SILOptimizer: make vtable pruning less aggressive

A class which is marked as internal or public can be visible outside
of the current file, where the use of the VWT indirectly is possible.
If the VWT is modified and inlined, it is possible that the offsets will
no longer match resulting in an invalid dispatch.  Limit the pass to
when WMO is enabled or the type is private in non-WMO cases.

Author: compnerd

lib/SILOptimizer/Transforms/PruneVTables.cpp

@@ -27,10 +27,16 @@ using namespace swift;
 
 namespace {
 class PruneVTables : public SILModuleTransform {
-  void runOnVTable(SILModule *M,
-                   SILVTable *vtable) {
+  void runOnVTable(SILModule *M, SILVTable *vtable) {
     LLVM_DEBUG(llvm::dbgs() << "PruneVTables inspecting table:\n";
                vtable->print(llvm::dbgs()));
+    if (!M->isWholeModule() &&
+        vtable->getClass()->getEffectiveAccess() >= AccessLevel::FilePrivate) {
+      LLVM_DEBUG(llvm::dbgs() << "Ignoring visible table: ";
+                 vtable->print(llvm::dbgs()));
+      return;
+    }
+
     for (auto &entry : vtable->getMutableEntries()) {
 
       // We don't need to worry about entries that are overridden,

test/SILOptimizer/prune-vtables.sil

@@ -14,9 +14,9 @@ sil @PrivateA_yesOverrides : $@convention(method) (@guaranteed PrivateA) -> ()
 sil @PrivateA_isFinal      : $@convention(method) (@guaranteed PrivateA) -> ()
 
 // NOWMO-LABEL: sil_vtable PrivateA {
-// NOWMO:         #PrivateA.noOverrides{{.*}} [nonoverridden]
+// NOWMO:         #PrivateA.noOverrides{{[^[]]*}}
 // NOWMO-NOT:     #PrivateA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #PrivateA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #PrivateA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable PrivateA {
 // WMO:         #PrivateA.noOverrides{{.*}} [nonoverridden]
@@ -35,9 +35,9 @@ private class PrivateB: PrivateA {
 sil @PrivateB_yesOverrides : $@convention(method) (@guaranteed PrivateB) -> ()
 
 // NOWMO-LABEL: sil_vtable PrivateB {
-// NOWMO:         #PrivateA.noOverrides{{.*}} [nonoverridden]
+// NOWMO:         #PrivateA.noOverrides{{[^[]]*}}
 // NOWMO-NOT:     #PrivateA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #PrivateA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #PrivateA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable PrivateB {
 // WMO:         #PrivateA.noOverrides{{.*}} [nonoverridden]
@@ -62,7 +62,7 @@ sil @InternalA_isFinal      : $@convention(method) (@guaranteed InternalA) -> ()
 // NOWMO-LABEL: sil_vtable InternalA {
 // NOWMO-NOT:     #InternalA.noOverrides{{.*}} [nonoverridden]
 // NOWMO-NOT:     #InternalA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #InternalA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #InternalA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable InternalA {
 // WMO:         #InternalA.noOverrides{{.*}} [nonoverridden]
@@ -83,7 +83,7 @@ sil @InternalB_yesOverrides : $@convention(method) (@guaranteed InternalB) -> ()
 // NOWMO-LABEL: sil_vtable InternalB {
 // NOWMO-NOT:     #InternalA.noOverrides{{.*}} [nonoverridden]
 // NOWMO-NOT:     #InternalA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #InternalA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #InternalA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable InternalB {
 // WMO:         #InternalA.noOverrides{{.*}} [nonoverridden]
@@ -108,7 +108,7 @@ sil @PublicA_isFinal      : $@convention(method) (@guaranteed PublicA) -> ()
 // NOWMO-LABEL: sil_vtable PublicA {
 // NOWMO-NOT:     #PublicA.noOverrides{{.*}} [nonoverridden]
 // NOWMO-NOT:     #PublicA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #PublicA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #PublicA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable PublicA {
 // WMO:         #PublicA.noOverrides{{.*}} [nonoverridden]
@@ -129,7 +129,7 @@ sil @PublicB_yesOverrides : $@convention(method) (@guaranteed PublicB) -> ()
 // NOWMO-LABEL: sil_vtable PublicB {
 // NOWMO-NOT:     #PublicA.noOverrides{{.*}} [nonoverridden]
 // NOWMO-NOT:     #PublicA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #PublicA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #PublicA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable PublicB {
 // WMO:         #PublicA.noOverrides{{.*}} [nonoverridden]
@@ -154,7 +154,7 @@ sil @OpenA_isFinal      : $@convention(method) (@guaranteed OpenA) -> ()
 // NOWMO-LABEL: sil_vtable OpenA {
 // NOWMO-NOT:     #OpenA.noOverrides{{.*}} [nonoverridden]
 // NOWMO-NOT:     #OpenA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #OpenA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #OpenA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable OpenA {
 // WMO-NOT:     #OpenA.noOverrides{{.*}} [nonoverridden]
@@ -175,7 +175,7 @@ sil @OpenB_yesOverrides : $@convention(method) (@guaranteed OpenB) -> ()
 // NOWMO-LABEL: sil_vtable OpenB {
 // NOWMO-NOT:     #OpenA.noOverrides{{.*}} [nonoverridden]
 // NOWMO-NOT:     #OpenA.yesOverrides{{.*}} [nonoverridden]
-// NOWMO:         #OpenA.isFinal{{.*}} [nonoverridden]
+// NOWMO:         #OpenA.isFinal{{[^[]]*}}
 
 // WMO-LABEL: sil_vtable OpenB {
 // WMO-NOT:     #OpenA.noOverrides{{.*}} [nonoverridden]