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fgbasic.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.
#include "jitpch.h"
#ifdef _MSC_VER
#pragma hdrstop
#endif
// Flowgraph Construction and Maintenance
void Compiler::fgInit()
{
impInit();
/* Initialization for fgWalkTreePre() and fgWalkTreePost() */
fgFirstBBScratch = nullptr;
#ifdef DEBUG
fgPrintInlinedMethods = false;
#endif // DEBUG
/* We haven't yet computed the bbPreds lists */
fgPredsComputed = false;
/* We haven't yet computed the edge weight */
fgEdgeWeightsComputed = false;
fgHaveValidEdgeWeights = false;
fgSlopUsedInEdgeWeights = false;
fgRangeUsedInEdgeWeights = true;
fgCalledCount = BB_ZERO_WEIGHT;
fgReturnBlocksComputed = false;
/* Initialize the basic block list */
fgFirstBB = nullptr;
fgLastBB = nullptr;
fgFirstColdBlock = nullptr;
fgEntryBB = nullptr;
fgOSREntryBB = nullptr;
fgEntryBBExtraRefs = 0;
#if defined(FEATURE_EH_FUNCLETS)
fgFirstFuncletBB = nullptr;
fgFuncletsCreated = false;
#endif // FEATURE_EH_FUNCLETS
fgBBcount = 0;
#ifdef DEBUG
fgBBcountAtCodegen = 0;
fgBBOrder = nullptr;
#endif // DEBUG
fgMightHaveNaturalLoops = false;
fgBBNumMax = 0;
fgEdgeCount = 0;
fgDomBBcount = 0;
fgBBVarSetsInited = false;
fgReturnCount = 0;
m_dfsTree = nullptr;
m_loops = nullptr;
m_loopSideEffects = nullptr;
m_blockToLoop = nullptr;
m_domTree = nullptr;
m_reachabilitySets = nullptr;
// Initialize BlockSet data.
fgCurBBEpoch = 0;
fgCurBBEpochSize = 0;
fgBBSetCountInSizeTUnits = 0;
genReturnBB = nullptr;
genReturnLocal = BAD_VAR_NUM;
/* We haven't reached the global morphing phase */
fgGlobalMorph = false;
fgGlobalMorphDone = false;
fgModified = false;
#ifdef DEBUG
fgSafeBasicBlockCreation = true;
fgSafeFlowEdgeCreation = true;
#endif // DEBUG
fgLocalVarLivenessDone = false;
fgIsDoingEarlyLiveness = false;
fgDidEarlyLiveness = false;
/* Statement list is not threaded yet */
fgNodeThreading = NodeThreading::None;
// Initialize the logic for adding code. This is used to insert code such
// as the code that raises an exception when an array range check fails.
fgAddCodeList = nullptr;
fgAddCodeDscMap = nullptr;
/* Keep track of the max count of pointer arguments */
fgPtrArgCntMax = 0;
/* This global flag is set whenever we remove a statement */
fgStmtRemoved = false;
// This global flag is set when we create throw helper blocks
fgRngChkThrowAdded = false;
/* Keep track of whether or not EH statements have been optimized */
fgOptimizedFinally = false;
/* We will record a list of all BBJ_RETURN blocks here */
fgReturnBlocks = nullptr;
fgUsedSharedTemps = nullptr;
#if !defined(FEATURE_EH_FUNCLETS)
ehMaxHndNestingCount = 0;
#endif // !FEATURE_EH_FUNCLETS
/* Init the fgBigOffsetMorphingTemps to be BAD_VAR_NUM. */
for (int i = 0; i < TYP_COUNT; i++)
{
fgBigOffsetMorphingTemps[i] = BAD_VAR_NUM;
}
fgNoStructPromotion = false;
fgNoStructParamPromotion = false;
optValnumCSE_phase = false; // referenced in fgMorphSmpOp()
#ifdef DEBUG
fgNormalizeEHDone = false;
#endif // DEBUG
#ifdef DEBUG
if (!compIsForInlining())
{
const int noStructPromotionValue = JitConfig.JitNoStructPromotion();
assert(0 <= noStructPromotionValue && noStructPromotionValue <= 2);
if (noStructPromotionValue == 1)
{
fgNoStructPromotion = true;
}
if (noStructPromotionValue == 2)
{
fgNoStructParamPromotion = true;
}
}
#endif // DEBUG
#ifdef FEATURE_SIMD
fgPreviousCandidateSIMDFieldStoreStmt = nullptr;
#endif
fgHasSwitch = false;
fgPgoDisabled = false;
fgPgoSchema = nullptr;
fgPgoData = nullptr;
fgPgoSchemaCount = 0;
fgNumProfileRuns = 0;
fgPgoBlockCounts = 0;
fgPgoEdgeCounts = 0;
fgPgoClassProfiles = 0;
fgPgoMethodProfiles = 0;
fgPgoInlineePgo = 0;
fgPgoInlineeNoPgo = 0;
fgPgoInlineeNoPgoSingleBlock = 0;
fgCountInstrumentor = nullptr;
fgHistogramInstrumentor = nullptr;
fgValueInstrumentor = nullptr;
fgPredListSortVector = nullptr;
fgCanonicalizedFirstBB = false;
}
//------------------------------------------------------------------------
// fgEnsureFirstBBisScratch: Ensure that fgFirstBB is a scratch BasicBlock
//
// Returns:
// True, if a new basic block was allocated.
