-//===- GVN.cpp - Eliminate redundant values and loads ------------===//
+//===- GVN.cpp - Eliminate redundant values and loads ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This pass performs global value numbering to eliminate fully redundant
// instructions. It also performs simple dead load elimination.
//
-// Note that this pass does the value numbering itself, it does not use the
+// Note that this pass does the value numbering itself; it does not use the
// ValueNumbering analysis passes.
//
//===----------------------------------------------------------------------===//
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
-#include "llvm/Instructions.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/LLVMContext.h"
+#include "llvm/Operator.h"
#include "llvm/Value.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/Analysis/MallocFreeHelper.h"
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
#include "llvm/Support/CFG.h"
#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/GetElementPtrTypeIterator.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
#include <cstdio>
using namespace llvm;
-STATISTIC(NumGVNInstr, "Number of instructions deleted");
-STATISTIC(NumGVNLoad, "Number of loads deleted");
-STATISTIC(NumGVNPRE, "Number of instructions PRE'd");
+STATISTIC(NumGVNInstr, "Number of instructions deleted");
+STATISTIC(NumGVNLoad, "Number of loads deleted");
+STATISTIC(NumGVNPRE, "Number of instructions PRE'd");
STATISTIC(NumGVNBlocks, "Number of blocks merged");
+STATISTIC(NumPRELoad, "Number of loads PRE'd");
static cl::opt<bool> EnablePRE("enable-pre",
cl::init(true), cl::Hidden);
+static cl::opt<bool> EnableLoadPRE("enable-load-pre", cl::init(true));
//===----------------------------------------------------------------------===//
// ValueTable Class
/// as an efficient mechanism to determine the expression-wise equivalence of
/// two values.
namespace {
- struct VISIBILITY_HIDDEN Expression {
- enum ExpressionOpcode { ADD, SUB, MUL, UDIV, SDIV, FDIV, UREM, SREM,
- FREM, SHL, LSHR, ASHR, AND, OR, XOR, ICMPEQ,
- ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
- ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
- FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
- FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
+ struct Expression {
+ enum ExpressionOpcode { ADD, FADD, SUB, FSUB, MUL, FMUL,
+ UDIV, SDIV, FDIV, UREM, SREM,
+ FREM, SHL, LSHR, ASHR, AND, OR, XOR, ICMPEQ,
+ ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
+ ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
+ FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
+ FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
SHUFFLE, SELECT, TRUNC, ZEXT, SEXT, FPTOUI,
- FPTOSI, UITOFP, SITOFP, FPTRUNC, FPEXT,
+ FPTOSI, UITOFP, SITOFP, FPTRUNC, FPEXT,
PTRTOINT, INTTOPTR, BITCAST, GEP, CALL, CONSTANT,
- EMPTY, TOMBSTONE };
+ INSERTVALUE, EXTRACTVALUE, EMPTY, TOMBSTONE };
ExpressionOpcode opcode;
const Type* type;
- uint32_t firstVN;
- uint32_t secondVN;
- uint32_t thirdVN;
SmallVector<uint32_t, 4> varargs;
- Value* function;
-
+ Value *function;
+
Expression() { }
Expression(ExpressionOpcode o) : opcode(o) { }
-
+
bool operator==(const Expression &other) const {
if (opcode != other.opcode)
return false;
return false;
else if (function != other.function)
return false;
- else if (firstVN != other.firstVN)
- return false;
- else if (secondVN != other.secondVN)
- return false;
- else if (thirdVN != other.thirdVN)
- return false;
else {
if (varargs.size() != other.varargs.size())
return false;
-
+
for (size_t i = 0; i < varargs.size(); ++i)
if (varargs[i] != other.varargs[i])
return false;
-
+
return true;
}
}
-
+
bool operator!=(const Expression &other) const {
- if (opcode != other.opcode)
- return true;
- else if (opcode == EMPTY || opcode == TOMBSTONE)
- return false;
- else if (type != other.type)
- return true;
- else if (function != other.function)
- return true;
- else if (firstVN != other.firstVN)
- return true;
- else if (secondVN != other.secondVN)
- return true;
- else if (thirdVN != other.thirdVN)
- return true;
- else {
- if (varargs.size() != other.varargs.size())
- return true;
-
- for (size_t i = 0; i < varargs.size(); ++i)
- if (varargs[i] != other.varargs[i])
- return true;
-
- return false;
- }
+ return !(*this == other);
}
};
-
- class VISIBILITY_HIDDEN ValueTable {
+
+ class ValueTable {
private:
DenseMap<Value*, uint32_t> valueNumbering;
DenseMap<Expression, uint32_t> expressionNumbering;
AliasAnalysis* AA;
MemoryDependenceAnalysis* MD;
DominatorTree* DT;
-
+
uint32_t nextValueNumber;
-
+
Expression::ExpressionOpcode getOpcode(BinaryOperator* BO);
Expression::ExpressionOpcode getOpcode(CmpInst* C);
Expression::ExpressionOpcode getOpcode(CastInst* C);
Expression create_expression(GetElementPtrInst* G);
Expression create_expression(CallInst* C);
Expression create_expression(Constant* C);
+ Expression create_expression(ExtractValueInst* C);
+ Expression create_expression(InsertValueInst* C);
+
+ uint32_t lookup_or_add_call(CallInst* C);
public:
ValueTable() : nextValueNumber(1) { }
- uint32_t lookup_or_add(Value* V);
- uint32_t lookup(Value* V) const;
- void add(Value* V, uint32_t num);
+ uint32_t lookup_or_add(Value *V);
+ uint32_t lookup(Value *V) const;
+ void add(Value *V, uint32_t num);
void clear();
- void erase(Value* v);
+ void erase(Value *v);
unsigned size();
void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
+ AliasAnalysis *getAliasAnalysis() const { return AA; }
void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
void setDomTree(DominatorTree* D) { DT = D; }
uint32_t getNextUnusedValueNumber() { return nextValueNumber; }
+ void verifyRemoved(const Value *) const;
};
}
static inline Expression getEmptyKey() {
return Expression(Expression::EMPTY);
}
-
+
static inline Expression getTombstoneKey() {
return Expression(Expression::TOMBSTONE);
}
-
+
static unsigned getHashValue(const Expression e) {
unsigned hash = e.opcode;
-
- hash = e.firstVN + hash * 37;
- hash = e.secondVN + hash * 37;
- hash = e.thirdVN + hash * 37;
-
+
hash = ((unsigned)((uintptr_t)e.type >> 4) ^
- (unsigned)((uintptr_t)e.type >> 9)) +
- hash * 37;
-
+ (unsigned)((uintptr_t)e.type >> 9));
+
for (SmallVector<uint32_t, 4>::const_iterator I = e.varargs.begin(),
E = e.varargs.end(); I != E; ++I)
hash = *I + hash * 37;
-
+
hash = ((unsigned)((uintptr_t)e.function >> 4) ^
(unsigned)((uintptr_t)e.function >> 9)) +
hash * 37;
-
+
return hash;
}
static bool isEqual(const Expression &LHS, const Expression &RHS) {
Expression::ExpressionOpcode ValueTable::getOpcode(BinaryOperator* BO) {
switch(BO->getOpcode()) {
default: // THIS SHOULD NEVER HAPPEN
- assert(0 && "Binary operator with unknown opcode?");
+ llvm_unreachable("Binary operator with unknown opcode?");
case Instruction::Add: return Expression::ADD;
+ case Instruction::FAdd: return Expression::FADD;
case Instruction::Sub: return Expression::SUB;
+ case Instruction::FSub: return Expression::FSUB;
case Instruction::Mul: return Expression::MUL;
+ case Instruction::FMul: return Expression::FMUL;
case Instruction::UDiv: return Expression::UDIV;
case Instruction::SDiv: return Expression::SDIV;
case Instruction::FDiv: return Expression::FDIV;
}
Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
- if (isa<ICmpInst>(C) || isa<VICmpInst>(C)) {
+ if (isa<ICmpInst>(C)) {
switch (C->getPredicate()) {
default: // THIS SHOULD NEVER HAPPEN
- assert(0 && "Comparison with unknown predicate?");
+ llvm_unreachable("Comparison with unknown predicate?");
case ICmpInst::ICMP_EQ: return Expression::ICMPEQ;
case ICmpInst::ICMP_NE: return Expression::ICMPNE;
case ICmpInst::ICMP_UGT: return Expression::ICMPUGT;
case ICmpInst::ICMP_SLT: return Expression::ICMPSLT;
case ICmpInst::ICMP_SLE: return Expression::ICMPSLE;
}
- }
- assert((isa<FCmpInst>(C) || isa<VFCmpInst>(C)) && "Unknown compare");
- switch (C->getPredicate()) {
- default: // THIS SHOULD NEVER HAPPEN
- assert(0 && "Comparison with unknown predicate?");
- case FCmpInst::FCMP_OEQ: return Expression::FCMPOEQ;
- case FCmpInst::FCMP_OGT: return Expression::FCMPOGT;
- case FCmpInst::FCMP_OGE: return Expression::FCMPOGE;
- case FCmpInst::FCMP_OLT: return Expression::FCMPOLT;
- case FCmpInst::FCMP_OLE: return Expression::FCMPOLE;
- case FCmpInst::FCMP_ONE: return Expression::FCMPONE;
- case FCmpInst::FCMP_ORD: return Expression::FCMPORD;
- case FCmpInst::FCMP_UNO: return Expression::FCMPUNO;
- case FCmpInst::FCMP_UEQ: return Expression::FCMPUEQ;
- case FCmpInst::FCMP_UGT: return Expression::FCMPUGT;
- case FCmpInst::FCMP_UGE: return Expression::FCMPUGE;
- case FCmpInst::FCMP_ULT: return Expression::FCMPULT;
- case FCmpInst::FCMP_ULE: return Expression::FCMPULE;
- case FCmpInst::FCMP_UNE: return Expression::FCMPUNE;
+ } else {
+ switch (C->getPredicate()) {
+ default: // THIS SHOULD NEVER HAPPEN
+ llvm_unreachable("Comparison with unknown predicate?");
+ case FCmpInst::FCMP_OEQ: return Expression::FCMPOEQ;
+ case FCmpInst::FCMP_OGT: return Expression::FCMPOGT;
+ case FCmpInst::FCMP_OGE: return Expression::FCMPOGE;
+ case FCmpInst::FCMP_OLT: return Expression::FCMPOLT;
+ case FCmpInst::FCMP_OLE: return Expression::FCMPOLE;
+ case FCmpInst::FCMP_ONE: return Expression::FCMPONE;
+ case FCmpInst::FCMP_ORD: return Expression::FCMPORD;
+ case FCmpInst::FCMP_UNO: return Expression::FCMPUNO;
+ case FCmpInst::FCMP_UEQ: return Expression::FCMPUEQ;
+ case FCmpInst::FCMP_UGT: return Expression::FCMPUGT;
+ case FCmpInst::FCMP_UGE: return Expression::FCMPUGE;
+ case FCmpInst::FCMP_ULT: return Expression::FCMPULT;
+ case FCmpInst::FCMP_ULE: return Expression::FCMPULE;
+ case FCmpInst::FCMP_UNE: return Expression::FCMPUNE;
+ }
}
}
Expression::ExpressionOpcode ValueTable::getOpcode(CastInst* C) {
switch(C->getOpcode()) {
default: // THIS SHOULD NEVER HAPPEN
- assert(0 && "Cast operator with unknown opcode?");
+ llvm_unreachable("Cast operator with unknown opcode?");
case Instruction::Trunc: return Expression::TRUNC;
case Instruction::ZExt: return Expression::ZEXT;
case Instruction::SExt: return Expression::SEXT;
