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llvm-6502/lib/Transforms/Scalar/CorrelatedExprs.cpp
Reid Spencer a6e8a955d6 Remove the "isSigned" parameters from ConstantRange. It turns out they 
are not needed as the results are the same with or without it.

Patch by Nicholas Lewycky.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34782 91177308-0d34-0410-b5e6-96231b3b80d8
2007-03-01 07:54:15 +00:00

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//===- CorrelatedExprs.cpp - Pass to detect and eliminated c.e.'s ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Correlated Expression Elimination propagates information from conditional
// branches to blocks dominated by destinations of the branch. It propagates
// information from the condition check itself into the body of the branch,
// allowing transformations like these for example:
//
// if (i == 7)
// ... 4*i; // constant propagation
//
// M = i+1; N = j+1;
// if (i == j)
// X = M-N; // = M-M == 0;
//
// This is called Correlated Expression Elimination because we eliminate or
// simplify expressions that are correlated with the direction of a branch. In
// this way we use static information to give us some information about the
// dynamic value of a variable.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "cee"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Constants.h"
#include "llvm/Pass.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Assembly/Writer.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/Statistic.h"
#include <algorithm>
using namespace llvm;
STATISTIC(NumCmpRemoved, "Number of cmp instruction eliminated");
STATISTIC(NumOperandsCann, "Number of operands canonicalized");
STATISTIC(BranchRevectors, "Number of branches revectored");
namespace {
class ValueInfo;
class VISIBILITY_HIDDEN Relation {
Value *Val; // Relation to what value?
unsigned Rel; // SetCC or ICmp relation, or Add if no information
public:
Relation(Value *V) : Val(V), Rel(Instruction::Add) {}
bool operator<(const Relation &R) const { return Val < R.Val; }
Value *getValue() const { return Val; }
unsigned getRelation() const { return Rel; }
// contradicts - Return true if the relationship specified by the operand
// contradicts already known information.
//
bool contradicts(unsigned Rel, const ValueInfo &VI) const;
// incorporate - Incorporate information in the argument into this relation
// entry. This assumes that the information doesn't contradict itself. If
// any new information is gained, true is returned, otherwise false is
// returned to indicate that nothing was updated.
//
bool incorporate(unsigned Rel, ValueInfo &VI);
// KnownResult - Whether or not this condition determines the result of a
// setcc or icmp in the program. False & True are intentionally 0 & 1
// so we can convert to bool by casting after checking for unknown.
//
enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 };
// getImpliedResult - If this relationship between two values implies that
// the specified relationship is true or false, return that. If we cannot
// determine the result required, return Unknown.
//
KnownResult getImpliedResult(unsigned Rel) const;
// print - Output this relation to the specified stream
void print(std::ostream &OS) const;
void dump() const;
};
// ValueInfo - One instance of this record exists for every value with
// relationships between other values. It keeps track of all of the
// relationships to other values in the program (specified with Relation) that
// are known to be valid in a region.
//
class VISIBILITY_HIDDEN ValueInfo {
// RelationShips - this value is know to have the specified relationships to
// other values. There can only be one entry per value, and this list is
// kept sorted by the Val field.
std::vector<Relation> Relationships;
// If information about this value is known or propagated from constant
// expressions, this range contains the possible values this value may hold.
ConstantRange Bounds;
// If we find that this value is equal to another value that has a lower
// rank, this value is used as it's replacement.
//
Value *Replacement;
public:
ValueInfo(const Type *Ty)
: Bounds(Ty->isInteger() ? cast<IntegerType>(Ty)->getBitWidth() : 32),
Replacement(0) {}
// getBounds() - Return the constant bounds of the value...
const ConstantRange &getBounds() const { return Bounds; }
ConstantRange &getBounds() { return Bounds; }
const std::vector<Relation> &getRelationships() { return Relationships; }
// getReplacement - Return the value this value is to be replaced with if it
// exists, otherwise return null.
//
Value *getReplacement() const { return Replacement; }
// setReplacement - Used by the replacement calculation pass to figure out
// what to replace this value with, if anything.
//
void setReplacement(Value *Repl) { Replacement = Repl; }
// getRelation - return the relationship entry for the specified value.
// This can invalidate references to other Relations, so use it carefully.
//
Relation &getRelation(Value *V) {
// Binary search for V's entry...
std::vector<Relation>::iterator I =
std::lower_bound(Relationships.begin(), Relationships.end(),
Relation(V));
// If we found the entry, return it...
if (I != Relationships.end() && I->getValue() == V)
return *I;
// Insert and return the new relationship...
return *Relationships.insert(I, V);
}
const Relation *requestRelation(Value *V) const {
// Binary search for V's entry...
std::vector<Relation>::const_iterator I =
std::lower_bound(Relationships.begin(), Relationships.end(),
Relation(V));
if (I != Relationships.end() && I->getValue() == V)
return &*I;
return 0;
}
// print - Output information about this value relation...
void print(std::ostream &OS, Value *V) const;
void dump() const;
};
// RegionInfo - Keeps track of all of the value relationships for a region. A
// region is the are dominated by a basic block. RegionInfo's keep track of
// the RegionInfo for their dominator, because anything known in a dominator
// is known to be true in a dominated block as well.
//
class VISIBILITY_HIDDEN RegionInfo {
BasicBlock *BB;
// ValueMap - Tracks the ValueInformation known for this region
typedef std::map<Value*, ValueInfo> ValueMapTy;
ValueMapTy ValueMap;
public:
RegionInfo(BasicBlock *bb) : BB(bb) {}
// getEntryBlock - Return the block that dominates all of the members of
// this region.