//
// Notes:
// This should be called before adding on-entry initialization code to
// the method, to ensure that fgFirstBB is not part of a loop.
//
// Does nothing, if fgFirstBB is already a scratch BB. After calling this,
// fgFirstBB may already contain code. Callers have to be careful
// that they do not mess up the order of things added to this block and
// inadvertently change semantics.
//
// We maintain the invariant that a scratch BB ends with BBJ_ALWAYS,
// so that when adding independent bits of initialization,
// callers can generally append to the fgFirstBB block without worrying
// about what code is there already.
//
// Can be called at any time, and can be called multiple times.
//
bool Compiler::fgEnsureFirstBBisScratch()
{
// Have we already allocated a scratch block?
if (fgFirstBBisScratch())
{
return false;
}
assert(fgFirstBBScratch == nullptr);
BasicBlock* block = BasicBlock::New(this, BBJ_ALWAYS, fgFirstBB);
block->SetFlags(BBF_NONE_QUIRK);
if (fgFirstBB != nullptr)
{
// If we have profile data the new block will inherit fgFirstBlock's weight
if (fgFirstBB->hasProfileWeight())
{
block->inheritWeight(fgFirstBB);
}
// The first block has an implicit ref count which we must
// remove. Note the ref count could be greater than one, if
// the first block is not scratch and is targeted by a
// branch.
assert(fgFirstBB->bbRefs >= 1);
fgFirstBB->bbRefs--;
// The new scratch bb will fall through to the old first bb
FlowEdge* const edge = fgAddRefPred(fgFirstBB, block);
edge->setLikelihood(1.0);
fgInsertBBbefore(fgFirstBB, block);
}
else
{
noway_assert(fgLastBB == nullptr);
fgFirstBB = block;
fgLastBB = block;
}
noway_assert(fgLastBB != nullptr);
// Set the expected flags
block->SetFlags(BBF_INTERNAL | BBF_IMPORTED);
// This new first BB has an implicit ref, and no others.
//
// But if we call this early, before fgLinkBasicBlocks,
// defer and let it handle adding the implicit ref.
//
block->bbRefs = fgPredsComputed ? 1 : 0;
fgFirstBBScratch = fgFirstBB;
#ifdef DEBUG
if (verbose)
{
printf("New scratch " FMT_BB "\n", block->bbNum);
}
#endif
return true;
}
//------------------------------------------------------------------------
// fgFirstBBisScratch: Check if fgFirstBB is a scratch block
//
// Returns:
// true if fgFirstBB is a scratch block.
//
bool Compiler::fgFirstBBisScratch()
{
if (fgFirstBBScratch != nullptr)
{
assert(fgFirstBBScratch == fgFirstBB);
assert(fgFirstBBScratch->HasFlag(BBF_INTERNAL));
if (fgPredsComputed)
{
assert(fgFirstBBScratch->countOfInEdges() == 1);
}
// Normally, the first scratch block is a fall-through block. However, if the block after it was an empty
// BBJ_ALWAYS block, it might get removed, and the code that removes it will make the first scratch block
// a BBJ_ALWAYS block.
assert(fgFirstBBScratch->KindIs(BBJ_ALWAYS));
return true;
}
else
{
return false;
}
}
//------------------------------------------------------------------------
// fgBBisScratch: Check if a given block is a scratch block.