Expression ValueTable::create_expression(CallInst* C) {
Expression e;
-
+
e.type = C->getType();
- e.firstVN = 0;
- e.secondVN = 0;
- e.thirdVN = 0;
e.function = C->getCalledFunction();
e.opcode = Expression::CALL;
-
+
for (CallInst::op_iterator I = C->op_begin()+1, E = C->op_end();
I != E; ++I)
e.varargs.push_back(lookup_or_add(*I));
-
+
return e;
}
Expression ValueTable::create_expression(BinaryOperator* BO) {
Expression e;
-
- e.firstVN = lookup_or_add(BO->getOperand(0));
- e.secondVN = lookup_or_add(BO->getOperand(1));
- e.thirdVN = 0;
+ e.varargs.push_back(lookup_or_add(BO->getOperand(0)));
+ e.varargs.push_back(lookup_or_add(BO->getOperand(1)));
e.function = 0;
e.type = BO->getType();
e.opcode = getOpcode(BO);
-
+
return e;
}
Expression ValueTable::create_expression(CmpInst* C) {
Expression e;
-
- e.firstVN = lookup_or_add(C->getOperand(0));
- e.secondVN = lookup_or_add(C->getOperand(1));
- e.thirdVN = 0;
+
+ e.varargs.push_back(lookup_or_add(C->getOperand(0)));
+ e.varargs.push_back(lookup_or_add(C->getOperand(1)));
e.function = 0;
e.type = C->getType();
e.opcode = getOpcode(C);
-
+
return e;
}
Expression ValueTable::create_expression(CastInst* C) {
Expression e;
-
- e.firstVN = lookup_or_add(C->getOperand(0));
- e.secondVN = 0;
- e.thirdVN = 0;
+
+ e.varargs.push_back(lookup_or_add(C->getOperand(0)));
e.function = 0;
e.type = C->getType();
e.opcode = getOpcode(C);
-
+
return e;
}
Expression ValueTable::create_expression(ShuffleVectorInst* S) {
Expression e;
-
- e.firstVN = lookup_or_add(S->getOperand(0));
- e.secondVN = lookup_or_add(S->getOperand(1));
- e.thirdVN = lookup_or_add(S->getOperand(2));
+
+ e.varargs.push_back(lookup_or_add(S->getOperand(0)));
+ e.varargs.push_back(lookup_or_add(S->getOperand(1)));
+ e.varargs.push_back(lookup_or_add(S->getOperand(2)));
e.function = 0;
e.type = S->getType();
e.opcode = Expression::SHUFFLE;
-
+
return e;
}
Expression ValueTable::create_expression(ExtractElementInst* E) {
Expression e;
-
- e.firstVN = lookup_or_add(E->getOperand(0));
- e.secondVN = lookup_or_add(E->getOperand(1));
- e.thirdVN = 0;
+
+ e.varargs.push_back(lookup_or_add(E->getOperand(0)));
+ e.varargs.push_back(lookup_or_add(E->getOperand(1)));
e.function = 0;
e.type = E->getType();
e.opcode = Expression::EXTRACT;
-
+
return e;
}
Expression ValueTable::create_expression(InsertElementInst* I) {
Expression e;
-
- e.firstVN = lookup_or_add(I->getOperand(0));
- e.secondVN = lookup_or_add(I->getOperand(1));
- e.thirdVN = lookup_or_add(I->getOperand(2));
+
+ e.varargs.push_back(lookup_or_add(I->getOperand(0)));
+ e.varargs.push_back(lookup_or_add(I->getOperand(1)));
+ e.varargs.push_back(lookup_or_add(I->getOperand(2)));
e.function = 0;
e.type = I->getType();
e.opcode = Expression::INSERT;
-
+
return e;
}
Expression ValueTable::create_expression(SelectInst* I) {
Expression e;
-
- e.firstVN = lookup_or_add(I->getCondition());
- e.secondVN = lookup_or_add(I->getTrueValue());
- e.thirdVN = lookup_or_add(I->getFalseValue());
+
+ e.varargs.push_back(lookup_or_add(I->getCondition()));
+ e.varargs.push_back(lookup_or_add(I->getTrueValue()));
+ e.varargs.push_back(lookup_or_add(I->getFalseValue()));
e.function = 0;
e.type = I->getType();
e.opcode = Expression::SELECT;
-
+
return e;
}
Expression ValueTable::create_expression(GetElementPtrInst* G) {
Expression e;
-
- e.firstVN = lookup_or_add(G->getPointerOperand());
- e.secondVN = 0;
- e.thirdVN = 0;
+
+ e.varargs.push_back(lookup_or_add(G->getPointerOperand()));
e.function = 0;
e.type = G->getType();
e.opcode = Expression::GEP;
-
+
for (GetElementPtrInst::op_iterator I = G->idx_begin(), E = G->idx_end();
I != E; ++I)
e.varargs.push_back(lookup_or_add(*I));
-
+
+ return e;
+}
+
+Expression ValueTable::create_expression(ExtractValueInst* E) {
+ Expression e;
+
+ e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
+ for (ExtractValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
+ II != IE; ++II)
+ e.varargs.push_back(*II);
+ e.function = 0;
+ e.type = E->getType();
+ e.opcode = Expression::EXTRACTVALUE;
+
+ return e;
+}
+
+Expression ValueTable::create_expression(InsertValueInst* E) {
+ Expression e;
+
+ e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
+ e.varargs.push_back(lookup_or_add(E->getInsertedValueOperand()));
+ for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
+ II != IE; ++II)
+ e.varargs.push_back(*II);
+ e.function = 0;
+ e.type = E->getType();
+ e.opcode = Expression::INSERTVALUE;
+
return e;
}
//===----------------------------------------------------------------------===//
/// add - Insert a value into the table with a specified value number.
-void ValueTable::add(Value* V, uint32_t num) {
+void ValueTable::add(Value *V, uint32_t num) {
valueNumbering.insert(std::make_pair(V, num));
}
-/// lookup_or_add - Returns the value number for the specified value, assigning
-/// it a new number if it did not have one before.
-uint32_t ValueTable::lookup_or_add(Value* V) {
- DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
- if (VI != valueNumbering.end())
- return VI->second;
-
- if (CallInst* C = dyn_cast<CallInst>(V)) {
- if (AA->doesNotAccessMemory(C)) {
- Expression e = create_expression(C);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
- return nextValueNumber++;
- }
- } else if (AA->onlyReadsMemory(C)) {
- Expression e = create_expression(C);
-
- if (expressionNumbering.find(e) == expressionNumbering.end()) {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
-
- MemDepResult local_dep = MD->getDependency(C);
-
- if (local_dep.isNone()) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
+uint32_t ValueTable::lookup_or_add_call(CallInst* C) {
+ if (AA->doesNotAccessMemory(C)) {
+ Expression exp = create_expression(C);
+ uint32_t& e = expressionNumbering[exp];
+ if (!e) e = nextValueNumber++;
+ valueNumbering[C] = e;
+ return e;
+ } else if (AA->onlyReadsMemory(C)) {
+ Expression exp = create_expression(C);
+ uint32_t& e = expressionNumbering[exp];
+ if (!e) {
+ e = nextValueNumber++;
+ valueNumbering[C] = e;
+ return e;
+ }
+
+ MemDepResult local_dep = MD->getDependency(C);
+
+ if (!local_dep.isDef() && !local_dep.isNonLocal()) {
+ valueNumbering[C] = nextValueNumber;
+ return nextValueNumber++;
+ }
+
+ if (local_dep.isDef()) {
+ CallInst* local_cdep = cast<CallInst>(local_dep.getInst());
+
+ if (local_cdep->getNumOperands() != C->getNumOperands()) {
+ valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
- } else if (Instruction *LocalDepInst = local_dep.getInst()) {
- // FIXME: INDENT PROPERLY!
- if (!isa<CallInst>(LocalDepInst)) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
-
- CallInst* local_cdep = cast<CallInst>(LocalDepInst);
-
- // FIXME: INDENT PROPERLY.
- if (local_cdep->getCalledFunction() != C->getCalledFunction() ||
- local_cdep->getNumOperands() != C->getNumOperands()) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- } else if (!C->getCalledFunction()) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- } else {
- for (unsigned i = 1; i < C->getNumOperands(); ++i) {
- uint32_t c_vn = lookup_or_add(C->getOperand(i));
- uint32_t cd_vn = lookup_or_add(local_cdep->getOperand(i));
- if (c_vn != cd_vn) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
- }
-
- uint32_t v = lookup_or_add(local_cdep);
- valueNumbering.insert(std::make_pair(V, v));
- return v;
- }
}
-
-
- SmallVector<std::pair<BasicBlock*, MemDepResult>, 32> deps;
- MD->getNonLocalDependency(C, deps);
- CallInst* cdep = 0;
-
- for (SmallVector<std::pair<BasicBlock*, MemDepResult>, 32>
- ::iterator I = deps.begin(), E = deps.end(); I != E; ++I) {
- if (I->second.isNone()) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ for (unsigned i = 1; i < C->getNumOperands(); ++i) {
+ uint32_t c_vn = lookup_or_add(C->getOperand(i));
+ uint32_t cd_vn = lookup_or_add(local_cdep->getOperand(i));
+ if (c_vn != cd_vn) {
+ valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
- } else if (Instruction *NonLocalDepInst = I->second.getInst()) {
- // FIXME: INDENT PROPERLY
- // FIXME: All duplicated with non-local case.
- if (cdep == 0 && DT->properlyDominates(I->first, C->getParent())) {
- if (CallInst* CD = dyn_cast<CallInst>(NonLocalDepInst))
- cdep = CD;
- else {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
- } else {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
}
}
-
- if (!cdep) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
+
+ uint32_t v = lookup_or_add(local_cdep);
+ valueNumbering[C] = v;
+ return v;
+ }
+
+ // Non-local case.
+ const MemoryDependenceAnalysis::NonLocalDepInfo &deps =
+ MD->getNonLocalCallDependency(CallSite(C));
+ // FIXME: call/call dependencies for readonly calls should return def, not
+ // clobber! Move the checking logic to MemDep!
+ CallInst* cdep = 0;
+
+ // Check to see if we have a single dominating call instruction that is
+ // identical to C.
+ for (unsigned i = 0, e = deps.size(); i != e; ++i) {
+ const MemoryDependenceAnalysis::NonLocalDepEntry *I = &deps[i];
+ // Ignore non-local dependencies.
+ if (I->second.isNonLocal())
+ continue;
+
+ // We don't handle non-depedencies. If we already have a call, reject
+ // instruction dependencies.
+ if (I->second.isClobber() || cdep != 0) {
+ cdep = 0;
+ break;
}
-
- // FIXME: THIS ISN'T SAFE: CONSIDER:
- // X = strlen(str)
- // if (C)
- // str[0] = 1;
- // Y = strlen(str)
- // This doesn't guarantee all-paths availability!
- if (cdep->getCalledFunction() != C->getCalledFunction() ||
- cdep->getNumOperands() != C->getNumOperands()) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- } else if (!C->getCalledFunction()) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- } else {
- for (unsigned i = 1; i < C->getNumOperands(); ++i) {
- uint32_t c_vn = lookup_or_add(C->getOperand(i));
- uint32_t cd_vn = lookup_or_add(cdep->getOperand(i));
- if (c_vn != cd_vn) {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
- }
-
- uint32_t v = lookup_or_add(cdep);
- valueNumbering.insert(std::make_pair(V, v));
- return v;
+
+ CallInst *NonLocalDepCall = dyn_cast<CallInst>(I->second.getInst());
+ // FIXME: All duplicated with non-local case.