BasicBlock *getEntryBlock() const { return BB; }
// empty - return true if this region has no information known about it.
bool empty() const { return ValueMap.empty(); }
const RegionInfo &operator=(const RegionInfo &RI) {
ValueMap = RI.ValueMap;
return *this;
}
// print - Output information about this region...
void print(std::ostream &OS) const;
void dump() const;
// Allow external access.
typedef ValueMapTy::iterator iterator;
iterator begin() { return ValueMap.begin(); }
iterator end() { return ValueMap.end(); }
ValueInfo &getValueInfo(Value *V) {
ValueMapTy::iterator I = ValueMap.lower_bound(V);
if (I != ValueMap.end() && I->first == V) return I->second;
return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
}
const ValueInfo *requestValueInfo(Value *V) const {
ValueMapTy::const_iterator I = ValueMap.find(V);
if (I != ValueMap.end()) return &I->second;
return 0;
}
/// removeValueInfo - Remove anything known about V from our records. This
/// works whether or not we know anything about V.
///
void removeValueInfo(Value *V) {
ValueMap.erase(V);
}
};
/// CEE - Correlated Expression Elimination
class VISIBILITY_HIDDEN CEE : public FunctionPass {
std::map<Value*, unsigned> RankMap;
std::map<BasicBlock*, RegionInfo> RegionInfoMap;
ETForest *EF;
DominatorTree *DT;
public:
virtual bool runOnFunction(Function &F);
// We don't modify the program, so we preserve all analyses
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<ETForest>();
AU.addRequired<DominatorTree>();
AU.addRequiredID(BreakCriticalEdgesID);
};
// print - Implement the standard print form to print out analysis
// information.
virtual void print(std::ostream &O, const Module *M) const;
private:
RegionInfo &getRegionInfo(BasicBlock *BB) {
std::map<BasicBlock*, RegionInfo>::iterator I
= RegionInfoMap.lower_bound(BB);
if (I != RegionInfoMap.end() && I->first == BB) return I->second;
return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
}
void BuildRankMap(Function &F);
unsigned getRank(Value *V) const {
if (isa<Constant>(V)) return 0;
std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
if (I != RankMap.end()) return I->second;
return 0; // Must be some other global thing
}
bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
RegionInfo &RI);
void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
RegionInfo &RI);
void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
BasicBlock *RegionDominator);
void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
std::vector<BasicBlock*> &RegionExitBlocks);
void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
const std::vector<BasicBlock*> &RegionExitBlocks);
void PropagateBranchInfo(BranchInst *BI);
void PropagateSwitchInfo(SwitchInst *SI);
void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
void PropagateRelation(unsigned Opcode, Value *Op0,
Value *Op1, RegionInfo &RI);
void UpdateUsersOfValue(Value *V, RegionInfo &RI);
void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
void ComputeReplacements(RegionInfo &RI);
// getCmpResult - Given a icmp instruction, determine if the result is
// determined by facts we already know about the region under analysis.
// Return KnownTrue, KnownFalse, or UnKnown based on what we can determine.
Relation::KnownResult getCmpResult(CmpInst *ICI, const RegionInfo &RI);
bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
};
RegisterPass<CEE> X("cee", "Correlated Expression Elimination");
}
FunctionPass *llvm::createCorrelatedExpressionEliminationPass() {
return new CEE();
}
bool CEE::runOnFunction(Function &F) {
// Build a rank map for the function...
BuildRankMap(F);
// Traverse the dominator tree, computing information for each node in the
// tree. Note that our traversal will not even touch unreachable basic
// blocks.
EF = &getAnalysis<ETForest>();
DT = &getAnalysis<DominatorTree>();
std::set<BasicBlock*> VisitedBlocks;
bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
RegionInfoMap.clear();
RankMap.clear();
return Changed;
}
// TransformRegion - Transform the region starting with BB according to the
// calculated region information for the block. Transforming the region
// involves analyzing any information this block provides to successors,
// propagating the information to successors, and finally transforming
// successors.
//
// This method processes the function in depth first order, which guarantees
// that we process the immediate dominator of a block before the block itself.
// Because we are passing information from immediate dominators down to
// dominatees, we obviously have to process the information source before the
// information consumer.
//
bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
// Prevent infinite recursion...
if (VisitedBlocks.count(BB)) return false;
VisitedBlocks.insert(BB);
// Get the computed region information for this block...
RegionInfo &RI = getRegionInfo(BB);
// Compute the replacement information for this block...
ComputeReplacements(RI);
// If debugging, print computed region information...
DEBUG(RI.print(*cerr.stream()));
// Simplify the contents of this block...
bool Changed = SimplifyBasicBlock(*BB, RI);
// Get the terminator of this basic block...
TerminatorInst *TI = BB->getTerminator();
// Loop over all of the blocks that this block is the immediate dominator for.
// Because all information known in this region is also known in all of the
// blocks that are dominated by this one, we can safely propagate the
// information down now.
//
DominatorTree::Node *BBN = (*DT)[BB];
if (!RI.empty()) // Time opt: only propagate if we can change something
for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i) {
BasicBlock *Dominated = BBN->getChildren()[i]->getBlock();
assert(RegionInfoMap.find(Dominated) == RegionInfoMap.end() &&
"RegionInfo should be calculated in dominanace order!");
getRegionInfo(Dominated) = RI;
}
// Now that all of our successors have information if they deserve it,
// propagate any information our terminator instruction finds to our
// successors.
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
if (BI->isConditional())
PropagateBranchInfo(BI);
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
PropagateSwitchInfo(SI);
}
// If this is a branch to a block outside our region that simply performs
// another conditional branch, one whose outcome is known inside of this
// region, then vector this outgoing edge directly to the known destination.
//
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
++BranchRevectors;
Changed = true;
}
// Now that all of our successors have information, recursively process them.
for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i)
Changed |= TransformRegion(BBN->getChildren()[i]->getBlock(),VisitedBlocks);
return Changed;
}
// isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
// revector the conditional branch in the bottom of the block, do so now.