//
// Arguments:
// block - block in question
//
// Returns:
// true if this block is the first block and is a scratch block.
//
bool Compiler::fgBBisScratch(BasicBlock* block)
{
return fgFirstBBisScratch() && (block == fgFirstBB);
}
/*
Removes a block from the return block list
*/
void Compiler::fgRemoveReturnBlock(BasicBlock* block)
{
if (fgReturnBlocks == nullptr)
{
return;
}
if (fgReturnBlocks->block == block)
{
// It's the 1st entry, assign new head of list.
fgReturnBlocks = fgReturnBlocks->next;
return;
}
for (BasicBlockList* retBlocks = fgReturnBlocks; retBlocks->next != nullptr; retBlocks = retBlocks->next)
{
if (retBlocks->next->block == block)
{
// Found it; splice it out.
retBlocks->next = retBlocks->next->next;
return;
}
}
}
//------------------------------------------------------------------------
// fgConvertBBToThrowBB: Change a given block to a throw block.
//
// Arguments:
// block - block in question
//
void Compiler::fgConvertBBToThrowBB(BasicBlock* block)
{
JITDUMP("Converting " FMT_BB " to BBJ_THROW\n", block->bbNum);
assert(fgPredsComputed);
// Ordering of the following operations matters.
// First, if we are looking at the first block of a callfinally pair, remove the pairing.
// Don't actually remove the BBJ_CALLFINALLYRET as that might affect block iteration in
// the callers.
if (block->isBBCallFinallyPair())
{
BasicBlock* const leaveBlock = block->Next();
fgPrepareCallFinallyRetForRemoval(leaveBlock);
}
// Scrub this block from the pred lists of any successors
fgRemoveBlockAsPred(block);
// Update jump kind after the scrub.
block->SetKindAndTarget(BBJ_THROW);
block->RemoveFlags(BBF_RETLESS_CALL); // no longer a BBJ_CALLFINALLY
// Any block with a throw is rare
block->bbSetRunRarely();
}
/*****************************************************************************
* fgChangeSwitchBlock:
*
* We have a BBJ_SWITCH jump at 'oldSwitchBlock' and we want to move this
* switch jump over to 'newSwitchBlock'. All of the blocks that are jumped
* to from jumpTab[] need to have their predecessor lists updated by removing
* the 'oldSwitchBlock' and adding 'newSwitchBlock'.
*/
void Compiler::fgChangeSwitchBlock(BasicBlock* oldSwitchBlock, BasicBlock* newSwitchBlock)
{
noway_assert(oldSwitchBlock != nullptr);
noway_assert(newSwitchBlock != nullptr);
noway_assert(oldSwitchBlock->KindIs(BBJ_SWITCH));
assert(fgPredsComputed);
// Walk the switch's jump table, updating the predecessor for each branch.
for (BasicBlock* const bJump : oldSwitchBlock->SwitchTargets())
{
noway_assert(bJump != nullptr);
// Note that if there are duplicate branch targets in the switch jump table,
// fgRemoveRefPred()/fgAddRefPred() will do the right thing: the second and
// subsequent duplicates will simply subtract from and add to the duplicate
// count (respectively).
//
// Remove the old edge [oldSwitchBlock => bJump]
//
assert(bJump->countOfInEdges() > 0);
fgRemoveRefPred(bJump, oldSwitchBlock);
//
// Create the new edge [newSwitchBlock => bJump]
//
fgAddRefPred(bJump, newSwitchBlock);
}
if (m_switchDescMap != nullptr)
{
SwitchUniqueSuccSet uniqueSuccSet;
// If already computed and cached the unique descriptors for the old block, let's
// update those for the new block.
if (m_switchDescMap->Lookup(oldSwitchBlock, &uniqueSuccSet))
{
m_switchDescMap->Set(newSwitchBlock, uniqueSuccSet, BlockToSwitchDescMap::Overwrite);
}
else
{
fgInvalidateSwitchDescMapEntry(newSwitchBlock);
}
fgInvalidateSwitchDescMapEntry(oldSwitchBlock);
}
}
//------------------------------------------------------------------------
// fgReplaceSwitchJumpTarget: update BBJ_SWITCH block so that all control
// that previously flowed to oldTarget now flows to newTarget.
