[PGO] fix prof symbol lookup bug

Patch by Rong Xu

The problem is exposed by intra-module indirect call promotion where
prof symtab is created from module which does not contain all symbols
from the program. With partial symtab, the result needs to be checked
more strictly.
 

llvm-svn: 260361

2 files changed, 7 insertions, 1 deletions

diff --git a/llvm/include/llvm/ProfileData/InstrProf.h b/llvm/include/llvm/ProfileData/InstrProf.h
index c1db9b63404..4a445d230f9 100644
--- a/llvm/include/llvm/ProfileData/InstrProf.h
+++ b/llvm/include/llvm/ProfileData/InstrProf.h
@@ -379,7 +379,7 @@ StringRef InstrProfSymtab::getFuncName(uint64_t FuncMD5Hash) {
       std::lower_bound(MD5NameMap.begin(), MD5NameMap.end(), FuncMD5Hash,
                        [](const std::pair<uint64_t, std::string> &LHS,
                           uint64_t RHS) { return LHS.first < RHS; });
-  if (Result != MD5NameMap.end())
+  if (Result != MD5NameMap.end() && Result->first == FuncMD5Hash)
     return Result->second;
   return StringRef();
 }
diff --git a/llvm/unittests/ProfileData/InstrProfTest.cpp b/llvm/unittests/ProfileData/InstrProfTest.cpp
index 3615b0a4359..e2349f4fc57 100644
--- a/llvm/unittests/ProfileData/InstrProfTest.cpp
+++ b/llvm/unittests/ProfileData/InstrProfTest.cpp
@@ -746,6 +746,12 @@ TEST_P(MaybeSparseInstrProfTest, instr_prof_symtab_test) {
   R = Symtab.getFuncName(IndexedInstrProf::ComputeHash("bar3"));
   ASSERT_EQ(StringRef("bar3"), R);
 
+  // negative tests
+  R = Symtab.getFuncName(IndexedInstrProf::ComputeHash("bar4"));
+  ASSERT_EQ(StringRef(), R);
+  R = Symtab.getFuncName(IndexedInstrProf::ComputeHash("foo4"));
+  ASSERT_EQ(StringRef(), R);
+
   // Now incrementally update the symtab
   Symtab.addFuncName("blah_1");
   Symtab.addFuncName("blah_2");