Always use inline asm DoNotOptimize with clang. (#452)

* Always use inline asm DoNotOptimize with clang. clang-cl masquerades as MSVC but not GCC, so it was using the MSVC-compatible definitions of DoNotOptimize and ClobberMemory. Presumably, it's better in general to use the targeted assembly for this functionality (the codegen is different), but the specific issue is that clang-cl deprecates the usage of _ReadWriteBarrier, and this gets rid of that warning. * triggering another AppVeyor run

Always use inline asm DoNotOptimize with clang. (#452)
f3cd636f · mwinterb · Dominic Hamon · 819adb4c · f3cd636f
Commit f3cd636f authored Oct 09, 2017 by mwinterb Committed by Dominic Hamon Oct 10, 2017
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benchmark.h include/benchmark/benchmark.h +3 -1

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--- a/include/benchmark/benchmark.h
+++ b/include/benchmark/benchmark.h
@@ -290,10 +290,12 @@ BENCHMARK_UNUSED static int stream_init_anchor = InitializeStreams();
 }  // namespace internal


-#if !defined(__GNUC__) || defined(__pnacl__) || defined(EMSCRIPTN)
+#if (!defined(__GNUC__) && !defined(__clang__)) || defined(__pnacl__) || \
+    defined(EMSCRIPTN)
 # define BENCHMARK_HAS_NO_INLINE_ASSEMBLY
 #endif

+
 // The DoNotOptimize(...) function can be used to prevent a value or
 // expression from being optimized away by the compiler. This function is
 // intended to add little to no overhead.