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-rw-r--r--lib/Transforms/IPO/GlobalOpt.cpp185
-rw-r--r--test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll2
-rw-r--r--test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll20
3 files changed, 9 insertions, 198 deletions
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index cae59b8976..4e1c23c198 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -296,165 +296,6 @@ static bool AnalyzeGlobal(const Value *V, GlobalStatus &GS,
return false;
}
-/// isLeakCheckerRoot - Is this global variable possibly used by a leak checker
-/// as a root? If so, we might not really want to eliminate the stores to it.
-static bool isLeakCheckerRoot(GlobalVariable *GV) {
- // A global variable is a root if it is a pointer, or could plausibly contain
- // a pointer. There are two challenges; one is that we could have a struct
- // the has an inner member which is a pointer. We recurse through the type to
- // detect these (up to a point). The other is that we may actually be a union
- // of a pointer and another type, and so our LLVM type is an integer which
- // gets converted into a pointer, or our type is an [i8 x #] with a pointer
- // potentially contained here.
-
- if (GV->hasPrivateLinkage())
- return false;
-
- SmallVector<Type *, 4> Types;
- Types.push_back(cast<PointerType>(GV->getType())->getElementType());
-
- unsigned Limit = 20;
- do {
- Type *Ty = Types.pop_back_val();
- switch (Ty->getTypeID()) {
- default: break;
- case Type::PointerTyID: return true;
- case Type::ArrayTyID:
- case Type::VectorTyID: {
- SequentialType *STy = cast<SequentialType>(Ty);
- Types.push_back(STy->getElementType());
- break;
- }
- case Type::StructTyID: {
- StructType *STy = cast<StructType>(Ty);
- if (STy->isOpaque()) return true;
- for (StructType::element_iterator I = STy->element_begin(),
- E = STy->element_end(); I != E; ++I) {
- Type *InnerTy = *I;
- if (isa<PointerType>(InnerTy)) return true;
- if (isa<CompositeType>(InnerTy))
- Types.push_back(InnerTy);
- }
- break;
- }
- }
- if (--Limit == 0) return true;
- } while (!Types.empty());
- return false;
-}
-
-/// Given a value that is stored to a global but never read, determine whether
-/// it's safe to remove the store and the chain of computation that feeds the
-/// store.
-static bool IsSafeComputationToRemove(Value *V) {
- do {
- if (isa<Constant>(V))
- return true;
- if (!V->hasOneUse())
- return false;
- if (isa<LoadInst>(V) || isa<Argument>(V) || isa<GlobalValue>(V))
- return false;
- if (isAllocationFn(V))
- return true;
-
- Instruction *I = cast<Instruction>(V);
- if (I->mayHaveSideEffects())
- return false;
- if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(I)) {
- if (!GEP->hasAllConstantIndices())
- return false;
- } else if (I->getNumOperands() != 1) {
- return false;
- }
-
- V = I->getOperand(0);
- } while (1);
-}
-
-/// CleanupPointerRootUsers - This GV is a pointer root. Loop over all users
-/// of the global and clean up any that obviously don't assign the global a
-/// value that isn't dynamically allocated.
-///
-static bool CleanupPointerRootUsers(GlobalVariable *GV) {
- // A brief explanation of leak checkers. The goal is to find bugs where
- // pointers are forgotten, causing an accumulating growth in memory
- // usage over time. The common strategy for leak checkers is to whitelist the
- // memory pointed to by globals at exit. This is popular because it also
- // solves another problem where the main thread of a C++ program may shut down
- // before other threads that are still expecting to use those globals. To
- // handle that case, we expect the program may create a singleton and never
- // destroy it.
-
- bool Changed = false;
-
- // If Dead[n].first is the only use of a malloc result, we can delete its
- // chain of computation and the store to the global in Dead[n].second.
- SmallVector<std::pair<Instruction *, Instruction *>, 32> Dead;
-
- // Constants can't be pointers to dynamically allocated memory.
- for (Value::use_iterator UI = GV->use_begin(), E = GV->use_end();
- UI != E;) {
- User *U = *UI++;
- if (StoreInst *SI = dyn_cast<StoreInst>(U)) {
- Value *V = SI->getValueOperand();
- if (isa<Constant>(V)) {
- Changed = true;
- SI->eraseFromParent();
- } else if (Instruction *I = dyn_cast<Instruction>(V)) {
- if (I->hasOneUse())
- Dead.push_back(std::make_pair(I, SI));
- }
- } else if (MemSetInst *MSI = dyn_cast<MemSetInst>(U)) {
- if (isa<Constant>(MSI->getValue())) {
- Changed = true;
- MSI->eraseFromParent();
- } else if (Instruction *I = dyn_cast<Instruction>(MSI->getValue())) {
- if (I->hasOneUse())
- Dead.push_back(std::make_pair(I, MSI));
- }
- } else if (MemTransferInst *MTI = dyn_cast<MemTransferInst>(U)) {
- GlobalVariable *MemSrc = dyn_cast<GlobalVariable>(MTI->getSource());
- if (MemSrc && MemSrc->isConstant()) {
- Changed = true;
- MTI->eraseFromParent();
- } else if (Instruction *I = dyn_cast<Instruction>(MemSrc)) {
- if (I->hasOneUse())
- Dead.push_back(std::make_pair(I, MTI));
- }
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(U)) {
- if (CE->use_empty()) {
- CE->destroyConstant();
- Changed = true;
- }
- } else if (Constant *C = dyn_cast<Constant>(U)) {
- if (SafeToDestroyConstant(C)) {
- C->destroyConstant();
- // This could have invalidated UI, start over from scratch.
