From 1001f843a45e95f6df1d44242b6b06c77898e870 Mon Sep 17 00:00:00 2001
From: Brian Osman <brianosman@google.com>
Date: Fri, 12 Jan 2018 10:16:41 -0500
Subject: Added SkSL workaround for devices which cannot safely access
 gl_FragCoord

This is the root cause of https://github.com/flutter/flutter/issues/13216
I've got a GM that demonstrates the bug, but only in Viewer.

Bug: skia:7410
Change-Id: Iaa1f27b10166aa09e4dc5949e5a6ca1bd14c99ac
Reviewed-on: https://skia-review.googlesource.com/93920
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
---
 src/gpu/GrShaderCaps.cpp | 2 ++
 src/gpu/gl/GrGLCaps.cpp  | 6 ++++++
 2 files changed, 8 insertions(+)

(limited to 'src/gpu')

diff --git a/src/gpu/GrShaderCaps.cpp b/src/gpu/GrShaderCaps.cpp
index 2041ada635..2ab19478af 100644
--- a/src/gpu/GrShaderCaps.cpp
+++ b/src/gpu/GrShaderCaps.cpp
@@ -38,6 +38,7 @@ GrShaderCaps::GrShaderCaps(const GrContextOptions& options) {
     fRequiresLocalOutputColorForFBFetch = false;
     fMustObfuscateUniformColor = false;
     fMustGuardDivisionEvenAfterExplicitZeroCheck = false;
+    fCanUseFragCoord = true;
     fFlatInterpolationSupport = false;
     fPreferFlatInterpolation = false;
     fNoPerspectiveInterpolationSupport = false;
@@ -113,6 +114,7 @@ void GrShaderCaps::dumpJSON(SkJSONWriter* writer) const {
     writer->appendBool("Must obfuscate uniform color", fMustObfuscateUniformColor);
     writer->appendBool("Must guard division even after explicit zero check",
                        fMustGuardDivisionEvenAfterExplicitZeroCheck);
+    writer->appendBool("Can use gl_FragCoord", fCanUseFragCoord);
     writer->appendBool("Flat interpolation support", fFlatInterpolationSupport);
     writer->appendBool("Prefer flat interpolation", fPreferFlatInterpolation);
     writer->appendBool("No perspective interpolation support", fNoPerspectiveInterpolationSupport);
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index 4996859c51..d310cd219b 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -1048,6 +1048,12 @@ void GrGLCaps::initGLSL(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli
         shaderCaps->fMustGuardDivisionEvenAfterExplicitZeroCheck = true;
     }
 #endif
+
+    // We've seen Adreno 3xx devices produce incorrect (flipped) values for gl_FragCoord, in some
+    // (rare) situations. It's sporadic, and mostly on older drviers.
+    if (kAdreno3xx_GrGLRenderer == ctxInfo.renderer()) {
+        shaderCaps->fCanUseFragCoord = false;
+    }
 }
 
 bool GrGLCaps::hasPathRenderingSupport(const GrGLContextInfo& ctxInfo, const GrGLInterface* gli) {
-- 
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