3 files changed, 9 insertions, 1 deletions
diff --git a/src/gallium/auxiliary/tgsi/tgsi_scan.c b/src/gallium/auxiliary/tgsi/tgsi_scan.c
index bd79405a8aa..0230267a5de 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_scan.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_scan.c
@@ -211,6 +211,12 @@ tgsi_scan_shader(const struct tgsi_token *tokens,
                       fulldecl->Semantic.Name == TGSI_SEMANTIC_EDGEFLAG) {
                      info->writes_edgeflag = TRUE;
                   }
+
+                  if (procType == TGSI_PROCESSOR_GEOMETRY &&
+                      fulldecl->Semantic.Name ==
+                      TGSI_SEMANTIC_VIEWPORT_INDEX) {
+                     info->writes_viewport_index = TRUE;
+                  }
                }
 
              }
diff --git a/src/gallium/auxiliary/tgsi/tgsi_scan.h b/src/gallium/auxiliary/tgsi/tgsi_scan.h
index 9debc341f52..676abf0c9a9 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_scan.h
+++ b/src/gallium/auxiliary/tgsi/tgsi_scan.h
@@ -75,6 +75,7 @@ struct tgsi_shader_info
    boolean origin_lower_left;
    boolean pixel_center_integer;
    boolean color0_writes_all_cbufs;
+   boolean writes_viewport_index;
 
    unsigned num_written_clipdistance;
    /**
diff --git a/src/gallium/auxiliary/tgsi/tgsi_strings.c b/src/gallium/auxiliary/tgsi/tgsi_strings.c
index 95a5aded819..6abf9272a26 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_strings.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_strings.c
@@ -78,7 +78,8 @@ const char *tgsi_semantic_names[TGSI_SEMANTIC_COUNT] =
    "BLOCK_SIZE",
    "THREAD_ID",
    "TEXCOORD",
-   "PCOORD"
+   "PCOORD",
+   "VIEWPORT_INDEX"
 };
 
 const char *tgsi_texture_names[TGSI_TEXTURE_COUNT] =