blob: 235521d0621354787089ae4a440f356947cc007e [file] [log] [blame]
/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "Dalvik.h"
#include "Dataflow.h"
/* Enter the node to the dfsOrder list then visit its successors */
STATIC void recordDFSPreOrder(CompilationUnit* cUnit, BasicBlock* block)
{
if (block->visited || block->hidden) return;
block->visited = true;
/* Enqueue the block id */
oatInsertGrowableList(&cUnit->dfsOrder, block->id);
if (block->fallThrough) recordDFSPreOrder(cUnit, block->fallThrough);
if (block->taken) recordDFSPreOrder(cUnit, block->taken);
if (block->successorBlockList.blockListType != kNotUsed) {
GrowableListIterator iterator;
oatGrowableListIteratorInit(&block->successorBlockList.blocks,
&iterator);
while (true) {
SuccessorBlockInfo *successorBlockInfo =
(SuccessorBlockInfo *) oatGrowableListIteratorNext(&iterator);
if (successorBlockInfo == NULL) break;
BasicBlock* succBB = successorBlockInfo->block;
recordDFSPreOrder(cUnit, succBB);
}
}
return;
}
/* Sort the blocks by the Depth-First-Search pre-order */
STATIC void computeDFSOrder(CompilationUnit* cUnit)
{
/* Initialize or reset the DFS order list */
if (cUnit->dfsOrder.elemList == NULL) {
oatInitGrowableList(&cUnit->dfsOrder, cUnit->numBlocks);
} else {
/* Just reset the used length on the counter */
cUnit->dfsOrder.numUsed = 0;
}
oatDataFlowAnalysisDispatcher(cUnit, oatClearVisitedFlag,
kAllNodes,
false /* isIterative */);
recordDFSPreOrder(cUnit, cUnit->entryBlock);
cUnit->numReachableBlocks = cUnit->dfsOrder.numUsed;
}
/*
* Mark block bit on the per-Dalvik register vector to denote that Dalvik
* register idx is defined in BasicBlock bb.
*/
STATIC bool fillDefBlockMatrix(CompilationUnit* cUnit, BasicBlock* bb)
{
if (bb->dataFlowInfo == NULL) return false;
ArenaBitVectorIterator iterator;
oatBitVectorIteratorInit(bb->dataFlowInfo->defV, &iterator);
while (true) {
int idx = oatBitVectorIteratorNext(&iterator);
if (idx == -1) break;
/* Block bb defines register idx */
oatSetBit(cUnit->defBlockMatrix[idx], bb->id);
}
return true;
}
STATIC void computeDefBlockMatrix(CompilationUnit* cUnit)
{
int numRegisters = cUnit->numDalvikRegisters;
/* Allocate numDalvikRegisters bit vector pointers */
cUnit->defBlockMatrix = (ArenaBitVector **)
oatNew(sizeof(ArenaBitVector *) * numRegisters, true);
int i;
/* Initialize numRegister vectors with numBlocks bits each */
for (i = 0; i < numRegisters; i++) {
cUnit->defBlockMatrix[i] = oatAllocBitVector(cUnit->numBlocks,
false);
}
oatDataFlowAnalysisDispatcher(cUnit, oatFindLocalLiveIn,
kAllNodes,
false /* isIterative */);
oatDataFlowAnalysisDispatcher(cUnit, fillDefBlockMatrix,
kAllNodes,
false /* isIterative */);
/*
* Also set the incoming parameters as defs in the entry block.
* Only need to handle the parameters for the outer method.
