D3D: Make sure Lod0 functions are never referenced in non-fragment shaders.

The lod0 functions would not be declared but could still be referenced by
vertex shaders.

BUG=angleproject:3471

Change-Id: I635a8465ce68dc22a6f7387b30bf7e93b14dd67d
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1622741
Commit-Queue: Geoff Lang <[email protected]>
Reviewed-by: Jiajia Qin <[email protected]>

Author: vonture

src/compiler/translator/OutputHLSL.cpp

@@ -2293,7 +2293,8 @@ bool OutputHLSL::visitAggregate(Visit visit, TIntermAggregate *node)
         {
             TIntermSequence *arguments = node->getSequence();
 
-            bool lod0 = mInsideDiscontinuousLoop || mOutputLod0Function;
+            bool lod0 = (mInsideDiscontinuousLoop || mOutputLod0Function) &&
+                        mShaderType == GL_FRAGMENT_SHADER;
             if (node->getOp() == EOpCallFunctionInAST)
             {
                 if (node->isArray())

src/tests/gl_tests/GLSLTest.cpp

@@ -1975,6 +1975,41 @@ TEST_P(GLSLTest, TextureLOD)
     glDeleteShader(shader);
 }
 
+// HLSL generates extra lod0 variants of functions. There was a bug that incorrectly reworte
+// function calls to use them in vertex shaders.  http://anglebug.com/3471
+TEST_P(GLSLTest, TextureLODRewriteInVertexShader)
+{
+    constexpr char kVS[] = R"(
+  precision highp float;
+  uniform int uni;
+  uniform sampler2D texture;
+
+  vec4 A();
+
+  vec4 B() {
+    vec4 a;
+    for(int r=0; r<14; r++){
+      if (r < uni) return vec4(0.0);
+      a = A();
+    }
+    return a;
+  }
+
+  vec4 A() {
+    return texture2D(texture, vec2(0.0, 0.0));
+  }
+
+  void main() {
+    gl_Position = B();
+  })";
+
+    constexpr char kFS[] = R"(
+void main() { gl_FragColor = vec4(gl_FragCoord.x / 640.0, gl_FragCoord.y / 480.0, 0, 1); }
+)";
+
+    ANGLE_GL_PROGRAM(program, kVS, kFS);
+}
+
 // Test to verify the a shader can have a sampler unused in a vertex shader
 // but used in the fragment shader.
 TEST_P(GLSLTest, VerifySamplerInBothVertexAndFragmentShaders)