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SwitchAnalyzer.cpp
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SwitchAnalyzer.cpp
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/*******************************************************************************
* Copyright (c) 2000, 2021 IBM Corp. and others
*
* This program and the accompanying materials are made available under
* the terms of the Eclipse Public License 2.0 which accompanies this
* distribution and is available at https://www.eclipse.org/legal/epl-2.0/
* or the Apache License, Version 2.0 which accompanies this distribution and
* is available at https://www.apache.org/licenses/LICENSE-2.0.
*
* This Source Code may also be made available under the following
* Secondary Licenses when the conditions for such availability set
* forth in the Eclipse Public License, v. 2.0 are satisfied: GNU
* General Public License, version 2 with the GNU Classpath
* Exception [1] and GNU General Public License, version 2 with the
* OpenJDK Assembly Exception [2].
*
* [1] https://www.gnu.org/software/classpath/license.html
* [2] http://openjdk.java.net/legal/assembly-exception.html
*
* SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 OR LicenseRef-GPL-2.0 WITH Assembly-exception
*******************************************************************************/
#include "optimizer/SwitchAnalyzer.hpp"
#include <stdint.h>
#include <string.h>
#include "env/FrontEnd.hpp"
#include "compile/Compilation.hpp"
#include "env/IO.hpp"
#include "il/Block.hpp"
#include "il/DataTypes.hpp"
#include "il/Node.hpp"
#include "il/Node_inlines.hpp"
#include "il/TreeTop.hpp"
#include "infra/Assert.hpp"
#include "infra/BitVector.hpp"
#include "infra/List.hpp"
#include "infra/TRCfgEdge.hpp"
#include "optimizer/Optimization_inlines.hpp"
#include "optimizer/TransformUtil.hpp"
#define MIN_SIZE_FOR_BIN_SEARCH 4
#define MIN_CASES_FOR_OPT 4
#define SWITCH_TO_IFS_THRESHOLD 3
#define LOOKUP_SWITCH_GEN_IN_IL_OVERRIDE 15
#define OPT_DETAILS "O^O SWITCH ANALYZER: "
TR::SwitchAnalyzer::SwitchAnalyzer(TR::OptimizationManager *manager)
: TR::Optimization(manager)
{
// default values //FIXME
_costMem = 1;
_costUnique = 3 + 6; // cost_cl + cost_bc
_costRange = 3 + 3 + 6; // cost_s + cost_cl + cost_bc
_costDense = _costRange + 10; // _costRange + cost_lba
_minDensity = .01f;
_binarySearchBound = 4;
_smallDense = 1 + ((_costDense + _costMem)/_costUnique);
}
int32_t TR::SwitchAnalyzer::perform()
{
TR::StackMemoryRegion stackMemoryRegion(*trMemory());
_cfg = comp()->getFlowGraph();
_haveProfilingInfo = (comp()->isOptServer()) ? _cfg->setFrequencies() : false;
_blocksGeneratedByMe = new (trStackMemory()) TR_BitVector(_cfg->getNextNodeNumber(),
trMemory(), stackAlloc, growable);
if (trace())
{
comp()->dumpMethodTrees("Trees Before Performing Switch Analysis");
}
TR::TreeTop *tt, *exitTree;
for (tt = comp()->getStartTree();
tt;
tt = exitTree->getNextRealTreeTop())
{
TR::Block *block = tt->getNode()->getBlock();
exitTree = block->getExit();
TR::TreeTop *lastTree = exitTree->getPrevRealTreeTop();
if (lastTree->getNode()->getOpCode().isSwitch())
{
switch (lastTree->getNode()->getOpCodeValue())
{
case TR::table:
case TR::lookup:
analyze(lastTree->getNode(), block);
break;
default:
break;
}
}
}
if (trace())
{
comp()->dumpMethodTrees("Trees After Performing Switch Analysis");
}
return 1;
}
const char *