*/
int numRegs = cUnit->numDalvikRegisters;
int inReg = numRegs - cUnit->numIns;
for (; inReg < numRegs; inReg++) {
oatSetBit(cUnit->defBlockMatrix[inReg], cUnit->entryBlock->id);
}
}
/* Compute the post-order traversal of the CFG */
STATIC void computeDomPostOrderTraversal(CompilationUnit* cUnit, BasicBlock* bb)
{
ArenaBitVectorIterator bvIterator;
oatBitVectorIteratorInit(bb->iDominated, &bvIterator);
GrowableList* blockList = &cUnit->blockList;
/* Iterate through the dominated blocks first */
while (true) {
int bbIdx = oatBitVectorIteratorNext(&bvIterator);
if (bbIdx == -1) break;
BasicBlock* dominatedBB =
(BasicBlock* ) oatGrowableListGetElement(blockList, bbIdx);
computeDomPostOrderTraversal(cUnit, dominatedBB);
}
/* Enter the current block id */
oatInsertGrowableList(&cUnit->domPostOrderTraversal, bb->id);
/* hacky loop detection */
if (bb->taken && oatIsBitSet(bb->dominators, bb->taken->id)) {
cUnit->hasLoop = true;
}
}
STATIC void checkForDominanceFrontier(BasicBlock* domBB,
const BasicBlock* succBB)
{
/*
* TODO - evaluate whether phi will ever need to be inserted into exit
* blocks.
*/
if (succBB->iDom != domBB &&
succBB->blockType == kDalvikByteCode &&
succBB->hidden == false) {
oatSetBit(domBB->domFrontier, succBB->id);
}
}
/* Worker function to compute the dominance frontier */
STATIC bool computeDominanceFrontier(CompilationUnit* cUnit, BasicBlock* bb)
{
GrowableList* blockList = &cUnit->blockList;
/* Calculate DF_local */
if (bb->taken) {
checkForDominanceFrontier(bb, bb->taken);
}
if (bb->fallThrough) {
checkForDominanceFrontier(bb, bb->fallThrough);
}
if (bb->successorBlockList.blockListType != kNotUsed) {
GrowableListIterator iterator;
oatGrowableListIteratorInit(&bb->successorBlockList.blocks,
&iterator);
while (true) {
SuccessorBlockInfo *successorBlockInfo =
(SuccessorBlockInfo *) oatGrowableListIteratorNext(&iterator);
if (successorBlockInfo == NULL) break;
BasicBlock* succBB = successorBlockInfo->block;
checkForDominanceFrontier(bb, succBB);
}
}
/* Calculate DF_up */
ArenaBitVectorIterator bvIterator;
oatBitVectorIteratorInit(bb->iDominated, &bvIterator);
while (true) {
int dominatedIdx = oatBitVectorIteratorNext(&bvIterator);
if (dominatedIdx == -1) break;
BasicBlock* dominatedBB = (BasicBlock* )
oatGrowableListGetElement(blockList, dominatedIdx);
ArenaBitVectorIterator dfIterator;
oatBitVectorIteratorInit(dominatedBB->domFrontier, &dfIterator);
while (true) {
int dfUpIdx = oatBitVectorIteratorNext(&dfIterator);
if (dfUpIdx == -1) break;
BasicBlock* dfUpBlock = (BasicBlock* )
oatGrowableListGetElement(blockList, dfUpIdx);
checkForDominanceFrontier(bb, dfUpBlock);
}
}
return true;
}
/* Worker function for initializing domination-related data structures */
STATIC bool initializeDominationInfo(CompilationUnit* cUnit, BasicBlock* bb)
{
int numTotalBlocks = cUnit->blockList.numUsed;
if (bb->dominators == NULL ) {
bb->dominators = oatAllocBitVector(numTotalBlocks,
false /* expandable */);
bb->iDominated = oatAllocBitVector(numTotalBlocks,
false /* expandable */);
bb->domFrontier = oatAllocBitVector(numTotalBlocks,
false /* expandable */);
} else {
oatClearAllBits(bb->dominators);
oatClearAllBits(bb->iDominated);
oatClearAllBits(bb->domFrontier);
}
/* Set all bits in the dominator vector */
oatSetInitialBits(bb->dominators, numTotalBlocks);
return true;
}
/* Worker function to compute each block's dominators */
STATIC bool computeBlockDominators(CompilationUnit* cUnit, BasicBlock* bb)
{
GrowableList* blockList = &cUnit->blockList;
int numTotalBlocks = blockList->numUsed;
ArenaBitVector* tempBlockV = cUnit->tempBlockV;
ArenaBitVectorIterator bvIterator;
/*
* The dominator of the entry block has been preset to itself and we need
* to skip the calculation here.
