commit 6f0a0dca16ff492e6aef30c34dcd294b019d07bf
author Shao <jiawei.shao@intel.com> Tue Sep 27 13:51:29 2016 +0800
committer Commit Bot <commit-bot@chromium.org> Wed Sep 28 16:34:11 2016 +0000
tree 46cef405f4d5e2d28ba0882ad61d6e336c883145
parent 42fad76d02feadb05fdda1f11e25770893bc9c5e

Workaround isnan() on Intel drivers

On some Intel drivers, calling function isnan() on highp float will get wrong
answer. This patch work arounds this bug by using an expression to emulate
this function.

BUG=chromium:650547

Change-Id: I5bc5e0352c434f42cd2c55103a74f9f7ba51a72c
Reviewed-on: https://chromium-review.googlesource.com/389834
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>

src/compiler/translator/OutputHLSL.cpp

diff --git a/src/compiler/translator/OutputHLSL.cpp b/src/compiler/translator/OutputHLSL.cpp
index 6835c2e..9da8720 100644
--- a/src/compiler/translator/OutputHLSL.cpp
+++ b/src/compiler/translator/OutputHLSL.cpp
@@ -161,6 +161,12 @@
 
     BuiltInFunctionEmulator builtInFunctionEmulator;
     InitBuiltInFunctionEmulatorForHLSL(&builtInFunctionEmulator);
+    if ((mCompileOptions & SH_EMULATE_ISNAN_FLOAT_FUNCTION) != 0)
+    {
+        InitBuiltInIsnanFunctionEmulatorForHLSLWorkarounds(&builtInFunctionEmulator,
+                                                           mShaderVersion);
+    }
+
     builtInFunctionEmulator.MarkBuiltInFunctionsForEmulation(treeRoot);
 
     // Now that we are done changing the AST, do the analyses need for HLSL generation
@@ -1299,9 +1305,12 @@
           outputTriplet(out, visit, "frac(", "", ")");
           break;
       case EOpIsNan:
-          outputTriplet(out, visit, "isnan(", "", ")");
-        mRequiresIEEEStrictCompiling = true;
-        break;
+          if (node->getUseEmulatedFunction())
+              writeEmulatedFunctionTriplet(out, visit, "isnan(");
+          else
+              outputTriplet(out, visit, "isnan(", "", ")");
+          mRequiresIEEEStrictCompiling = true;
+          break;
       case EOpIsInf:
           outputTriplet(out, visit, "isinf(", "", ")");
           break;