TR::SwitchAnalyzer::optDetailString() const throw()
{
return "O^O SWITCH ANALYZER: ";
}
void TR::SwitchAnalyzer::analyze(TR::Node *node, TR::Block *block)
{
if (_blocksGeneratedByMe->isSet(block->getNumber())) return;
_switch = node;
_switchTree = block->getLastRealTreeTop();
_defaultDest= node->getChild(1)->getBranchDestination();
_block = block;
_nextBlock = block->getNextBlock();
_temp = 0;
if (_switch->getChild(0)->getType().isInt64())
_isInt64 = true;
else
_isInt64 = false;
int32_t *frequencies = setupFrequencies(node);
CASECONST_TYPE lowVal = 0;
CASECONST_TYPE highVal = 0;
uint16_t upperBound = node->getCaseIndexUpperBound();
if (upperBound <= 2)
return;
// Build Switch Info
//
TR_LinkHead<SwitchInfo> *chain = new (trStackMemory()) TR_LinkHead<SwitchInfo>();
TR_LinkHead<SwitchInfo> *earlyUniques = new (trStackMemory()) TR_LinkHead<SwitchInfo>();
for (int32_t i = upperBound - 1; i > 1; --i)
{
TR::Node *caseNode = node->getChild(i);
CASECONST_TYPE konst;
if (node->getOpCodeValue() == TR::table)
konst = i - 2;
else
konst = caseNode->getCaseConstant();
if (i == upperBound - 1)
highVal = konst;
if (i == 2)
lowVal = konst;
TR::TreeTop *target = caseNode->getBranchDestination();
SwitchInfo *info = new (trStackMemory()) SwitchInfo(konst, target, _costUnique);
if (frequencies)
{
info->_freq = ((float)frequencies[i]) / block->getFrequency();
}
if (trace())
traceMsg(comp(), "Switch info pointing at target tree top 0x%p has frequency scale of %f\n", target->getNode(), info->_freq);
if ((upperBound - 2) >= MIN_CASES_FOR_OPT && keepAsUnique(info, i))
{
info->setNext(earlyUniques->getFirst());
earlyUniques->setFirst(info);
}
else
chainInsert(chain, info);
}
// We are guaranteed that the case children are sorted.
// Image the Z32 number lines
// [------------------------|--------------------------] signed
// TR::getMinSigned<TR::Int32>() 0 TR::getMaxSigned<TR::Int32>() TR::getMaxUnsigned<TR::Int32>()
// [--------------------------|------------------------------------] unsigned
// If all the cases of the lookup are on the same 'half' of the number lines, it doesn't matter
// if we use signed or unsigned comparisons, lets use signed.
// For the signed case, we better use signed if the numbers straddle the 0 boundary; we already do.
// For the unsigned case, we better use unsigned if the numbers straddle the TR::getMaxSigned<TR::Int32>() boundary. If that's
// the case, the highVal will be less than (in the signed sense) the lowVal.
//
if (highVal < lowVal)
_signed = false;
else
_signed = true;
if (trace())
{
printInfo(comp()->fe(), comp()->getOutFile(), chain);
traceMsg(comp(), "Early Unique Chain:\n");
printInfo(comp()->fe(), comp()->getOutFile(), earlyUniques);
}
// Find Dense Sets
//
findDenseSets(chain);
// Merge Dense Sets to form Larger Dense Sets
//
bool change=true;
while (change)
{
change=mergeDenseSets(chain);
}
// Gather lonely uniq's and small dense nodes out of the main switch
//
TR_LinkHead<SwitchInfo> *bound = gather(chain);
if (trace())
{
traceMsg(comp(), "Early Unique Chain:\n");
printInfo(comp()->fe(), comp()->getOutFile(), earlyUniques);
}
// Remerge bound nodes back into the primary chain if small // FIXME: implement
//
//remerge(chain, bound);
// Fix-up sorting order. If unsigned, we need to put it back to unsigned sorting order for correct emit since
// merge part made it signed sorting order. The merge logic can be reused with this fix-up.