*/
if (bb == cUnit->entryBlock) return false;
oatSetInitialBits(tempBlockV, numTotalBlocks);
/* Iterate through the predecessors */
oatBitVectorIteratorInit(bb->predecessors, &bvIterator);
while (true) {
int predIdx = oatBitVectorIteratorNext(&bvIterator);
if (predIdx == -1) break;
BasicBlock* predBB = (BasicBlock* ) oatGrowableListGetElement(
blockList, predIdx);
/* tempBlockV = tempBlockV ^ dominators */
if (predBB->dominators != NULL) {
oatIntersectBitVectors(tempBlockV, tempBlockV, predBB->dominators);
}
}
oatSetBit(tempBlockV, bb->id);
if (oatCompareBitVectors(tempBlockV, bb->dominators)) {
oatCopyBitVector(bb->dominators, tempBlockV);
return true;
}
return false;
}
/* Worker function to compute the idom */
STATIC bool computeImmediateDominator(CompilationUnit* cUnit, BasicBlock* bb)
{
GrowableList* blockList = &cUnit->blockList;
ArenaBitVector* tempBlockV = cUnit->tempBlockV;
ArenaBitVectorIterator bvIterator;
BasicBlock* iDom;
if (bb == cUnit->entryBlock) return false;
oatCopyBitVector(tempBlockV, bb->dominators);
oatClearBit(tempBlockV, bb->id);
oatBitVectorIteratorInit(tempBlockV, &bvIterator);
/* Should not see any dead block */
DCHECK_NE(oatCountSetBits(tempBlockV), 0);
if (oatCountSetBits(tempBlockV) == 1) {
iDom = (BasicBlock* ) oatGrowableListGetElement(
blockList, oatBitVectorIteratorNext(&bvIterator));
bb->iDom = iDom;
} else {
int iDomIdx = oatBitVectorIteratorNext(&bvIterator);
DCHECK_NE(iDomIdx, -1);
while (true) {
int nextDom = oatBitVectorIteratorNext(&bvIterator);
if (nextDom == -1) break;
BasicBlock* nextDomBB = (BasicBlock* )
oatGrowableListGetElement(blockList, nextDom);
/* iDom dominates nextDom - set new iDom */
if (oatIsBitSet(nextDomBB->dominators, iDomIdx)) {
iDomIdx = nextDom;
}
}
iDom = (BasicBlock* ) oatGrowableListGetElement(blockList, iDomIdx);
/* Set the immediate dominator block for bb */
bb->iDom = iDom;
}
/* Add bb to the iDominated set of the immediate dominator block */
oatSetBit(iDom->iDominated, bb->id);
return true;
}
/* Compute dominators, immediate dominator, and dominance fronter */
STATIC void computeDominators(CompilationUnit* cUnit)
{
int numReachableBlocks = cUnit->numReachableBlocks;
int numTotalBlocks = cUnit->blockList.numUsed;
/* Initialize domination-related data structures */
oatDataFlowAnalysisDispatcher(cUnit, initializeDominationInfo,
kReachableNodes,
false /* isIterative */);
/* Set the dominator for the root node */
oatClearAllBits(cUnit->entryBlock->dominators);
oatSetBit(cUnit->entryBlock->dominators, cUnit->entryBlock->id);
if (cUnit->tempBlockV == NULL) {
cUnit->tempBlockV = oatAllocBitVector(numTotalBlocks,
false /* expandable */);
} else {
oatClearAllBits(cUnit->tempBlockV);
}
oatDataFlowAnalysisDispatcher(cUnit, computeBlockDominators,
kPreOrderDFSTraversal,
true /* isIterative */);
cUnit->entryBlock->iDom = NULL;
oatDataFlowAnalysisDispatcher(cUnit, computeImmediateDominator,
kReachableNodes,
false /* isIterative */);
/*
* Now go ahead and compute the post order traversal based on the
* iDominated sets.
