[LTO][WPD] Suppress WPD on a class if the LTO unit doesn't have the prevailing definition of this class or any of its superclass

llvm/lib/LTO/LTO.cpp

@@ -1905,7 +1905,7 @@ Error LTO::runThinLTO(AddStreamFn AddStream, FileCache Cache,
     auto IsVisibleToRegularObj = [&](StringRef name) {
       auto It = GlobalResolutions->find(name);
       return (It == GlobalResolutions->end() ||
-              It->second.VisibleOutsideSummary);
+              It->second.VisibleOutsideSummary || It->second.ExportDynamic);
     };
 
     getVisibleToRegularObjVtableGUIDs(ThinLTO.CombinedIndex,

llvm/test/ThinLTO/X86/nodevirt_exort_dynamic.ll

@@ -0,0 +1,111 @@
+; RUN: rm -rf %t && mkdir %t && cd %t
+
+; Generate unsplit module with summary for ThinLTO index-based WPD.
+; RUN: opt -thinlto-bc -o summary.o %s
+
+; RUN: llvm-dis -o - summary.o
+
+;; TODO: Implement the fix for WPD in regular or hybrid LTO, and add test coverage.
+
+; Index based WPD
+; For `_ZTI7Derived`, the 'llvm-lto2' resolution arguments specifies  `VisibleOutsideSummary` as false
+; and `ExportDynamic` as false. The callsite inside @_ZN4Base8dispatchEv
+; got devirtualized.
+; RUN: llvm-lto2 run summary.o -save-temps -pass-remarks=. \
+; RUN:   -o tmp \
+; RUN:   --whole-program-visibility-enabled-in-lto=true \
+; RUN:   --validate-all-vtables-have-type-infos=true \
+; RUN:   --all-vtables-have-type-infos=true \
+; RUN:   -r=summary.o,__cxa_pure_virtual, \
+; RUN:   -r=summary.o,_ZN8DerivedNC2Ev,x \
+; RUN:   -r=summary.o,_ZN4Base8dispatchEv,px \
+; RUN:   -r=summary.o,_ZN7DerivedC2Ev, \
+; RUN:   -r=summary.o,_ZN8DerivedN5printEv,px \
+; RUN:   -r=summary.o,_ZTS4Base, \
+; RUN:   -r=summary.o,_ZTV8DerivedN,p \
+; RUN:   -r=summary.o,_ZTI8DerivedN,p \
+; RUN:   -r=summary.o,_ZTI4Base, \
+; RUN:   -r=summary.o,_ZTS8DerivedN,p \
+; RUN:   -r=summary.o,_ZTI7Derived, \
+; RUN:   -r=summary.o,_ZTV4Base 2>&1 | FileCheck --allow-empty %s --check-prefix=REMARK
+
+; REMARK: single-impl: devirtualized a call to _ZN8DerivedN5printEv 
+
+; Index based WPD
+; For `_ZTI7Derived`, the 'llvm-lto2' resolution arguments specifies  `VisibleOutsideSummary` as false
+; and `ExportDynamic` as true. The callsite inside @_ZN4Base8dispatchEv won't
+; get devirtualized.
+; RUN: llvm-lto2  run summary.o -save-temps -pass-remarks=. \
+; RUN:   -o tmp \
+; RUN:   --whole-program-visibility-enabled-in-lto=true \
+; RUN:   --validate-all-vtables-have-type-infos=true \
+; RUN:   --all-vtables-have-type-infos=true \
+; RUN:   -r=summary.o,__cxa_pure_virtual, \
+; RUN:   -r=summary.o,_ZN8DerivedNC2Ev,x \
+; RUN:   -r=summary.o,_ZN4Base8dispatchEv,px \
+; RUN:   -r=summary.o,_ZN7DerivedC2Ev, \
+; RUN:   -r=summary.o,_ZN8DerivedN5printEv,px \
+; RUN:   -r=summary.o,_ZTS4Base, \
+; RUN:   -r=summary.o,_ZTV8DerivedN,p \
+; RUN:   -r=summary.o,_ZTI8DerivedN,p \
+; RUN:   -r=summary.o,_ZTI4Base, \
+; RUN:   -r=summary.o,_ZTS8DerivedN,p \
+; RUN:   -r=summary.o,_ZTI7Derived,d \
+; RUN:   -r=summary.o,_ZTV4Base 2>&1 | FileCheck %s --allow-empty --implicit-check-not='single-impl: devirtualized a call to'
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@_ZTV8DerivedN = linkonce_odr hidden constant { [3 x ptr] } { [3 x ptr] [ptr null, ptr @_ZTI8DerivedN, ptr @_ZN8DerivedN5printEv] }, !type !0, !type !1, !type !2, !type !3, !type !4, !type !5, !vcall_visibility !6
+@_ZTI8DerivedN = linkonce_odr hidden constant { ptr, ptr, ptr } { ptr null, ptr @_ZTS8DerivedN, ptr @_ZTI7Derived }
+@_ZTS8DerivedN = linkonce_odr hidden constant [10 x i8] c"8DerivedN\00", align 1
+@_ZTI7Derived = external constant ptr
+@_ZTV4Base = linkonce_odr hidden constant { [3 x ptr] } { [3 x ptr] [ptr null, ptr @_ZTI4Base, ptr @__cxa_pure_virtual] }, !type !0, !type !1, !vcall_visibility !6
+@_ZTI4Base = linkonce_odr hidden constant { ptr, ptr } { ptr null, ptr @_ZTS4Base }
+@_ZTS4Base = linkonce_odr hidden constant [6 x i8] c"4Base\00", align 1
+
+@llvm.used = appending global [1 x ptr] [ptr @_ZN8DerivedNC2Ev], section "llvm.metadata"
+
+define hidden void @_ZN4Base8dispatchEv(ptr %this) {
+entry:
+  %this.addr = alloca ptr
+  store ptr %this, ptr %this.addr
+  %this1 = load ptr, ptr %this.addr
+  %vtable = load ptr, ptr %this1
+  %0 = call i1 @llvm.type.test(ptr %vtable, metadata !"_ZTS7Derived")
+  call void @llvm.assume(i1 %0)
+  %vfn = getelementptr inbounds ptr, ptr %vtable, i64 0
+  %1 = load ptr, ptr %vfn
+  call void %1(ptr %this1)
+  ret void
+}
+
+define linkonce_odr hidden void @_ZN8DerivedNC2Ev(ptr %this) #0 {
+entry:
+  %this.addr = alloca ptr
+  store ptr %this, ptr %this.addr
+  %this1 = load ptr, ptr %this.addr
+  call void @_ZN7DerivedC2Ev(ptr %this1)
+  store ptr getelementptr inbounds inrange(-16, 8) ({ [3 x ptr] }, ptr @_ZTV8DerivedN, i32 0, i32 0, i32 2), ptr %this1
+  ret void
+}
+
+define linkonce_odr hidden void @_ZN8DerivedN5printEv(ptr %this) #0 {
+entry:
+  ret void
+}
+
+attributes #0 = { noinline optnone }
+
+declare void @__cxa_pure_virtual()
+declare i1 @llvm.type.test(ptr, metadata)
+declare void @llvm.assume(i1)
+declare void @_ZN7DerivedC2Ev(ptr)
+
+!0 = !{i64 16, !"_ZTS4Base"}
+!1 = !{i64 16, !"_ZTSM4BaseFvvE.virtual"}
+!2 = !{i64 16, !"_ZTS7Derived"}
+!3 = !{i64 16, !"_ZTSM7DerivedFvvE.virtual"}
+!4 = !{i64 16, !"_ZTS8DerivedN"}
+!5 = !{i64 16, !"_ZTSM8DerivedNFvvE.virtual"}
+!6 = !{i64 0}