- Dead.clear();
- CleanupPointerRootUsers(GV);
- return true;
- }
- }
- }
-
- for (int i = 0, e = Dead.size(); i != e; ++i) {
- if (IsSafeComputationToRemove(Dead[i].first)) {
- Dead[i].second->eraseFromParent();
- Instruction *I = Dead[i].first;
- do {
- Instruction *J = dyn_cast<Instruction>(I->getOperand(0));
- I->eraseFromParent();
- if (!J)
- break;
- I = J;
- } while (!isAllocationFn(I));
- I->eraseFromParent();
- }
- }
-
- return Changed;
-}
-
/// CleanupConstantGlobalUsers - We just marked GV constant. Loop over all
/// users of the global, cleaning up the obvious ones. This is largely just a
/// quick scan over the use list to clean up the easy and obvious cruft. This
@@ -971,18 +812,13 @@ static bool OptimizeAwayTrappingUsesOfLoads(GlobalVariable *GV, Constant *LV,
// If we nuked all of the loads, then none of the stores are needed either,
// nor is the global.
if (AllNonStoreUsesGone) {
- if (isLeakCheckerRoot(GV)) {
- Changed |= CleanupPointerRootUsers(GV);
- } else {
- Changed = true;
- CleanupConstantGlobalUsers(GV, 0, TD, TLI);
- }
+ DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n");
+ CleanupConstantGlobalUsers(GV, 0, TD, TLI);
if (GV->use_empty()) {
- DEBUG(dbgs() << " *** GLOBAL NOW DEAD!\n");
- Changed = true;
GV->eraseFromParent();
++NumDeleted;
}
+ Changed = true;
}
return Changed;
}
@@ -1958,15 +1794,10 @@ bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
if (!GS.isLoaded) {
DEBUG(dbgs() << "GLOBAL NEVER LOADED: " << *GV);
- bool Changed;
- if (isLeakCheckerRoot(GV)) {
- // Delete any constant stores to the global.
- Changed = CleanupPointerRootUsers(GV);
- } else {
- // Delete any stores we can find to the global. We may not be able to
- // make it completely dead though.
- Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(), TD, TLI);
- }
+ // Delete any stores we can find to the global. We may not be able to
+ // make it completely dead though.
+ bool Changed = CleanupConstantGlobalUsers(GV, GV->getInitializer(),
+ TD, TLI);
// If the global is dead now, delete it.
if (GV->use_empty()) {
@@ -2014,7 +1845,7 @@ bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
if (GV->use_empty()) {
DEBUG(dbgs() << " *** Substituting initializer allowed us to "
- << "simplify all users and delete global!\n");
+ << "simplify all users and delete global!\n");
GV->eraseFromParent();
++NumDeleted;
} else {
diff --git a/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll b/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll
index 40862bd038..54e8f90979 100644
--- a/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll
+++ b/test/Transforms/GlobalOpt/2009-11-16-BrokenPerformHeapAllocSRoA.ll
@@ -17,7 +17,7 @@ define void @test() nounwind ssp {
%2 = sext i32 %1 to i64 ; <i64> [#uses=1]
%3 = mul i64 %2, ptrtoint (%struct.strchartype* getelementptr (%struct.strchartype* null, i64 1) to i64) ; <i64> [#uses=1]
%4 = tail call i8* @malloc(i64 %3) ; <i8*> [#uses=1]
-; CHECK-NOT: call i8* @malloc(i64
+; CHECK: call i8* @malloc(i64
%5 = bitcast i8* %4 to %struct.strchartype* ; <%struct.strchartype*> [#uses=1]
store %struct.strchartype* %5, %struct.strchartype** @chartypes, align 8
ret void
diff --git a/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll b/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll
deleted file mode 100644
index 0d5cbf5333..0000000000
--- a/test/Transforms/GlobalOpt/cleanup-pointer-root-users.ll
+++ /dev/null
@@ -1,20 +0,0 @@
-; RUN: opt -globalopt -S -o - < %s | FileCheck %s
-
-@test1 = internal global i8* null
-
-define void @test1a() {
-; CHECK: @test1a
-; CHECK-NOT: store
-; CHECK-NEXT: ret void
- store i8* null, i8** @test1
- ret void
-}
-
-define void @test1b(i8* %p) {
-; CHECK: @test1b
-; CHECK-NEXT: store
-; CHECK-NEXT: ret void
- store i8* %p, i8** @test1
- ret void
-}
-
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-11-28 18:20:10 +0000