added SkSL support for mustForceNegatedAtanParamToFloat cap

tests/SkSLGLSLTest.cpp

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkSLCompiler.h"
 
 #include "Test.h"
@@ skipping 15 matching lines @@
     }
 }
 
 static SkSL::GLCaps default_caps() {
     return { 
              400, 
              SkSL::GLCaps::kGL_Standard,
              false, // isCoreProfile
              false, // usesPrecisionModifiers;
              false, // mustDeclareFragmentShaderOutput
-             true   // canUseMinAndAbsTogether
+             true,  // canUseMinAndAbsTogether
+             false  // mustForceNegatedAtanParamToFloat
            };
 }
 
 DEF_TEST(SkSLHelloWorld, r) {
     test(r,
          "void main() { sk_FragColor = vec4(0.75); }",
          default_caps(),
          "#version 400\n"
          "void main() {\n"
          "    gl_FragColor = vec4(0.75);\n"
@@ skipping 261 matching lines @@
          "#version 400\n"
          "void main() {\n"
          "    float minAbsHackVar0;\n"
          "    float minAbsHackVar1;\n"
          "    float x = -5.0;\n"
          "    x = ((minAbsHackVar0 = abs(x)) < (minAbsHackVar1 = 6.0) ? minAbsHackVar0 : "
                                                                                 "minAbsHackVar1);\n"
          "}\n");
 }
 
+DEF_TEST(SkSLNegatedAtan, r) {
+    test(r,
+         "void main() { vec2 x = vec2(1, 2); float y = atan(x.x, -(2 * x.y)); }",
+         default_caps(),
+         "#version 400\n"
+         "void main() {\n"
+         "    vec2 x = vec2(1.0, 2.0);\n"
+         "    float y = atan(x.x, -(2.0 * x.y));\n"
+         "}\n");
+    SkSL::GLCaps caps = default_caps();
+    caps.fMustForceNegatedAtanParamToFloat = true;
+    test(r,
+         "void main() { vec2 x = vec2(1, 2); float y = atan(x.x, -(2 * x.y)); }",
+         caps,
+         "#version 400\n"
+         "void main() {\n"
+         "    vec2 x = vec2(1.0, 2.0);\n"
+         "    float y = atan(x.x, -1.0 * (2.0 * x.y));\n"
+         "}\n");
+}
+
 DEF_TEST(SkSLModifiersDeclaration, r) {
     test(r,
          "layout(blend_support_all_equations) out;"
          "void main() { }",
          default_caps(),
          "#version 400\n"
          "layout (blend_support_all_equations) out ;\n"
          "void main() {\n"
          "}\n");
 }
@@ skipping 30 matching lines @@
     test(r,
          "float test1[] = float[](1, 2, 3, 4);"
          "vec2 test2[] = vec2[](vec2(1, 2), vec2(3, 4));"
          "mat4 test3[] = mat4[]();",
          default_caps(),
          "#version 400\n"
          "float test1[] = float[](1.0, 2.0, 3.0, 4.0);\n"
          "vec2 test2[] = vec2[](vec2(1.0, 2.0), vec2(3.0, 4.0));\n"
          "mat4 test3[] = mat4[]();\n");
 }