gallium/hud: Fix support for PIPE_DRIVER_QUERY_TYPE_FLOAT

Evidently, nobody has used PIPE_DRIVER_QUERY_TYPE_FLOAT up to this
point.  Adding a driver query of this type which returns the query
value in pipe_query_result::f resulted in garbage output in the HUD.

The problem is the pipe_query_result::f field was being accessed as
through the u64 field and being added to the query_info::results_cumulative
field.  This patch checks for PIPE_DRIVER_QUERY_TYPE_FLOAT in a few
places and scales the float by 1000 before converting to uint64_t.

Also, add some comments to explain the query_info::result_index field.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/auxiliary/hud/hud_context.c

@@ -224,6 +224,7 @@ number_to_human_readable(double num, enum pipe_driver_query_type type,
    static const char *volt_units[] = {" mV", " V"};
    static const char *amp_units[] = {" mA", " A"};
    static const char *watt_units[] = {" mW", " W"};
+   static const char *float_units[] = {""};
 
    const char **units;
    unsigned max_unit;
@@ -252,6 +253,10 @@ number_to_human_readable(double num, enum pipe_driver_query_type type,
       max_unit = ARRAY_SIZE(temperature_units)-1;
       units = temperature_units;
       break;
+   case PIPE_DRIVER_QUERY_TYPE_FLOAT:
+      max_unit = ARRAY_SIZE(float_units)-1;
+      units = float_units;
+      break;
    case PIPE_DRIVER_QUERY_TYPE_PERCENTAGE:
       max_unit = ARRAY_SIZE(percent_units)-1;
       units = percent_units;

src/gallium/auxiliary/hud/hud_driver_query.c

@@ -195,8 +195,13 @@ hud_batch_query_cleanup(struct hud_batch_query_context **pbq,
 struct query_info {
    struct hud_batch_query_context *batch;
    enum pipe_query_type query_type;
-   unsigned result_index; /* unit depends on query_type */
+
+   /** index to choose fields in pipe_query_data_pipeline_statistics,
+    * for example.
+    */
+   unsigned result_index;
    enum pipe_driver_query_result_type result_type;
+   enum pipe_driver_query_type type;
 
    /* Ring of queries. If a query is busy, we use another slot. */
    struct pipe_query *query[NUM_QUERIES];
@@ -238,7 +243,13 @@ query_new_value_normal(struct query_info *info, struct pipe_context *pipe)
          uint64_t *res64 = (uint64_t *)&result;
 
          if (query && pipe->get_query_result(pipe, query, FALSE, &result)) {
-            info->results_cumulative += res64[info->result_index];
+            if (info->type == PIPE_DRIVER_QUERY_TYPE_FLOAT) {
+               assert(info->result_index == 0);
+               info->results_cumulative += (uint64_t) (result.f * 1000.0f);
+            }
+            else {
+               info->results_cumulative += res64[info->result_index];
+            }
             info->num_results++;
 
             if (info->tail == info->head)
@@ -307,7 +318,7 @@ query_new_value(struct hud_graph *gr, struct pipe_context *pipe)
    }
 
    if (info->num_results && info->last_time + gr->pane->period <= now) {
-      uint64_t value;
+      double value;
 
       switch (info->result_type) {
       default:
@@ -319,6 +330,10 @@ query_new_value(struct hud_graph *gr, struct pipe_context *pipe)
          break;
       }
 
+      if (info->type == PIPE_DRIVER_QUERY_TYPE_FLOAT) {
+         value /= 1000.0;
+      }
+
       hud_graph_add_value(gr, value);
 
       info->last_time = now;
@@ -346,6 +361,11 @@ free_query_info(void *ptr, struct pipe_context *pipe)
    FREE(info);
 }
 
+
+/**
+ * \param result_index  to select fields of pipe_query_data_pipeline_statistics,
+ *                      for example.
+ */
 void
 hud_pipe_query_install(struct hud_batch_query_context **pbq,
                        struct hud_pane *pane,
@@ -374,6 +394,7 @@ hud_pipe_query_install(struct hud_batch_query_context **pbq,
 
    info = gr->query_data;
    info->result_type = result_type;
+   info->type = type;
 
    if (flags & PIPE_DRIVER_QUERY_FLAG_BATCH) {
       if (!batch_query_add(pbq, query_type, &info->result_index))