//
static bool isBlockSimpleEnough(BasicBlock *BB) {
assert(isa<BranchInst>(BB->getTerminator()));
BranchInst *BI = cast<BranchInst>(BB->getTerminator());
assert(BI->isConditional());
// Check the common case first: empty block, or block with just a setcc.
if (BB->size() == 1 ||
(BB->size() == 2 && &BB->front() == BI->getCondition() &&
BI->getCondition()->hasOneUse()))
return true;
// Check the more complex case now...
BasicBlock::iterator I = BB->begin();
// FIXME: This should be reenabled once the regression with SIM is fixed!
#if 0
// PHI Nodes are ok, just skip over them...
while (isa<PHINode>(*I)) ++I;
#endif
// Accept the setcc instruction...
if (&*I == BI->getCondition())
++I;
// Nothing else is acceptable here yet. We must not revector... unless we are
// at the terminator instruction.
if (&*I == BI)
return true;
return false;
}
bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
RegionInfo &RI) {
// If this successor is a simple block not in the current region, which
// contains only a conditional branch, we decide if the outcome of the branch
// can be determined from information inside of the region. Instead of going
// to this block, we can instead go to the destination we know is the right
// target.
//
// Check to see if we dominate the block. If so, this block will get the
// condition turned to a constant anyway.
//
//if (EF->dominates(RI.getEntryBlock(), BB))
// return 0;
BasicBlock *BB = TI->getParent();
// Get the destination block of this edge...
BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
// Make sure that the block ends with a conditional branch and is simple
// enough for use to be able to revector over.
BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
return false;
// We can only forward the branch over the block if the block ends with a
// cmp we can determine the outcome for.
//
// FIXME: we can make this more generic. Code below already handles more
// generic case.
if (!isa<CmpInst>(BI->getCondition()))
return false;
// Make a new RegionInfo structure so that we can simulate the effect of the
// PHI nodes in the block we are skipping over...
//
RegionInfo NewRI(RI);
// Remove value information for all of the values we are simulating... to make
// sure we don't have any stale information.
for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
if (I->getType() != Type::VoidTy)
NewRI.removeValueInfo(I);
// Put the newly discovered information into the RegionInfo...
for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
if (PHINode *PN = dyn_cast<PHINode>(I)) {
int OpNum = PN->getBasicBlockIndex(BB);
assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
} else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
Relation::KnownResult Res = getCmpResult(CI, NewRI);
if (Res == Relation::Unknown) return false;
PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Res), NewRI);
} else {
assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
}
// Compute the facts implied by what we have discovered...
ComputeReplacements(NewRI);
ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
if (PredicateVI.getReplacement() &&
isa<Constant>(PredicateVI.getReplacement()) &&
!isa<GlobalValue>(PredicateVI.getReplacement())) {
ConstantInt *CB = cast<ConstantInt>(PredicateVI.getReplacement());
// Forward to the successor that corresponds to the branch we will take.
ForwardSuccessorTo(TI, SuccNo,
BI->getSuccessor(!CB->getZExtValue()), NewRI);
return true;
}
return false;
}
static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
if (const ValueInfo *VI = RI.requestValueInfo(V))
if (Value *Repl = VI->getReplacement())
return Repl;
return V;
}
/// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
/// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
/// mechanics of updating SSA information and revectoring the branch.
///
void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
BasicBlock *Dest, RegionInfo &RI) {
// If there are any PHI nodes in the Dest BB, we must duplicate the entry
// in the PHI node for the old successor to now include an entry from the
// current basic block.
//
BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
BasicBlock *BB = TI->getParent();
DOUT << "Forwarding branch in basic block %" << BB->getName()
<< " from block %" << OldSucc->getName() << " to block %"
<< Dest->getName() << "\n"
<< "Before forwarding: " << *BB->getParent();
// Because we know that there cannot be critical edges in the flow graph, and
// that OldSucc has multiple outgoing edges, this means that Dest cannot have
// multiple incoming edges.
//
#ifndef NDEBUG
pred_iterator DPI = pred_begin(Dest); ++DPI;
assert(DPI == pred_end(Dest) && "Critical edge found!!");
#endif
// Loop over any PHI nodes in the destination, eliminating them, because they
// may only have one input.
//
while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
// Eliminate the PHI node
PN->replaceAllUsesWith(PN->getIncomingValue(0));
Dest->getInstList().erase(PN);
}
// If there are values defined in the "OldSucc" basic block, we need to insert
// PHI nodes in the regions we are dealing with to emulate them. This can
// insert dead phi nodes, but it is more trouble to see if they are used than
// to just blindly insert them.
//
if (EF->dominates(OldSucc, Dest)) {
// RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
// but have predecessors that are. Additionally, prune down the set to only
// include blocks that are dominated by OldSucc as well.
//
std::vector<BasicBlock*> RegionExitBlocks;
CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
I != E; ++I)
if (I->getType() != Type::VoidTy) {
// Create and insert the PHI node into the top of Dest.
PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
Dest->begin());
// There is definitely an edge from OldSucc... add the edge now
NewPN->addIncoming(I, OldSucc);
// There is also an edge from BB now, add the edge with the calculated
// value from the RI.
NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
// Make everything in the Dest region use the new PHI node now...
ReplaceUsesOfValueInRegion(I, NewPN, Dest);
// Make sure that exits out of the region dominated by NewPN get PHI
// nodes that merge the values as appropriate.
InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
}
}
// If there were PHI nodes in OldSucc, we need to remove the entry for this
// edge from the PHI node, and we need to replace any references to the PHI
// node with a new value.
//
for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
PHINode *PN = cast<PHINode>(I);
// Get the value flowing across the old edge and remove the PHI node entry
// for this edge: we are about to remove the edge! Don't remove the PHI
// node yet though if this is the last edge into it.
