, "cfe"},
{BBF_LOOP_ALIGN, "align"},
{BBF_HAS_ALIGN, "has-align"},
{BBF_HAS_MDARRAYREF, "mdarr"},
{BBF_NEEDS_GCPOLL, "gcpoll"},
{BBF_NONE_QUIRK, "q"},
};
bool first = true;
for (unsigned i = 0; i < ArrLen(bbFlagDisplay); i++)
{
if (HasFlag(bbFlagDisplay[i].flag))
{
if (!first)
{
printf(" ");
}
printf("%s", bbFlagDisplay[i].displayString);
first = false;
}
}
}
/*****************************************************************************
*
* Display the bbPreds basic block list (the block predecessors).
* Returns the number of characters printed.
*/
unsigned BasicBlock::dspPreds() const
{
unsigned count = 0;
for (FlowEdge* const pred : PredEdges())
{
if (count != 0)
{
printf(",");
count += 1;
}
printf(FMT_BB, pred->getSourceBlock()->bbNum);
count += 4;
// Account for %02u only handling 2 digits, but we can display more than that.
unsigned digits = CountDigits(pred->getSourceBlock()->bbNum);
if (digits > 2)
{
count += digits - 2;
}
// Does this predecessor have an interesting dup count? If so, display it.
if (pred->getDupCount() > 1)
{
printf("(%u)", pred->getDupCount());
count += 2 + CountDigits(pred->getDupCount());
}
}
return count;
}
//------------------------------------------------------------------------
// dspSuccs: Display the basic block successors.
//
// Arguments:
// compiler - compiler instance; passed to NumSucc(Compiler*) -- see that function for implications.
//
void BasicBlock::dspSuccs(Compiler* compiler)
{
bool first = true;
// If this is a switch, we don't want to call `Succs(Compiler*)` because it will eventually call
// `GetSwitchDescMap()`, and that will have the side-effect of allocating the unique switch descriptor map
// and/or compute this switch block's unique succ set if it is not present. Debug output functions should
// never have an effect on codegen. We also don't want to assume the unique succ set is accurate, so we
// compute it ourselves here.
if (bbKind == BBJ_SWITCH)
{
// Create a set with all the successors. Don't use BlockSet, so we don't need to worry
// about the BlockSet epoch.
unsigned bbNumMax = compiler->fgBBNumMax;
BitVecTraits bitVecTraits(bbNumMax + 1, compiler);
BitVec uniqueSuccBlocks(BitVecOps::MakeEmpty(&bitVecTraits));
for (BasicBlock* const bTarget : SwitchTargets())
{
BitVecOps::AddElemD(&bitVecTraits, uniqueSuccBlocks, bTarget->bbNum);
}
BitVecOps::Iter iter(&bitVecTraits, uniqueSuccBlocks);
unsigned bbNum = 0;
while (iter.NextElem(&bbNum))
{
// Note that we will output switch successors in increasing numerical bbNum order, which is
// not related to their order in the bbSwtTargets->bbsDstTab table.
printf("%s" FMT_BB, first ? "" : ",", bbNum);
first = false;
}
}
else
{
for (const BasicBlock* const succ : Succs(compiler))
{
printf("%s" FMT_BB, first ? "" : ",", succ->bbNum);
first = false;
}
}
}
// Display a compact representation of the bbKind, that is, where this block branches.
// This is similar to code in Compiler::fgTableDispBasicBlock(), but doesn't have that code's requirements to align
// things strictly.
void BasicBlock::dspKind() const
{
auto dspBlockNum = [](const BasicBlock* b) -> const char* {
static char buffers[3][64]; // static array of 3 to allow 3 concurrent calls in one printf()
static int nextBufferIndex = 0;
auto& buffer = buffers[nextBufferIndex];
nextBufferIndex = (nextBufferIndex + 1) % ArrLen(buffers);
if (b == nullptr)
{
_snprintf_s(buffer, ArrLen(buffer), ArrLen(buffer), "NULL");
}
else
{
_snprintf_s(buffer, ArrLen(buffer), ArrLen(buffer), FMT_BB, b->bbNum);
}
return buffer;
};
switch (bbKind)
{
case BBJ_EHFINALLYRET:
{
printf(" ->");
// Early in compilation, we display the jump kind before the BBJ_EHFINALLYRET successors have been set.
