glsl: store uniform slot id in var location field

This will allow us to access the uniform later on without resorting to
building a name string and looking it up in UniformHash.

V3: remove line wrap change from this patch

V2: store slot number for all non-UBO uniforms to make code more
consitent, renamed explicit_binding to explicit_location and added
comment about what it does. Store the location at every shader stage.
Updated data.location comments in ir/nir.h.

Reviewed-by: Jason Ekstrand <jason.ekstrand@intel.com>

src/glsl/ir.h

@@ -819,6 +819,8 @@ public:
        *   - Fragment shader output: one of the values from \c gl_frag_result.
        *   - Uniforms: Per-stage uniform slot number for default uniform block.
        *   - Uniforms: Index within the uniform block definition for UBO members.
+       *   - Non-UBO Uniforms: explicit location until linking then reused to
+       *     store uniform slot number.
        *   - Other: This field is not currently used.
        *
        * If the variable is a uniform, shader input, or shader output, and the

src/glsl/link_uniforms.cpp

@@ -527,7 +527,13 @@ public:
                     var->get_interface_type()->name);
          else
             process(var);
-      } else
+      } else {
+         /* Store any explicit location and reset data location so we can
+          * reuse this variable for storing the uniform slot number.
+          */
+         this->explicit_location = current_var->data.location;
+         current_var->data.location = -1;
+
          process(var);
       }
       delete this->record_next_sampler;
@@ -710,6 +716,13 @@ private:
       handle_images(base_type, &this->uniforms[id]);
       handle_subroutines(base_type, &this->uniforms[id]);
 
+      /* For array of arrays or struct arrays the base location may have
+       * already been set so dont set it again.
+       */
+      if (ubo_block_index == -1 && current_var->data.location == -1) {
+         current_var->data.location = id;
+      }
+
       /* If there is already storage associated with this uniform or if the
        * uniform is set as builtin, it means that it was set while processing
        * an earlier shader stage.  For example, we may be processing the
@@ -726,10 +739,10 @@ private:
          if (record_type != NULL) {
             const unsigned entries = MAX2(1, this->uniforms[id].array_elements);
             this->uniforms[id].remap_location =
-               current_var->data.location + field_counter;
+               this->explicit_location + field_counter;
             field_counter += entries;
          } else {
-            this->uniforms[id].remap_location = current_var->data.location;
+         this->uniforms[id].remap_location = this->explicit_location;
          }
       } else {
          /* Initialize to to indicate that no location is set */
@@ -795,6 +808,11 @@ private:
    unsigned next_image;
    unsigned next_subroutine;
 
+   /* Used to store the explicit location from current_var so that we can
+    * reuse the location field for storing the uniform slot id.
+    */
+   int explicit_location;
+
    /* Stores total struct array elements including nested structs */
    unsigned record_array_count;
 

src/glsl/nir/nir.h

@@ -278,6 +278,7 @@ typedef struct {
        *   - Fragment shader output: one of the values from \c gl_frag_result.
        *   - Uniforms: Per-stage uniform slot number for default uniform block.
        *   - Uniforms: Index within the uniform block definition for UBO members.
+       *   - Non-UBO Uniforms: uniform slot number.
        *   - Other: This field is not currently used.
        *
        * If the variable is a uniform, shader input, or shader output, and the