Value *EdgeValue = PN->removeIncomingValue(BB, false);
// Make sure that anything that used to use PN now refers to EdgeValue
ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
// If there is only one value left coming into the PHI node, replace the PHI
// node itself with the one incoming value left.
//
if (PN->getNumIncomingValues() == 1) {
assert(PN->getNumIncomingValues() == 1);
PN->replaceAllUsesWith(PN->getIncomingValue(0));
PN->getParent()->getInstList().erase(PN);
I = OldSucc->begin();
} else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
// If we removed the last incoming value to this PHI, nuke the PHI node
// now.
PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
PN->getParent()->getInstList().erase(PN);
I = OldSucc->begin();
} else {
++I; // Otherwise, move on to the next PHI node
}
}
// Actually revector the branch now...
TI->setSuccessor(SuccNo, Dest);
// If we just introduced a critical edge in the flow graph, make sure to break
// it right away...
SplitCriticalEdge(TI, SuccNo, this);
// Make sure that we don't introduce critical edges from oldsucc now!
for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
i != e; ++i)
SplitCriticalEdge(OldSucc->getTerminator(), i, this);
// Since we invalidated the CFG, recalculate the dominator set so that it is
// useful for later processing!
// FIXME: This is much worse than it really should be!
//EF->recalculate();
DOUT << "After forwarding: " << *BB->getParent();
}
/// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
/// of New. It only affects instructions that are defined in basic blocks that
/// are dominated by Head.
///
void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
BasicBlock *RegionDominator) {
assert(Orig != New && "Cannot replace value with itself");
std::vector<Instruction*> InstsToChange;
std::vector<PHINode*> PHIsToChange;
InstsToChange.reserve(Orig->getNumUses());
// Loop over instructions adding them to InstsToChange vector, this allows us
// an easy way to avoid invalidating the use_iterator at a bad time.
for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
I != E; ++I)
if (Instruction *User = dyn_cast<Instruction>(*I))
if (EF->dominates(RegionDominator, User->getParent()))
InstsToChange.push_back(User);
else if (PHINode *PN = dyn_cast<PHINode>(User)) {
PHIsToChange.push_back(PN);
}
// PHIsToChange contains PHI nodes that use Orig that do not live in blocks
// dominated by orig. If the block the value flows in from is dominated by
// RegionDominator, then we rewrite the PHI
for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
PHINode *PN = PHIsToChange[i];
for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
if (PN->getIncomingValue(j) == Orig &&
EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
PN->setIncomingValue(j, New);
}
// Loop over the InstsToChange list, replacing all uses of Orig with uses of
// New. This list contains all of the instructions in our region that use
// Orig.
for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
// PHINodes must be handled carefully. If the PHI node itself is in the
// region, we have to make sure to only do the replacement for incoming
// values that correspond to basic blocks in the region.
for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
if (PN->getIncomingValue(j) == Orig &&
EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
PN->setIncomingValue(j, New);
} else {
InstsToChange[i]->replaceUsesOfWith(Orig, New);
}
}
static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
std::set<BasicBlock*> &Visited,
ETForest &EF,
std::vector<BasicBlock*> &RegionExitBlocks) {
if (Visited.count(BB)) return;
Visited.insert(BB);
if (EF.dominates(Header, BB)) { // Block in the region, recursively traverse
for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
CalcRegionExitBlocks(Header, *I, Visited, EF, RegionExitBlocks);
} else {
// Header does not dominate this block, but we have a predecessor that does
// dominate us. Add ourself to the list.
RegionExitBlocks.push_back(BB);
}
}
/// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
/// BB, but have predecessors that are. Additionally, prune down the set to
/// only include blocks that are dominated by OldSucc as well.
///
void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
std::vector<BasicBlock*> &RegionExitBlocks){
std::set<BasicBlock*> Visited; // Don't infinite loop
// Recursively calculate blocks we are interested in...
CalcRegionExitBlocks(BB, BB, Visited, *EF, RegionExitBlocks);
// Filter out blocks that are not dominated by OldSucc...
for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
if (EF->dominates(OldSucc, RegionExitBlocks[i]))
++i; // Block is ok, keep it.
else {
// Move to end of list...
std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
RegionExitBlocks.pop_back(); // Nuke the end
}
}
}
void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
const std::vector<BasicBlock*> &RegionExitBlocks) {
assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
BasicBlock *BB = BBVal->getParent();
// Loop over all of the blocks we have to place PHIs in, doing it.
for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
// Create the new PHI node
PHINode *NewPN = new PHINode(BBVal->getType(),
OldVal->getName()+".fw_frontier",
FBlock->begin());
// Add an incoming value for every predecessor of the block...
for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
PI != PE; ++PI) {
// If the incoming edge is from the region dominated by BB, use BBVal,
// otherwise use OldVal.
NewPN->addIncoming(EF->dominates(BB, *PI) ? BBVal : OldVal, *PI);
}
// Now make everyone dominated by this block use this new value!
ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
}
}
// BuildRankMap - This method builds the rank map data structure which gives
// each instruction/value in the function a value based on how early it appears
// in the function. We give constants and globals rank 0, arguments are
// numbered starting at one, and instructions are numbered in reverse post-order
// from where the arguments leave off. This gives instructions in loops higher
// values than instructions not in loops.
//
void CEE::BuildRankMap(Function &F) {
unsigned Rank = 1; // Skip rank zero.
// Number the arguments...
for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
RankMap[I] = Rank++;
// Number the instructions in reverse post order...
ReversePostOrderTraversal<Function*> RPOT(&F);
for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
E = RPOT.end(); I != E; ++I)
for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
BBI != E; ++BBI)
if (BBI->getType() != Type::VoidTy)
RankMap[BBI] = Rank++;
}
// PropagateBranchInfo - When this method is invoked, we need to propagate
// information derived from the branch condition into the true and false
// branches of BI. Since we know that there aren't any critical edges in the
// flow graph, this can proceed unconditionally.
