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Don't build switch lookup tables for dllimport or TLS variables

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We would previously put dllimport variables in switch lookup tables, which
doesn't work because the address cannot be used in a constant initializer.
This is basically the same problem that we have in PR19955.

Putting TLS variables in switch tables also desn't work, because the
address of such a variable is not constant.

Differential Revision: http://reviews.llvm.org/D4220

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211331 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hans Wennborg
2014-06-20 00:38:12 +00:00
parent 6fda71e05e
commit 160dcf5b61
4 changed files with 92 additions and 20 deletions
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lib/IR/Constants.cpp
+33 -20
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@@ -278,35 +278,48 @@ bool Constant::canTrap() const {
return canTrapImpl(this, NonTrappingOps);
}
/// isThreadDependent - Return true if the value can vary between threads.
bool Constant::isThreadDependent() const {
SmallPtrSet<const Constant*, 64> Visited;
SmallVector<const Constant*, 64> WorkList;
WorkList.push_back(this);
Visited.insert(this);
/// Check if C contains a GlobalValue for which Predicate is true.
static bool
ConstHasGlobalValuePredicate(const Constant *C,
bool (*Predicate)(const GlobalValue *)) {
SmallPtrSet<const Constant *, 8> Visited;
SmallVector<const Constant *, 8> WorkList;
WorkList.push_back(C);
Visited.insert(C);
while (!WorkList.empty()) {
const Constant *C = WorkList.pop_back_val();
if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
if (GV->isThreadLocal())
const Constant *WorkItem = WorkList.pop_back_val();
if (const auto *GV = dyn_cast<GlobalValue>(WorkItem))
if (Predicate(GV))
return true;
}
for (unsigned I = 0, E = C->getNumOperands(); I != E; ++I) {
const Constant *D = dyn_cast<Constant>(C->getOperand(I));
if (!D)
for (const Value *Op : WorkItem->operands()) {
const Constant *ConstOp = dyn_cast<Constant>(Op);
if (!ConstOp)
continue;
if (Visited.insert(D))
WorkList.push_back(D);
if (Visited.insert(ConstOp))
WorkList.push_back(ConstOp);
}
}
return false;
}
/// isConstantUsed - Return true if the constant has users other than constant
/// exprs and other dangling things.
/// Return true if the value can vary between threads.
bool Constant::isThreadDependent() const {
auto DLLImportPredicate = [](const GlobalValue *GV) {
return GV->isThreadLocal();
};
return ConstHasGlobalValuePredicate(this, DLLImportPredicate);
}
bool Constant::isDLLImportDependent() const {
auto DLLImportPredicate = [](const GlobalValue *GV) {
return GV->hasDLLImportStorageClass();
};
return ConstHasGlobalValuePredicate(this, DLLImportPredicate);
}
/// Return true if the constant has users other than constant exprs and other
/// dangling things.
bool Constant::isConstantUsed() const {
for (const User *U : users()) {
const Constant *UC = dyn_cast<Constant>(U);