// Caveats are that zero straddling set must be subdivided and TR::getMaxSigned<TR::Int32>() straddling set could be merged back.
if (!_signed)
{
fixUpUnsigned(chain);
fixUpUnsigned(bound);
fixUpUnsigned(earlyUniques);
if (trace())
{
traceMsg(comp(), "After fixing unsigned sort order\n");
printInfo(comp()->fe(), comp()->getOutFile(), chain);
printInfo(comp()->fe(), comp()->getOutFile(), bound);
printInfo(comp()->fe(), comp()->getOutFile(), earlyUniques);
}
}
// Emit
//
emit(chain, bound, earlyUniques);
if (trace())
traceMsg(comp(), "Done.\n");
}
void TR::SwitchAnalyzer::findDenseSets(TR_LinkHead<SwitchInfo> *chain)
{
// find consecutive uniques (they must have different targets)
// and group them together into a dense node
//
for (SwitchInfo *prev = 0, *cur = chain->getFirst();
cur;
prev = cur, cur = cur->getNext())
{
if (cur->_kind == Unique)
{
SwitchInfo *end = getConsecutiveUniques(cur);
if (end != cur)
{
SwitchInfo *dense = new (trStackMemory()) SwitchInfo(trMemory());
SwitchInfo *tail = end->getNext();
for (SwitchInfo *t = cur, *next = t->getNext();
t != tail;)
{
denseInsert(dense, t);
t = next;
if (!next)
break;
next = next->getNext();
}
if (prev)
prev->setNext(dense);
else
chain->setFirst(dense);
dense->setNext(tail);
cur = dense;
}
}
}
if (trace())
{
traceMsg(comp(), "After finding dense sets\n");
printInfo(comp()->fe(), comp()->getOutFile(), chain);
}
}
bool TR::SwitchAnalyzer::mergeDenseSets(TR_LinkHead<SwitchInfo> *chain)
{
SwitchInfo *prev = 0;
SwitchInfo *cur = chain->getFirst();
SwitchInfo *next = cur->getNext();
bool change=false;
while (next)
{
int32_t count = cur->_count + next->_count;
CASECONST_TYPE span = 1 + next->_max - cur->_min;
int32_t origCost = cur->_cost + next->_cost + _costRange;
int32_t newCost = _costDense + _costMem * span;
if (newCost < origCost &&
((float)count / span) > _minDensity)
{
dumpOptDetails(comp(), "%smerging dense set %p\n", optDetailString(), cur);
change=true;
if (cur->_kind != Dense)
{
SwitchInfo *dense = new (trStackMemory()) SwitchInfo(trMemory());
denseInsert(dense, cur);
if (prev)
prev->setNext(dense);
else
chain->setFirst(dense);
cur = dense;
}
SwitchInfo *nextOfNext = next->getNext();
denseInsert(cur, next);
cur->setNext(nextOfNext);
// go back one to process cur with the new next again
//
next = cur;
cur = prev;
}
prev = cur;
cur = next;
next = next->getNext();
}
if (trace())
{
traceMsg(comp(), "After merging dense sets\n");
printInfo(comp()->fe(), comp()->getOutFile(), chain);
}
return change;
}
TR_LinkHead<TR::SwitchAnalyzer::SwitchInfo> *TR::SwitchAnalyzer::gather(TR_LinkHead<SwitchInfo> *chain)
{
SwitchInfo *prev = 0;
SwitchInfo *cur = chain->getFirst(); // will be non-null, chain cannot be empty
SwitchInfo *next = cur->getNext();
TR_LinkHead<SwitchInfo> *bound = new (trStackMemory()) TR_LinkHead<SwitchInfo>();
// Remove lonely uniques and small denses from the chain
//
for (; cur; cur = next)
{
next = cur->getNext();
dumpOptDetails(comp(), "%sgathering set %p\n", optDetailString(), cur);
// ignore range nodes and dense nodes that are large
//
if ((cur->_kind == Range) ||
(cur->_kind == Dense && cur->_count >= _smallDense))
{
prev = cur;
continue;
}
// Remove cur from the chain and insert it into the bound chain
//
if (prev)
prev->setNext(next);
else
chain->setFirst(next);
if (cur->_kind == Unique)
chainInsert(bound, cur);
else
{
// Split the Dense node
//
SwitchInfo *ptr = cur->_chain->getFirst();
while (ptr)
{
SwitchInfo *next = ptr->getNext();
chainInsert(bound, ptr);