//
// Arguments:
// blockSwitch - block ending in a switch
// newTarget - new branch target
// oldTarget - old branch target
//
// Notes:
// Updates the jump table and the cached unique target set (if any).
//
void Compiler::fgReplaceSwitchJumpTarget(BasicBlock* blockSwitch, BasicBlock* newTarget, BasicBlock* oldTarget)
{
noway_assert(blockSwitch != nullptr);
noway_assert(newTarget != nullptr);
noway_assert(oldTarget != nullptr);
noway_assert(blockSwitch->KindIs(BBJ_SWITCH));
assert(fgPredsComputed);
// For the jump targets values that match oldTarget of our BBJ_SWITCH
// replace predecessor 'blockSwitch' with 'newTarget'
unsigned jumpCnt = blockSwitch->GetSwitchTargets()->bbsCount;
BasicBlock** jumpTab = blockSwitch->GetSwitchTargets()->bbsDstTab;
unsigned i = 0;
// Walk the switch's jump table looking for blocks to update the preds for
while (i < jumpCnt)
{
if (jumpTab[i] == oldTarget) // We will update when jumpTab[i] matches
{
// Remove the old edge [oldTarget from blockSwitch]
//
fgRemoveAllRefPreds(oldTarget, blockSwitch);
//
// Change the jumpTab entry to branch to the new location
//
jumpTab[i] = newTarget;
//
// Create the new edge [newTarget from blockSwitch]
//
FlowEdge* const newEdge = fgAddRefPred(newTarget, blockSwitch);
// Now set the correct value of newEdge's DupCount
// and replace any other jumps in jumpTab[] that go to oldTarget.
//
i++;
while (i < jumpCnt)
{
if (jumpTab[i] == oldTarget)
{
//
// We also must update this entry in the jumpTab
//
jumpTab[i] = newTarget;
newTarget->bbRefs++;
newEdge->incrementDupCount();
}
i++; // Check the next entry in jumpTab[]
}
// Maintain, if necessary, the set of unique targets of "block."
UpdateSwitchTableTarget(blockSwitch, oldTarget, newTarget);
return; // We have replaced the jumps to oldTarget with newTarget
}
i++; // Check the next entry in jumpTab[] for a match
}
noway_assert(!"Did not find oldTarget in jumpTab[]");
}
//------------------------------------------------------------------------
// fgChangeEhfBlock: We have a BBJ_EHFINALLYRET block at 'oldBlock' and we want to move this
// to 'newBlock'. All of the 'oldBlock' successors need to have their predecessor lists updated
// by removing edges to 'oldBlock' and adding edges to 'newBlock'.
//
// Arguments:
// oldBlock - previous BBJ_EHFINALLYRET block
// newBlock - block that is replacing 'oldBlock'
//
void Compiler::fgChangeEhfBlock(BasicBlock* oldBlock, BasicBlock* newBlock)
{
assert(oldBlock != nullptr);
assert(newBlock != nullptr);
assert(oldBlock->KindIs(BBJ_EHFINALLYRET));
assert(fgPredsComputed);
for (BasicBlock* const succ : oldBlock->EHFinallyRetSuccs())
{
assert(succ != nullptr);
// Remove the old edge [oldBlock => succ]
//
assert(succ->countOfInEdges() > 0);
fgRemoveRefPred(succ, oldBlock);
// Create the new edge [newBlock => succ]
//
fgAddRefPred(succ, newBlock);
}
}
//------------------------------------------------------------------------
// fgReplaceEhfSuccessor: update BBJ_EHFINALLYRET block so that all control
// that previously flowed to oldSucc now flows to newSucc. It is assumed
// that oldSucc is currently a successor of `block`. We only allow a successor
// block to appear once in the successor list. Thus, if the new successor
// already exists in the list, we simply remove the old successor.