if (bbEhfTargets == nullptr)
{
printf(" ????");
}
else
{
const unsigned jumpCnt = bbEhfTargets->bbeCount;
BasicBlock** const jumpTab = bbEhfTargets->bbeSuccs;
for (unsigned i = 0; i < jumpCnt; i++)
{
printf("%c%s", (i == 0) ? ' ' : ',', dspBlockNum(jumpTab[i]));
}
}
printf(" (finret)");
break;
}
case BBJ_EHFAULTRET:
printf(" (falret)");
break;
case BBJ_EHFILTERRET:
printf(" -> %s (fltret)", dspBlockNum(bbTarget));
break;
case BBJ_EHCATCHRET:
printf(" -> %s (cret)", dspBlockNum(bbTarget));
break;
case BBJ_THROW:
printf(" (throw)");
break;
case BBJ_RETURN:
printf(" (return)");
break;
case BBJ_ALWAYS:
if (HasFlag(BBF_KEEP_BBJ_ALWAYS))
{
printf(" -> %s (ALWAYS)", dspBlockNum(bbTarget));
}
else
{
printf(" -> %s (always)", dspBlockNum(bbTarget));
}
break;
case BBJ_LEAVE:
printf(" -> %s (leave)", dspBlockNum(bbTarget));
break;
case BBJ_CALLFINALLY:
printf(" -> %s (callf)", dspBlockNum(bbTarget));
break;
case BBJ_CALLFINALLYRET:
printf(" -> %s (callfr)", dspBlockNum(bbTarget));
break;
case BBJ_COND:
printf(" -> %s,%s (cond)", dspBlockNum(bbTrueTarget), dspBlockNum(bbFalseTarget));
break;
case BBJ_SWITCH:
{
printf(" ->");
const unsigned jumpCnt = bbSwtTargets->bbsCount;
BasicBlock** const jumpTab = bbSwtTargets->bbsDstTab;
for (unsigned i = 0; i < jumpCnt; i++)
{
printf("%c%s", (i == 0) ? ' ' : ',', dspBlockNum(jumpTab[i]));
const bool isDefault = bbSwtTargets->bbsHasDefault && (i == jumpCnt - 1);
if (isDefault)
{
printf("[def]");
}
const bool isDominant = bbSwtTargets->bbsHasDominantCase && (i == bbSwtTargets->bbsDominantCase);
if (isDominant)
{
printf("[dom(" FMT_WT ")]", bbSwtTargets->bbsDominantFraction);
}
}
printf(" (switch)");
}
break;
default:
unreached();
break;
}
}
void BasicBlock::dspBlockHeader(Compiler* compiler,
bool showKind /*= true*/,
bool showFlags /*= false*/,
bool showPreds /*= true*/)
{
printf("%s ", dspToString());
dspBlockILRange();
if (showKind)
{
dspKind();
}
if (showPreds)
{
printf(", preds={");
dspPreds();
printf("} succs={");
dspSuccs(compiler);
printf("}");
}
if (showFlags)
{
const unsigned lowFlags = (unsigned)bbFlags;
const unsigned highFlags = (unsigned)(bbFlags >> 32);
printf(" flags=0x%08x.%08x: ", highFlags, lowFlags);
dspFlags();
}
printf("\n");
}
const char* BasicBlock::dspToString(int blockNumPadding /* = 0 */) const
{
static char buffers[3][64]; // static array of 3 to allow 3 concurrent calls in one printf()
static int nextBufferIndex = 0;
auto& buffer = buffers[nextBufferIndex];
nextBufferIndex = (nextBufferIndex + 1) % ArrLen(buffers);
_snprintf_s(buffer, ArrLen(buffer), ArrLen(buffer), FMT_BB "%*s [%04u]", bbNum, blockNumPadding, "", bbID);
return buffer;
}
#endif // DEBUG
// Allocation function for MemoryPhiArg.
void* BasicBlock::MemoryPhiArg::operator new(size_t sz, Compiler* comp)
{
return comp->getAllocator(CMK_MemoryPhiArg).allocate<char>(sz);
}
//------------------------------------------------------------------------
// CloneBlockState: Try to populate `to` block with a copy of `from` block's statements, replacing
// uses of local `varNum` with IntCns `varVal`.
//
// Arguments:
// compiler - Jit compiler instance
// to - New/empty block to copy statements into
// from - Block to copy statements from
//
// Note:
// Leaves block ref count at zero, and pred edge list empty.
//
void BasicBlock::CloneBlockState(Compiler* compiler, BasicBlock* to, const BasicBlock* from)
{
assert(to->bbStmtList == nullptr);
to->CopyFlags(from);
to->bbWeight = from->bbWeight;
to->copyEHRegion(from);
to->bbCatchTyp = from->bbCatchTyp;
to->bbStkTempsIn = from->bbStkTempsIn;
to->bbStkTempsOut = from->bbStkTempsOut;
to->bbStkDepth = from->bbStkDepth;
to->bbCodeOffs = from->bbCodeOffs;
to->bbCodeOffsEnd = from->bbCodeOffsEnd;
VarSetOps::AssignAllowUninitRhs(compiler, to->bbScope, from->bbScope);
#ifdef DEBUG
to->bbTgtStkDepth = from->bbTgtStkDepth;
#endif // DEBUG
for (Statement* const fromStmt : from->Statements())
{
GenTree* newExpr = compiler->gtCloneExpr(fromStmt->GetRootNode());
assert(newExpr != nullptr);
compiler->fgInsertStmtAtEnd(to, compiler->fgNewStmtFromTree(newExpr, fromStmt->GetDebugInfo()));
}
}
//------------------------------------------------------------------------
// CopyTarget: Copy the block kind and targets. The targets in the `from` block remain valid.