llvm/tools/llvm-lto2/llvm-lto2.cpp

@@ -187,6 +187,18 @@ static cl::opt<bool> EnableFreestanding(
     cl::desc("Enable Freestanding (disable builtins / TLI) during LTO"),
     cl::Hidden);
 
+static cl::opt<bool> WholeProgramVisibilityEnabledInLTO(
+    "whole-program-visibility-enabled-in-lto",
+    cl::desc("Enable whole program visibility during LTO"), cl::Hidden);
+
+static cl::opt<bool> ValidateAllVtablesHaveTypeInfos(
+    "validate-all-vtables-have-type-infos",
+    cl::desc("Validate that all vtables have type infos in LTO"), cl::Hidden);
+
+static cl::opt<bool>
+    AllVtablesHaveTypeInfos("all-vtables-have-type-infos", cl::Hidden,
+                            cl::desc("All vtables have type infos"));
+
 extern cl::opt<cl::boolOrDefault> LoadBitcodeIntoNewDbgInfoFormat;
 extern cl::opt<cl::boolOrDefault> PreserveInputDbgFormat;
 
@@ -257,6 +269,8 @@ static int run(int argc, char **argv) {
         Res.VisibleToRegularObj = true;
       else if (C == 'r')
         Res.LinkerRedefined = true;
+      else if (C == 'd')
+        Res.ExportDynamic = true;
       else {
         llvm::errs() << "invalid character " << C << " in resolution: " << R
                      << '\n';
@@ -332,6 +346,13 @@ static int run(int argc, char **argv) {
   Conf.PTO.LoopVectorization = Conf.OptLevel > 1;
   Conf.PTO.SLPVectorization = Conf.OptLevel > 1;
 
+  if (WholeProgramVisibilityEnabledInLTO.getNumOccurrences() > 0)
+    Conf.HasWholeProgramVisibility = WholeProgramVisibilityEnabledInLTO;
+  if (ValidateAllVtablesHaveTypeInfos.getNumOccurrences() > 0)
+    Conf.ValidateAllVtablesHaveTypeInfos = ValidateAllVtablesHaveTypeInfos;
+  if (AllVtablesHaveTypeInfos.getNumOccurrences() > 0)
+    Conf.AllVtablesHaveTypeInfos = AllVtablesHaveTypeInfos;
+
   ThinBackend Backend;
   if (ThinLTODistributedIndexes)
     Backend = createWriteIndexesThinBackend(llvm::hardware_concurrency(Threads),