*/
if (cUnit->domPostOrderTraversal.elemList == NULL) {
oatInitGrowableList(&cUnit->domPostOrderTraversal, numReachableBlocks);
} else {
cUnit->domPostOrderTraversal.numUsed = 0;
}
computeDomPostOrderTraversal(cUnit, cUnit->entryBlock);
DCHECK_EQ(cUnit->domPostOrderTraversal.numUsed,
(unsigned) cUnit->numReachableBlocks);
/* Now compute the dominance frontier for each block */
oatDataFlowAnalysisDispatcher(cUnit, computeDominanceFrontier,
kPostOrderDOMTraversal,
false /* isIterative */);
}
/*
* Perform dest U= src1 ^ ~src2
* This is probably not general enough to be placed in BitVector.[ch].
*/
STATIC void computeSuccLiveIn(ArenaBitVector* dest,
const ArenaBitVector* src1,
const ArenaBitVector* src2)
{
if (dest->storageSize != src1->storageSize ||
dest->storageSize != src2->storageSize ||
dest->expandable != src1->expandable ||
dest->expandable != src2->expandable) {
LOG(FATAL) << "Incompatible set properties";
}
unsigned int idx;
for (idx = 0; idx < dest->storageSize; idx++) {
dest->storage[idx] |= src1->storage[idx] & ~src2->storage[idx];
}
}
/*
* Iterate through all successor blocks and propagate up the live-in sets.
* The calculated result is used for phi-node pruning - where we only need to
* insert a phi node if the variable is live-in to the block.
*/
STATIC bool computeBlockLiveIns(CompilationUnit* cUnit, BasicBlock* bb)
{
ArenaBitVector* tempDalvikRegisterV = cUnit->tempDalvikRegisterV;
if (bb->dataFlowInfo == NULL) return false;
oatCopyBitVector(tempDalvikRegisterV, bb->dataFlowInfo->liveInV);
if (bb->taken && bb->taken->dataFlowInfo)
computeSuccLiveIn(tempDalvikRegisterV, bb->taken->dataFlowInfo->liveInV,
bb->dataFlowInfo->defV);
if (bb->fallThrough && bb->fallThrough->dataFlowInfo)
computeSuccLiveIn(tempDalvikRegisterV,
bb->fallThrough->dataFlowInfo->liveInV,
bb->dataFlowInfo->defV);
if (bb->successorBlockList.blockListType != kNotUsed) {
GrowableListIterator iterator;
oatGrowableListIteratorInit(&bb->successorBlockList.blocks,
&iterator);
while (true) {
SuccessorBlockInfo *successorBlockInfo =
(SuccessorBlockInfo *) oatGrowableListIteratorNext(&iterator);
if (successorBlockInfo == NULL) break;
BasicBlock* succBB = successorBlockInfo->block;
if (succBB->dataFlowInfo) {
computeSuccLiveIn(tempDalvikRegisterV,
succBB->dataFlowInfo->liveInV,
bb->dataFlowInfo->defV);
}
}
}
if (oatCompareBitVectors(tempDalvikRegisterV, bb->dataFlowInfo->liveInV)) {
oatCopyBitVector(bb->dataFlowInfo->liveInV, tempDalvikRegisterV);
return true;
}
return false;
}
/* Insert phi nodes to for each variable to the dominance frontiers */
STATIC void insertPhiNodes(CompilationUnit* cUnit)
{
int dalvikReg;
const GrowableList* blockList = &cUnit->blockList;
ArenaBitVector* phiBlocks =
oatAllocBitVector(cUnit->numBlocks, false);
ArenaBitVector* tmpBlocks =
oatAllocBitVector(cUnit->numBlocks, false);
ArenaBitVector* inputBlocks =
oatAllocBitVector(cUnit->numBlocks, false);
cUnit->tempDalvikRegisterV =
