From e2bbd632e220be7626efd34acb9a517430d36004 Mon Sep 17 00:00:00 2001
From: Andrew Comminos <andrew@comminos.com>
Date: Fri, 23 Oct 2015 21:35:16 -0700
Subject: [PATCH] Bug 1203135 - Terminate linking if maximum vertex attribute
 count is exceeded on Mesa. r=jgilbert, a=ritu

--HG--
extra : source : 8021382da9722db0ad97ebd93698b69a74f0d9b0
extra : intermediate-source : 90eff805d2810e9d9ea88f6869335b0500b1a536
---
 dom/canvas/WebGLProgram.cpp         | 28 ++++++++++++++++++----------
 dom/canvas/WebGLShader.cpp          | 10 ++++++++++
 dom/canvas/WebGLShader.h            |  1 +
 dom/canvas/WebGLShaderValidator.cpp |  6 ++++++
 dom/canvas/WebGLShaderValidator.h   |  1 +
 5 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/dom/canvas/WebGLProgram.cpp b/dom/canvas/WebGLProgram.cpp
index 78f7413..0e056e8 100644
--- a/dom/canvas/WebGLProgram.cpp
+++ b/dom/canvas/WebGLProgram.cpp
@@ -569,18 +569,26 @@ WebGLProgram::LinkProgram()
     gl::GLContext* gl = mContext->gl;
     gl->MakeCurrent();
 
-    // Bug 777028: Mesa can't handle more than 16 samplers per program,
-    // counting each array entry.
-    size_t numSamplerUniforms_upperBound = mVertShader->CalcNumSamplerUniforms() +
-                                           mFragShader->CalcNumSamplerUniforms();
     if (gl->WorkAroundDriverBugs() &&
-        mContext->mIsMesa &&
-        numSamplerUniforms_upperBound > 16)
+        mContext->mIsMesa)
     {
-        mLinkLog.AssignLiteral("Programs with more than 16 samplers are disallowed on"
-                               " Mesa drivers to avoid crashing.");
-        mContext->GenerateWarning("linkProgram: %s", mLinkLog.BeginReading());
-        return false;
+        // Bug 777028: Mesa can't handle more than 16 samplers per program,
+        // counting each array entry.
+        size_t numSamplerUniforms_upperBound = mVertShader->CalcNumSamplerUniforms() +
+                                               mFragShader->CalcNumSamplerUniforms();
+        if (numSamplerUniforms_upperBound > 16) {
+            mLinkLog.AssignLiteral("Programs with more than 16 samplers are disallowed on"
+                                   " Mesa drivers to avoid crashing.");
+            mContext->GenerateWarning("linkProgram: %s", mLinkLog.BeginReading());
+            return false;
+        }
+
+        // Bug 1203135: Mesa crashes internally if we exceed the reported maximum attribute count.
+        if (mVertShader->NumAttributes() > mContext->MaxVertexAttribs()) {
+            mLinkLog.AssignLiteral("Number of attributes exceeds Mesa's reported max attribute count.");
+            mContext->GenerateWarning("linkProgram: %s", mLinkLog.BeginReading());
+            return false;
+        }
     }
 
     // Bind the attrib locations.
diff --git a/dom/canvas/WebGLShader.cpp b/dom/canvas/WebGLShader.cpp
index 85a3809..bab4157 100644
--- a/dom/canvas/WebGLShader.cpp
+++ b/dom/canvas/WebGLShader.cpp
@@ -299,6 +299,16 @@ WebGLShader::CalcNumSamplerUniforms() const
     return 0;
 }
 
+size_t
+WebGLShader::NumAttributes() const
+{
+    if (mValidator)
+        return mValidator->NumAttributes();
+
+    // TODO
+    return 0;
+}
+
 void
 WebGLShader::BindAttribLocation(GLuint prog, const nsCString& userName,
                                 GLuint index) const
diff --git a/dom/canvas/WebGLShader.h b/dom/canvas/WebGLShader.h
index 698e30c..2c80b16a 100644
--- a/dom/canvas/WebGLShader.h
+++ b/dom/canvas/WebGLShader.h
@@ -45,6 +45,7 @@ public:
     // Util funcs
     bool CanLinkTo(const WebGLShader* prev, nsCString* const out_log) const;
     size_t CalcNumSamplerUniforms() const;
+    size_t NumAttributes() const;
     void BindAttribLocation(GLuint prog, const nsCString& userName, GLuint index) const;
     bool FindAttribUserNameByMappedName(const nsACString& mappedName,
                                         nsDependentCString* const out_userName) const;
diff --git a/dom/canvas/WebGLShaderValidator.cpp b/dom/canvas/WebGLShaderValidator.cpp
index 80005e2..8bedf88 100644
--- a/dom/canvas/WebGLShaderValidator.cpp
+++ b/dom/canvas/WebGLShaderValidator.cpp
@@ -274,6 +274,12 @@ ShaderValidator::CalcNumSamplerUniforms() const
     return accum;
 }
 
+size_t
+ShaderValidator::NumAttributes() const
+{
+  return ShGetAttributes(mHandle)->size();
+}
+
 // Attribs cannot be structs or arrays, and neither can vertex inputs in ES3.
 // Therefore, attrib names are always simple.
 bool
diff --git a/dom/canvas/WebGLShaderValidator.h b/dom/canvas/WebGLShaderValidator.h
index 35db2f1..1f794bf0 100644
--- a/dom/canvas/WebGLShaderValidator.h
+++ b/dom/canvas/WebGLShaderValidator.h
@@ -41,6 +41,7 @@ public:
     void GetOutput(nsACString* out) const;
     bool CanLinkTo(const ShaderValidator* prev, nsCString* const out_log) const;
     size_t CalcNumSamplerUniforms() const;
+    size_t NumAttributes() const;
 
     bool FindAttribUserNameByMappedName(const std::string& mappedName,
                                         const std::string** const out_userName) const;
-- 
2.6.3