LTO hackery, make unittests pass under LTO, closes #179

test/unit/from_current.cpp

@@ -13,21 +13,24 @@
 using namespace std::literals;
 
 
-// NOTE: returning something and then return stacktrace_from_current_3(line_numbers) * 2; later helps prevent the call from
+// NOTE: returning something and then return stacktrace_multi_3(line_numbers) * rand(); is done to prevent TCO even
-// being optimized to a jmp
+// under LTO https://github.com/jeremy-rifkin/cpptrace/issues/179#issuecomment-2467302052
 CPPTRACE_FORCE_NO_INLINE int stacktrace_from_current_3(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     throw std::runtime_error("foobar");
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_from_current_2(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_from_current_3(line_numbers) * 2;
+    return stacktrace_from_current_3(line_numbers) * rand();
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_from_current_1(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_from_current_2(line_numbers) * 2;
+    return stacktrace_from_current_2(line_numbers) * rand();
 }
 
 TEST(FromCurrent, Basic) {

test/unit/from_current_z.cpp

@@ -13,27 +13,24 @@
 using namespace std::literals;
 
 
-// NOTE: returning something and then return stacktrace_from_current_3(line_numbers) * 2; later helps prevent the call from
+// NOTE: returning something and then return stacktrace_multi_3(line_numbers) * rand(); is done to prevent TCO even
-// being optimized to a jmp
+// under LTO https://github.com/jeremy-rifkin/cpptrace/issues/179#issuecomment-2467302052
 CPPTRACE_FORCE_NO_INLINE int stacktrace_from_current_z_3(std::vector<int>& line_numbers) {
-    // just here to differentiate from the non-z version to prevent ICF if LTO is being used
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
-    [[maybe_unused]] volatile int x = 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     throw std::runtime_error("foobar");
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_from_current_z_2(std::vector<int>& line_numbers) {
-    // just here to differentiate from the non-z version to prevent ICF if LTO is being used
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
-    [[maybe_unused]] volatile int x = 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_from_current_z_3(line_numbers) * 2;
+    return stacktrace_from_current_z_3(line_numbers) * rand();
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_from_current_z_1(std::vector<int>& line_numbers) {
-    // just here to differentiate from the non-z version to prevent ICF if LTO is being used
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
-    [[maybe_unused]] volatile int x = 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_from_current_z_2(line_numbers) * 2;
+    return stacktrace_from_current_z_2(line_numbers) * rand();
 }
 
 TEST(FromCurrentZ, Basic) {

test/unit/object_trace.cpp

@@ -1,3 +1,4 @@
+#include <random>
 #include <vector>
 
 #include <gtest/gtest.h>
@@ -19,6 +20,7 @@ TEST(ObjectTrace, Empty) {
 
 
 CPPTRACE_FORCE_NO_INLINE void object_basic() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     auto trace = cpptrace::generate_object_trace();
     EXPECT_FALSE(trace.empty());
     EXPECT_NE(trace.frames[0].raw_address, 0);
@@ -33,6 +35,7 @@ TEST(ObjectTrace, Basic) {
 
 
 CPPTRACE_FORCE_NO_INLINE void object_basic_resolution() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     auto line = __LINE__ + 1;
     auto trace = cpptrace::generate_object_trace().resolve();
     ASSERT_GE(trace.frames.size(), 1);
@@ -49,6 +52,7 @@ TEST(ObjectTrace, BasicResolution) {
 // TODO: dbghelp uses raw address, not object
 #ifndef _MSC_VER
 CPPTRACE_FORCE_NO_INLINE int object_resolve_3(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     auto dummy = cpptrace::generate_trace();
     auto dummy_otrace = cpptrace::generate_object_trace();
@@ -89,14 +93,18 @@ CPPTRACE_FORCE_NO_INLINE int object_resolve_3(std::vector<int>& line_numbers) {
     return 2;
 }
 