+ if (NonLocalDepCall && DT->properlyDominates(I->first, C->getParent())){
+ cdep = NonLocalDepCall;
+ continue;
}
-
- } else {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
- return nextValueNumber++;
- }
- } else if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
- Expression e = create_expression(BO);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
- return nextValueNumber++;
- }
- } else if (CmpInst* C = dyn_cast<CmpInst>(V)) {
- Expression e = create_expression(C);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
- return nextValueNumber++;
- }
- } else if (ShuffleVectorInst* U = dyn_cast<ShuffleVectorInst>(V)) {
- Expression e = create_expression(U);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
- return nextValueNumber++;
- }
- } else if (ExtractElementInst* U = dyn_cast<ExtractElementInst>(V)) {
- Expression e = create_expression(U);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
- return nextValueNumber++;
- }
- } else if (InsertElementInst* U = dyn_cast<InsertElementInst>(V)) {
- Expression e = create_expression(U);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
- return nextValueNumber++;
+
+ cdep = 0;
+ break;
}
- } else if (SelectInst* U = dyn_cast<SelectInst>(V)) {
- Expression e = create_expression(U);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
+
+ if (!cdep) {
+ valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
- } else if (CastInst* U = dyn_cast<CastInst>(V)) {
- Expression e = create_expression(U);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
+
+ if (cdep->getNumOperands() != C->getNumOperands()) {
+ valueNumbering[C] = nextValueNumber;
return nextValueNumber++;
}
- } else if (GetElementPtrInst* U = dyn_cast<GetElementPtrInst>(V)) {
- Expression e = create_expression(U);
-
- DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
- if (EI != expressionNumbering.end()) {
- valueNumbering.insert(std::make_pair(V, EI->second));
- return EI->second;
- } else {
- expressionNumbering.insert(std::make_pair(e, nextValueNumber));
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
-
- return nextValueNumber++;
+ for (unsigned i = 1; i < C->getNumOperands(); ++i) {
+ uint32_t c_vn = lookup_or_add(C->getOperand(i));
+ uint32_t cd_vn = lookup_or_add(cdep->getOperand(i));
+ if (c_vn != cd_vn) {
+ valueNumbering[C] = nextValueNumber;
+ return nextValueNumber++;
+ }
}
+
+ uint32_t v = lookup_or_add(cdep);
+ valueNumbering[C] = v;
+ return v;
+
} else {
- valueNumbering.insert(std::make_pair(V, nextValueNumber));
+ valueNumbering[C] = nextValueNumber;
+ return nextValueNumber++;
+ }
+}
+
+/// lookup_or_add - Returns the value number for the specified value, assigning
+/// it a new number if it did not have one before.
+uint32_t ValueTable::lookup_or_add(Value *V) {
+ DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+ if (VI != valueNumbering.end())
+ return VI->second;
+
+ if (!isa<Instruction>(V)) {
+ valueNumbering[V] = nextValueNumber;
return nextValueNumber++;
}
+
+ Instruction* I = cast<Instruction>(V);
+ Expression exp;
+ switch (I->getOpcode()) {
+ case Instruction::Call:
+ return lookup_or_add_call(cast<CallInst>(I));
+ case Instruction::Add:
+ case Instruction::FAdd:
+ case Instruction::Sub:
+ case Instruction::FSub:
+ case Instruction::Mul:
+ case Instruction::FMul:
+ case Instruction::UDiv:
+ case Instruction::SDiv:
+ case Instruction::FDiv:
+ case Instruction::URem:
+ case Instruction::SRem:
+ case Instruction::FRem:
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ case Instruction::And:
+ case Instruction::Or :
+ case Instruction::Xor:
+ exp = create_expression(cast<BinaryOperator>(I));
+ break;
+ case Instruction::ICmp:
+ case Instruction::FCmp:
+ exp = create_expression(cast<CmpInst>(I));
+ break;
+ case Instruction::Trunc:
+ case Instruction::ZExt:
+ case Instruction::SExt:
+ case Instruction::FPToUI:
+ case Instruction::FPToSI:
+ case Instruction::UIToFP:
+ case Instruction::SIToFP:
+ case Instruction::FPTrunc:
+ case Instruction::FPExt:
+ case Instruction::PtrToInt:
+ case Instruction::IntToPtr:
+ case Instruction::BitCast:
+ exp = create_expression(cast<CastInst>(I));
+ break;
+ case Instruction::Select:
+ exp = create_expression(cast<SelectInst>(I));
+ break;
+ case Instruction::ExtractElement:
+ exp = create_expression(cast<ExtractElementInst>(I));
+ break;
+ case Instruction::InsertElement:
+ exp = create_expression(cast<InsertElementInst>(I));
+ break;
+ case Instruction::ShuffleVector:
+ exp = create_expression(cast<ShuffleVectorInst>(I));
+ break;
+ case Instruction::ExtractValue:
+ exp = create_expression(cast<ExtractValueInst>(I));
+ break;
+ case Instruction::InsertValue:
+ exp = create_expression(cast<InsertValueInst>(I));
+ break;
+ case Instruction::GetElementPtr:
+ exp = create_expression(cast<GetElementPtrInst>(I));
+ break;
+ default:
+ valueNumbering[V] = nextValueNumber;
+ return nextValueNumber++;
+ }
+
+ uint32_t& e = expressionNumbering[exp];
+ if (!e) e = nextValueNumber++;
+ valueNumbering[V] = e;
+ return e;
}
/// lookup - Returns the value number of the specified value. Fails if
/// the value has not yet been numbered.
-uint32_t ValueTable::lookup(Value* V) const {
+uint32_t ValueTable::lookup(Value *V) const {
DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
assert(VI != valueNumbering.end() && "Value not numbered?");
return VI->second;
}
/// erase - Remove a value from the value numbering
-void ValueTable::erase(Value* V) {
+void ValueTable::erase(Value *V) {
valueNumbering.erase(V);
}
+/// verifyRemoved - Verify that the value is removed from all internal data
+/// structures.
+void ValueTable::verifyRemoved(const Value *V) const {
+ for (DenseMap<Value*, uint32_t>::iterator
+ I = valueNumbering.begin(), E = valueNumbering.end(); I != E; ++I) {
+ assert(I->first != V && "Inst still occurs in value numbering map!");
+ }
+}
+
//===----------------------------------------------------------------------===//
-// GVN Pass
+// GVN Pass
//===----------------------------------------------------------------------===//
namespace {
- struct VISIBILITY_HIDDEN ValueNumberScope {
+ struct ValueNumberScope {
ValueNumberScope* parent;
DenseMap<uint32_t, Value*> table;
-
+
ValueNumberScope(ValueNumberScope* p) : parent(p) { }
};
}
namespace {
- class VISIBILITY_HIDDEN GVN : public FunctionPass {
+ class GVN : public FunctionPass {
bool runOnFunction(Function &F);
public:
static char ID; // Pass identification, replacement for typeid
GVN() : FunctionPass(&ID) { }
private:
+ MemoryDependenceAnalysis *MD;
+ DominatorTree *DT;
+
ValueTable VN;
DenseMap<BasicBlock*, ValueNumberScope*> localAvail;
-
- typedef DenseMap<Value*, SmallPtrSet<Instruction*, 4> > PhiMapType;
- PhiMapType phiMap;
-
-
+
// This transformation requires dominator postdominator info
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<DominatorTree>();
AU.addRequired<MemoryDependenceAnalysis>();
AU.addRequired<AliasAnalysis>();
-
+
AU.addPreserved<DominatorTree>();
AU.addPreserved<AliasAnalysis>();
}
-
+
// Helper fuctions
// FIXME: eliminate or document these better
bool processLoad(LoadInst* L,
- DenseMap<Value*, LoadInst*> &lastLoad,
SmallVectorImpl<Instruction*> &toErase);
- bool processInstruction(Instruction* I,
- DenseMap<Value*, LoadInst*>& lastSeenLoad,
+ bool processInstruction(Instruction *I,
SmallVectorImpl<Instruction*> &toErase);
bool processNonLocalLoad(LoadInst* L,
SmallVectorImpl<Instruction*> &toErase);
- bool processBlock(DomTreeNode* DTN);
- Value *GetValueForBlock(BasicBlock *BB, LoadInst* orig,
- DenseMap<BasicBlock*, Value*> &Phis,
- bool top_level = false);
+ bool processBlock(BasicBlock *BB);
void dump(DenseMap<uint32_t, Value*>& d);
bool iterateOnFunction(Function &F);
- Value* CollapsePhi(PHINode* p);
- bool isSafeReplacement(PHINode* p, Instruction* inst);
+ Value *CollapsePhi(PHINode* p);
bool performPRE(Function& F);
- Value* lookupNumber(BasicBlock* BB, uint32_t num);
- bool mergeBlockIntoPredecessor(BasicBlock* BB);
+ Value *lookupNumber(BasicBlock *BB, uint32_t num);
void cleanupGlobalSets();
+ void verifyRemoved(const Instruction *I) const;
};
-
+
char GVN::ID = 0;
}
printf("}\n");
}
-Value* GVN::CollapsePhi(PHINode* p) {
- DominatorTree &DT = getAnalysis<DominatorTree>();
- Value* constVal = p->hasConstantValue();
-
- if (!constVal) return 0;
-
- Instruction* inst = dyn_cast<Instruction>(constVal);
- if (!inst)
- return constVal;
-
- if (DT.dominates(inst, p))
- if (isSafeReplacement(p, inst))
- return inst;
- return 0;
-}
-
-bool GVN::isSafeReplacement(PHINode* p, Instruction* inst) {
+static bool isSafeReplacement(PHINode* p, Instruction *inst) {
if (!isa<PHINode>(inst))
return true;
-
+
for (Instruction::use_iterator UI = p->use_begin(), E = p->use_end();
UI != E; ++UI)
if (PHINode* use_phi = dyn_cast<PHINode>(UI))
if (use_phi->getParent() == inst->getParent())
return false;
+
+ return true;
+}
+
+Value *GVN::CollapsePhi(PHINode *PN) {
+ Value *ConstVal = PN->hasConstantValue(DT);
+ if (!ConstVal) return 0;
+
+ Instruction *Inst = dyn_cast<Instruction>(ConstVal);
+ if (!Inst)
+ return ConstVal;
+
+ if (DT->dominates(Inst, PN))
+ if (isSafeReplacement(PN, Inst))
+ return Inst;
+ return 0;
+}
+
+/// IsValueFullyAvailableInBlock - Return true if we can prove that the value
+/// we're analyzing is fully available in the specified block. As we go, keep
+/// track of which blocks we know are fully alive in FullyAvailableBlocks. This
+/// map is actually a tri-state map with the following values:
+/// 0) we know the block *is not* fully available.
+/// 1) we know the block *is* fully available.
+/// 2) we do not know whether the block is fully available or not, but we are
+/// currently speculating that it will be.
+/// 3) we are speculating for this block and have used that to speculate for
+/// other blocks.
+static bool IsValueFullyAvailableInBlock(BasicBlock *BB,
+ DenseMap<BasicBlock*, char> &FullyAvailableBlocks) {
+ // Optimistically assume that the block is fully available and check to see
+ // if we already know about this block in one lookup.
+ std::pair<DenseMap<BasicBlock*, char>::iterator, char> IV =
+ FullyAvailableBlocks.insert(std::make_pair(BB, 2));
+
+ // If the entry already existed for this block, return the precomputed value.