ptr = next;
}
}
}
if (trace())
{
traceMsg(comp(), "After Gathering\nPrimary Chain:\n");
printInfo(comp()->fe(), comp()->getOutFile(), chain);
traceMsg(comp(), "Bound Chain:\n");
printInfo(comp()->fe(), comp()->getOutFile(), bound);
}
return bound;
}
TR::SwitchAnalyzer::SwitchInfo *TR::SwitchAnalyzer::getConsecutiveUniques(SwitchInfo *info)
{
SwitchInfo *cur = info;
SwitchInfo *next = cur->getNext();
while (next &&
next->_kind == Unique &&
next->_min == cur->_max+1)
{
cur = next;
next = next->getNext();
}
return cur;
}
bool TR::SwitchAnalyzer::SwitchInfo::operator >(SwitchInfo &other)
{
return (_min > other._max);
}
// Inserts into a sorted linked list
//
void TR::SwitchAnalyzer::chainInsert(TR_LinkHead<SwitchInfo> *chain, SwitchInfo *info)
{
TR_ASSERT(info->_kind != Dense, "Not expecting a dense node");
SwitchInfo *cur, *prev;
for (prev = 0, cur = chain->getFirst();
cur != NULL;
prev = cur, cur = cur->getNext())
if (*cur > *info)
break;
if (cur &&
cur->_target == info->_target &&
cur->_min == info->_max+1)
{
if (cur->_kind != Range)
{
cur->_kind = Range;
cur->_cost = _costRange;
}
cur->_min = info->_min;
cur->_freq += info->_freq;
cur->_count+= info->_count;
}
else
{
info->setNext(cur);
if (!prev)
chain->setFirst(info);
else
prev->setNext(info);
}
}
void TR::SwitchAnalyzer::denseInsert(SwitchInfo *dense, SwitchInfo *info)
{
TR_ASSERT(dense->_kind == Dense, "assertion failure");
if (info->_kind == Dense)
{
denseMerge(dense, info);
return;
}
if (info->_kind == Range)
{
// Split the range into unique nodes, and insert the nodes
for (CASECONST_TYPE i = info->_min; i <= info->_max; ++i)
denseInsert(dense, new (trStackMemory()) SwitchInfo(i, info->_target, _costUnique));
return;
}
// Info is a Unique Node
//
chainInsert(dense->_chain, info);
if (info->_min < dense->_min)
dense->_min = info->_min;
if (info->_max > dense->_max)
dense->_max = info->_max;
dense->_freq += info->_freq;
dense->_count+= info->_count;
dense->_cost = _costDense + _costMem * dense->_count;
}
void TR::SwitchAnalyzer::denseMerge(SwitchInfo *to, SwitchInfo *from)
{
SwitchInfo *cur = from->_chain->getFirst();
TR_ASSERT(cur, "a dense node must have >= 2 elements in the chain");
while (cur)
{
SwitchInfo *next = cur->getNext();
denseInsert(to, cur);
cur = next;
}
}
void TR::SwitchAnalyzer::printInfo(TR_FrontEnd *fe, TR::FILE *pOutFile, TR_LinkHead<SwitchInfo> *chain)
{
if (!pOutFile) return;
trfprintf(pOutFile, "------------------------------------------------ for lookup node [%p] in block_%d\n", _switch, _block->getNumber());
for (SwitchInfo *info = chain->getFirst(); info; info = info->getNext())
{
info->print(fe, pOutFile, 0);
}
trfprintf(pOutFile, "================================================\n");
trfflush(pOutFile);
}
void TR::SwitchAnalyzer::SwitchInfo::print(TR_FrontEnd *fe, TR::FILE *pOutFile, int32_t indent)
{
if (!pOutFile) return;
trfprintf(pOutFile, "%*s %0.8g %4d %8d [%4d -%4d] ",
indent, " ", _freq, _count, _cost, _min, _max);
switch (_kind)
{
case Unique:
trfprintf(pOutFile, " -> %3d Unique\n", _target->getNode()->getBlock()->getNumber());
break;
case Range:
trfprintf(pOutFile, " -> %3d Range\n", _target->getNode()->getBlock()->getNumber());
break;
case Dense:
trfprintf(pOutFile, " [====] Dense\n");
for (SwitchInfo *info = _chain->getFirst(); info; info = info->getNext())
info->print(fe, pOutFile, indent+40);
break;
}
}
int32_t TR::SwitchAnalyzer::countMajorsInChain(TR_LinkHead<SwitchInfo> *chain)
{
if (!chain) return 0;
int32_t numNonUnique = 0;
