Fix llvm-symbolizer to correctly sort a symbol array and calculate symbol sizes

Sometimes, llvm-symbolizer gives wrong results due to incorrect sizes of some symbols. The reason for that was an incorrectly sorted array in computeSymbolSizes. The comparison function used subtraction of unsigned types, which is incorrect. Let's change this to return explicit -1 or 1.

Differential Revision: https://reviews.llvm.org/D26537

llvm-svn: 287028

5 files changed, 59 insertions, 12 deletions

diff --git a/llvm/include/llvm/Object/SymbolSize.h b/llvm/include/llvm/Object/SymbolSize.h
index f2ce70f4208..1a1dc875294 100644
--- a/llvm/include/llvm/Object/SymbolSize.h
+++ b/llvm/include/llvm/Object/SymbolSize.h
@@ -15,8 +15,19 @@
 
 namespace llvm {
 namespace object {
+
+struct SymEntry {
+  symbol_iterator I;
+  uint64_t Address;
+  unsigned Number;
+  unsigned SectionID;
+};
+
+int compareAddress(const SymEntry *A, const SymEntry *B);
+
 std::vector<std::pair<SymbolRef, uint64_t>>
 computeSymbolSizes(const ObjectFile &O);
+
 }
 } // namespace llvm
 
diff --git a/llvm/lib/Object/SymbolSize.cpp b/llvm/lib/Object/SymbolSize.cpp
index 1d5cd78e6d9..dd49d5f116b 100644
--- a/llvm/lib/Object/SymbolSize.cpp
+++ b/llvm/lib/Object/SymbolSize.cpp
@@ -16,19 +16,13 @@
 using namespace llvm;
 using namespace object;
 
-namespace {
-struct SymEntry {
-  symbol_iterator I;
-  uint64_t Address;
-  unsigned Number;
-  unsigned SectionID;
-};
-}
-
-static int compareAddress(const SymEntry *A, const SymEntry *B) {
+// Orders increasingly by (SectionID, Address).
+int llvm::object::compareAddress(const SymEntry *A, const SymEntry *B) {
   if (A->SectionID != B->SectionID)
-    return A->SectionID - B->SectionID;
-  return A->Address - B->Address;
+    return A->SectionID < B->SectionID ? -1 : 1;
+  if (A->Address != B->Address)
+    return A->Address < B->Address ? -1 : 1;
+  return 0;
 }
 
 static unsigned getSectionID(const ObjectFile &O, SectionRef Sec) {
diff --git a/llvm/unittests/CMakeLists.txt b/llvm/unittests/CMakeLists.txt
index 6caed0e5d19..8dbca211d02 100644
--- a/llvm/unittests/CMakeLists.txt
+++ b/llvm/unittests/CMakeLists.txt
@@ -17,6 +17,7 @@ add_subdirectory(LineEditor)
 add_subdirectory(Linker)
 add_subdirectory(MC)
 add_subdirectory(MI)
+add_subdirectory(Object)
 add_subdirectory(ObjectYAML)
 add_subdirectory(Option)
 add_subdirectory(ProfileData)
diff --git a/llvm/unittests/Object/CMakeLists.txt b/llvm/unittests/Object/CMakeLists.txt
new file mode 100644
index 00000000000..7a63c167a30
--- /dev/null
+++ b/llvm/unittests/Object/CMakeLists.txt
@@ -0,0 +1,8 @@
+set(LLVM_LINK_COMPONENTS
+  Object
+  )
+
+add_llvm_unittest(ObjectTests
+  SymbolSizeTest.cpp
+  )
+
diff --git a/llvm/unittests/Object/SymbolSizeTest.cpp b/llvm/unittests/Object/SymbolSizeTest.cpp
new file mode 100644
index 00000000000..ad9c40b986d
--- /dev/null
+++ b/llvm/unittests/Object/SymbolSizeTest.cpp
@@ -0,0 +1,33 @@
+//===- SymbolSizeTest.cpp - Tests for SymbolSize.cpp ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Object/SymbolSize.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace llvm::object;
+
+TEST(Object, SymbolSizeSort) {
+  auto it = symbol_iterator(SymbolRef());
+  std::vector<SymEntry> Syms{
+      SymEntry{it, 0xffffffff00000000ull, 1, 0},
+      SymEntry{it, 0x00ffffff00000000ull, 2, 0},
+      SymEntry{it, 0x00ffffff000000ffull, 3, 0},
+      SymEntry{it, 0x0000000100000000ull, 4, 0},
+      SymEntry{it, 0x00000000000000ffull, 5, 0},
+      SymEntry{it, 0x00000001000000ffull, 6, 0},
+      SymEntry{it, 0x000000010000ffffull, 7, 0},
+  };
+
+  array_pod_sort(Syms.begin(), Syms.end(), compareAddress);
+
+  for (unsigned I = 0, N = Syms.size(); I < N - 1; ++I) {
+    EXPECT_LE(Syms[I].Address, Syms[I + 1].Address);
+  }
+}