//
// Arguments:
// block - BBJ_EHFINALLYRET block
// oldSucc - old successor
// newSucc - new successor
//
void Compiler::fgReplaceEhfSuccessor(BasicBlock* block, BasicBlock* oldSucc, BasicBlock* newSucc)
{
assert(block != nullptr);
assert(oldSucc != nullptr);
assert(newSucc != nullptr);
assert(block->KindIs(BBJ_EHFINALLYRET));
assert(fgPredsComputed);
BBehfDesc* const ehfDesc = block->GetEhfTargets();
const unsigned succCount = ehfDesc->bbeCount;
BasicBlock** const succTab = ehfDesc->bbeSuccs;
// Walk the successor table looking for the old successor, which we expect to find.
unsigned oldSuccNum = UINT_MAX;
unsigned newSuccNum = UINT_MAX;
for (unsigned i = 0; i < succCount; i++)
{
if (succTab[i] == newSucc)
{
newSuccNum = i;
}
if (succTab[i] == oldSucc)
{
oldSuccNum = i;
}
}
noway_assert((oldSuccNum != UINT_MAX) && "Did not find oldSucc in succTab[]");
if (newSuccNum != UINT_MAX)
{
// The new successor is already in the table; simply remove the old one.
fgRemoveEhfSuccessor(block, oldSucc);
JITDUMP("Remove existing BBJ_EHFINALLYRET " FMT_BB " successor " FMT_BB "; replacement successor " FMT_BB
" already exists in list\n",
block->bbNum, oldSucc->bbNum, newSucc->bbNum);
}
else
{
// Replace the old one with the new one.
succTab[oldSuccNum] = newSucc;
// Remove the old edge [block => oldSucc]
//
fgRemoveAllRefPreds(oldSucc, block);
// Create the new edge [block => newSucc]
//
fgAddRefPred(newSucc, block);
JITDUMP("Replace BBJ_EHFINALLYRET " FMT_BB " successor " FMT_BB " with " FMT_BB "\n", block->bbNum,
oldSucc->bbNum, newSucc->bbNum);
}
}
//------------------------------------------------------------------------
// fgRemoveEhfSuccessor: update BBJ_EHFINALLYRET block to remove `succ` as a successor.
// Updates the predecessor list of `succ`.
//
// Arguments:
// block - BBJ_EHFINALLYRET block
// succ - successor
//
void Compiler::fgRemoveEhfSuccessor(BasicBlock* block, BasicBlock* succ)
{
assert(block != nullptr);
assert(succ != nullptr);
assert(fgPredsComputed);
assert(block->KindIs(BBJ_EHFINALLYRET));
// Don't `assert(succ->isBBCallFinallyPairTail())`; we've already unlinked the CALLFINALLY
assert(succ->KindIs(BBJ_CALLFINALLYRET));
fgRemoveRefPred(succ, block);
BBehfDesc* const ehfDesc = block->GetEhfTargets();
unsigned succCount = ehfDesc->bbeCount;
BasicBlock** succTab = ehfDesc->bbeSuccs;
bool found = false;
// Walk the successor table looking for the specified successor block.
for (unsigned i = 0; i < succCount; i++)
{
if (succTab[i] == succ)
{
// If it's not the last one, move everything after in the table down one slot.
if (i + 1 < succCount)
{
memmove_s(&succTab[i], (succCount - i) * sizeof(BasicBlock*), &succTab[i + 1],
(succCount - i - 1) * sizeof(BasicBlock*));
}
--succCount;
found = true;
#ifdef DEBUG
// We only expect to see a successor once in the table.
for (; i < succCount; i++)
{
assert(succTab[i] != succ);
}
#endif // DEBUG
break;
}
}
assert(found);
ehfDesc->bbeCount = succCount;
}
//------------------------------------------------------------------------
// Compiler::fgReplaceJumpTarget: For a given block, replace the target 'oldTarget' with 'newTarget'.
//
// Arguments:
// block - the block in which a jump target will be replaced.
// newTarget - the new branch target of the block.
// oldTarget - the old branch target of the block.
//
// Notes:
// 1. Only branches are changed: BBJ_ALWAYS, the non-fallthrough path of BBJ_COND, BBJ_SWITCH, etc.
// We assert for other jump kinds.
// 2. All branch targets found are updated. If there are multiple ways for a block
// to reach 'oldTarget' (e.g., multiple arms of a switch), all of them are changed.
// 3. The predecessor lists are updated.
