Work around VS 2015 Update 3 optimizer internal compiler error

VS 2015 Update 3 comes with a fancy new optimizer and this optimizer
causes an internal compiler error on one skia function. This change
works around the bug by disabling optimize-for-time for that function.

Other options would be to add /d2SSAOptimizer- to the command-line for
the file or project but that would *require* Update 3 which is not yet
desirable.

VS bug report is here:
https://connect.microsoft.com/VisualStudio/feedback/details/3100520
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2308833002

Review-Url: https://codereview.chromium.org/2308833002
diff --git a/src/gpu/effects/GrConfigConversionEffect.cpp b/src/gpu/effects/GrConfigConversionEffect.cpp
index 2808af6..aeb0393 100644
--- a/src/gpu/effects/GrConfigConversionEffect.cpp
+++ b/src/gpu/effects/GrConfigConversionEffect.cpp
@@ -125,6 +125,12 @@
 
 GR_DEFINE_FRAGMENT_PROCESSOR_TEST(GrConfigConversionEffect);
 
+#if !defined(__clang__) && _MSC_FULL_VER >= 190024213
+// Work around VS 2015 Update 3 optimizer bug that causes internal compiler error
+//https://connect.microsoft.com/VisualStudio/feedback/details/3100520/internal-compiler-error
+#pragma optimize("t", off)
+#endif
+
 sk_sp<GrFragmentProcessor> GrConfigConversionEffect::TestCreate(GrProcessorTestData* d) {
     PMConversion pmConv = static_cast<PMConversion>(d->fRandom->nextULessThan(kPMConversionCnt));
     GrSwizzle swizzle;
@@ -136,6 +142,11 @@
                                      swizzle, pmConv, GrTest::TestMatrix(d->fRandom)));
 }
 
+#if !defined(__clang__) && _MSC_FULL_VER >= 190024213
+// Restore optimization settings.
+#pragma optimize("", on)
+#endif
+
 ///////////////////////////////////////////////////////////////////////////////
 
 void GrConfigConversionEffect::onGetGLSLProcessorKey(const GrGLSLCaps& caps,