+// NOTE: returning something and then return stacktrace_multi_3(line_numbers) * rand(); is done to prevent TCO even
+// under LTO https://github.com/jeremy-rifkin/cpptrace/issues/179#issuecomment-2467302052
 CPPTRACE_FORCE_NO_INLINE int object_resolve_2(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return object_resolve_3(line_numbers) * 2;
+    return object_resolve_3(line_numbers) * rand();
 }
 
 CPPTRACE_FORCE_NO_INLINE int object_resolve_1(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return object_resolve_2(line_numbers) * 2;
+    return object_resolve_2(line_numbers) * rand();
 }
 
 TEST(ObjectTrace, Resolution) {

test/unit/raw_trace.cpp

@@ -18,6 +18,7 @@ using namespace std::literals;
 
 // NOTE: MSVC likes creating trampoline-like entries for non-static functions
 CPPTRACE_FORCE_NO_INLINE static void raw_trace_basic() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     auto raw_trace = cpptrace::generate_raw_trace();
     // look for within 90 bytes of the start of the function
     ASSERT_GE(raw_trace.frames.size(), 1);
@@ -27,6 +28,7 @@ CPPTRACE_FORCE_NO_INLINE static void raw_trace_basic() {
 
 #ifndef _MSC_VER
 CPPTRACE_FORCE_NO_INLINE void raw_trace_basic_precise() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     a:
     auto raw_trace = cpptrace::generate_raw_trace();
     b:
@@ -58,6 +60,7 @@ CPPTRACE_FORCE_NO_INLINE static void raw_trace_multi_2(
     cpptrace::frame_ptr parent_low_bound,
     cpptrace::frame_ptr parent_high_bound
 ) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     auto raw_trace = cpptrace::generate_raw_trace();
     ASSERT_GE(raw_trace.frames.size(), 2);
     EXPECT_GE(raw_trace.frames[0], reinterpret_cast<uintptr_t>(raw_trace_multi_2));
@@ -67,6 +70,7 @@ CPPTRACE_FORCE_NO_INLINE static void raw_trace_multi_2(
 }
 
 CPPTRACE_FORCE_NO_INLINE static void raw_trace_multi_1() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     auto raw_trace = cpptrace::generate_raw_trace();
     raw_trace_multi_2(reinterpret_cast<uintptr_t>(raw_trace_multi_1), reinterpret_cast<uintptr_t>(raw_trace_multi_1) + 300);
     ASSERT_GE(raw_trace.frames.size(), 1);
@@ -77,11 +81,13 @@ CPPTRACE_FORCE_NO_INLINE static void raw_trace_multi_1() {
 std::vector<std::pair<cpptrace::frame_ptr, cpptrace::frame_ptr>> parents;
 
 CPPTRACE_FORCE_NO_INLINE void record_parent(uintptr_t low_bound, uintptr_t high_bound) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     parents.insert(parents.begin(), {low_bound, high_bound});
 }
 
 #ifndef _MSC_VER
 CPPTRACE_FORCE_NO_INLINE void raw_trace_multi_precise_3() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     a:
     auto raw_trace = cpptrace::generate_raw_trace();
     b:
@@ -102,6 +108,7 @@ CPPTRACE_FORCE_NO_INLINE void raw_trace_multi_precise_3() {
 }
 
 CPPTRACE_FORCE_NO_INLINE void raw_trace_multi_precise_2() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     a:
     auto raw_trace = cpptrace::generate_raw_trace();
     b:
@@ -132,6 +139,7 @@ CPPTRACE_FORCE_NO_INLINE void raw_trace_multi_precise_2() {
 }
 
 CPPTRACE_FORCE_NO_INLINE void raw_trace_multi_precise_1() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     a:
     auto raw_trace = cpptrace::generate_raw_trace();
     b:

test/unit/stacktrace.cpp

@@ -25,6 +25,7 @@ TEST(Stacktrace, Empty) {
 
 
 CPPTRACE_FORCE_NO_INLINE void stacktrace_basic() {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     auto line = __LINE__ + 1;
     auto trace = cpptrace::generate_trace();
     ASSERT_GE(trace.frames.size(), 1);
@@ -39,9 +40,10 @@ TEST(Stacktrace, Basic) {
 