// Use `TransferTarget` to copy the pointer to the target descriptor (e.g., for BBJ_SWITCH/BBJ_EHFINALLYRET)
// after which the `from` block target is invalid.
//
// Arguments:
// compiler - Jit compiler instance
// from - Block to copy from
//
void BasicBlock::CopyTarget(Compiler* compiler, const BasicBlock* from)
{
switch (from->GetKind())
{
case BBJ_SWITCH:
SetSwitch(new (compiler, CMK_BasicBlock) BBswtDesc(compiler, from->GetSwitchTargets()));
break;
case BBJ_EHFINALLYRET:
SetEhf(new (compiler, CMK_BasicBlock) BBehfDesc(compiler, from->GetEhfTargets()));
break;
case BBJ_COND:
SetCond(from->GetTrueTarget(), from->GetFalseTarget());
break;
case BBJ_ALWAYS:
SetKindAndTarget(from->GetKind(), from->GetTarget());
CopyFlags(from, BBF_NONE_QUIRK);
break;
case BBJ_CALLFINALLY:
case BBJ_CALLFINALLYRET:
case BBJ_EHCATCHRET:
case BBJ_EHFILTERRET:
case BBJ_LEAVE:
SetKindAndTarget(from->GetKind(), from->GetTarget());
break;
default:
SetKindAndTarget(from->GetKind()); // Clear the target
break;
}
assert(KindIs(from->GetKind()));
}
//------------------------------------------------------------------------
// TransferTarget: Like CopyTarget, but copies the target descriptors for block types which have
// them (BBJ_SWITCH/BBJ_EHFINALLYRET), that is, take their memory, after which the `from` block
// target is invalid.
//
// Arguments:
// from - Block to transfer from
//
void BasicBlock::TransferTarget(BasicBlock* from)
{
switch (from->GetKind())
{
case BBJ_SWITCH:
SetSwitch(from->GetSwitchTargets());
from->bbSwtTargets = nullptr; // Make sure nobody uses the descriptor after this.
break;
case BBJ_EHFINALLYRET:
SetEhf(from->GetEhfTargets());
from->bbEhfTargets = nullptr; // Make sure nobody uses the descriptor after this.
break;
case BBJ_COND:
SetCond(from->GetTrueTarget(), from->GetFalseTarget());
break;
case BBJ_ALWAYS:
SetKindAndTarget(from->GetKind(), from->GetTarget());
CopyFlags(from, BBF_NONE_QUIRK);
break;
case BBJ_CALLFINALLY:
case BBJ_CALLFINALLYRET:
case BBJ_EHCATCHRET:
case BBJ_EHFILTERRET:
case BBJ_LEAVE:
SetKindAndTarget(from->GetKind(), from->GetTarget());
break;
default:
SetKindAndTarget(from->GetKind()); // Clear the target
break;
}
assert(KindIs(from->GetKind()));
}
// LIR helpers
void BasicBlock::MakeLIR(GenTree* firstNode, GenTree* lastNode)
{
assert(!IsLIR());
assert((firstNode == nullptr) == (lastNode == nullptr));
assert((firstNode == lastNode) || firstNode->Precedes(lastNode));
m_firstNode = firstNode;
m_lastNode = lastNode;
SetFlags(BBF_IS_LIR);
}
bool BasicBlock::IsLIR() const
{
assert(isValid());
return HasFlag(BBF_IS_LIR);
}
//------------------------------------------------------------------------
// firstStmt: Returns the first statement in the block
//
// Return Value:
// The first statement in the block's bbStmtList.
//
Statement* BasicBlock::firstStmt() const
{
return bbStmtList;
}
//------------------------------------------------------------------------
// hasSingleStmt: Returns true if block has a single statement
//
// Return Value:
// true if block has a single statement, false otherwise
//
bool BasicBlock::hasSingleStmt() const
{
return (firstStmt() != nullptr) && (firstStmt() == lastStmt());
}
//------------------------------------------------------------------------
// lastStmt: Returns the last statement in the block
//
// Return Value:
// The last statement in the block's bbStmtList.
//
Statement* BasicBlock::lastStmt() const
{
if (bbStmtList == nullptr)
{
return nullptr;
}
Statement* result = bbStmtList->GetPrevStmt();
assert(result != nullptr && result->GetNextStmt() == nullptr);
return result;
}
//------------------------------------------------------------------------
// BasicBlock::lastNode: Returns the last node in the block.
//
GenTree* BasicBlock::lastNode() const
{
return IsLIR() ? m_lastNode : lastStmt()->GetRootNode();
}
//------------------------------------------------------------------------
// GetUniquePred: Returns the unique predecessor of a block, if one exists.
// The predecessor lists must be accurate.
//
// Arguments:
// None.
//
// Return Value:
// The unique predecessor of a block, or nullptr if there is no unique predecessor.
//
// Notes:
// If the first block has a predecessor (which it may have, if it is the target of
// a backedge), we never want to consider it "unique" because the prolog is an
// implicit predecessor.