// 4. If any switch table entry was updated, the switch table "unique successor" cache is invalidated.
//
void Compiler::fgReplaceJumpTarget(BasicBlock* block, BasicBlock* newTarget, BasicBlock* oldTarget)
{
assert(block != nullptr);
assert(fgPredsComputed);
switch (block->GetKind())
{
case BBJ_CALLFINALLY:
case BBJ_CALLFINALLYRET:
case BBJ_ALWAYS:
case BBJ_EHCATCHRET:
case BBJ_EHFILTERRET:
case BBJ_LEAVE: // This function can be called before import, so we still have BBJ_LEAVE
if (block->TargetIs(oldTarget))
{
block->SetTarget(newTarget);
fgRemoveRefPred(oldTarget, block);
fgAddRefPred(newTarget, block);
}
break;
case BBJ_COND:
{
FlowEdge* oldEdge = fgRemoveRefPred(oldTarget, block);
if (block->TrueTargetIs(oldTarget))
{
if (block->FalseTargetIs(oldTarget))
{
// fgRemoveRefPred returns nullptr for BBJ_COND blocks with two flow edges to target
assert(oldEdge == nullptr);
fgRemoveConditionalJump(block);
assert(block->KindIs(BBJ_ALWAYS));
block->SetTarget(newTarget);
}
else
{
// fgRemoveRefPred should have removed the flow edge
assert(oldEdge != nullptr);
block->SetTrueTarget(newTarget);
}
// TODO-NoFallThrough: Proliferate weight from oldEdge
// (we avoid doing so when updating the true target to reduce diffs for now, as a quirk)
fgAddRefPred(newTarget, block);
}
else
{
// fgRemoveRefPred should have removed the flow edge
assert(oldEdge != nullptr);
assert(block->FalseTargetIs(oldTarget));
block->SetFalseTarget(newTarget);
fgAddRefPred(newTarget, block, oldEdge);
}
break;
}
case BBJ_SWITCH:
{
unsigned const jumpCnt = block->GetSwitchTargets()->bbsCount;
BasicBlock** const jumpTab = block->GetSwitchTargets()->bbsDstTab;
bool changed = false;
for (unsigned i = 0; i < jumpCnt; i++)
{
if (jumpTab[i] == oldTarget)
{
jumpTab[i] = newTarget;
changed = true;
fgRemoveRefPred(oldTarget, block);
fgAddRefPred(newTarget, block);
}
}
if (changed)
{
InvalidateUniqueSwitchSuccMap();
}
break;
}
default:
assert(!"Block doesn't have a jump target!");
unreached();
break;
}
}
//------------------------------------------------------------------------
// fgReplacePred: update the predecessor list, swapping one pred for another
//
// Arguments:
// block - block with the pred list we want to update
// oldPred - pred currently appearing in block's pred list
// newPred - pred that will take oldPred's place.
//
// Notes:
//
// A block can only appear once in the preds list. If a predecessor has multiple
// ways to get to this block, then the pred edge DupCount will be >1.
//
// This function assumes that all branches from the predecessor (practically, that all
// switch cases that target this block) are changed to branch from the new predecessor,
// with the same dup count.
//
// Note that the block bbRefs is not changed, since 'block' has the same number of
// references as before, just from a different predecessor block.
//
// Also note this may cause sorting of the pred list.
//
void Compiler::fgReplacePred(BasicBlock* block, BasicBlock* oldPred, BasicBlock* newPred)
{
noway_assert(block != nullptr);
noway_assert(oldPred != nullptr);
noway_assert(newPred != nullptr);
bool modified = false;
for (FlowEdge* const pred : block->PredEdges())
{
if (oldPred == pred->getSourceBlock())
{
pred->setSourceBlock(newPred);
modified = true;
break;
}
}
// We may now need to reorder the pred list.
//
if (modified)
{
block->ensurePredListOrder(this);
}
}
/*****************************************************************************
* For a block that is in a handler region, find the first block of the most-nested
* handler containing the block.
*/
BasicBlock* Compiler::fgFirstBlockOfHandler(BasicBlock* block)
{
assert(block->hasHndIndex());
return ehGetDsc(block->getHndIndex())->ebdHndBeg;
}
#ifdef DEBUG
//------------------------------------------------------------------------
// fgInvalidateBBLookup: In non-Release builds, set fgBBs to a dummy value.