+ if (!IV.second) {
+ // If this is a speculative "available" value, mark it as being used for
+ // speculation of other blocks.
+ if (IV.first->second == 2)
+ IV.first->second = 3;
+ return IV.first->second != 0;
+ }
+
+ // Otherwise, see if it is fully available in all predecessors.
+ pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
+
+ // If this block has no predecessors, it isn't live-in here.
+ if (PI == PE)
+ goto SpeculationFailure;
+
+ for (; PI != PE; ++PI)
+ // If the value isn't fully available in one of our predecessors, then it
+ // isn't fully available in this block either. Undo our previous
+ // optimistic assumption and bail out.
+ if (!IsValueFullyAvailableInBlock(*PI, FullyAvailableBlocks))
+ goto SpeculationFailure;
+
+ return true;
+
+// SpeculationFailure - If we get here, we found out that this is not, after
+// all, a fully-available block. We have a problem if we speculated on this and
+// used the speculation to mark other blocks as available.
+SpeculationFailure:
+ char &BBVal = FullyAvailableBlocks[BB];
+
+ // If we didn't speculate on this, just return with it set to false.
+ if (BBVal == 2) {
+ BBVal = 0;
+ return false;
+ }
+
+ // If we did speculate on this value, we could have blocks set to 1 that are
+ // incorrect. Walk the (transitive) successors of this block and mark them as
+ // 0 if set to one.
+ SmallVector<BasicBlock*, 32> BBWorklist;
+ BBWorklist.push_back(BB);
+
+ while (!BBWorklist.empty()) {
+ BasicBlock *Entry = BBWorklist.pop_back_val();
+ // Note that this sets blocks to 0 (unavailable) if they happen to not
+ // already be in FullyAvailableBlocks. This is safe.
+ char &EntryVal = FullyAvailableBlocks[Entry];
+ if (EntryVal == 0) continue; // Already unavailable.
+
+ // Mark as unavailable.
+ EntryVal = 0;
+
+ for (succ_iterator I = succ_begin(Entry), E = succ_end(Entry); I != E; ++I)
+ BBWorklist.push_back(*I);
+ }
+
+ return false;
+}
+
+
+/// CanCoerceMustAliasedValueToLoad - Return true if
+/// CoerceAvailableValueToLoadType will succeed.
+static bool CanCoerceMustAliasedValueToLoad(Value *StoredVal,
+ const Type *LoadTy,
+ const TargetData &TD) {
+ // If the loaded or stored value is an first class array or struct, don't try
+ // to transform them. We need to be able to bitcast to integer.
+ if (isa<StructType>(LoadTy) || isa<ArrayType>(LoadTy) ||
+ isa<StructType>(StoredVal->getType()) ||
+ isa<ArrayType>(StoredVal->getType()))
+ return false;
+
+ // The store has to be at least as big as the load.
+ if (TD.getTypeSizeInBits(StoredVal->getType()) <
+ TD.getTypeSizeInBits(LoadTy))
+ return false;
return true;
}
+
-/// GetValueForBlock - Get the value to use within the specified basic block.
-/// available values are in Phis.
-Value *GVN::GetValueForBlock(BasicBlock *BB, LoadInst* orig,
- DenseMap<BasicBlock*, Value*> &Phis,
- bool top_level) {
-
- // If we have already computed this value, return the previously computed val.
- DenseMap<BasicBlock*, Value*>::iterator V = Phis.find(BB);
- if (V != Phis.end() && !top_level) return V->second;
+/// CoerceAvailableValueToLoadType - If we saw a store of a value to memory, and
+/// then a load from a must-aliased pointer of a different type, try to coerce
+/// the stored value. LoadedTy is the type of the load we want to replace and
+/// InsertPt is the place to insert new instructions.
+///
+/// If we can't do it, return null.
+static Value *CoerceAvailableValueToLoadType(Value *StoredVal,
+ const Type *LoadedTy,
+ Instruction *InsertPt,
+ const TargetData &TD) {
+ if (!CanCoerceMustAliasedValueToLoad(StoredVal, LoadedTy, TD))
+ return 0;
- // If the block is unreachable, just return undef, since this path
- // can't actually occur at runtime.
- if (!getAnalysis<DominatorTree>().isReachableFromEntry(BB))
- return Phis[BB] = UndefValue::get(orig->getType());
+ const Type *StoredValTy = StoredVal->getType();
- BasicBlock* singlePred = BB->getSinglePredecessor();
- if (singlePred) {
- Value *ret = GetValueForBlock(singlePred, orig, Phis);
- Phis[BB] = ret;
- return ret;
- }
+ uint64_t StoreSize = TD.getTypeSizeInBits(StoredValTy);
+ uint64_t LoadSize = TD.getTypeSizeInBits(LoadedTy);
- // Otherwise, the idom is the loop, so we need to insert a PHI node. Do so
- // now, then get values to fill in the incoming values for the PHI.
- PHINode *PN = PHINode::Create(orig->getType(), orig->getName()+".rle",
- BB->begin());
- PN->reserveOperandSpace(std::distance(pred_begin(BB), pred_end(BB)));
+ // If the store and reload are the same size, we can always reuse it.
+ if (StoreSize == LoadSize) {
+ if (isa<PointerType>(StoredValTy) && isa<PointerType>(LoadedTy)) {
+ // Pointer to Pointer -> use bitcast.
+ return new BitCastInst(StoredVal, LoadedTy, "", InsertPt);
+ }
+
+ // Convert source pointers to integers, which can be bitcast.
+ if (isa<PointerType>(StoredValTy)) {
+ StoredValTy = TD.getIntPtrType(StoredValTy->getContext());
+ StoredVal = new PtrToIntInst(StoredVal, StoredValTy, "", InsertPt);
+ }
+
+ const Type *TypeToCastTo = LoadedTy;
+ if (isa<PointerType>(TypeToCastTo))
+ TypeToCastTo = TD.getIntPtrType(StoredValTy->getContext());
+
+ if (StoredValTy != TypeToCastTo)
+ StoredVal = new BitCastInst(StoredVal, TypeToCastTo, "", InsertPt);
+
+ // Cast to pointer if the load needs a pointer type.
+ if (isa<PointerType>(LoadedTy))
+ StoredVal = new IntToPtrInst(StoredVal, LoadedTy, "", InsertPt);
+
+ return StoredVal;
+ }
- if (Phis.count(BB) == 0)
- Phis.insert(std::make_pair(BB, PN));
+ // If the loaded value is smaller than the available value, then we can
+ // extract out a piece from it. If the available value is too small, then we
+ // can't do anything.
+ assert(StoreSize >= LoadSize && "CanCoerceMustAliasedValueToLoad fail");
- // Fill in the incoming values for the block.
- for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
- Value* val = GetValueForBlock(*PI, orig, Phis);
- PN->addIncoming(val, *PI);
+ // Convert source pointers to integers, which can be manipulated.
+ if (isa<PointerType>(StoredValTy)) {
+ StoredValTy = TD.getIntPtrType(StoredValTy->getContext());
+ StoredVal = new PtrToIntInst(StoredVal, StoredValTy, "", InsertPt);
}
- AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
- AA.copyValue(orig, PN);
+ // Convert vectors and fp to integer, which can be manipulated.
+ if (!isa<IntegerType>(StoredValTy)) {
+ StoredValTy = IntegerType::get(StoredValTy->getContext(), StoreSize);
+ StoredVal = new BitCastInst(StoredVal, StoredValTy, "", InsertPt);
+ }
- // Attempt to collapse PHI nodes that are trivially redundant
- Value* v = CollapsePhi(PN);
- if (!v) {
- // Cache our phi construction results
- phiMap[orig->getPointerOperand()].insert(PN);
- return PN;
+ // If this is a big-endian system, we need to shift the value down to the low
+ // bits so that a truncate will work.
+ if (TD.isBigEndian()) {
+ Constant *Val = ConstantInt::get(StoredVal->getType(), StoreSize-LoadSize);
+ StoredVal = BinaryOperator::CreateLShr(StoredVal, Val, "tmp", InsertPt);
}
+
+ // Truncate the integer to the right size now.
+ const Type *NewIntTy = IntegerType::get(StoredValTy->getContext(), LoadSize);
+ StoredVal = new TruncInst(StoredVal, NewIntTy, "trunc", InsertPt);
+
+ if (LoadedTy == NewIntTy)
+ return StoredVal;
+
+ // If the result is a pointer, inttoptr.
+ if (isa<PointerType>(LoadedTy))
+ return new IntToPtrInst(StoredVal, LoadedTy, "inttoptr", InsertPt);
+
+ // Otherwise, bitcast.
+ return new BitCastInst(StoredVal, LoadedTy, "bitcast", InsertPt);
+}
+
+/// GetBaseWithConstantOffset - Analyze the specified pointer to see if it can
+/// be expressed as a base pointer plus a constant offset. Return the base and
+/// offset to the caller.
+static Value *GetBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
+ const TargetData &TD) {
+ Operator *PtrOp = dyn_cast<Operator>(Ptr);
+ if (PtrOp == 0) return Ptr;
+
+ // Just look through bitcasts.
+ if (PtrOp->getOpcode() == Instruction::BitCast)
+ return GetBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD);
+
+ // If this is a GEP with constant indices, we can look through it.
+ GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp);
+ if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr;
+
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E;
+ ++I, ++GTI) {
+ ConstantInt *OpC = cast<ConstantInt>(*I);
+ if (OpC->isZero()) continue;
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
+ // Handle a struct and array indices which add their offset to the pointer.
+ if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
+ Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
+ } else {
+ uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
+ Offset += OpC->getSExtValue()*Size;
+ }
+ }
+
+ // Re-sign extend from the pointer size if needed to get overflow edge cases
+ // right.
+ unsigned PtrSize = TD.getPointerSizeInBits();
+ if (PtrSize < 64)
+ Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
+
+ return GetBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
+}
- MD.removeInstruction(PN);
- PN->replaceAllUsesWith(v);
- for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
- E = Phis.end(); I != E; ++I)
- if (I->second == PN)
- I->second = v;
+/// AnalyzeLoadFromClobberingStore - This function is called when we have a
+/// memdep query of a load that ends up being a clobbering store. This means
+/// that the store *may* provide bits used by the load but we can't be sure
+/// because the pointers don't mustalias. Check this case to see if there is
+/// anything more we can do before we give up. This returns -1 if we have to
+/// give up, or a byte number in the stored value of the piece that feeds the
+/// load.
+static int AnalyzeLoadFromClobberingStore(LoadInst *L, StoreInst *DepSI,
+ const TargetData &TD) {
+ // If the loaded or stored value is an first class array or struct, don't try
+ // to transform them. We need to be able to bitcast to integer.
+ if (isa<StructType>(L->getType()) || isa<ArrayType>(L->getType()) ||
+ isa<StructType>(DepSI->getOperand(0)->getType()) ||
+ isa<ArrayType>(DepSI->getOperand(0)->getType()))
+ return -1;
+
+ int64_t StoreOffset = 0, LoadOffset = 0;
+ Value *StoreBase =
+ GetBaseWithConstantOffset(DepSI->getPointerOperand(), StoreOffset, TD);
+ Value *LoadBase =
+ GetBaseWithConstantOffset(L->getPointerOperand(), LoadOffset, TD);
+ if (StoreBase != LoadBase)
+ return -1;
+
+ // If the load and store are to the exact same address, they should have been
+ // a must alias. AA must have gotten confused.
+ // FIXME: Study to see if/when this happens.
