[libcxx-commits] [libcxx] [libcxx] [test] Fix odr_signature tests with optimizations enabled (PR #144317)

[Martin Storsjö via libcxx-commits]

https://github.com/mstorsjo created https://github.com/llvm/llvm-project/pull/144317

If optimization is enabled, the inline `f()` function actually gets inlined, meaning that the functions `tu1()` and `tu2()` trivially return 1 and 2, instead of actually referencing the potentially linker deduplicated function `f()`, which is what the test tries to test.

Therefore, this test previously actually failed to test what it was supposed to test, if optimization was enabled.

Mark the inline functions with `__attribute__((noinline))` to make sure that they don't get inlined even with optimizations enabled.

Also update the TODO comments to explain why we have an XFAIL for msvc mode here.

This avoids these tests unexpectedly passing if building in msvc mode, with optimizations enabled
(`-DLIBCXX_TEST_PARAMS="optimization=speed"`).

>From 8dc0e862aa91ea7756904f87935fbfa0dab1e82b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Storsj=C3=B6?= <martin at martin.st>
Date: Sat, 14 Jun 2025 01:11:51 +0300
Subject: [PATCH] [libcxx] [test] Fix odr_signature tests with optimizations
 enabled

If optimization is enabled, the inline `f()` function actually gets
inlined, meaning that the functions `tu1()` and `tu2()` trivially
return 1 and 2, instead of actually referencing the potentially
linker deduplicated function `f()`, which is what the test tries
to test.

Mark the inline functions with `__attribute__((noinline))` to make
sure that they don't get inlined even with optimizations enabled.

Also update the TODO comments to explain why we have an XFAIL for
msvc mode here.

This avoids these tests unexpectedly passing if building in
msvc mode, with optimizations enabled
(`-DLIBCXX_TEST_PARAMS="optimization=speed"`).
---
 libcxx/test/libcxx/odr_signature.exceptions.sh.cpp |  6 +++---
 libcxx/test/libcxx/odr_signature.hardening.sh.cpp  | 10 +++++-----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/libcxx/test/libcxx/odr_signature.exceptions.sh.cpp b/libcxx/test/libcxx/odr_signature.exceptions.sh.cpp
index 6bf60b5e82d3c..8bc7f6cffbd0c 100644
--- a/libcxx/test/libcxx/odr_signature.exceptions.sh.cpp
+++ b/libcxx/test/libcxx/odr_signature.exceptions.sh.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-// TODO: Investigate
+// ABI tags have no effect in MSVC mode.
 // XFAIL: msvc
 
 // Test that we encode whether exceptions are supported in an ABI tag to avoid
@@ -21,14 +21,14 @@
 // -fno-exceptions
 #ifdef TU1
 #  include <__config>
-_LIBCPP_HIDE_FROM_ABI inline int f() { return 1; }
+_LIBCPP_HIDE_FROM_ABI __attribute__((noinline)) inline int f() { return 1; }
 int tu1() { return f(); }
 #endif // TU1
 
 // -fexceptions
 #ifdef TU2
 #  include <__config>
-_LIBCPP_HIDE_FROM_ABI inline int f() { return 2; }
+_LIBCPP_HIDE_FROM_ABI __attribute__((noinline)) inline int f() { return 2; }
 int tu2() { return f(); }
 #endif // TU2
 
diff --git a/libcxx/test/libcxx/odr_signature.hardening.sh.cpp b/libcxx/test/libcxx/odr_signature.hardening.sh.cpp
index 0dc280bf28182..e2ea6bf4a597a 100644
--- a/libcxx/test/libcxx/odr_signature.hardening.sh.cpp
+++ b/libcxx/test/libcxx/odr_signature.hardening.sh.cpp
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-// TODO: Investigate
+// ABI tags have no effect in MSVC mode.
 // XFAIL: msvc
 
 // Test that we encode the hardening mode in an ABI tag to avoid ODR violations
@@ -24,28 +24,28 @@
 // fast hardening mode
 #ifdef TU1
 #  include <__config>
-_LIBCPP_HIDE_FROM_ABI inline int f() { return 1; }
+_LIBCPP_HIDE_FROM_ABI __attribute__((noinline)) inline int f() { return 1; }
 int tu1() { return f(); }
 #endif // TU1
 
 // extensive hardening mode
 #ifdef TU2
 #  include <__config>
-_LIBCPP_HIDE_FROM_ABI inline int f() { return 2; }
+_LIBCPP_HIDE_FROM_ABI __attribute__((noinline)) inline int f() { return 2; }
 int tu2() { return f(); }
 #endif // TU2
 
 // debug hardening mode
 #ifdef TU3
 #  include <__config>
-_LIBCPP_HIDE_FROM_ABI inline int f() { return 3; }
+_LIBCPP_HIDE_FROM_ABI __attribute__((noinline)) inline int f() { return 3; }
 int tu3() { return f(); }
 #endif // TU3
 
 // No hardening
 #ifdef TU4
 #  include <__config>
-_LIBCPP_HIDE_FROM_ABI inline int f() { return 4; }
+_LIBCPP_HIDE_FROM_ABI __attribute__((noinline)) inline int f() { return 4; }
 int tu4() { return f(); }
 #endif // TU4