vkd3d-shader/hlsl: Split deref-offset into a node and a constant uint.

This uint will be used for the following:

- Since SM4's relative addressing (the capability of passing a register
  as an index to another register) only has whole-register granularity,
  we will need to make the offset node express the offset in
  whole-registers and specify the register component in this uint,
  otherwise we would have to add additional / and % operations in the
  output binary.

- If, after we apply constant folding and copy propagation, we determine
  that the offset is a single constant node, we can store all the offset
  in this uint constant, and remove the offset src.

  This allows DCE to remove a good bunch of the nodes previously required
  only for the offset constants, which makes the output more liteweight
  and readable, and simplifies the implementation of relative addressing
  when writing tpf in the following patches.

In dump_deref(), we use "c" to indicate components instead of whole
registers. Since now both the offset node and the offset uint are in
components a lowered deref would look like:

    var[@42c + 2c]

But, once we express the offset node in whole registers we will remove
the "c" from the node part:

    var[@22 + 3c]

libs/vkd3d-shader/hlsl.c

@@ -513,6 +513,7 @@ static bool init_deref(struct hlsl_ctx *ctx, struct hlsl_deref *deref, struct hl
     deref->var = var;
     deref->path_len = path_len;
     deref->offset.node = NULL;
+    deref->const_offset = 0;
     deref->data_type = NULL;
 
     if (path_len == 0)
@@ -541,6 +542,7 @@ bool hlsl_init_deref_from_index_chain(struct hlsl_ctx *ctx, struct hlsl_deref *d
     deref->path = NULL;
     deref->path_len = 0;
     deref->offset.node = NULL;
+    deref->const_offset = 0;
 
     assert(chain);
     if (chain->type == HLSL_IR_INDEX)
@@ -1137,6 +1139,7 @@ void hlsl_cleanup_deref(struct hlsl_deref *deref)
     deref->path_len = 0;
 
     hlsl_src_remove(&deref->offset);
+    deref->const_offset = 0;
 }
 
 /* Initializes a simple variable dereference, so that it can be passed to load/store functions. */
@@ -2411,21 +2414,37 @@ static void dump_deref(struct vkd3d_string_buffer *buffer, const struct hlsl_der
     if (deref->var)
     {
         vkd3d_string_buffer_printf(buffer, "%s", deref->var->name);
-        if (deref->path_len)
+        if (!hlsl_deref_is_lowered(deref))
         {
-            vkd3d_string_buffer_printf(buffer, "[");
-            for (i = 0; i < deref->path_len; ++i)
+            if (deref->path_len)
             {
                 vkd3d_string_buffer_printf(buffer, "[");
-                dump_src(buffer, &deref->path[i]);
+                for (i = 0; i < deref->path_len; ++i)
+                {
+                    vkd3d_string_buffer_printf(buffer, "[");
+                    dump_src(buffer, &deref->path[i]);
+                    vkd3d_string_buffer_printf(buffer, "]");
+                }
                 vkd3d_string_buffer_printf(buffer, "]");
             }
-            vkd3d_string_buffer_printf(buffer, "]");
         }
-        else if (deref->offset.node)
+        else
         {
+            bool show_rel, show_const;
+
+            show_rel = deref->offset.node;
+            show_const = deref->const_offset != 0 || !show_rel;
+
             vkd3d_string_buffer_printf(buffer, "[");
-            dump_src(buffer, &deref->offset);
+            if (show_rel)
+            {
+                dump_src(buffer, &deref->offset);
+                vkd3d_string_buffer_printf(buffer, "c");
+            }
+            if (show_rel && show_const)
+                vkd3d_string_buffer_printf(buffer, " + ");
+            if (show_const)
+                vkd3d_string_buffer_printf(buffer, "%uc", deref->const_offset);
             vkd3d_string_buffer_printf(buffer, "]");
         }
     }