mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-21 18:29:46 +00:00
clean up handling of 'free', detangling it from everything else.
It can be seriously improved, but at least now it isn't intertwined with the other logic. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120377 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
parent
feea8fb6b4
commit
1ab4285b72
@ -74,6 +74,10 @@ Value *getMallocArraySize(CallInst *CI, const TargetData *TD,
|
||||
|
||||
/// isFreeCall - Returns non-null if the value is a call to the builtin free()
|
||||
const CallInst *isFreeCall(const Value *I);
|
||||
|
||||
static inline CallInst *isFreeCall(Value *I) {
|
||||
return const_cast<CallInst*>(isFreeCall((const Value*)I));
|
||||
}
|
||||
|
||||
} // End llvm namespace
|
||||
|
||||
|
@ -58,9 +58,7 @@ namespace {
|
||||
}
|
||||
|
||||
bool runOnBasicBlock(BasicBlock &BB);
|
||||
bool handleFreeWithNonTrivialDependency(const CallInst *F,
|
||||
Instruction *Inst,
|
||||
MemDepResult Dep);
|
||||
bool HandleFree(CallInst *F);
|
||||
bool handleEndBlock(BasicBlock &BB);
|
||||
bool RemoveUndeadPointers(Value *Ptr, uint64_t killPointerSize,
|
||||
BasicBlock::iterator &BBI,
|
||||
@ -124,7 +122,7 @@ static bool isElidable(Instruction *I) {
|
||||
return true;
|
||||
}
|
||||
|
||||
/// getPointerOperand - Return the pointer that is being clobbered.
|
||||
/// getPointerOperand - Return the pointer that is being written to.
|
||||
static Value *getPointerOperand(Instruction *I) {
|
||||
assert(doesClobberMemory(I));
|
||||
if (StoreInst *SI = dyn_cast<StoreInst>(I))
|
||||
@ -202,8 +200,14 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
|
||||
for (BasicBlock::iterator BBI = BB.begin(), BBE = BB.end(); BBI != BBE; ) {
|
||||
Instruction *Inst = BBI++;
|
||||
|
||||
// If we find a store or a free, get its memory dependence.
|
||||
if (!doesClobberMemory(Inst) && !isFreeCall(Inst))
|
||||
// Handle 'free' calls specially.
|
||||
if (CallInst *F = isFreeCall(Inst)) {
|
||||
MadeChange |= HandleFree(F);
|
||||
continue;
|
||||
}
|
||||
|
||||
// If we find a store, get its memory dependence.
|
||||
if (!doesClobberMemory(Inst))
|
||||
continue;
|
||||
|
||||
MemDepResult InstDep = MD.getDependency(Inst);
|
||||
@ -211,13 +215,7 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
|
||||
// Ignore non-local store liveness.
|
||||
// FIXME: cross-block DSE would be fun. :)
|
||||
if (InstDep.isNonLocal()) continue;
|
||||
|
||||
// Handle frees whose dependencies are non-trivial.
|
||||
if (const CallInst *F = isFreeCall(Inst)) {
|
||||
MadeChange |= handleFreeWithNonTrivialDependency(F, Inst, InstDep);
|
||||
continue;
|
||||
}
|
||||
|
||||
|
||||
// If we're storing the same value back to a pointer that we just
|
||||
// loaded from, then the store can be removed.
|
||||
if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
|
||||
@ -292,24 +290,25 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
|
||||
return MadeChange;
|
||||
}
|
||||
|
||||
/// handleFreeWithNonTrivialDependency - Handle frees of entire structures whose
|
||||
/// dependency is a store to a field of that structure.
|
||||
bool DSE::handleFreeWithNonTrivialDependency(const CallInst *F,
|
||||
Instruction *Inst,
|
||||
MemDepResult Dep) {
|
||||
/// HandleFree - Handle frees of entire structures whose dependency is a store
|
||||
/// to a field of that structure.
|
||||
bool DSE::HandleFree(CallInst *F) {
|
||||
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
|
||||
MemoryDependenceAnalysis &MD = getAnalysis<MemoryDependenceAnalysis>();
|
||||
|
||||
|
||||
MemDepResult Dep = MD.getDependency(F);
|
||||
do {
|
||||
if (Dep.isNonLocal()) return false;
|
||||
|
||||
Instruction *Dependency = Dep.getInst();
|
||||
if (!Dependency || !doesClobberMemory(Dependency) || !isElidable(Dependency))
|
||||
if (!doesClobberMemory(Dependency) || !isElidable(Dependency))
|
||||
return false;
|
||||
|
||||
Value *DepPointer = getPointerOperand(Dependency)->getUnderlyingObject();
|
||||
|
||||
// Check for aliasing.
|
||||
if (AA.alias(F->getArgOperand(0), 1, DepPointer, 1) !=
|
||||
AliasAnalysis::MustAlias)
|
||||
AliasAnalysis::MustAlias)
|
||||
return false;
|
||||
|
||||
// DCE instructions only used to calculate that store
|
||||
@ -321,8 +320,9 @@ bool DSE::handleFreeWithNonTrivialDependency(const CallInst *F,
|
||||
// s[0] = 0;
|
||||
// s[1] = 0; // This has just been deleted.
|
||||
// free(s);
|
||||
Dep = MD.getDependency(Inst);
|
||||
Dep = MD.getDependency(F);
|
||||
} while (!Dep.isNonLocal());
|
||||
|
||||
return true;
|
||||
}
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user