int32_t numUnique = 0;
for (SwitchInfo *info = chain->getFirst(); info; info = info->getNext())
{
if (info->_kind != Unique)
numNonUnique++;
else
numUnique++;
}
return 2 * numNonUnique + numUnique;
}
TR::SwitchAnalyzer::SwitchInfo *TR::SwitchAnalyzer::getLastInChain(TR_LinkHead<SwitchInfo> *chain)
{
if (!chain) return 0;
SwitchInfo *info = chain->getFirst();
if (!info) return 0;
while (info->getNext())
info = info->getNext();
return info;
}
TR::Block *TR::SwitchAnalyzer::peelOffTheHottestValue(TR_LinkHead<SwitchInfo> *chain)
{
if (!_haveProfilingInfo)
return NULL;
if (!chain)
return NULL;
printInfo(comp()->fe(), comp()->getOutFile(), chain);
float cutOffFrequency = 0.33f;
if (trace())
{
traceMsg(comp(), "\nLooking to see if we have a value that's more than 33%% of all cases.\n");
}
TR_LinkHead<SwitchInfo> *list = chain;
SwitchInfo *first = chain->getFirst();
if (first->_kind == Dense)
list = first->_chain;
SwitchInfo *cursor = NULL;
float maxFreq = 0.0f;
SwitchInfo *topNode = NULL;
for (cursor = list->getFirst(); cursor; cursor= cursor->getNext())
{
if (cursor->_freq >= maxFreq)
{
maxFreq = cursor->_freq;
topNode = cursor;
}
}
if (topNode && (topNode->_kind == Unique) && (maxFreq>cutOffFrequency))
{
bool _isInt64 = false;
if (_switch->getChild(0)->getType().isInt64())
_isInt64 = true;
TR::ILOpCodes cmpOp = TR::BadILOp;
TR::Block *newBlock = NULL;
cmpOp = _isInt64 ? TR::iflcmpeq : TR::ificmpeq;
newBlock = addIfBlock(cmpOp, topNode->_min, topNode->_target);
if (trace())
{
traceMsg(comp(), "Found a dominant entry in a dense node for target 0x%p with frequency of %f.\n", topNode->_target->getNode(), maxFreq);
traceMsg(comp(), "Peeling off a quick test for this entry.\n");
}
return newBlock;
}
return NULL;
}
TR::Block *TR::SwitchAnalyzer::checkIfDefaultIsDominant(SwitchInfo *start)
{
if (!_haveProfilingInfo)
return NULL;
if (!start)
return NULL;
bool hasChildWithDecentFrequency = false;
int32_t numCases = _switch->getNumChildren() - 2;
float cutOffFrequency = .5f / ((float)numCases);
if (trace())
{
traceMsg(comp(), "Looking to see if the default case is dominant. Number of cases is %d, cut off frequency set to %f\n", numCases, cutOffFrequency);
}
for (SwitchInfo *temp = start;temp; temp = temp->getNext())
{
if (temp->_freq >= cutOffFrequency)
{
hasChildWithDecentFrequency = true;
if (trace())
{
traceMsg(comp(), "Found child with frequency of %f. The default case isn't that dominant.\n", temp->_freq);
}
break;
}
}
if (!hasChildWithDecentFrequency)
{
int64_t absMin = start->_min;
int64_t absMax = start->_max;
if (trace())
{
traceMsg(comp(), "The default case is dominant, we'll generate the range tests.\n");
}
for (SwitchInfo *temp = start->getNext();temp; temp = temp->getNext())
{
if (absMin > temp->_min)
absMin = temp->_min;
if (absMax < temp->_max)
absMax = temp->_max;
}
if (trace())
{
traceMsg(comp(), "Range [%d, %d]\n", absMin, absMax);
}
bool _isInt64 = false;
if (_switch->getChild(0)->getType().isInt64()) _isInt64 = true;
TR::ILOpCodes cmpOp = TR::BadILOp;
TR::Block *newBlock = NULL;
cmpOp = _isInt64 ? (_signed ? TR::iflcmplt : TR::iflucmplt) : (_signed ? TR::ificmplt : TR::ifiucmplt);
addIfBlock(cmpOp, absMin, _defaultDest);
cmpOp = _isInt64 ? (_signed ? TR::iflcmpgt : TR::iflucmpgt) : (_signed ? TR::ificmpgt : TR::ifiucmpgt);
newBlock = addIfBlock(cmpOp, absMax, _defaultDest);
return newBlock;
}
return NULL;
}
// If unsigned, break consecutive range that straddles 0, TR::getMaxUnsigned<TR::Int32>(), and sort by unsigned order.