+ if (LoadOffset == StoreOffset) {
+#if 0
+ errs() << "STORE/LOAD DEP WITH COMMON POINTER MISSED:\n"
+ << "Base = " << *StoreBase << "\n"
+ << "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
+ << "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
+ << "Load Ptr = " << *L->getPointerOperand() << "\n"
+ << "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
+ errs() << "'" << L->getParent()->getParent()->getName() << "'"
+ << *L->getParent();
+#endif
+ return -1;
+ }
+
+ // If the load and store don't overlap at all, the store doesn't provide
+ // anything to the load. In this case, they really don't alias at all, AA
+ // must have gotten confused.
+ // FIXME: Investigate cases where this bails out, e.g. rdar://7238614. Then
+ // remove this check, as it is duplicated with what we have below.
+ uint64_t StoreSize = TD.getTypeSizeInBits(DepSI->getOperand(0)->getType());
+ uint64_t LoadSize = TD.getTypeSizeInBits(L->getType());
+
+ if ((StoreSize & 7) | (LoadSize & 7))
+ return -1;
+ StoreSize >>= 3; // Convert to bytes.
+ LoadSize >>= 3;
+
+
+ bool isAAFailure = false;
+ if (StoreOffset < LoadOffset) {
+ isAAFailure = StoreOffset+int64_t(StoreSize) <= LoadOffset;
+ } else {
+ isAAFailure = LoadOffset+int64_t(LoadSize) <= StoreOffset;
+ }
+ if (isAAFailure) {
+#if 0
+ errs() << "STORE LOAD DEP WITH COMMON BASE:\n"
+ << "Base = " << *StoreBase << "\n"
+ << "Store Ptr = " << *DepSI->getPointerOperand() << "\n"
+ << "Store Offs = " << StoreOffset << " - " << *DepSI << "\n"
+ << "Load Ptr = " << *L->getPointerOperand() << "\n"
+ << "Load Offs = " << LoadOffset << " - " << *L << "\n\n";
+ errs() << "'" << L->getParent()->getParent()->getName() << "'"
+ << *L->getParent();
+#endif
+ return -1;
+ }
+
+ // If the Load isn't completely contained within the stored bits, we don't
+ // have all the bits to feed it. We could do something crazy in the future
+ // (issue a smaller load then merge the bits in) but this seems unlikely to be
+ // valuable.
+ if (StoreOffset > LoadOffset ||
+ StoreOffset+StoreSize < LoadOffset+LoadSize)
+ return -1;
+
+ // Okay, we can do this transformation. Return the number of bytes into the
+ // store that the load is.
+ return LoadOffset-StoreOffset;
+}
+
- PN->eraseFromParent();
+/// GetStoreValueForLoad - This function is called when we have a
+/// memdep query of a load that ends up being a clobbering store. This means
+/// that the store *may* provide bits used by the load but we can't be sure
+/// because the pointers don't mustalias. Check this case to see if there is
+/// anything more we can do before we give up.
+static Value *GetStoreValueForLoad(Value *SrcVal, unsigned Offset,
+ const Type *LoadTy,
+ Instruction *InsertPt, const TargetData &TD){
+ LLVMContext &Ctx = SrcVal->getType()->getContext();
+
+ uint64_t StoreSize = TD.getTypeSizeInBits(SrcVal->getType())/8;
+ uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy)/8;
+
+
+ // Compute which bits of the stored value are being used by the load. Convert
+ // to an integer type to start with.
+ if (isa<PointerType>(SrcVal->getType()))
+ SrcVal = new PtrToIntInst(SrcVal, TD.getIntPtrType(Ctx), "tmp", InsertPt);
+ if (!isa<IntegerType>(SrcVal->getType()))
+ SrcVal = new BitCastInst(SrcVal, IntegerType::get(Ctx, StoreSize*8),
+ "tmp", InsertPt);
+
+ // Shift the bits to the least significant depending on endianness.
+ unsigned ShiftAmt;
+ if (TD.isLittleEndian()) {
+ ShiftAmt = Offset*8;
+ } else {
+ ShiftAmt = (StoreSize-LoadSize-Offset)*8;
+ }
+
+ if (ShiftAmt)
+ SrcVal = BinaryOperator::CreateLShr(SrcVal,
+ ConstantInt::get(SrcVal->getType(), ShiftAmt), "tmp", InsertPt);
+
+ if (LoadSize != StoreSize)
+ SrcVal = new TruncInst(SrcVal, IntegerType::get(Ctx, LoadSize*8),
+ "tmp", InsertPt);
+
+ return CoerceAvailableValueToLoadType(SrcVal, LoadTy, InsertPt, TD);
+}
+
+struct AvailableValueInBlock {
+ /// BB - The basic block in question.
+ BasicBlock *BB;
+ /// V - The value that is live out of the block.
+ Value *V;
+ /// Offset - The byte offset in V that is interesting for the load query.
+ unsigned Offset;
+
+ static AvailableValueInBlock get(BasicBlock *BB, Value *V,
+ unsigned Offset = 0) {
+ AvailableValueInBlock Res;
+ Res.BB = BB;
+ Res.V = V;
+ Res.Offset = Offset;
+ return Res;
+ }
+};
+
+/// ConstructSSAForLoadSet - Given a set of loads specified by ValuesPerBlock,
+/// construct SSA form, allowing us to eliminate LI. This returns the value
+/// that should be used at LI's definition site.
+static Value *ConstructSSAForLoadSet(LoadInst *LI,
+ SmallVectorImpl<AvailableValueInBlock> &ValuesPerBlock,
+ const TargetData *TD,
+ AliasAnalysis *AA) {
+ SmallVector<PHINode*, 8> NewPHIs;
+ SSAUpdater SSAUpdate(&NewPHIs);
+ SSAUpdate.Initialize(LI);
+
+ const Type *LoadTy = LI->getType();
+
+ for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
+ BasicBlock *BB = ValuesPerBlock[i].BB;
+ Value *AvailableVal = ValuesPerBlock[i].V;
+ unsigned Offset = ValuesPerBlock[i].Offset;
+
+ if (SSAUpdate.HasValueForBlock(BB))
+ continue;
+
+ if (AvailableVal->getType() != LoadTy) {
+ assert(TD && "Need target data to handle type mismatch case");
+ AvailableVal = GetStoreValueForLoad(AvailableVal, Offset, LoadTy,
+ BB->getTerminator(), *TD);
+
+ if (Offset) {
+ DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\n"
+ << *ValuesPerBlock[i].V << '\n'
+ << *AvailableVal << '\n' << "\n\n\n");
+ }
+
+
+ DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\n"
+ << *ValuesPerBlock[i].V << '\n'
+ << *AvailableVal << '\n' << "\n\n\n");
+ }
+
+ SSAUpdate.AddAvailableValue(BB, AvailableVal);
+ }
+
+ // Perform PHI construction.
+ Value *V = SSAUpdate.GetValueInMiddleOfBlock(LI->getParent());
+
+ // If new PHI nodes were created, notify alias analysis.
+ if (isa<PointerType>(V->getType()))
+ for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
+ AA->copyValue(LI, NewPHIs[i]);
- Phis[BB] = v;
- return v;
+ return V;
}
/// processNonLocalLoad - Attempt to eliminate a load whose dependencies are
/// non-local by performing PHI construction.
-bool GVN::processNonLocalLoad(LoadInst* L,
+bool GVN::processNonLocalLoad(LoadInst *LI,
SmallVectorImpl<Instruction*> &toErase) {
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
-
- // Find the non-local dependencies of the load
- SmallVector<std::pair<BasicBlock*, MemDepResult>, 32> deps;
- MD.getNonLocalDependency(L, deps);
-
+ // Find the non-local dependencies of the load.
+ SmallVector<MemoryDependenceAnalysis::NonLocalDepEntry, 64> Deps;
+ MD->getNonLocalPointerDependency(LI->getOperand(0), true, LI->getParent(),
+ Deps);
+ //DEBUG(errs() << "INVESTIGATING NONLOCAL LOAD: "
+ // << Deps.size() << *LI << '\n');
+
// If we had to process more than one hundred blocks to find the
// dependencies, this load isn't worth worrying about. Optimizing
// it will be too expensive.
- if (deps.size() > 100)
+ if (Deps.size() > 100)
return false;
+
+ // If we had a phi translation failure, we'll have a single entry which is a
+ // clobber in the current block. Reject this early.
+ if (Deps.size() == 1 && Deps[0].second.isClobber()) {
+ DEBUG(
+ errs() << "GVN: non-local load ";
+ WriteAsOperand(errs(), LI);
+ errs() << " is clobbered by " << *Deps[0].second.getInst() << '\n';
+ );
+ return false;
+ }
+
+ // Filter out useless results (non-locals, etc). Keep track of the blocks
+ // where we have a value available in repl, also keep track of whether we see
+ // dependencies that produce an unknown value for the load (such as a call
+ // that could potentially clobber the load).
+ SmallVector<AvailableValueInBlock, 16> ValuesPerBlock;
+ SmallVector<BasicBlock*, 16> UnavailableBlocks;
+
+ const TargetData *TD = 0;
- BasicBlock *EntryBlock = &L->getParent()->getParent()->getEntryBlock();
-
- DenseMap<BasicBlock*, Value*> repl;
-
- // Filter out useless results (non-locals, etc)
- for (SmallVector<std::pair<BasicBlock*, MemDepResult>, 32>::iterator
- I = deps.begin(), E = deps.end(); I != E; ++I) {
- if (I->second.isNone()) {
- repl[I->first] = UndefValue::get(L->getType());
+ for (unsigned i = 0, e = Deps.size(); i != e; ++i) {
+ BasicBlock *DepBB = Deps[i].first;
+ MemDepResult DepInfo = Deps[i].second;
+
+ if (DepInfo.isClobber()) {
+ // If the dependence is to a store that writes to a superset of the bits
+ // read by the load, we can extract the bits we need for the load from the
+ // stored value.
+ if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInfo.getInst())) {
+ if (TD == 0)
+ TD = getAnalysisIfAvailable<TargetData>();
+ if (TD) {
+ int Offset = AnalyzeLoadFromClobberingStore(LI, DepSI, *TD);
+ if (Offset != -1) {
+ ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
+ DepSI->getOperand(0),
+ Offset));
+ continue;
+ }
+ }
+ }
+
+ // FIXME: Handle memset/memcpy.
+ UnavailableBlocks.push_back(DepBB);
continue;
}
-
- if (I->second.isNonLocal()) {
- // If this is a non-local dependency in the entry block, then we depend on
- // the value live-in at the start of the function. We could insert a load
- // in the entry block to get this, but for now we'll just bail out.
- // FIXME: Consider emitting a load in the entry block to catch this case!
- if (I->first == EntryBlock)
- return false;
+
+ Instruction *DepInst = DepInfo.getInst();
+
+ // Loading the allocation -> undef.
+ if (isa<AllocaInst>(DepInst) || isMalloc(DepInst)) {
+ ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
+ UndefValue::get(LI->getType())));
continue;
}
-
- if (StoreInst* S = dyn_cast<StoreInst>(I->second.getInst())) {
- if (S->getPointerOperand() != L->getPointerOperand())
- return false;
- repl[I->first] = S->getOperand(0);
- } else if (LoadInst* LD = dyn_cast<LoadInst>(I->second.getInst())) {
- if (LD->getPointerOperand() != L->getPointerOperand())
- return false;
- repl[I->first] = LD;
- } else {
- return false;
+
+ if (StoreInst *S = dyn_cast<StoreInst>(DepInst)) {
+ // Reject loads and stores that are to the same address but are of
+ // different types if we have to.