oatAllocBitVector(cUnit->numDalvikRegisters, false);
oatDataFlowAnalysisDispatcher(cUnit, computeBlockLiveIns,
kPostOrderDFSTraversal,
true /* isIterative */);
/* Iterate through each Dalvik register */
for (dalvikReg = 0; dalvikReg < cUnit->numDalvikRegisters; dalvikReg++) {
bool change;
ArenaBitVectorIterator iterator;
oatCopyBitVector(inputBlocks, cUnit->defBlockMatrix[dalvikReg]);
oatClearAllBits(phiBlocks);
/* Calculate the phi blocks for each Dalvik register */
do {
change = false;
oatClearAllBits(tmpBlocks);
oatBitVectorIteratorInit(inputBlocks, &iterator);
while (true) {
int idx = oatBitVectorIteratorNext(&iterator);
if (idx == -1) break;
BasicBlock* defBB =
(BasicBlock* ) oatGrowableListGetElement(blockList, idx);
/* Merge the dominance frontier to tmpBlocks */
if (defBB->domFrontier != NULL) {
oatUnifyBitVectors(tmpBlocks, tmpBlocks, defBB->domFrontier);
}
}
if (oatCompareBitVectors(phiBlocks, tmpBlocks)) {
change = true;
oatCopyBitVector(phiBlocks, tmpBlocks);
/*
* Iterate through the original blocks plus the new ones in
* the dominance frontier.
*/
oatCopyBitVector(inputBlocks, phiBlocks);
oatUnifyBitVectors(inputBlocks, inputBlocks,
cUnit->defBlockMatrix[dalvikReg]);
}
} while (change);
/*
* Insert a phi node for dalvikReg in the phiBlocks if the Dalvik
* register is in the live-in set.
*/
oatBitVectorIteratorInit(phiBlocks, &iterator);
while (true) {
int idx = oatBitVectorIteratorNext(&iterator);
if (idx == -1) break;
BasicBlock* phiBB =
(BasicBlock* ) oatGrowableListGetElement(blockList, idx);
/* Variable will be clobbered before being used - no need for phi */
if (!oatIsBitSet(phiBB->dataFlowInfo->liveInV, dalvikReg)) continue;
MIR *phi = (MIR *) oatNew(sizeof(MIR), true);
phi->dalvikInsn.opcode = (Opcode)kMirOpPhi;
phi->dalvikInsn.vA = dalvikReg;
phi->offset = phiBB->startOffset;
phi->meta.phiNext = cUnit->phiList;
cUnit->phiList = phi;
oatPrependMIR(phiBB, phi);
}
}
}
/*
* Worker function to insert phi-operands with latest SSA names from
* predecessor blocks
*/
STATIC bool insertPhiNodeOperands(CompilationUnit* cUnit, BasicBlock* bb)
{
ArenaBitVector* ssaRegV = cUnit->tempSSARegisterV;
ArenaBitVectorIterator bvIterator;
GrowableList* blockList = &cUnit->blockList;
MIR *mir;
/* Phi nodes are at the beginning of each block */
for (mir = bb->firstMIRInsn; mir; mir = mir->next) {
if (mir->dalvikInsn.opcode != (Opcode)kMirOpPhi)
return true;
int ssaReg = mir->ssaRep->defs[0];
int encodedDalvikValue =
(int) oatGrowableListGetElement(cUnit->ssaToDalvikMap, ssaReg);
int dalvikReg = DECODE_REG(encodedDalvikValue);
oatClearAllBits(ssaRegV);
/* Iterate through the predecessors */
oatBitVectorIteratorInit(bb->predecessors, &bvIterator);
while (true) {
int predIdx = oatBitVectorIteratorNext(&bvIterator);
if (predIdx == -1) break;
BasicBlock* predBB = (BasicBlock* ) oatGrowableListGetElement(
blockList, predIdx);
int encodedSSAValue =
predBB->dataFlowInfo->dalvikToSSAMap[dalvikReg];
