FBFetch refactor + arm support

src/gpu/gl/GrGLCaps.cpp

Index: src/gpu/gl/GrGLCaps.cpp
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 8474873ffff5d937f5edc2084e67e0bc5002ac17..c6ab3268f43f0e7dbf2f60db7fe2bd405b5251a2 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -22,7 +22,6 @@ void GrGLCaps::reset() {
     fStencilFormats.reset();
     fStencilVerifiedColorConfigs.reset();
     fMSFBOType = kNone_MSFBOType;
-    fFBFetchType = kNone_FBFetchType;
     fInvalidateFBType = kNone_InvalidateFBType;
     fLATCAlias = kLATC_LATCAlias;
     fMapBufferType = kNone_MapBufferType;
@@ -48,6 +47,9 @@ void GrGLCaps::reset() {
     fIsCoreProfile = false;
     fFullClearIsFree = false;
     fDropsTileOnZeroDivide = false;
+    fFBFetchSupport = false;
+    fFBFetchColorName = NULL;
+    fFBFetchExtensionString = NULL;
 }
 
 GrGLCaps::GrGLCaps(const GrGLCaps& caps) : GrDrawTargetCaps() {
@@ -65,7 +67,6 @@ GrGLCaps& GrGLCaps::operator= (const GrGLCaps& caps) {
     fMaxFragmentTextureUnits = caps.fMaxFragmentTextureUnits;
     fMaxFixedFunctionTextureCoords = caps.fMaxFixedFunctionTextureCoords;
     fMSFBOType = caps.fMSFBOType;
-    fFBFetchType = caps.fFBFetchType;
     fInvalidateFBType = caps.fInvalidateFBType;
     fMapBufferType = caps.fMapBufferType;
     fRGBA8RenderbufferSupport = caps.fRGBA8RenderbufferSupport;
@@ -86,6 +87,9 @@ GrGLCaps& GrGLCaps::operator= (const GrGLCaps& caps) {
     fIsCoreProfile = caps.fIsCoreProfile;
     fFullClearIsFree = caps.fFullClearIsFree;
     fDropsTileOnZeroDivide = caps.fDropsTileOnZeroDivide;
+    fFBFetchSupport = caps.fFBFetchSupport;
+    fFBFetchColorName = caps.fFBFetchColorName;
+    fFBFetchExtensionString = caps.fFBFetchExtensionString;
 
     return *this;
 }
@@ -233,9 +237,20 @@ bool GrGLCaps::init(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
 
     if (kGLES_GrGLStandard == standard) {
         if (ctxInfo.hasExtension("GL_EXT_shader_framebuffer_fetch")) {
-            fFBFetchType = kEXT_FBFetchType;
+            fFBFetchSupport = true;
+            fFBFetchColorName = "gl_LastFragData[0]";
+            fFBFetchExtensionString = "GL_EXT_shader_framebuffer_fetch";
         } else if (ctxInfo.hasExtension("GL_NV_shader_framebuffer_fetch")) {
-            fFBFetchType = kNV_FBFetchType;
+            fFBFetchSupport = true;
+            fFBFetchColorName = "gl_LastFragData[0]";
+            fFBFetchExtensionString = "GL_NV_shader_framebuffer_fetch";
+        } else if (ctxInfo.hasExtension("GL_ARM_shader_framebuffer_fetch")) {
+            // The arm extension requires specifically enabling MSAA fetching per sample.
+            // On some devices this may have a perf hit.  Also multiple render targets are disabled
+            GR_GL_CALL(gli, Enable(GR_GL_FETCH_PER_SAMPLE_ARM));

[bsalomon, 2014/07/31 13:45:05]

I don't think that this is the right place for this call. We don't set any other
state through the caps class. We would enable this once at startup but we are
not always the only user of the GL context. It could be disabled by other code.
It should happen in a function called when we flush the graphics state so that
it gets set again when we get a GrContext::resetContext() call (which is how our
client lets us know that someone else was messing with the GL context).

+            fFBFetchSupport = true;
+            fFBFetchColorName = "gl_LastFragColorARM";
+            fFBFetchExtensionString = "GL_ARM_shader_framebuffer_fetch";
         }
     }
 
@@ -335,7 +350,8 @@ bool GrGLCaps::init(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
 
     fGpuTracingSupport = ctxInfo.hasExtension("GL_EXT_debug_marker");
 
-    fDstReadInShaderSupport = kNone_FBFetchType != fFBFetchType;
+    // For now these two are equivalent but we could have dst read in shader via some other method
+    fDstReadInShaderSupport = fFBFetchSupport;
 
     // Disable scratch texture reuse on Mali and Adreno devices
     fReuseScratchTextures = kARM_GrGLVendor != ctxInfo.vendor() &&
@@ -775,16 +791,6 @@ SkString GrGLCaps::dump() const {
     GR_STATIC_ASSERT(6 == kES_EXT_MsToTexture_MSFBOType);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kMSFBOExtStr) == kLast_MSFBOType + 1);
 
-    static const char* kFBFetchTypeStr[] = {
-        "None",
-        "EXT",
-        "NV",
-    };
-    GR_STATIC_ASSERT(0 == kNone_FBFetchType);
-    GR_STATIC_ASSERT(1 == kEXT_FBFetchType);
-    GR_STATIC_ASSERT(2 == kNV_FBFetchType);
-    GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFBFetchTypeStr) == kLast_FBFetchType + 1);
-
     static const char* kInvalidateFBTypeStr[] = {
         "None",
         "Discard",
@@ -809,7 +815,7 @@ SkString GrGLCaps::dump() const {
 
     r.appendf("Core Profile: %s\n", (fIsCoreProfile ? "YES" : "NO"));
     r.appendf("MSAA Type: %s\n", kMSFBOExtStr[fMSFBOType]);
-    r.appendf("FB Fetch Type: %s\n", kFBFetchTypeStr[fFBFetchType]);
+    r.appendf("FB Fetch Support: %s\n", (fFBFetchSupport ? "YES" : "NO"));
     r.appendf("Invalidate FB Type: %s\n", kInvalidateFBTypeStr[fInvalidateFBType]);
     r.appendf("Map Buffer Type: %s\n", kMapBufferTypeStr[fMapBufferType]);
     r.appendf("Max FS Uniform Vectors: %d\n", fMaxFragmentUniformVectors);