//
void CEE::PropagateBranchInfo(BranchInst *BI) {
assert(BI->isConditional() && "Must be a conditional branch!");
// Propagate information into the true block...
//
PropagateEquality(BI->getCondition(), ConstantInt::getTrue(),
getRegionInfo(BI->getSuccessor(0)));
// Propagate information into the false block...
//
PropagateEquality(BI->getCondition(), ConstantInt::getFalse(),
getRegionInfo(BI->getSuccessor(1)));
}
// PropagateSwitchInfo - We need to propagate the value tested by the
// switch statement through each case block.
//
void CEE::PropagateSwitchInfo(SwitchInst *SI) {
// Propagate information down each of our non-default case labels. We
// don't yet propagate information down the default label, because a
// potentially large number of inequality constraints provide less
// benefit per unit work than a single equality constraint.
//
Value *cond = SI->getCondition();
for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
PropagateEquality(cond, SI->getSuccessorValue(i),
getRegionInfo(SI->getSuccessor(i)));
}
// PropagateEquality - If we discover that two values are equal to each other in
// a specified region, propagate this knowledge recursively.
//
void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
if (isa<Constant>(Op0)) // Make sure the constant is always Op1
std::swap(Op0, Op1);
// Make sure we don't already know these are equal, to avoid infinite loops...
ValueInfo &VI = RI.getValueInfo(Op0);
// Get information about the known relationship between Op0 & Op1
Relation &KnownRelation = VI.getRelation(Op1);
// If we already know they're equal, don't reprocess...
if (KnownRelation.getRelation() == FCmpInst::FCMP_OEQ ||
KnownRelation.getRelation() == ICmpInst::ICMP_EQ)
return;
// If this is boolean, check to see if one of the operands is a constant. If
// it's a constant, then see if the other one is one of a setcc instruction,
// an AND, OR, or XOR instruction.
//
ConstantInt *CB = dyn_cast<ConstantInt>(Op1);
if (CB && Op1->getType() == Type::Int1Ty) {
if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
// If we know that this instruction is an AND instruction, and the
// result is true, this means that both operands to the OR are known
// to be true as well.
//
if (CB->getZExtValue() && Inst->getOpcode() == Instruction::And) {
PropagateEquality(Inst->getOperand(0), CB, RI);
PropagateEquality(Inst->getOperand(1), CB, RI);
}
// If we know that this instruction is an OR instruction, and the result
// is false, this means that both operands to the OR are know to be
// false as well.
//
if (!CB->getZExtValue() && Inst->getOpcode() == Instruction::Or) {
PropagateEquality(Inst->getOperand(0), CB, RI);
PropagateEquality(Inst->getOperand(1), CB, RI);
}
// If we know that this instruction is a NOT instruction, we know that
// the operand is known to be the inverse of whatever the current
// value is.
//
if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
if (BinaryOperator::isNot(BOp))
PropagateEquality(BinaryOperator::getNotArgument(BOp),
ConstantInt::get(Type::Int1Ty,
!CB->getZExtValue()), RI);
// If we know the value of a FCmp instruction, propagate the information
// about the relation into this region as well.
//
if (FCmpInst *FCI = dyn_cast<FCmpInst>(Inst)) {
if (CB->getZExtValue()) { // If we know the condition is true...
// Propagate info about the LHS to the RHS & RHS to LHS
PropagateRelation(FCI->getPredicate(), FCI->getOperand(0),
FCI->getOperand(1), RI);
PropagateRelation(FCI->getSwappedPredicate(),
FCI->getOperand(1), FCI->getOperand(0), RI);
} else { // If we know the condition is false...
// We know the opposite of the condition is true...
FCmpInst::Predicate C = FCI->getInversePredicate();
PropagateRelation(C, FCI->getOperand(0), FCI->getOperand(1), RI);
PropagateRelation(FCmpInst::getSwappedPredicate(C),
FCI->getOperand(1), FCI->getOperand(0), RI);
}
}
// If we know the value of a ICmp instruction, propagate the information
// about the relation into this region as well.
//
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
if (CB->getZExtValue()) { // If we know the condition is true...
// Propagate info about the LHS to the RHS & RHS to LHS
PropagateRelation(ICI->getPredicate(), ICI->getOperand(0),
ICI->getOperand(1), RI);
PropagateRelation(ICI->getSwappedPredicate(), ICI->getOperand(1),
ICI->getOperand(1), RI);
} else { // If we know the condition is false ...
// We know the opposite of the condition is true...
ICmpInst::Predicate C = ICI->getInversePredicate();
PropagateRelation(C, ICI->getOperand(0), ICI->getOperand(1), RI);
PropagateRelation(ICmpInst::getSwappedPredicate(C),
ICI->getOperand(1), ICI->getOperand(0), RI);
}
}
}
}
// Propagate information about Op0 to Op1 & visa versa
PropagateRelation(ICmpInst::ICMP_EQ, Op0, Op1, RI);
PropagateRelation(ICmpInst::ICMP_EQ, Op1, Op0, RI);
PropagateRelation(FCmpInst::FCMP_OEQ, Op0, Op1, RI);
PropagateRelation(FCmpInst::FCMP_OEQ, Op1, Op0, RI);
}
// PropagateRelation - We know that the specified relation is true in all of the
// blocks in the specified region. Propagate the information about Op0 and
// anything derived from it into this region.
//
void CEE::PropagateRelation(unsigned Opcode, Value *Op0,
Value *Op1, RegionInfo &RI) {
assert(Op0->getType() == Op1->getType() && "Equal types expected!");
// Constants are already pretty well understood. We will apply information
// about the constant to Op1 in another call to PropagateRelation.
//
if (isa<Constant>(Op0)) return;
// Get the region information for this block to update...