int ssaReg = DECODE_REG(encodedSSAValue);
oatSetBit(ssaRegV, ssaReg);
}
/* Count the number of SSA registers for a Dalvik register */
int numUses = oatCountSetBits(ssaRegV);
mir->ssaRep->numUses = numUses;
mir->ssaRep->uses =
(int *) oatNew(sizeof(int) * numUses, false);
mir->ssaRep->fpUse =
(bool *) oatNew(sizeof(bool) * numUses, true);
ArenaBitVectorIterator phiIterator;
oatBitVectorIteratorInit(ssaRegV, &phiIterator);
int *usePtr = mir->ssaRep->uses;
/* Set the uses array for the phi node */
while (true) {
int ssaRegIdx = oatBitVectorIteratorNext(&phiIterator);
if (ssaRegIdx == -1) break;
*usePtr++ = ssaRegIdx;
}
}
return true;
}
STATIC void doDFSPreOrderSSARename(CompilationUnit* cUnit, BasicBlock* block)
{
if (block->visited || block->hidden) return;
block->visited = true;
/* Process this block */
oatDoSSAConversion(cUnit, block);
int mapSize = sizeof(int) * cUnit->numDalvikRegisters;
/* Save SSA map snapshot */
int* savedSSAMap = (int*)oatNew(mapSize, false);
memcpy(savedSSAMap, cUnit->dalvikToSSAMap, mapSize);
if (block->fallThrough) {
doDFSPreOrderSSARename(cUnit, block->fallThrough);
/* Restore SSA map snapshot */
memcpy(cUnit->dalvikToSSAMap, savedSSAMap, mapSize);
}
if (block->taken) {
doDFSPreOrderSSARename(cUnit, block->taken);
/* Restore SSA map snapshot */
memcpy(cUnit->dalvikToSSAMap, savedSSAMap, mapSize);
}
if (block->successorBlockList.blockListType != kNotUsed) {
GrowableListIterator iterator;
oatGrowableListIteratorInit(&block->successorBlockList.blocks,
&iterator);
while (true) {
SuccessorBlockInfo *successorBlockInfo =
(SuccessorBlockInfo *) oatGrowableListIteratorNext(&iterator);
if (successorBlockInfo == NULL) break;
BasicBlock* succBB = successorBlockInfo->block;
doDFSPreOrderSSARename(cUnit, succBB);
/* Restore SSA map snapshot */
memcpy(cUnit->dalvikToSSAMap, savedSSAMap, mapSize);
}
}
cUnit->dalvikToSSAMap = savedSSAMap;
return;
}
/* Perform SSA transformation for the whole method */
void oatMethodSSATransformation(CompilationUnit* cUnit)
{
/* Compute the DFS order */
computeDFSOrder(cUnit);
/* Compute the dominator info */
computeDominators(cUnit);
/* Allocate data structures in preparation for SSA conversion */
oatInitializeSSAConversion(cUnit);
/* Find out the "Dalvik reg def x block" relation */
computeDefBlockMatrix(cUnit);
/* Insert phi nodes to dominance frontiers for all variables */
insertPhiNodes(cUnit);
/* Rename register names by local defs and phi nodes */
oatDataFlowAnalysisDispatcher(cUnit, oatClearVisitedFlag,
kAllNodes,
false /* isIterative */);
doDFSPreOrderSSARename(cUnit, cUnit->entryBlock);
/*
* Shared temp bit vector used by each block to count the number of defs
* from all the predecessor blocks.
*/
cUnit->tempSSARegisterV = oatAllocBitVector(cUnit->numSSARegs,
false);
/* Insert phi-operands with latest SSA names from predecessor blocks */
oatDataFlowAnalysisDispatcher(cUnit, insertPhiNodeOperands,
kReachableNodes,
false /* isIterative */);
}