[llvm][EmbedBitcodePass] Pre-commit test for using WPD with FatLTO

This is a reduced test case from #139440.

Author: ilovepi

llvm/test/Transforms/EmbedBitcode/embed-wpd.ll

@@ -0,0 +1,32 @@
+; RUN: opt --mtriple x86_64-unknown-linux-gnu < %s -passes="embed-bitcode<thinlto>" -S | FileCheck %s
+
+; CHECK-NOT: $_ZTV3Foo = comdat any
+$_ZTV3Foo = comdat any
+
+$_ZTI3Foo = comdat any
+
+; CHECK: @_ZTV3Foo = external hidden unnamed_addr constant { [5 x ptr] }, align 8
+; CHECK: @_ZTI3Foo = linkonce_odr hidden constant { ptr, ptr, ptr } { ptr getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr @_ZTS3Foo, ptr @_ZTISt13runtime_error }, comdat, align 8
+; CHECK: @llvm.embedded.object = private constant {{.*}}, section ".llvm.lto", align 1
+; CHECK: @llvm.compiler.used = appending global [1 x ptr] [ptr @llvm.embedded.object], section "llvm.metadata"
+@_ZTV3Foo = linkonce_odr hidden unnamed_addr constant { [5 x ptr] } { [5 x ptr] [ptr null, ptr @_ZTI3Foo, ptr @_ZN3FooD2Ev, ptr @_ZN3FooD0Ev, ptr @_ZNKSt13runtime_error4whatEv] }, comdat, align 8, !type !0, !type !1, !type !2, !type !3, !type !4, !type !5
+@_ZTI3Foo = linkonce_odr hidden constant { ptr, ptr, ptr } { ptr getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv120__si_class_type_infoE, i64 2), ptr @_ZTS3Foo, ptr @_ZTISt13runtime_error }, comdat, align 8
+@_ZTVN10__cxxabiv120__si_class_type_infoE = external global [0 x ptr]
+@_ZTS3Foo = constant [5 x i8] c"3Foo\00"
+@_ZTISt13runtime_error = external constant ptr
+
+declare void @_ZN3FooD2Ev()
+
+declare void @_ZN3FooD0Ev()
+
+declare ptr @_ZNKSt13runtime_error4whatEv()
+
+!llvm.module.flags = !{!6}
+
+!0 = !{i64 16, !"_ZTS3Foo"}
+!1 = !{i64 32, !"_ZTSM3FooKDoFPKcvE.virtual"}
+!2 = !{i64 16, !"_ZTSSt13runtime_error"}
+!3 = !{i64 32, !"_ZTSMSt13runtime_errorKDoFPKcvE.virtual"}
+!4 = !{i64 16, !"_ZTSSt9exception"}
+!5 = !{i64 32, !"_ZTSMSt9exceptionKDoFPKcvE.virtual"}
+!6 = !{i32 1, !"EnableSplitLTOUnit", i32 1}