From bc50e5ce6c039f02dc805361ae5b0b66f40b4820 Mon Sep 17 00:00:00 2001
From: bsalomon <bsalomon@google.com>
Date: Thu, 4 Jun 2015 08:49:34 -0700
Subject: Disable dual source blending support when GLSL version is too old

BUG=skia:3891

Review URL: https://codereview.chromium.org/1160923007
---
 src/gpu/gl/GrGLCaps.cpp |  5 +++--
 src/gpu/gl/GrGLSL.cpp   | 18 +++++++++++++++---
 src/gpu/gl/GrGLSL.h     |  2 ++
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index dd4ba65f77..ad0f2caf78 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -984,8 +984,9 @@ void GrGLSLCaps::init(const GrGLContextInfo& ctxInfo,
 
     // Enable supported shader-related caps
     if (kGL_GrGLStandard == standard) {
-        fDualSourceBlendingSupport = ctxInfo.version() >= GR_GL_VER(3, 3) ||
-            ctxInfo.hasExtension("GL_ARB_blend_func_extended");
+        fDualSourceBlendingSupport = (ctxInfo.version() >= GR_GL_VER(3, 3) ||
+            ctxInfo.hasExtension("GL_ARB_blend_func_extended")) &&
+            GrGLSLSupportsNamedFragmentShaderOutputs(ctxInfo.glslGeneration());
         fShaderDerivativeSupport = true;
         // we don't support GL_ARB_geometry_shader4, just GL 3.2+ GS
         fGeometryShaderSupport = ctxInfo.version() >= GR_GL_VER(3, 2) &&
diff --git a/src/gpu/gl/GrGLSL.cpp b/src/gpu/gl/GrGLSL.cpp
index f4caf52012..20e6e20938 100644
--- a/src/gpu/gl/GrGLSL.cpp
+++ b/src/gpu/gl/GrGLSL.cpp
@@ -85,10 +85,22 @@ const char* GrGetGLSLVersionDecl(const GrGLContextInfo& info) {
         case k310es_GrGLSLGeneration:
             SkASSERT(kGLES_GrGLStandard == info.standard());
             return "#version 310 es\n";
-        default:
-            SkFAIL("Unknown GL version.");
-            return ""; // suppress warning
     }
+    return "<no version>";
+}
+
+bool GrGLSLSupportsNamedFragmentShaderOutputs(GrGLSLGeneration gen) {
+    switch (gen) {
+        case k110_GrGLSLGeneration:
+            return false;
+        case k130_GrGLSLGeneration:
+        case k140_GrGLSLGeneration:
+        case k150_GrGLSLGeneration:
+        case k330_GrGLSLGeneration:
+        case k310es_GrGLSLGeneration:
+            return true;
+    }
+    return false;
 }
 
 void GrGLSLAppendDefaultFloatPrecisionDeclaration(GrSLPrecision p, GrGLStandard s, SkString* out) {
diff --git a/src/gpu/gl/GrGLSL.h b/src/gpu/gl/GrGLSL.h
index db8e1bdca5..b338c991a6 100644
--- a/src/gpu/gl/GrGLSL.h
+++ b/src/gpu/gl/GrGLSL.h
@@ -50,6 +50,8 @@ enum GrGLSLGeneration {
  */
 bool GrGetGLSLGeneration(const GrGLInterface* gl, GrGLSLGeneration* generation);
 
+bool GrGLSLSupportsNamedFragmentShaderOutputs(GrGLSLGeneration);
+
 /**
  * Returns a string to include at the beginning of a shader to declare the GLSL
  * version.
-- 
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