ValueInfo &VI = RI.getValueInfo(Op0);
// Get information about the known relationship between Op0 & Op1
Relation &Op1R = VI.getRelation(Op1);
// Quick bailout for common case if we are reprocessing an instruction...
if (Op1R.getRelation() == Opcode)
return;
// If we already have information that contradicts the current information we
// are propagating, ignore this info. Something bad must have happened!
//
if (Op1R.contradicts(Opcode, VI)) {
Op1R.contradicts(Opcode, VI);
cerr << "Contradiction found for opcode: "
<< ((isa<ICmpInst>(Op0)||isa<ICmpInst>(Op1)) ?
Instruction::getOpcodeName(Instruction::ICmp) :
Instruction::getOpcodeName(Opcode))
<< "\n";
Op1R.print(*cerr.stream());
return;
}
// If the information propagated is new, then we want process the uses of this
// instruction to propagate the information down to them.
//
if (Op1R.incorporate(Opcode, VI))
UpdateUsersOfValue(Op0, RI);
}
// UpdateUsersOfValue - The information about V in this region has been updated.
// Propagate this to all consumers of the value.
//
void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
for (Value::use_iterator I = V->use_begin(), E = V->use_end();
I != E; ++I)
if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
// If this is an instruction using a value that we know something about,
// try to propagate information to the value produced by the
// instruction. We can only do this if it is an instruction we can
// propagate information for (a setcc for example), and we only WANT to
// do this if the instruction dominates this region.
//
// If the instruction doesn't dominate this region, then it cannot be
// used in this region and we don't care about it. If the instruction
// is IN this region, then we will simplify the instruction before we
// get to uses of it anyway, so there is no reason to bother with it
// here. This check is also effectively checking to make sure that Inst
// is in the same function as our region (in case V is a global f.e.).
//
if (EF->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
IncorporateInstruction(Inst, RI);
}
}
// IncorporateInstruction - We just updated the information about one of the
// operands to the specified instruction. Update the information about the
// value produced by this instruction
//
void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
// See if we can figure out a result for this instruction...
Relation::KnownResult Result = getCmpResult(CI, RI);
if (Result != Relation::Unknown) {
PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Result != 0), RI);
}
}
}
// ComputeReplacements - Some values are known to be equal to other values in a
// region. For example if there is a comparison of equality between a variable
// X and a constant C, we can replace all uses of X with C in the region we are
// interested in. We generalize this replacement to replace variables with
// other variables if they are equal and there is a variable with lower rank
// than the current one. This offers a canonicalizing property that exposes
// more redundancies for later transformations to take advantage of.
//
void CEE::ComputeReplacements(RegionInfo &RI) {
// Loop over all of the values in the region info map...
for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
ValueInfo &VI = I->second;
// If we know that this value is a particular constant, set Replacement to
// the constant...
Value *Replacement = 0;
const APInt * Rplcmnt = VI.getBounds().getSingleElement();
if (Rplcmnt)
Replacement = ConstantInt::get(*Rplcmnt);
// If this value is not known to be some constant, figure out the lowest
// rank value that it is known to be equal to (if anything).
//
if (Replacement == 0) {
// Find out if there are any equality relationships with values of lower
// rank than VI itself...
unsigned MinRank = getRank(I->first);
// Loop over the relationships known about Op0.
const std::vector<Relation> &Relationships = VI.getRelationships();
for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
if (Relationships[i].getRelation() == FCmpInst::FCMP_OEQ) {
unsigned R = getRank(Relationships[i].getValue());
if (R < MinRank) {
MinRank = R;
Replacement = Relationships[i].getValue();
}
}
else if (Relationships[i].getRelation() == ICmpInst::ICMP_EQ) {
unsigned R = getRank(Relationships[i].getValue());
if (R < MinRank) {
MinRank = R;
Replacement = Relationships[i].getValue();
}
}
}
// If we found something to replace this value with, keep track of it.
if (Replacement)
VI.setReplacement(Replacement);
}
}
// SimplifyBasicBlock - Given information about values in region RI, simplify
// the instructions in the specified basic block.
//
bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
bool Changed = false;
for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
Instruction *Inst = I++;
// Convert instruction arguments to canonical forms...
Changed |= SimplifyInstruction(Inst, RI);
if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
// Try to simplify a setcc instruction based on inherited information
Relation::KnownResult Result = getCmpResult(CI, RI);
if (Result != Relation::Unknown) {
DEBUG(cerr << "Replacing icmp with " << Result
<< " constant: " << *CI);
CI->replaceAllUsesWith(ConstantInt::get(Type::Int1Ty, (bool)Result));
// The instruction is now dead, remove it from the program.
CI->getParent()->getInstList().erase(CI);
++NumCmpRemoved;
Changed = true;
}
}
}
return Changed;
}
// SimplifyInstruction - Inspect the operands of the instruction, converting
// them to their canonical form if possible. This takes care of, for example,
// replacing a value 'X' with a constant 'C' if the instruction in question is
// dominated by a true seteq 'X', 'C'.
//
bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
bool Changed = false;
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
if (Value *Repl = VI->getReplacement()) {
// If we know if a replacement with lower rank than Op0, make the
// replacement now.
DOUT << "In Inst: " << *I << " Replacing operand #" << i
<< " with " << *Repl << "\n";
I->setOperand(i, Repl);
Changed = true;
++NumOperandsCann;
}
return Changed;
}
// getCmpResult - Try to simplify a cmp instruction based on information
// inherited from a dominating icmp instruction. V is one of the operands to
// the icmp instruction, and VI is the set of information known about it. We
// take two cases into consideration here. If the comparison is against a
// constant value, we can use the constant range to see if the comparison is
// possible to succeed. If it is not a comparison against a constant, we check
// to see if there is a known relationship between the two values. If so, we
// may be able to eliminate the check.