 
 
-// NOTE: returning something and then return stacktrace_multi_3(line_numbers) * 2; later helps prevent the call from
+// NOTE: returning something and then return stacktrace_multi_3(line_numbers) * rand(); is done to prevent TCO even
-// being optimized to a jmp
+// under LTO https://github.com/jeremy-rifkin/cpptrace/issues/179#issuecomment-2467302052
 CPPTRACE_FORCE_NO_INLINE int stacktrace_multi_3(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     auto trace = cpptrace::generate_trace();
     if(trace.frames.size() < 4) {
@@ -68,13 +70,15 @@ CPPTRACE_FORCE_NO_INLINE int stacktrace_multi_3(std::vector<int>& line_numbers)
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_multi_2(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_multi_3(line_numbers) * 2;
+    return stacktrace_multi_3(line_numbers) * rand();
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_multi_1(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_multi_2(line_numbers) * 2;
+    return stacktrace_multi_2(line_numbers) * rand();
 }
 
 TEST(Stacktrace, MultipleFrames) {
@@ -86,16 +90,19 @@ TEST(Stacktrace, MultipleFrames) {
 
 
 CPPTRACE_FORCE_NO_INLINE cpptrace::raw_trace stacktrace_raw_resolve_3(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     return cpptrace::generate_raw_trace();
 }
 
 CPPTRACE_FORCE_NO_INLINE cpptrace::raw_trace stacktrace_raw_resolve_2(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     return stacktrace_raw_resolve_3(line_numbers);
 }
 
 CPPTRACE_FORCE_NO_INLINE cpptrace::raw_trace stacktrace_raw_resolve_1(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     return stacktrace_raw_resolve_2(line_numbers);
 }
@@ -127,6 +134,7 @@ TEST(Stacktrace, RawTraceResolution) {
 
 #ifdef CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF
 CPPTRACE_FORCE_NO_INLINE int stacktrace_inline_resolution_3(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     auto trace = cpptrace::generate_trace();
     if(trace.frames.size() < 4) {
@@ -165,13 +173,15 @@ CPPTRACE_FORCE_NO_INLINE int stacktrace_inline_resolution_3(std::vector<int>& li
 }
 
 CPPTRACE_FORCE_INLINE int stacktrace_inline_resolution_2(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_inline_resolution_3(line_numbers) * 2;
+    return stacktrace_inline_resolution_3(line_numbers) * rand();
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_inline_resolution_1(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_inline_resolution_2(line_numbers) * 2;
+    return stacktrace_inline_resolution_2(line_numbers) * rand();
 }
 
 TEST(Stacktrace, InlineResolution) {

test/unit/traced_exception.cpp

@@ -11,21 +11,24 @@
 using namespace std::literals;
 
 
-// NOTE: returning something and then return stacktrace_traced_object_3(line_numbers) * 2; later helps prevent the call from
+// NOTE: returning something and then return stacktrace_multi_3(line_numbers) * rand(); is done to prevent TCO even
-// being optimized to a jmp
+// under LTO https://github.com/jeremy-rifkin/cpptrace/issues/179#issuecomment-2467302052
 CPPTRACE_FORCE_NO_INLINE int stacktrace_traced_object_3(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
     throw cpptrace::runtime_error("foobar");
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_traced_object_2(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_traced_object_3(line_numbers) * 2;
+    return stacktrace_traced_object_3(line_numbers) * rand();
 }
 
 CPPTRACE_FORCE_NO_INLINE int stacktrace_traced_object_1(std::vector<int>& line_numbers) {
+    static volatile int lto_guard; lto_guard = lto_guard + 1;
     line_numbers.insert(line_numbers.begin(), __LINE__ + 1);
-    return stacktrace_traced_object_2(line_numbers) * 2;
+    return stacktrace_traced_object_2(line_numbers) * rand();
 }
 
 TEST(TracedException, Basic) {