+ if (S->getOperand(0)->getType() != LI->getType()) {
+ if (TD == 0)
+ TD = getAnalysisIfAvailable<TargetData>();
+
+ // If the stored value is larger or equal to the loaded value, we can
+ // reuse it.
+ if (TD == 0 || !CanCoerceMustAliasedValueToLoad(S->getOperand(0),
+ LI->getType(), *TD)) {
+ UnavailableBlocks.push_back(DepBB);
+ continue;
+ }
+ }
+
+ ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
+ S->getOperand(0)));
+ continue;
}
- }
-
- // Use cached PHI construction information from previous runs
- SmallPtrSet<Instruction*, 4>& p = phiMap[L->getPointerOperand()];
- for (SmallPtrSet<Instruction*, 4>::iterator I = p.begin(), E = p.end();
- I != E; ++I) {
- if ((*I)->getParent() == L->getParent()) {
- MD.removeInstruction(L);
- L->replaceAllUsesWith(*I);
- toErase.push_back(L);
- NumGVNLoad++;
- return true;
+
+ if (LoadInst *LD = dyn_cast<LoadInst>(DepInst)) {
+ // If the types mismatch and we can't handle it, reject reuse of the load.
+ if (LD->getType() != LI->getType()) {
+ if (TD == 0)
+ TD = getAnalysisIfAvailable<TargetData>();
+
+ // If the stored value is larger or equal to the loaded value, we can
+ // reuse it.
+ if (TD == 0 || !CanCoerceMustAliasedValueToLoad(LD, LI->getType(),*TD)){
+ UnavailableBlocks.push_back(DepBB);
+ continue;
+ }
+ }
+ ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB, LD));
+ continue;
}
- repl.insert(std::make_pair((*I)->getParent(), *I));
+ UnavailableBlocks.push_back(DepBB);
+ continue;
+ }
+
+ // If we have no predecessors that produce a known value for this load, exit
+ // early.
+ if (ValuesPerBlock.empty()) return false;
+
+ // If all of the instructions we depend on produce a known value for this
+ // load, then it is fully redundant and we can use PHI insertion to compute
+ // its value. Insert PHIs and remove the fully redundant value now.
+ if (UnavailableBlocks.empty()) {
+ DEBUG(errs() << "GVN REMOVING NONLOCAL LOAD: " << *LI << '\n');
+
+ // Perform PHI construction.
+ Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD,
+ VN.getAliasAnalysis());
+ LI->replaceAllUsesWith(V);
+
+ if (isa<PHINode>(V))
+ V->takeName(LI);
+ if (isa<PointerType>(V->getType()))
+ MD->invalidateCachedPointerInfo(V);
+ toErase.push_back(LI);
+ NumGVNLoad++;
+ return true;
+ }
+
+ if (!EnablePRE || !EnableLoadPRE)
+ return false;
+
+ // Okay, we have *some* definitions of the value. This means that the value
+ // is available in some of our (transitive) predecessors. Lets think about
+ // doing PRE of this load. This will involve inserting a new load into the
+ // predecessor when it's not available. We could do this in general, but
+ // prefer to not increase code size. As such, we only do this when we know
+ // that we only have to insert *one* load (which means we're basically moving
+ // the load, not inserting a new one).
+
+ SmallPtrSet<BasicBlock *, 4> Blockers;
+ for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
+ Blockers.insert(UnavailableBlocks[i]);
+
+ // Lets find first basic block with more than one predecessor. Walk backwards
+ // through predecessors if needed.
+ BasicBlock *LoadBB = LI->getParent();
+ BasicBlock *TmpBB = LoadBB;
+
+ bool isSinglePred = false;
+ bool allSingleSucc = true;
+ while (TmpBB->getSinglePredecessor()) {
+ isSinglePred = true;
+ TmpBB = TmpBB->getSinglePredecessor();
+ if (!TmpBB) // If haven't found any, bail now.
+ return false;
+ if (TmpBB == LoadBB) // Infinite (unreachable) loop.
+ return false;
+ if (Blockers.count(TmpBB))
+ return false;
+ if (TmpBB->getTerminator()->getNumSuccessors() != 1)
+ allSingleSucc = false;
+ }
+
+ assert(TmpBB);
+ LoadBB = TmpBB;
+
+ // If we have a repl set with LI itself in it, this means we have a loop where
+ // at least one of the values is LI. Since this means that we won't be able
+ // to eliminate LI even if we insert uses in the other predecessors, we will
+ // end up increasing code size. Reject this by scanning for LI.
+ for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
+ if (ValuesPerBlock[i].V == LI)
+ return false;
+
+ if (isSinglePred) {
+ bool isHot = false;
+ for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
+ if (Instruction *I = dyn_cast<Instruction>(ValuesPerBlock[i].V))
+ // "Hot" Instruction is in some loop (because it dominates its dep.
+ // instruction).
+ if (DT->dominates(LI, I)) {
+ isHot = true;
+ break;
+ }
+
+ // We are interested only in "hot" instructions. We don't want to do any
+ // mis-optimizations here.
+ if (!isHot)
+ return false;
+ }
+
+ // Okay, we have some hope :). Check to see if the loaded value is fully
+ // available in all but one predecessor.
+ // FIXME: If we could restructure the CFG, we could make a common pred with
+ // all the preds that don't have an available LI and insert a new load into
+ // that one block.
+ BasicBlock *UnavailablePred = 0;
+
+ DenseMap<BasicBlock*, char> FullyAvailableBlocks;
+ for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
+ FullyAvailableBlocks[ValuesPerBlock[i].BB] = true;
+ for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
+ FullyAvailableBlocks[UnavailableBlocks[i]] = false;
+
+ for (pred_iterator PI = pred_begin(LoadBB), E = pred_end(LoadBB);
+ PI != E; ++PI) {
+ if (IsValueFullyAvailableInBlock(*PI, FullyAvailableBlocks))
+ continue;
+
+ // If this load is not available in multiple predecessors, reject it.
+ if (UnavailablePred && UnavailablePred != *PI)
+ return false;
+ UnavailablePred = *PI;
+ }
+
+ assert(UnavailablePred != 0 &&
+ "Fully available value should be eliminated above!");
+
+ // If the loaded pointer is PHI node defined in this block, do PHI translation
+ // to get its value in the predecessor.
+ Value *LoadPtr = LI->getOperand(0)->DoPHITranslation(LoadBB, UnavailablePred);
+
+ // Make sure the value is live in the predecessor. If it was defined by a
+ // non-PHI instruction in this block, we don't know how to recompute it above.
+ if (Instruction *LPInst = dyn_cast<Instruction>(LoadPtr))
+ if (!DT->dominates(LPInst->getParent(), UnavailablePred)) {
+ DEBUG(errs() << "COULDN'T PRE LOAD BECAUSE PTR IS UNAVAILABLE IN PRED: "
+ << *LPInst << '\n' << *LI << "\n");
+ return false;
+ }
+
+ // We don't currently handle critical edges :(
+ if (UnavailablePred->getTerminator()->getNumSuccessors() != 1) {
+ DEBUG(errs() << "COULD NOT PRE LOAD BECAUSE OF CRITICAL EDGE '"
+ << UnavailablePred->getName() << "': " << *LI << '\n');
+ return false;
}
-
- // Perform PHI construction
- SmallPtrSet<BasicBlock*, 4> visited;
- Value* v = GetValueForBlock(L->getParent(), L, repl, true);
-
- MD.removeInstruction(L);
- L->replaceAllUsesWith(v);
- toErase.push_back(L);
- NumGVNLoad++;
+ // Make sure it is valid to move this load here. We have to watch out for:
+ // @1 = getelementptr (i8* p, ...
+ // test p and branch if == 0
+ // load @1
+ // It is valid to have the getelementptr before the test, even if p can be 0,
+ // as getelementptr only does address arithmetic.
+ // If we are not pushing the value through any multiple-successor blocks
+ // we do not have this case. Otherwise, check that the load is safe to
+ // put anywhere; this can be improved, but should be conservatively safe.
+ if (!allSingleSucc &&
+ !isSafeToLoadUnconditionally(LoadPtr, UnavailablePred->getTerminator()))
+ return false;
+
+ // Okay, we can eliminate this load by inserting a reload in the predecessor
+ // and using PHI construction to get the value in the other predecessors, do
+ // it.
+ DEBUG(errs() << "GVN REMOVING PRE LOAD: " << *LI << '\n');
+
+ Value *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
+ LI->getAlignment(),
+ UnavailablePred->getTerminator());
+
+ // Add the newly created load.
+ ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,NewLoad));
+
+ // Perform PHI construction.
+ Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD,
+ VN.getAliasAnalysis());
+ LI->replaceAllUsesWith(V);
+ if (isa<PHINode>(V))
+ V->takeName(LI);
+ if (isa<PointerType>(V->getType()))
+ MD->invalidateCachedPointerInfo(V);
+ toErase.push_back(LI);
+ NumPRELoad++;
return true;
}
/// processLoad - Attempt to eliminate a load, first by eliminating it
/// locally, and then attempting non-local elimination if that fails.
-bool GVN::processLoad(LoadInst *L, DenseMap<Value*, LoadInst*> &lastLoad,
- SmallVectorImpl<Instruction*> &toErase) {
- if (L->isVolatile()) {
- lastLoad[L->getPointerOperand()] = L;
+bool GVN::processLoad(LoadInst *L, SmallVectorImpl<Instruction*> &toErase) {
+ if (L->isVolatile())
return false;
- }
-
- Value* pointer = L->getPointerOperand();
- LoadInst*& last = lastLoad[pointer];
-
+
// ... to a pointer that has been loaded from before...
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
- bool removedNonLocal = false;
- MemDepResult dep = MD.getDependency(L);
- if (dep.isNonLocal() &&
- L->getParent() != &L->getParent()->getParent()->getEntryBlock()) {
- removedNonLocal = processNonLocalLoad(L, toErase);
+ MemDepResult Dep = MD->getDependency(L);
+
+ // If the value isn't available, don't do anything!
+ if (Dep.isClobber()) {
+ // FIXME: We should handle memset/memcpy/memmove as dependent instructions
+ // to forward the value if available.
+ //if (isa<MemIntrinsic>(Dep.getInst()))
+ //errs() << "LOAD DEPENDS ON MEM: " << *L << "\n" << *Dep.getInst()<<"\n\n";
+
+ // Check to see if we have something like this:
+ // store i32 123, i32* %P
+ // %A = bitcast i32* %P to i8*
+ // %B = gep i8* %A, i32 1
+ // %C = load i8* %B
+ //
+ // We could do that by recognizing if the clobber instructions are obviously
+ // a common base + constant offset, and if the previous store (or memset)
+ // completely covers this load. This sort of thing can happen in bitfield
+ // access code.
+ if (StoreInst *DepSI = dyn_cast<StoreInst>(Dep.getInst()))
+ if (const TargetData *TD = getAnalysisIfAvailable<TargetData>()) {
+ int Offset = AnalyzeLoadFromClobberingStore(L, DepSI, *TD);
+ if (Offset != -1) {
+ Value *AvailVal = GetStoreValueForLoad(DepSI->getOperand(0), Offset,
+ L->getType(), L, *TD);
+ DEBUG(errs() << "GVN COERCED STORE BITS:\n" << *DepSI << '\n'
+ << *AvailVal << '\n' << *L << "\n\n\n");
- if (!removedNonLocal)
- last = L;
+ // Replace the load!