//
Relation::KnownResult CEE::getCmpResult(CmpInst *CI,
const RegionInfo &RI) {
Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
unsigned short predicate = CI->getPredicate();
if (isa<Constant>(Op0)) {
if (isa<Constant>(Op1)) {
if (Constant *Result = ConstantFoldInstruction(CI)) {
// Wow, this is easy, directly eliminate the ICmpInst.
DEBUG(cerr << "Replacing cmp with constant fold: " << *CI);
return cast<ConstantInt>(Result)->getZExtValue()
? Relation::KnownTrue : Relation::KnownFalse;
}
} else {
// We want to swap this instruction so that operand #0 is the constant.
std::swap(Op0, Op1);
if (isa<ICmpInst>(CI))
predicate = cast<ICmpInst>(CI)->getSwappedPredicate();
else
predicate = cast<FCmpInst>(CI)->getSwappedPredicate();
}
}
// Try to figure out what the result of this comparison will be...
Relation::KnownResult Result = Relation::Unknown;
// We have to know something about the relationship to prove anything...
if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
// At this point, we know that if we have a constant argument that it is in
// Op1. Check to see if we know anything about comparing value with a
// constant, and if we can use this info to fold the icmp.
//
if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
// Check to see if we already know the result of this comparison...
ICmpInst::Predicate ipred = ICmpInst::Predicate(predicate);
ConstantRange R = ICmpInst::makeConstantRange(ipred, C->getValue());
ConstantRange Int = R.intersectWith(Op0VI->getBounds());
// If the intersection of the two ranges is empty, then the condition
// could never be true!
//
if (Int.isEmptySet()) {
Result = Relation::KnownFalse;
// Otherwise, if VI.getBounds() (the possible values) is a subset of R
// (the allowed values) then we know that the condition must always be
// true!
//
} else if (Int == Op0VI->getBounds()) {
Result = Relation::KnownTrue;
}
} else {
// If we are here, we know that the second argument is not a constant
// integral. See if we know anything about Op0 & Op1 that allows us to
// fold this anyway.
//
// Do we have value information about Op0 and a relation to Op1?
if (const Relation *Op2R = Op0VI->requestRelation(Op1))
Result = Op2R->getImpliedResult(predicate);
}
}
return Result;
}
//===----------------------------------------------------------------------===//
// Relation Implementation
//===----------------------------------------------------------------------===//
// contradicts - Return true if the relationship specified by the operand
// contradicts already known information.
//
bool Relation::contradicts(unsigned Op,
const ValueInfo &VI) const {
assert (Op != Instruction::Add && "Invalid relation argument!");
// If this is a relationship with a constant, make sure that this relationship
// does not contradict properties known about the bounds of the constant.
//
if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
Op <= ICmpInst::LAST_ICMP_PREDICATE) {
ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
if (ICmpInst::makeConstantRange(ipred, C->getValue())
.intersectWith(VI.getBounds()).isEmptySet())
return true;
}
switch (Rel) {
default: assert(0 && "Unknown Relationship code!");
case Instruction::Add: return false; // Nothing known, nothing contradicts
case ICmpInst::ICMP_EQ:
return Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT ||
Op == ICmpInst::ICMP_NE;
case ICmpInst::ICMP_NE: return Op == ICmpInst::ICMP_EQ;
case ICmpInst::ICMP_ULE:
case ICmpInst::ICMP_SLE: return Op == ICmpInst::ICMP_UGT ||
Op == ICmpInst::ICMP_SGT;
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_SGE: return Op == ICmpInst::ICMP_ULT ||
Op == ICmpInst::ICMP_SLT;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_SLT:
return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_UGT ||
Op == ICmpInst::ICMP_SGT || Op == ICmpInst::ICMP_UGE ||
Op == ICmpInst::ICMP_SGE;
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT:
return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
Op == ICmpInst::ICMP_SLT || Op == ICmpInst::ICMP_ULE ||
Op == ICmpInst::ICMP_SLE;
case FCmpInst::FCMP_OEQ:
return Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT ||
Op == FCmpInst::FCMP_ONE;
case FCmpInst::FCMP_ONE: return Op == FCmpInst::FCMP_OEQ;
case FCmpInst::FCMP_OLE: return Op == FCmpInst::FCMP_OGT;
case FCmpInst::FCMP_OGE: return Op == FCmpInst::FCMP_OLT;
case FCmpInst::FCMP_OLT:
return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT ||
Op == FCmpInst::FCMP_OGE;
case FCmpInst::FCMP_OGT:
return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT ||
Op == FCmpInst::FCMP_OLE;
}
}
// incorporate - Incorporate information in the argument into this relation
// entry. This assumes that the information doesn't contradict itself. If any
// new information is gained, true is returned, otherwise false is returned to
// indicate that nothing was updated.
//
bool Relation::incorporate(unsigned Op, ValueInfo &VI) {
assert(!contradicts(Op, VI) &&
"Cannot incorporate contradictory information!");
// If this is a relationship with a constant, make sure that we update the
// range that is possible for the value to have...