// todo: join range/dense that straddle TR::getMaxSigned<TR::Int32>(),TR::getMaxSigned<TR::Int32>()+1
// Assumes that it's in signed sorted order
/*
* [-110,-100] [0,10]
* [-10,10] ==> [100,110]
* [100,110] [-110,-100]
* [-10,-1]
*/
void TR::SwitchAnalyzer::fixUpUnsigned(TR_LinkHead<SwitchInfo> *chain)
{
SwitchInfo *csr = chain->getFirst();
if (!csr)
return;
if (csr->_min >= 0)
return; // nothing to do
SwitchInfo *lastNeg = NULL;
SwitchInfo *firstPos = NULL;
for(;; csr = csr->getNext())
{
if (csr->_max >= 0 && csr->_min < 0)
{
// break up zero straddler
SwitchInfo *next = csr->getNext();
firstPos = new (trStackMemory()) SwitchInfo(*csr);
firstPos->_max = csr->_max;
SwitchInfo *firstPosFirstChainInfo = NULL, *prev = NULL;
for (auto info = firstPos->_chain->getFirst(); info; info = info->getNext())
{
if (info->_min >= 0 || info->_max >= 0)
{
firstPosFirstChainInfo = info;
if (prev)
prev->setNext(NULL);
break;
}
prev = info;
}
TR_ASSERT(firstPosFirstChainInfo != NULL, "Could not find the neg to pos SwitchInfo\n");
firstPos->_chain = new (trStackMemory()) TR_LinkHead<SwitchInfo>();
firstPos->_chain->setFirst(firstPosFirstChainInfo);
firstPos->_min = firstPosFirstChainInfo->_min;
lastNeg = csr;
lastNeg->_max = prev ? prev->_max : -1;
lastNeg->setNext(NULL);
csr = firstPos; // continue searching positive chain until tail
}
else if(firstPos == NULL && csr->_min >= 0)
{
firstPos = csr;
lastNeg->setNext(NULL);
}
else if(csr->_max < 0)
lastNeg = csr;
if (!csr->getNext()) // stop if last node
break;
}
// set firstPos as first in the chain and replace NULL after csr with firstNeg.