// After calling this, fgInitBBLookup must be called before using fgBBs again.
//
void Compiler::fgInvalidateBBLookup()
{
fgBBs = (BasicBlock**)0xCDCD;
}
#endif // DEBUG
/*****************************************************************************
*
* The following helps find a basic block given its PC offset.
*/
void Compiler::fgInitBBLookup()
{
BasicBlock** dscBBptr;
/* Allocate the basic block table */
dscBBptr = fgBBs = new (this, CMK_BasicBlock) BasicBlock*[fgBBcount];
/* Walk all the basic blocks, filling in the table */
for (BasicBlock* const block : Blocks())
{
*dscBBptr++ = block;
}
noway_assert(dscBBptr == fgBBs + fgBBcount);
}
BasicBlock* Compiler::fgLookupBB(unsigned addr)
{
unsigned lo;
unsigned hi;
/* Do a binary search */
for (lo = 0, hi = fgBBcount - 1;;)
{
AGAIN:;
if (lo > hi)
{
break;
}
unsigned mid = (lo + hi) / 2;
BasicBlock* dsc = fgBBs[mid];
// We introduce internal blocks for BBJ_CALLFINALLY. Skip over these.
while (dsc->HasFlag(BBF_INTERNAL))
{
dsc = dsc->Next();
mid++;
// We skipped over too many, Set hi back to the original mid - 1
if (mid > hi)
{
mid = (lo + hi) / 2;
hi = mid - 1;
goto AGAIN;
}
}
unsigned pos = dsc->bbCodeOffs;
if (pos < addr)
{
if ((lo == hi) && (lo == (fgBBcount - 1)))
{
noway_assert(addr == dsc->bbCodeOffsEnd);
return nullptr; // NULL means the end of method
}
lo = mid + 1;
continue;
}
if (pos > addr)
{
hi = mid - 1;
continue;
}
return dsc;
}
#ifdef DEBUG
printf("ERROR: Couldn't find basic block at offset %04X\n", addr);
#endif // DEBUG
NO_WAY("fgLookupBB failed.");
}
//------------------------------------------------------------------------
// FgStack: simple stack model for the inlinee's evaluation stack.
//
// Model the inputs available to various operations in the inline body.
// Tracks constants, arguments, array lengths.
class FgStack
{
public:
FgStack() : slot0(SLOT_INVALID), slot1(SLOT_INVALID), depth(0)
{
// Empty
}
enum FgSlot
{
SLOT_INVALID = UINT_MAX,
SLOT_UNKNOWN = 0,
SLOT_CONSTANT = 1,
SLOT_ARRAYLEN = 2,
SLOT_ARGUMENT = 3
};
void Clear()
{
depth = 0;
}
void PushUnknown()
{
Push(SLOT_UNKNOWN);
}
void PushConstant()
{
Push(SLOT_CONSTANT);
}
void PushArrayLen()
{
Push(SLOT_ARRAYLEN);
}
void PushArgument(unsigned arg)
{
Push((FgSlot)(SLOT_ARGUMENT + arg));
}
FgSlot GetSlot0() const
{
return depth >= 1 ? slot0 : FgSlot::SLOT_UNKNOWN;
}
FgSlot GetSlot1() const
{
return depth >= 2 ? slot1 : FgSlot::SLOT_UNKNOWN;
}
FgSlot Top(const int n = 0)
{
if (n == 0)
{
return depth >= 1 ? slot0 : SLOT_UNKNOWN;
}
if (n == 1)
{
return depth == 2 ? slot1 : SLOT_UNKNOWN;
}
unreached();
}
static bool IsConstant(FgSlot value)
{
return value == SLOT_CONSTANT;
}
static bool IsConstantOrConstArg(FgSlot value, InlineInfo* info)
{
return IsConstant(value) || IsConstArgument(value, info);
}
static bool IsArrayLen(FgSlot value)
{
return value == SLOT_ARRAYLEN;
}
static bool IsArgument(FgSlot value)
{
return value >= SLOT_ARGUMENT;
}
static bool IsConstArgument(FgSlot value, InlineInfo* info)
{
if ((info == nullptr) || !IsArgument(value))
{
return false;