//
if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
Op <= ICmpInst::LAST_ICMP_PREDICATE) {
ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
VI.getBounds() =
ICmpInst::makeConstantRange(ipred, C->getValue())
.intersectWith(VI.getBounds());
}
switch (Rel) {
default: assert(0 && "Unknown prior value!");
case Instruction::Add: Rel = Op; return true;
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT: return false; // Nothing is more precise
case ICmpInst::ICMP_ULE:
case ICmpInst::ICMP_SLE:
if (Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
Op == ICmpInst::ICMP_SLT) {
Rel = Op;
return true;
} else if (Op == ICmpInst::ICMP_NE) {
Rel = Rel == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_ULT :
ICmpInst::ICMP_SLT;
return true;
}
return false;
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_SGE:
if (Op == ICmpInst::ICMP_EQ || ICmpInst::ICMP_UGT ||
Op == ICmpInst::ICMP_SGT) {
Rel = Op;
return true;
} else if (Op == ICmpInst::ICMP_NE) {
Rel = Rel == ICmpInst::ICMP_UGE ? ICmpInst::ICMP_UGT :
ICmpInst::ICMP_SGT;
return true;
}
return false;
case FCmpInst::FCMP_OEQ: return false; // Nothing is more precise
case FCmpInst::FCMP_ONE: return false; // Nothing is more precise
case FCmpInst::FCMP_OLT: return false; // Nothing is more precise
case FCmpInst::FCMP_OGT: return false; // Nothing is more precise
case FCmpInst::FCMP_OLE:
if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT) {
Rel = Op;
return true;
} else if (Op == FCmpInst::FCMP_ONE) {
Rel = FCmpInst::FCMP_OLT;
return true;
}
return false;
case FCmpInst::FCMP_OGE:
return Op == FCmpInst::FCMP_OLT;
if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT) {
Rel = Op;
return true;
} else if (Op == FCmpInst::FCMP_ONE) {
Rel = FCmpInst::FCMP_OGT;
return true;
}
return false;
}
}
// getImpliedResult - If this relationship between two values implies that
// the specified relationship is true or false, return that. If we cannot
// determine the result required, return Unknown.
//
Relation::KnownResult
Relation::getImpliedResult(unsigned Op) const {
if (Rel == Op) return KnownTrue;
if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
Op <= ICmpInst::LAST_ICMP_PREDICATE) {
if (Rel == unsigned(ICmpInst::getInversePredicate(ICmpInst::Predicate(Op))))
return KnownFalse;
} else if (Op <= FCmpInst::LAST_FCMP_PREDICATE) {
if (Rel == unsigned(FCmpInst::getInversePredicate(FCmpInst::Predicate(Op))))
return KnownFalse;
}
switch (Rel) {
default: assert(0 && "Unknown prior value!");
case ICmpInst::ICMP_EQ:
if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE) return KnownTrue;
if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT) return KnownFalse;
break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_SLT:
if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
Op == ICmpInst::ICMP_NE) return KnownTrue;
if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
break;
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT:
if (Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE ||
Op == ICmpInst::ICMP_NE) return KnownTrue;
if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
break;
case FCmpInst::FCMP_OEQ:
if (Op == FCmpInst::FCMP_OLE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
if (Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT) return KnownFalse;
break;
case FCmpInst::FCMP_OLT:
if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OLE) return KnownTrue;
if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
break;
case FCmpInst::FCMP_OGT:
if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_SLE:
case ICmpInst::ICMP_ULE:
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_SGE:
case FCmpInst::FCMP_ONE:
case FCmpInst::FCMP_OLE:
case FCmpInst::FCMP_OGE:
case FCmpInst::FCMP_FALSE:
case FCmpInst::FCMP_ORD:
case FCmpInst::FCMP_UNO:
case FCmpInst::FCMP_UEQ:
case FCmpInst::FCMP_UGT:
case FCmpInst::FCMP_UGE:
case FCmpInst::FCMP_ULT:
case FCmpInst::FCMP_ULE:
case FCmpInst::FCMP_UNE:
case FCmpInst::FCMP_TRUE:
break;
}
return Unknown;
}
//===----------------------------------------------------------------------===//
// Printing Support...
//===----------------------------------------------------------------------===//
// print - Implement the standard print form to print out analysis information.
void CEE::print(std::ostream &O, const Module *M) const {
O << "\nPrinting Correlated Expression Info:\n";
for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
I->second.print(O);
}
// print - Output information about this region...
void RegionInfo::print(std::ostream &OS) const {
if (ValueMap.empty()) return;
OS << " RegionInfo for basic block: " << BB->getName() << "\n";
for (std::map<Value*, ValueInfo>::const_iterator
I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
I->second.print(OS, I->first);
OS << "\n";
}
// print - Output information about this value relation...
void ValueInfo::print(std::ostream &OS, Value *V) const {
if (Relationships.empty()) return;
if (V) {
OS << " ValueInfo for: ";
WriteAsOperand(OS, V);
}
OS << "\n Bounds = " << Bounds << "\n";
if (Replacement) {
OS << " Replacement = ";
WriteAsOperand(OS, Replacement);
OS << "\n";
}
for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
Relationships[i].print(OS);
}
// print - Output this relation to the specified stream
void Relation::print(std::ostream &OS) const {
OS << " is ";
switch (Rel) {
default: OS << "*UNKNOWN*"; break;
case ICmpInst::ICMP_EQ:
case FCmpInst::FCMP_ORD:
case FCmpInst::FCMP_UEQ:
case FCmpInst::FCMP_OEQ: OS << "== "; break;
case ICmpInst::ICMP_NE:
case FCmpInst::FCMP_UNO:
case FCmpInst::FCMP_UNE:
case FCmpInst::FCMP_ONE: OS << "!= "; break;
case ICmpInst::ICMP_ULT:
case ICmpInst::ICMP_SLT:
case FCmpInst::FCMP_ULT:
case FCmpInst::FCMP_OLT: OS << "< "; break;
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT:
case FCmpInst::FCMP_UGT:
case FCmpInst::FCMP_OGT: OS << "> "; break;
case ICmpInst::ICMP_ULE:
case ICmpInst::ICMP_SLE:
case FCmpInst::FCMP_ULE:
case FCmpInst::FCMP_OLE: OS << "<= "; break;
case ICmpInst::ICMP_UGE:
case ICmpInst::ICMP_SGE:
case FCmpInst::FCMP_UGE:
case FCmpInst::FCMP_OGE: OS << ">= "; break;
}
WriteAsOperand(OS, Val);
OS << "\n";
}
// Don't inline these methods or else we won't be able to call them from GDB!
void Relation::dump() const { print(*cerr.stream()); }
void ValueInfo::dump() const { print(*cerr.stream(), 0); }
void RegionInfo::dump() const { print(*cerr.stream()); }
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