// [pos range ... ->csr->NULL] -> [neg range]
if (lastNeg && firstPos)
{
SwitchInfo *firstNeg = chain->getFirst();
chain->setFirst(firstPos);
csr->setNext(firstNeg);
}
}
void TR::SwitchAnalyzer::emit(TR_LinkHead<SwitchInfo> *chain, TR_LinkHead<SwitchInfo> *bound, TR_LinkHead<SwitchInfo> *earlyUniques)
{
int32_t majorsInChain = countMajorsInChain(chain);
int32_t majorsInBound = countMajorsInChain(bound);
int32_t majorsInEarly = countMajorsInChain(earlyUniques);
int32_t numCases = _switch->getCaseIndexUpperBound() - 2;
int32_t numMajors = majorsInChain + majorsInBound + majorsInEarly;
if (_switch->getOpCodeValue() == TR::lookup && (!comp()->isOptServer() || numCases>LOOKUP_SWITCH_GEN_IN_IL_OVERRIDE))
{
if (trace())
traceMsg(comp(),"numMajors %d, majorsInBound %d, numCases %d\n", numMajors, majorsInBound, numCases);
// if the number of cases is so small that it's always better to convert the switch to ifs, skip checks for backing out
if (numCases > SWITCH_TO_IFS_THRESHOLD)
{
// Do the tranformation only if we know that the search space is decreasing in size
if (4 * numMajors > 3 * numCases) // if nummajors must be no more than 3/4th of numcases
return;
if (numCases < MIN_CASES_FOR_OPT) // if numcases is small
return;
// Do the transformation only if we know that the primary chain contains most
// of the cases (majorsInBound == numCasesInBound, since bound does not have range
// or dense nodes)
if (majorsInBound * 3 > numCases) // bound-cases must be no more than a third of the toal cases
return;
}
}
if (!performTransformation(comp(), "%soptimized switch in block_%d\n", OPT_DETAILS, _block->getNumber()))
return;
// Check if CannotOverflow flag on switch should be propagated
// This flag indicates that the possible values of the switch operand are withing the min max range of all the case statements
bool keepOverflow=true;
if(majorsInBound != 0 || majorsInEarly != 0 || !_switch->chkCannotOverflow())
keepOverflow=false;
SwitchInfo *info=chain->getFirst();
if(info == NULL || info->getNext() != NULL || info->_kind != Dense)
keepOverflow = false;
if(!keepOverflow || !performTransformation(comp(), "%sUnneeded range check on switch propagated\n", OPT_DETAILS))
_switch->setCannotOverflow(false); // Cancel the unneeded range check
// check if some element needs to be extracted because it is high frequency
// we can pull them out and test them first before searching the rest of the chain
//
// log(numMajors in range) * (probability of range) > 2 for ranges to be extracted
// log(numMajors in dense) * (probability of dense) > 2 for denses to be extracted
// uniques cannot be extracted since they don't exist in the primary chain
//
// extracting multiple elements will almost never be practical unless they have very
// high probablity (first = 60%, second = 30%, etc.)
//
// FIXME: implement the above
//
// We now have a list of elements, earlyUniques, that we want to check early. When the above is
// implemented, we can simply add the items to this list; code below issues
// them before anything else.
//FIXME: the following code doesn't seem to be too graceful for unsigned values
CASECONST_TYPE rangeLeft, rangeRight;
switch (_switch->getChild(0)->getDataType())
{
case TR::Int16:
rangeLeft = _signed ? TR::getMinSigned<TR::Int16>() : TR::getMinUnsigned<TR::Int16>();
rangeRight = _signed ? TR::getMaxSigned<TR::Int16>() : TR::getMaxUnsigned<TR::Int16>();
default:
rangeLeft = TR::getMinSigned<TR::Int32>();
rangeRight = TR::getMaxSigned<TR::Int32>();
break;
}
_temp = comp()->getSymRefTab()->
createTemporary(comp()->getMethodSymbol(), _isInt64 ? TR::Int64 : TR::Int32);
TR::Block *newBlock = 0;
if (majorsInBound > 0)
{
if (majorsInBound <= MIN_SIZE_FOR_BIN_SEARCH)
