WholeProgramDevirt: Implement importing for single-impl devirtualization.
Differential Revision: https://reviews.llvm.org/D29844
llvm-svn: 297333
diff --git a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
index 09a982a..f321a8c 100644
--- a/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
+++ b/llvm/lib/Transforms/IPO/WholeProgramDevirt.cpp
@@ -445,6 +445,13 @@
void rebuildGlobal(VTableBits &B);
+ // Apply the summary resolution for Slot to all virtual calls in SlotInfo.
+ void importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo);
+
+ // If we were able to eliminate all unsafe uses for a type checked load,
+ // eliminate the associated type tests by replacing them with true.
+ void removeRedundantTypeTests();
+
bool run();
// Lower the module using the action and summary passed as command line
@@ -1103,6 +1110,34 @@
}
}
+void DevirtModule::importResolution(VTableSlot Slot, VTableSlotInfo &SlotInfo) {
+ const WholeProgramDevirtResolution &Res =
+ Summary->getTypeIdSummary(cast<MDString>(Slot.TypeID)->getString())
+ .WPDRes[Slot.ByteOffset];
+
+ if (Res.TheKind == WholeProgramDevirtResolution::SingleImpl) {
+ // The type of the function in the declaration is irrelevant because every
+ // call site will cast it to the correct type.
+ auto *SingleImpl = M.getOrInsertFunction(
+ Res.SingleImplName, Type::getVoidTy(M.getContext()), nullptr);
+
+ // This is the import phase so we should not be exporting anything.
+ bool IsExported = false;
+ applySingleImplDevirt(SlotInfo, SingleImpl, IsExported);
+ assert(!IsExported);
+ }
+}
+
+void DevirtModule::removeRedundantTypeTests() {
+ auto True = ConstantInt::getTrue(M.getContext());
+ for (auto &&U : NumUnsafeUsesForTypeTest) {
+ if (U.second == 0) {
+ U.first->replaceAllUsesWith(True);
+ U.first->eraseFromParent();
+ }
+ }
+}
+
bool DevirtModule::run() {
Function *TypeTestFunc =
M.getFunction(Intrinsic::getName(Intrinsic::type_test));
@@ -1125,6 +1160,17 @@
if (TypeCheckedLoadFunc)
scanTypeCheckedLoadUsers(TypeCheckedLoadFunc);
+ if (Action == PassSummaryAction::Import) {
+ for (auto &S : CallSlots)
+ importResolution(S.first, S.second);
+
+ removeRedundantTypeTests();
+
+ // The rest of the code is only necessary when exporting or during regular
+ // LTO, so we are done.
+ return true;
+ }
+
// Rebuild type metadata into a map for easy lookup.
std::vector<VTableBits> Bits;
DenseMap<Metadata *, std::set<TypeMemberInfo>> TypeIdMap;
@@ -1223,17 +1269,7 @@
}
}
- // If we were able to eliminate all unsafe uses for a type checked load,
- // eliminate the type test by replacing it with true.
- if (TypeCheckedLoadFunc) {
- auto True = ConstantInt::getTrue(M.getContext());
- for (auto &&U : NumUnsafeUsesForTypeTest) {
- if (U.second == 0) {
- U.first->replaceAllUsesWith(True);
- U.first->eraseFromParent();
- }
- }
- }
+ removeRedundantTypeTests();
// Rebuild each global we touched as part of virtual constant propagation to
// include the before and after bytes.