Issue #1354 - Don't allow glsl[130,400] unless we have gpu_shader5

- Teach GLContext about gpu_shader5
- Downgrade shader language version if gpu_shader5 support isn't found.

dom/canvas/WebGLShaderValidator.cpp

@@ -5,6 +5,7 @@
 
 #include "WebGLShaderValidator.h"
 
+#include <algorithm>
 #include "angle/ShaderLang.h"
 #include "gfxPrefs.h"
 #include "GLContext.h"
@@ -112,6 +113,16 @@ ShaderOutput(gl::GLContext* gl)
         return SH_ESSL_OUTPUT;
     } else {
         uint32_t version = gl->ShadingLanguageVersion();
+
+        // Version 130 starts to require integral constant expressions for loop indices,
+        // instead of "constant-index-expression".
+        // Both version 400 and gpu_shader5 remove this restrictions.
+        // gpu_shader5 went core in 400, so we can just check for the GLFeature.
+        // If we're compiling for webglsl1, even for webgl2, we need gpu_shader5, or GLSL_COMPAT.
+        if (!gl->IsSupported(gl::GLFeature::gpu_shader5)) {
+            version = std::min<uint32_t>(version, 120);
+        }
+
         switch (version) {
         case 100: return SH_GLSL_COMPATIBILITY_OUTPUT;
         case 120: return SH_GLSL_COMPATIBILITY_OUTPUT;

gfx/gl/GLContext.cpp

@@ -95,6 +95,7 @@ static const char* const sExtensionNames[] = {
     "GL_ARB_framebuffer_object",
     "GL_ARB_framebuffer_sRGB",
     "GL_ARB_geometry_shader4",
+    "GL_ARB_gpu_shader5",
     "GL_ARB_half_float_pixel",
     "GL_ARB_instanced_arrays",
     "GL_ARB_internalformat_query",
@@ -134,6 +135,7 @@ static const char* const sExtensionNames[] = {
     "GL_EXT_framebuffer_object",
     "GL_EXT_framebuffer_sRGB",
     "GL_EXT_gpu_shader4",
+    "GL_EXT_gpu_shader5",
     "GL_EXT_multisampled_render_to_texture",
     "GL_EXT_occlusion_query_boolean",
     "GL_EXT_packed_depth_stencil",
@@ -160,6 +162,7 @@ static const char* const sExtensionNames[] = {
     "GL_NV_fence",
     "GL_NV_framebuffer_blit",
     "GL_NV_geometry_program4",
+    "GL_NV_gpu_shader5",
     "GL_NV_half_float",
     "GL_NV_instanced_arrays",
     "GL_NV_primitive_restart",

gfx/gl/GLContext.h

@@ -102,6 +102,7 @@ enum class GLFeature {
     get_query_object_iv,
     get_string_indexed,
     gpu_shader4,
+    gpu_shader5,
     instanced_arrays,
     instanced_non_arrays,
     internalformat_query,
@@ -421,6 +422,7 @@ public:
         ARB_framebuffer_object,
         ARB_framebuffer_sRGB,
         ARB_geometry_shader4,
+        ARB_gpu_shader5,
         ARB_half_float_pixel,
         ARB_instanced_arrays,
         ARB_internalformat_query,
@@ -460,6 +462,7 @@ public:
         EXT_framebuffer_object,
         EXT_framebuffer_sRGB,
         EXT_gpu_shader4,
+        EXT_gpu_shader5,
         EXT_multisampled_render_to_texture,
         EXT_occlusion_query_boolean,
         EXT_packed_depth_stencil,
@@ -486,6 +489,7 @@ public:
         NV_fence,
         NV_framebuffer_blit,
         NV_geometry_program4,
+        NV_gpu_shader5,
         NV_half_float,
         NV_instanced_arrays,
         NV_primitive_restart,

gfx/gl/GLContextFeatures.cpp

@@ -331,6 +331,18 @@ static const FeatureInfo sFeatureInfoArr[] = {
             GLContext::Extensions_End
         }
     },
+    {
+        "gpu_shader5",
+        GLVersion::GL4,
+        GLESVersion::NONE,
+        GLContext::Extension_None,
+        {
+            GLContext::ARB_gpu_shader5,
+            GLContext::EXT_gpu_shader5,
+            GLContext::NV_gpu_shader5,
+            GLContext::Extensions_End
+        }
+    },    
     {
         "instanced_arrays",
         GLVersion::GL3_3,