tgsi: add prolog() method to tgsi_transform_context

Called when the user can insert new decls, instructions.
This could be used in a few places in the 'draw' module.

Reviewed-by: Charmaine Lee <charmainel@vmware.com>

2 files changed, 13 insertions, 0 deletions

diff --git a/src/gallium/auxiliary/tgsi/tgsi_transform.c b/src/gallium/auxiliary/tgsi/tgsi_transform.c
index b16d296..93e5b98 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_transform.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_transform.c
@@ -109,6 +109,7 @@ tgsi_transform_shader(const struct tgsi_token *tokens_in,
                       struct tgsi_transform_context *ctx)
 {
    uint procType;
+   boolean first_instruction = TRUE;
 
    /* input shader */
    struct tgsi_parse_context parse;
@@ -166,10 +167,16 @@ tgsi_transform_shader(const struct tgsi_token *tokens_in,
             struct tgsi_full_instruction *fullinst
                = &parse.FullToken.FullInstruction;
 
+            if (first_instruction && ctx->prolog) {
+               ctx->prolog(ctx);
+            }
+
             if (ctx->transform_instruction)
                ctx->transform_instruction(ctx, fullinst);
             else
                ctx->emit_instruction(ctx, fullinst);
+
+            first_instruction = FALSE;
          }
          break;
 
diff --git a/src/gallium/auxiliary/tgsi/tgsi_transform.h b/src/gallium/auxiliary/tgsi/tgsi_transform.h
index 8b96664..5ec0719 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_transform.h
+++ b/src/gallium/auxiliary/tgsi/tgsi_transform.h
@@ -57,6 +57,12 @@ struct tgsi_transform_context
                               struct tgsi_full_property *prop);
 
    /**
+    * Called after last declaration, before first instruction.  This is
+    * where the user might insert new declarations and/or instructions.
+    */
+   void (*prolog)(struct tgsi_transform_context *ctx);
+
+   /**
     * Called at end of input program to allow caller to append extra
     * instructions.  Return number of tokens emitted.
     */