Do not add bindings LiteralToUniformReductionOpportunity

The LiteralToUniformReductionOpportunity adds new uniforms to a shader
job.  It should not provide these uniforms with bindings -- it is up
to the reducer to add bindings if they are deemed necessary, right
before emitting the shader as a text file.

This change fixes that issue.  However, it turns out that the reducer
was not adding bindings in the case that no uniforms were present in
the first place -- it was treating a uniform-free shader as a
non-Vulkan shader.  As a temporary workaround, a uniform-free shader
is now treated by the reducer as a Vulkan shader so that if uniforms
are then created, they get bindings when written out as text files.

Related issue to fix this more elegantly in the long-run: #1046.

reducer/src/main/java/com/graphicsfuzz/reducer/ReductionDriver.java

@@ -185,7 +185,12 @@ public String doReduction(
         int stepLimit) throws IOException {
 
     // This is used for Vulkan compatibility.
-    final boolean requiresUniformBindings = initialState.hasUniformBindings();
+    // TODO(https://github.com/google/graphicsfuzz/issues/1046): The check for zero uniforms is a
+    //  workaround for the fact that we don't have a way to infer what the right thing to do is
+    //  when there are no uniforms.  As per the issue, we should really have a --vulkan option that
+    //  instructs the reducer as to whether we want Vulkan-style uniform blocks.
+    final boolean requiresUniformBindings =
+        initialState.getPipelineInfo().getNumUniforms() == 0 || initialState.hasUniformBindings();
     final Optional<String> pushConstant = initialState.getPushConstant();
     if (initialState.hasUniformBindings()) {
       // We eliminate uniform bindings while applying reduction steps, and re-introduce them

reducer/src/main/java/com/graphicsfuzz/reducer/reductionopportunities/LiteralToUniformReductionOpportunity.java

@@ -82,8 +82,6 @@ void applyReductionImpl() {
     if (!shaderJob.getPipelineInfo().hasUniform(arrayName)) {
       shaderJob.getPipelineInfo().addUniform(arrayName, basicType,
           Optional.of(0), new ArrayList<>());
-      shaderJob.getPipelineInfo().addUniformBinding(arrayName, false,
-          shaderJob.getPipelineInfo().getUnusedBindingNumber());
     }
 
     final int index;

reducer/src/test/java/com/graphicsfuzz/reducer/reductionopportunities/LiteralToUniformReductionOpportunitiesTest.java

@@ -327,8 +327,7 @@ public void testReplaceUInts() throws Exception {
    * opportunity at first. Then checks that the one shader had the array uniform added,
    * and the other shader stays the same. After that, another uniform is manually added to
    * the pipeline info and the rest of the opportunities are applied. The test succeeds if
-   * the bindings have not changed, the amount of opportunies is correct and literals in the
-   * shaders are replaced as expected.
+   * the number of opportunities is correct and literals in the shaders are replaced as expected.
    */
   @Test
   public void testManuallyAddedUniform() throws Exception {
@@ -396,13 +395,8 @@ public void testManuallyAddedUniform() throws Exception {
     CompareAsts.assertEqualAsts(fragmentShaderNotReplaced, shaderJob.getFragmentShader().get());
     assertEquals(1, pipelineInfo.getNumUniforms());
 
-    final int bindingNumber = shaderJob.getPipelineInfo().getBinding("_GLF_uniform_int_values");
-
-    final int nextUnusedBindingNumber = shaderJob.getPipelineInfo().getUnusedBindingNumber();
     shaderJob.getPipelineInfo().addUniform("TEST", BasicType.INT,
         Optional.of(0), new ArrayList<>());
-    shaderJob.getPipelineInfo().addUniformBinding("TEST", false,
-        nextUnusedBindingNumber);
 
     ops.forEach(AbstractReductionOpportunity::applyReduction);
     assertEquals("There should be three opportunities", 3, ops.size());
@@ -411,10 +405,6 @@ public void testManuallyAddedUniform() throws Exception {
     CompareAsts.assertEqualAsts(vertexShaderReplaced2, shaderJob.getVertexShader().get());
     CompareAsts.assertEqualAsts(fragmentShaderReplaced, shaderJob.getFragmentShader().get());
 
-    // check that the binding numbers remain the same.
-    assertEquals(bindingNumber, shaderJob.getPipelineInfo().getBinding("_GLF_uniform_int_values"));
-    assertEquals(nextUnusedBindingNumber, shaderJob.getPipelineInfo().getBinding("TEST"));
-
     // Check that the uniforms won't be recursively replaced in the next pass.
     final List<LiteralToUniformReductionOpportunity> ops2 =
         LiteralToUniformReductionOpportunities