[InstrProf] Add vtables with type metadata into symtab (#81051)

The indirect-call-promotion pass will look up the vtable to find out
the virtual function [1],
and add vtable-derived information in icall
candidate [2] for cost-benefit analysis.

[1] https://github.com/llvm/llvm-project/pull/81442/files#diff-a95d1ac8a0da69713fcb3346135d4b219f0a73920318d2549495620ea215191bR395-R416
[2] https://github.com/llvm/llvm-project/pull/81442/files#diff-a95d1ac8a0da69713fcb3346135d4b219f0a73920318d2549495620ea215191bR195-R199

1 files changed, 47 insertions, 0 deletions

diff --git a/llvm/unittests/ProfileData/InstrProfTest.cpp b/llvm/unittests/ProfileData/InstrProfTest.cpp
index 402de64..8f2c5ae 100644
--- a/llvm/unittests/ProfileData/InstrProfTest.cpp
+++ b/llvm/unittests/ProfileData/InstrProfTest.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/LLVMContext.h"
@@ -1730,6 +1732,34 @@ TEST(SymtabTest, instr_prof_symtab_module_test) {
   Function::Create(FTy, Function::WeakODRLinkage, "Wblah", M.get());
   Function::Create(FTy, Function::WeakODRLinkage, "Wbar", M.get());
 
+  // [ptr, ptr, ptr]
+  ArrayType *VTableArrayType = ArrayType::get(
+      PointerType::get(Ctx, M->getDataLayout().getDefaultGlobalsAddressSpace()),
+      3);
+  Constant *Int32TyNull =
+      llvm::ConstantExpr::getNullValue(PointerType::getUnqual(Ctx));
+  SmallVector<llvm::Type *, 1> tys = {VTableArrayType};
+  StructType *VTableType = llvm::StructType::get(Ctx, tys);
+
+  // Create two vtables in the module, one with external linkage and the other
+  // with local linkage.
+  for (auto [Name, Linkage] :
+       {std::pair{"ExternalGV", GlobalValue::ExternalLinkage},
+        {"LocalGV", GlobalValue::InternalLinkage}}) {
+    llvm::Twine FuncName(Name, StringRef("VFunc"));
+    Function *VFunc = Function::Create(FTy, Linkage, FuncName, M.get());
+    GlobalVariable *GV = new llvm::GlobalVariable(
+        *M, VTableType, /* isConstant= */ true, Linkage,
+        llvm::ConstantStruct::get(
+            VTableType,
+            {llvm::ConstantArray::get(VTableArrayType,
+                                      {Int32TyNull, Int32TyNull, VFunc})}),
+        Name);
+    // Add type metadata for the test data, since vtables with type metadata
+    // are added to symtab.
+    GV->addTypeMetadata(16, MDString::get(Ctx, Name));
+  }
+
   InstrProfSymtab ProfSymtab;
   EXPECT_THAT_ERROR(ProfSymtab.create(*M), Succeeded());
 
@@ -1751,6 +1781,23 @@ TEST(SymtabTest, instr_prof_symtab_module_test) {
     EXPECT_EQ(PGOName, PGOFuncName);
     EXPECT_THAT(PGOFuncName.str(), EndsWith(Funcs[I].str()));
   }
+
+  StringRef VTables[] = {"ExternalGV", "LocalGV"};
+  for (auto [VTableName, PGOName] : {std::pair{"ExternalGV", "ExternalGV"},
+                                     {"LocalGV", "MyModule.cpp;LocalGV"}}) {
+    GlobalVariable *GV =
+        M->getGlobalVariable(VTableName, /* AllowInternal=*/true);
+
+    // Test that ProfSymtab returns the expected name given a hash.
+    std::string IRPGOName = getPGOName(*GV);
+    EXPECT_STREQ(IRPGOName.c_str(), PGOName);
+    uint64_t GUID = IndexedInstrProf::ComputeHash(IRPGOName);
+    EXPECT_EQ(IRPGOName, ProfSymtab.getFuncOrVarName(GUID));
+    EXPECT_EQ(VTableName, getParsedIRPGOName(IRPGOName).second);
+
+    // Test that ProfSymtab returns the expected global variable
+    EXPECT_EQ(GV, ProfSymtab.getGlobalVariable(GUID));
+  }
 }
 
 // Testing symtab serialization and creator/deserialization interface