+ L->replaceAllUsesWith(AvailVal);
+ if (isa<PointerType>(AvailVal->getType()))
+ MD->invalidateCachedPointerInfo(AvailVal);
+ toErase.push_back(L);
+ NumGVNLoad++;
+ return true;
+ }
+ }
- return removedNonLocal;
+ DEBUG(
+ // fast print dep, using operator<< on instruction would be too slow
+ errs() << "GVN: load ";
+ WriteAsOperand(errs(), L);
+ Instruction *I = Dep.getInst();
+ errs() << " is clobbered by " << *I << '\n';
+ );
+ return false;
}
-
-
- bool deletedLoad = false;
-
- // Walk up the dependency chain until we either find
- // a dependency we can use, or we can't walk any further
- while (Instruction *DepInst = dep.getInst()) {
- // ... that depends on a store ...
- if (StoreInst* S = dyn_cast<StoreInst>(DepInst)) {
- if (S->getPointerOperand() == pointer) {
- // Remove it!
- MD.removeInstruction(L);
+
+ // If it is defined in another block, try harder.
+ if (Dep.isNonLocal())
+ return processNonLocalLoad(L, toErase);
+
+ Instruction *DepInst = Dep.getInst();
+ if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInst)) {
+ Value *StoredVal = DepSI->getOperand(0);
+
+ // The store and load are to a must-aliased pointer, but they may not
+ // actually have the same type. See if we know how to reuse the stored
+ // value (depending on its type).
+ const TargetData *TD = 0;
+ if (StoredVal->getType() != L->getType()) {
+ if ((TD = getAnalysisIfAvailable<TargetData>())) {
+ StoredVal = CoerceAvailableValueToLoadType(StoredVal, L->getType(),
+ L, *TD);
+ if (StoredVal == 0)
+ return false;
- L->replaceAllUsesWith(S->getOperand(0));
- toErase.push_back(L);
- deletedLoad = true;
- NumGVNLoad++;
+ DEBUG(errs() << "GVN COERCED STORE:\n" << *DepSI << '\n' << *StoredVal
+ << '\n' << *L << "\n\n\n");
}
+ else
+ return false;
+ }
+
+ // Remove it!
+ L->replaceAllUsesWith(StoredVal);
+ if (isa<PointerType>(StoredVal->getType()))
+ MD->invalidateCachedPointerInfo(StoredVal);
+ toErase.push_back(L);
+ NumGVNLoad++;
+ return true;
+ }
+
+ if (LoadInst *DepLI = dyn_cast<LoadInst>(DepInst)) {
+ Value *AvailableVal = DepLI;
+
+ // The loads are of a must-aliased pointer, but they may not actually have
+ // the same type. See if we know how to reuse the previously loaded value
+ // (depending on its type).
+ const TargetData *TD = 0;
+ if (DepLI->getType() != L->getType()) {
+ if ((TD = getAnalysisIfAvailable<TargetData>())) {
+ AvailableVal = CoerceAvailableValueToLoadType(DepLI, L->getType(), L,*TD);
+ if (AvailableVal == 0)
+ return false;
- // Whether we removed it or not, we can't
- // go any further
- break;
- } else if (!isa<LoadInst>(DepInst)) {
- // Only want to handle loads below.
- break;
- } else if (!last) {
- // If we don't depend on a store, and we haven't
- // been loaded before, bail.
- break;
- } else if (DepInst == last) {
- // Remove it!
- MD.removeInstruction(L);
-
- L->replaceAllUsesWith(last);
- toErase.push_back(L);
- deletedLoad = true;
- NumGVNLoad++;
- break;
- } else {
- dep = MD.getDependencyFrom(L, DepInst, DepInst->getParent());
+ DEBUG(errs() << "GVN COERCED LOAD:\n" << *DepLI << "\n" << *AvailableVal
+ << "\n" << *L << "\n\n\n");
+ }
+ else
+ return false;
}
+
+ // Remove it!
+ L->replaceAllUsesWith(AvailableVal);
+ if (isa<PointerType>(DepLI->getType()))
+ MD->invalidateCachedPointerInfo(DepLI);
+ toErase.push_back(L);
+ NumGVNLoad++;
+ return true;
}
// If this load really doesn't depend on anything, then we must be loading an
// undef value. This can happen when loading for a fresh allocation with no
// intervening stores, for example.
- if (dep.isNone()) {
- // If this load depends directly on an allocation, there isn't
- // anything stored there; therefore, we can optimize this load
- // to undef.
- MD.removeInstruction(L);
+ if (isa<AllocaInst>(DepInst) || isMalloc(DepInst)) {
L->replaceAllUsesWith(UndefValue::get(L->getType()));
toErase.push_back(L);
- deletedLoad = true;
NumGVNLoad++;
+ return true;
}
- if (!deletedLoad)
- last = L;
-
- return deletedLoad;
+ return false;
}
-Value* GVN::lookupNumber(BasicBlock* BB, uint32_t num) {
+Value *GVN::lookupNumber(BasicBlock *BB, uint32_t num) {
DenseMap<BasicBlock*, ValueNumberScope*>::iterator I = localAvail.find(BB);
if (I == localAvail.end())
return 0;
-
- ValueNumberScope* locals = I->second;
-
- while (locals) {
- DenseMap<uint32_t, Value*>::iterator I = locals->table.find(num);
- if (I != locals->table.end())
+
+ ValueNumberScope *Locals = I->second;
+ while (Locals) {
+ DenseMap<uint32_t, Value*>::iterator I = Locals->table.find(num);
+ if (I != Locals->table.end())
return I->second;
- else
- locals = locals->parent;
+ Locals = Locals->parent;
}
-
+
return 0;
}
+
/// processInstruction - When calculating availability, handle an instruction
/// by inserting it into the appropriate sets
bool GVN::processInstruction(Instruction *I,
- DenseMap<Value*, LoadInst*> &lastSeenLoad,
SmallVectorImpl<Instruction*> &toErase) {
- if (LoadInst* L = dyn_cast<LoadInst>(I)) {
- bool changed = processLoad(L, lastSeenLoad, toErase);
-
- if (!changed) {
- unsigned num = VN.lookup_or_add(L);
- localAvail[I->getParent()]->table.insert(std::make_pair(num, L));
+ if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
+ bool Changed = processLoad(LI, toErase);
+
+ if (!Changed) {
+ unsigned Num = VN.lookup_or_add(LI);
+ localAvail[I->getParent()]->table.insert(std::make_pair(Num, LI));
}
-
- return changed;
+
+ return Changed;
}
-
- uint32_t nextNum = VN.getNextUnusedValueNumber();
- unsigned num = VN.lookup_or_add(I);
-
+
+ uint32_t NextNum = VN.getNextUnusedValueNumber();
+ unsigned Num = VN.lookup_or_add(I);
+
+ if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
+ localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
+
+ if (!BI->isConditional() || isa<Constant>(BI->getCondition()))
+ return false;
+
+ Value *BranchCond = BI->getCondition();
+ uint32_t CondVN = VN.lookup_or_add(BranchCond);
+
+ BasicBlock *TrueSucc = BI->getSuccessor(0);
+ BasicBlock *FalseSucc = BI->getSuccessor(1);
+
+ if (TrueSucc->getSinglePredecessor())
+ localAvail[TrueSucc]->table[CondVN] =
+ ConstantInt::getTrue(TrueSucc->getContext());
+ if (FalseSucc->getSinglePredecessor())
+ localAvail[FalseSucc]->table[CondVN] =
+ ConstantInt::getFalse(TrueSucc->getContext());
+
+ return false;
+
// Allocations are always uniquely numbered, so we can save time and memory
// by fast failing them.
- if (isa<AllocationInst>(I) || isa<TerminatorInst>(I)) {
- localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
+ } else if (isa<AllocaInst>(I) || isa<TerminatorInst>(I)) {
+ localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
return false;
}
-
+
// Collapse PHI nodes
if (PHINode* p = dyn_cast<PHINode>(I)) {
- Value* constVal = CollapsePhi(p);
-
+ Value *constVal = CollapsePhi(p);
+
if (constVal) {
- for (PhiMapType::iterator PI = phiMap.begin(), PE = phiMap.end();
- PI != PE; ++PI)
- if (PI->second.count(p))
- PI->second.erase(p);
-
p->replaceAllUsesWith(constVal);
+ if (isa<PointerType>(constVal->getType()))
+ MD->invalidateCachedPointerInfo(constVal);
+ VN.erase(p);
+
toErase.push_back(p);
} else {
- localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
+ localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
}
-
+
// If the number we were assigned was a brand new VN, then we don't
// need to do a lookup to see if the number already exists
// somewhere in the domtree: it can't!
- } else if (num == nextNum) {
- localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
-
- // Perform value-number based elimination
- } else if (Value* repl = lookupNumber(I->getParent(), num)) {
+ } else if (Num == NextNum) {
+ localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
+
+ // Perform fast-path value-number based elimination of values inherited from
+ // dominators.
+ } else if (Value *repl = lookupNumber(I->getParent(), Num)) {
// Remove it!
- MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
- MD.removeInstruction(I);
-
VN.erase(I);
I->replaceAllUsesWith(repl);
+ if (isa<PointerType>(repl->getType()))
+ MD->invalidateCachedPointerInfo(repl);
toErase.push_back(I);
return true;
+
} else {
- localAvail[I->getParent()]->table.insert(std::make_pair(num, I));
+ localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
}
-
+
return false;
}
-// GVN::runOnFunction - This is the main transformation entry point for a
-// function.
-//
+/// runOnFunction - This is the main transformation entry point for a function.
bool GVN::runOnFunction(Function& F) {
+ MD = &getAnalysis<MemoryDependenceAnalysis>();
+ DT = &getAnalysis<DominatorTree>();
VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
- VN.setMemDep(&getAnalysis<MemoryDependenceAnalysis>());
- VN.setDomTree(&getAnalysis<DominatorTree>());
-
- bool changed = false;
- bool shouldContinue = true;
-
+ VN.setMemDep(MD);
+ VN.setDomTree(DT);
+
+ bool Changed = false;
+ bool ShouldContinue = true;
+
// Merge unconditional branches, allowing PRE to catch more
// optimization opportunities.
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ) {
- BasicBlock* BB = FI;
+ BasicBlock *BB = FI;
++FI;
bool removedBlock = MergeBlockIntoPredecessor(BB, this);
if (removedBlock) NumGVNBlocks++;
-
- changed |= removedBlock;
+
+ Changed |= removedBlock;
}
-
- while (shouldContinue) {
- shouldContinue = iterateOnFunction(F);
- changed |= shouldContinue;
+
+ unsigned Iteration = 0;
+
+ while (ShouldContinue) {
+ DEBUG(errs() << "GVN iteration: " << Iteration << "\n");
+ ShouldContinue = iterateOnFunction(F);
+ Changed |= ShouldContinue;
+ ++Iteration;
}
-
+
if (EnablePRE) {
bool PREChanged = true;
while (PREChanged) {
PREChanged = performPRE(F);
- changed |= PREChanged;
+ Changed |= PREChanged;
}
}
+ // FIXME: Should perform GVN again after PRE does something. PRE can move
+ // computations into blocks where they become fully redundant. Note that
+ // we can't do this until PRE's critical edge splitting updates memdep.
+ // Actually, when this happens, we should just fully integrate PRE into GVN.
cleanupGlobalSets();
- return changed;
+ return Changed;
}
-bool GVN::processBlock(DomTreeNode* DTN) {
- BasicBlock* BB = DTN->getBlock();
-
+bool GVN::processBlock(BasicBlock *BB) {
+ // FIXME: Kill off toErase by doing erasing eagerly in a helper function (and
+ // incrementing BI before processing an instruction).
