[Mesa-dev] [PATCH] glsl: handle same struct redeclaration (v2)

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

This works around a bug in older version of UE4, where a shader
defines the same structure twice. Although we aren't sure this is correct
GLSL (it most likely isn't) there are enough UE4 based things out there
we should deal with this.

This drops the error to a warning if the struct names and contents match.

v1.1: do better C++ on record_compare declaration (Rob)
v2: restrict this to desktop GL only (Ian)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=95005
Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 src/compiler/glsl/ast_to_hir.cpp | 7 ++++++-
 src/compiler/glsl_types.cpp      | 4 ++--
 src/compiler/glsl_types.h        | 4 +++-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index b4c6de2..ecfe684 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -6918,7 +6918,12 @@ ast_struct_specifier::hir(exec_list *instructions,
       glsl_type::get_record_instance(fields, decl_count, this->name);
 
    if (!state->symbols->add_type(name, t)) {
-      _mesa_glsl_error(& loc, state, "struct `%s' previously defined", name);
+      const glsl_type *match = state->symbols->get_type(name);
+      /* allow struct matching for desktop GL - older UE4 does this */
+      if (state->is_version(130, 0) && match->record_compare(t, false))
+         _mesa_glsl_warning(& loc, state, "struct `%s' previously defined", name);
+      else
+         _mesa_glsl_error(& loc, state, "struct `%s' previously defined", name);
    } else {
       const glsl_type **s = reralloc(state, state->user_structures,
                                      const glsl_type *,
diff --git a/src/compiler/glsl_types.cpp b/src/compiler/glsl_types.cpp
index c058283..11f1e85 100644
--- a/src/compiler/glsl_types.cpp
+++ b/src/compiler/glsl_types.cpp
@@ -856,7 +856,7 @@ glsl_type::get_array_instance(const glsl_type *base, unsigned array_size)
 
 
 bool
-glsl_type::record_compare(const glsl_type *b) const
+glsl_type::record_compare(const glsl_type *b, bool match_locations) const
 {
    if (this->length != b->length)
       return false;
@@ -887,7 +887,7 @@ glsl_type::record_compare(const glsl_type *b) const
       if (this->fields.structure[i].matrix_layout
          != b->fields.structure[i].matrix_layout)
         return false;
-      if (this->fields.structure[i].location
+      if (match_locations && this->fields.structure[i].location
           != b->fields.structure[i].location)
          return false;
       if (this->fields.structure[i].offset
diff --git a/src/compiler/glsl_types.h b/src/compiler/glsl_types.h
index a47b0ff..7f9e318 100644
--- a/src/compiler/glsl_types.h
+++ b/src/compiler/glsl_types.h
@@ -740,8 +740,10 @@ struct glsl_type {
     * Compare a record type against another record type.
     *
     * This is useful for matching record types declared across shader stages.
+    * The option to not match locations is to deal with places where the
+    * same struct is defined in a block which has a location set on it.
     */
-   bool record_compare(const glsl_type *b) const;
+   bool record_compare(const glsl_type *b, bool match_locations = true) const;
 
 private:
 
-- 
2.5.5