Fancier solution

eggrobin · Mar 30, 2024 · 87ab5a6 · 87ab5a6
1 parent 0d65cc0
commit 87ab5a6
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 5 deletions.
diff --git a/ksp_plugin_test/plugin_compatibility_test.cpp b/ksp_plugin_test/plugin_compatibility_test.cpp
@@ -145,6 +145,8 @@ TEST_P(PluginCompatibilityTest, Reach) {
   std::optional<FMAPreventer> fma_preventer;
   if (!GetParam()) {
     fma_preventer.emplace();
+  } else if (!UseHardwareFMA) {
+    GTEST_SKIP() << "FMA not used by default";
   }
   StringLogSink log_warning(google::WARNING);
   not_null<std::unique_ptr<Plugin const>> plugin = ReadPluginFromFile(

diff --git a/numerics/fma.hpp b/numerics/fma.hpp
@@ -43,11 +43,10 @@ inline bool const& UseHardwareFMA = FMAPreventer::use_hardware_fma;
 // The functions in this file unconditionally wrap the appropriate intrinsics.
 // The caller may only use them if |UseHardwareFMA| is true.
 inline bool const UseHardwareFMA = PRINCIPIA_USE_HARDWARE_FMA_DEFAULT;
-#if PRINCIPIA_COMPILER_MSVC
-class FMAPreventer;  // Undefined.
-#else
-class FMAPreventer {};  // Nothing to prevent.
-#endif
+struct TrivialFMAPreventer {};
+using FMAPreventer = std::conditional_t<CanEmitFMAInstructions,
+                                        struct UndefinedFMAPreventer,
+                                        TrivialFMAPreventer>;
 #endif
 
 #undef PRINCIPIA_USE_HARDWARE_FMA_DEFAULT