{
newBlock = linearSearch(bound->getFirst());
if (comp()->isOptServer() &&
_switch->getOpCodeValue() != TR::lookup)
{
TR::Block *peeledOffBlock = peelOffTheHottestValue(bound);
if (peeledOffBlock)
newBlock = peeledOffBlock;
}
}
else
{
newBlock = binSearch(bound->getFirst(), getLastInChain(bound), majorsInBound,
rangeLeft, rangeRight);
if (comp()->isOptServer())
{
TR::Block *defaultNewBlock = checkIfDefaultIsDominant(bound->getFirst());
if (defaultNewBlock)
newBlock = defaultNewBlock;
}
}
TR_ASSERT(newBlock == _nextBlock, "assertion failure");
_defaultDest = newBlock->getEntry();
}
if (majorsInChain > 0)
{
if (majorsInChain <= MIN_SIZE_FOR_BIN_SEARCH)
{
newBlock = linearSearch(chain->getFirst());
if (comp()->isOptServer() &&
_switch->getOpCodeValue() != TR::lookup)
{
TR::Block *peeledOffBlock = peelOffTheHottestValue(chain);
if (peeledOffBlock)
newBlock = peeledOffBlock;
}
}
else
{
newBlock = binSearch(chain->getFirst(), getLastInChain(chain), majorsInChain,
rangeLeft, rangeRight);
if (comp()->isOptServer())
{
TR::Block *defaultNewBlock = checkIfDefaultIsDominant(chain->getFirst());
if (defaultNewBlock)
newBlock = defaultNewBlock;
}
}
_defaultDest = newBlock->getEntry();
}
if (majorsInEarly > 0)
{
if (majorsInEarly <= MIN_SIZE_FOR_BIN_SEARCH)
newBlock = linearSearch(earlyUniques->getFirst());
else
newBlock = binSearch(earlyUniques->getFirst(), getLastInChain(earlyUniques), majorsInEarly,
rangeLeft, rangeRight);
}
TR_ASSERT(newBlock, "At least one of primary, early unique, and bound chains must not be empty");
_cfg->addEdge(_block, newBlock);
TR::Node *store = TR::Node::createStore(_temp, _switch->getChild(0));
_block->append(TR::TreeTop::create(comp(), store));
TR::TransformUtil::removeTree(comp(), _switchTree);
for (auto edge = _block->getSuccessors().begin(); edge != _block->getSuccessors().end();)
{
if ((*edge)->getTo() != newBlock)
_cfg->removeEdge(*(edge++));
else
edge++;
}
}
TR::Block *TR::SwitchAnalyzer::binSearch(SwitchInfo *startNode, SwitchInfo *endNode, int32_t numMajors, CASECONST_TYPE rangeLeft, CASECONST_TYPE rangeRight)
{
TR_ASSERT(numMajors > 0, "majors must be > 0");
TR::ILOpCodes cmpOp = TR::BadILOp;
// Unique Left
//
if (numMajors == 1)
{
TR_ASSERT(startNode == endNode && startNode->_kind == Unique, "illegal leaf node");
if (rangeLeft == rangeRight)
return addGotoBlock(endNode->_target);
else
{
addGotoBlock(_defaultDest);
cmpOp = _isInt64 ? TR::iflcmpeq : TR::ificmpeq;
return addIfBlock (cmpOp, endNode->_max, endNode->_target);
}
}
// Range or Dense Leafs
//
if (numMajors == 2 && startNode == endNode)
{
TR_ASSERT(startNode->_kind != Unique, "cannot have two majors in a unique leaf");
if (endNode->_kind == Range)
{
if (rangeRight == endNode->_max && rangeLeft == endNode->_min)
{
// Both bound tests can be omitted
//
return addGotoBlock(endNode->_target);
}
else if (rangeRight == endNode->_max)
{
// Upper bound test can be omitted
//
addGotoBlock(_defaultDest);
cmpOp = _isInt64 ? (_signed ? TR::iflcmpge : TR::iflucmpge) : (_signed ? TR::ificmpge : TR::ifiucmpge);
return addIfBlock (cmpOp, endNode->_min, endNode->_target);
}
else if (rangeLeft == endNode->_min)
{
// Lower bound test can be omitted
//
addGotoBlock(_defaultDest);
cmpOp = _isInt64 ? (_signed ? TR::iflcmple : TR::iflucmple) : (_signed ? TR::ificmple : TR::ifiucmple);
return addIfBlock (cmpOp, endNode->_max, endNode->_target);
}
// Both bound tests must be done
//
addGotoBlock(_defaultDest);
addIfBlock (_signed ? TR::ificmpge : TR::ifiucmpge, endNode->_min, endNode->_target);
cmpOp = _isInt64 ? (_signed ? TR::iflcmpgt : TR::iflucmpgt) : (_signed ? TR::ificmpgt : TR::ifiucmpgt);
return addIfBlock (cmpOp, endNode->_max, _defaultDest);
}