SmallVector<Instruction*, 8> toErase;
- DenseMap<Value*, LoadInst*> lastSeenLoad;
- bool changed_function = false;
-
- if (DTN->getIDom())
- localAvail[BB] =
- new ValueNumberScope(localAvail[DTN->getIDom()->getBlock()]);
- else
- localAvail[BB] = new ValueNumberScope(0);
-
+ bool ChangedFunction = false;
+
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
BI != BE;) {
- changed_function |= processInstruction(BI, lastSeenLoad, toErase);
+ ChangedFunction |= processInstruction(BI, toErase);
if (toErase.empty()) {
++BI;
continue;
}
-
+
// If we need some instructions deleted, do it now.
NumGVNInstr += toErase.size();
-
+
// Avoid iterator invalidation.
bool AtStart = BI == BB->begin();
if (!AtStart)
--BI;
for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I)
+ E = toErase.end(); I != E; ++I) {
+ DEBUG(errs() << "GVN removed: " << **I << '\n');
+ MD->removeInstruction(*I);
(*I)->eraseFromParent();
+ DEBUG(verifyRemoved(*I));
+ }
+ toErase.clear();
if (AtStart)
BI = BB->begin();
else
++BI;
-
- toErase.clear();
}
-
- return changed_function;
+
+ return ChangedFunction;
}
/// performPRE - Perform a purely local form of PRE that looks for diamond
/// control flow patterns and attempts to perform simple PRE at the join point.
bool GVN::performPRE(Function& F) {
- bool changed = false;
+ bool Changed = false;
SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
+ DenseMap<BasicBlock*, Value*> predMap;
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
- BasicBlock* CurrentBlock = *DI;
-
+ BasicBlock *CurrentBlock = *DI;
+
// Nothing to PRE in the entry block.
if (CurrentBlock == &F.getEntryBlock()) continue;
-
+
for (BasicBlock::iterator BI = CurrentBlock->begin(),
BE = CurrentBlock->end(); BI != BE; ) {
- if (isa<AllocationInst>(BI) || isa<TerminatorInst>(BI) ||
- isa<PHINode>(BI) || BI->mayReadFromMemory() ||
- BI->mayWriteToMemory()) {
- BI++;
+ Instruction *CurInst = BI++;
+
+ if (isa<AllocaInst>(CurInst) ||
+ isa<TerminatorInst>(CurInst) || isa<PHINode>(CurInst) ||
+ CurInst->getType()->isVoidTy() ||
+ CurInst->mayReadFromMemory() || CurInst->mayHaveSideEffects() ||
+ isa<DbgInfoIntrinsic>(CurInst))
continue;
- }
-
- uint32_t valno = VN.lookup(BI);
-
+
+ uint32_t ValNo = VN.lookup(CurInst);
+
// Look for the predecessors for PRE opportunities. We're
// only trying to solve the basic diamond case, where
// a value is computed in the successor and one predecessor,
// but not the other. We also explicitly disallow cases
// where the successor is its own predecessor, because they're
// more complicated to get right.
- unsigned numWith = 0;
- unsigned numWithout = 0;
- BasicBlock* PREPred = 0;
- DenseMap<BasicBlock*, Value*> predMap;
+ unsigned NumWith = 0;
+ unsigned NumWithout = 0;
+ BasicBlock *PREPred = 0;
+ predMap.clear();
+
for (pred_iterator PI = pred_begin(CurrentBlock),
PE = pred_end(CurrentBlock); PI != PE; ++PI) {
// We're not interested in PRE where the block is its
// own predecessor, on in blocks with predecessors
// that are not reachable.
if (*PI == CurrentBlock) {
- numWithout = 2;
+ NumWithout = 2;
break;
} else if (!localAvail.count(*PI)) {
- numWithout = 2;
+ NumWithout = 2;
break;
}
-
- DenseMap<uint32_t, Value*>::iterator predV =
- localAvail[*PI]->table.find(valno);
+
+ DenseMap<uint32_t, Value*>::iterator predV =
+ localAvail[*PI]->table.find(ValNo);
if (predV == localAvail[*PI]->table.end()) {
PREPred = *PI;
- numWithout++;
- } else if (predV->second == BI) {
- numWithout = 2;
+ NumWithout++;
+ } else if (predV->second == CurInst) {
+ NumWithout = 2;
} else {
predMap[*PI] = predV->second;
- numWith++;
+ NumWith++;
}
}
-
+
// Don't do PRE when it might increase code size, i.e. when
// we would need to insert instructions in more than one pred.
- if (numWithout != 1 || numWith == 0) {
- BI++;
+ if (NumWithout != 1 || NumWith == 0)
continue;
- }
-
+
// We can't do PRE safely on a critical edge, so instead we schedule
// the edge to be split and perform the PRE the next time we iterate
// on the function.
- unsigned succNum = 0;
+ unsigned SuccNum = 0;
for (unsigned i = 0, e = PREPred->getTerminator()->getNumSuccessors();
i != e; ++i)
if (PREPred->getTerminator()->getSuccessor(i) == CurrentBlock) {
- succNum = i;
+ SuccNum = i;
break;
}
-
- if (isCriticalEdge(PREPred->getTerminator(), succNum)) {
- toSplit.push_back(std::make_pair(PREPred->getTerminator(), succNum));
- changed = true;
- BI++;
+
+ if (isCriticalEdge(PREPred->getTerminator(), SuccNum)) {
+ toSplit.push_back(std::make_pair(PREPred->getTerminator(), SuccNum));
continue;
}
-
+
// Instantiate the expression the in predecessor that lacked it.
// Because we are going top-down through the block, all value numbers
// will be available in the predecessor by the time we need them. Any
// that weren't original present will have been instantiated earlier
// in this loop.
- Instruction* PREInstr = BI->clone();
+ Instruction *PREInstr = CurInst->clone();
bool success = true;
- for (unsigned i = 0; i < BI->getNumOperands(); ++i) {
- Value* op = BI->getOperand(i);
- if (isa<Argument>(op) || isa<Constant>(op) || isa<GlobalValue>(op))
- PREInstr->setOperand(i, op);
- else {
- Value* V = lookupNumber(PREPred, VN.lookup(op));
- if (!V) {
- success = false;
- break;
- } else
- PREInstr->setOperand(i, V);
+ for (unsigned i = 0, e = CurInst->getNumOperands(); i != e; ++i) {
+ Value *Op = PREInstr->getOperand(i);
+ if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
+ continue;
+
+ if (Value *V = lookupNumber(PREPred, VN.lookup(Op))) {
+ PREInstr->setOperand(i, V);
+ } else {
+ success = false;
+ break;
}
}
-
+
// Fail out if we encounter an operand that is not available in
- // the PRE predecessor. This is typically because of loads which
+ // the PRE predecessor. This is typically because of loads which
// are not value numbered precisely.
if (!success) {
delete PREInstr;
- BI++;
+ DEBUG(verifyRemoved(PREInstr));
continue;
}
-
+
PREInstr->insertBefore(PREPred->getTerminator());
- PREInstr->setName(BI->getName() + ".pre");
+ PREInstr->setName(CurInst->getName() + ".pre");
predMap[PREPred] = PREInstr;
- VN.add(PREInstr, valno);
+ VN.add(PREInstr, ValNo);
NumGVNPRE++;
-
+
// Update the availability map to include the new instruction.
- localAvail[PREPred]->table.insert(std::make_pair(valno, PREInstr));
-
+ localAvail[PREPred]->table.insert(std::make_pair(ValNo, PREInstr));
+
// Create a PHI to make the value available in this block.
- PHINode* Phi = PHINode::Create(BI->getType(),
- BI->getName() + ".pre-phi",
+ PHINode* Phi = PHINode::Create(CurInst->getType(),
+ CurInst->getName() + ".pre-phi",
CurrentBlock->begin());
for (pred_iterator PI = pred_begin(CurrentBlock),
PE = pred_end(CurrentBlock); PI != PE; ++PI)
Phi->addIncoming(predMap[*PI], *PI);
-
- VN.add(Phi, valno);
- localAvail[CurrentBlock]->table[valno] = Phi;
-
- BI->replaceAllUsesWith(Phi);
- VN.erase(BI);
-
- Instruction* erase = BI;
- BI++;
- erase->eraseFromParent();
-
- changed = true;
+
+ VN.add(Phi, ValNo);
+ localAvail[CurrentBlock]->table[ValNo] = Phi;
+
+ CurInst->replaceAllUsesWith(Phi);
+ if (isa<PointerType>(Phi->getType()))
+ MD->invalidateCachedPointerInfo(Phi);
+ VN.erase(CurInst);
+
+ DEBUG(errs() << "GVN PRE removed: " << *CurInst << '\n');
+ MD->removeInstruction(CurInst);
+ CurInst->eraseFromParent();
+ DEBUG(verifyRemoved(CurInst));
+ Changed = true;
}
}
-
+
for (SmallVector<std::pair<TerminatorInst*, unsigned>, 4>::iterator
I = toSplit.begin(), E = toSplit.end(); I != E; ++I)
SplitCriticalEdge(I->first, I->second, this);
-
- return changed || toSplit.size();
+
+ return Changed || toSplit.size();
}
-// iterateOnFunction - Executes one iteration of GVN
+/// iterateOnFunction - Executes one iteration of GVN
bool GVN::iterateOnFunction(Function &F) {
- DominatorTree &DT = getAnalysis<DominatorTree>();
-
cleanupGlobalSets();
+ for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
+ DE = df_end(DT->getRootNode()); DI != DE; ++DI) {
+ if (DI->getIDom())
+ localAvail[DI->getBlock()] =
+ new ValueNumberScope(localAvail[DI->getIDom()->getBlock()]);
+ else
+ localAvail[DI->getBlock()] = new ValueNumberScope(0);
+ }
+
// Top-down walk of the dominator tree
- bool changed = false;
- for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
- DE = df_end(DT.getRootNode()); DI != DE; ++DI)
- changed |= processBlock(*DI);
-
- return changed;
+ bool Changed = false;
+#if 0
+ // Needed for value numbering with phi construction to work.
+ ReversePostOrderTraversal<Function*> RPOT(&F);
+ for (ReversePostOrderTraversal<Function*>::rpo_iterator RI = RPOT.begin(),
+ RE = RPOT.end(); RI != RE; ++RI)
+ Changed |= processBlock(*RI);
+#else
+ for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
+ DE = df_end(DT->getRootNode()); DI != DE; ++DI)
+ Changed |= processBlock(DI->getBlock());
+#endif
+
+ return Changed;
}
void GVN::cleanupGlobalSets() {
VN.clear();
- phiMap.clear();
for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
I = localAvail.begin(), E = localAvail.end(); I != E; ++I)
delete I->second;
localAvail.clear();
}
+
+/// verifyRemoved - Verify that the specified instruction does not occur in our
+/// internal data structures.
+void GVN::verifyRemoved(const Instruction *Inst) const {
+ VN.verifyRemoved(Inst);
+
+ // Walk through the value number scope to make sure the instruction isn't
+ // ferreted away in it.
+ for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
+ I = localAvail.begin(), E = localAvail.end(); I != E; ++I) {
+ const ValueNumberScope *VNS = I->second;
+
+ while (VNS) {
+ for (DenseMap<uint32_t, Value*>::iterator
+ II = VNS->table.begin(), IE = VNS->table.end(); II != IE; ++II) {
+ assert(II->second != Inst && "Inst still in value numbering scope!");
+ }
+
+ VNS = VNS->parent;
+ }
+ }
+}
projects / oota-llvm.git / blobdiff