mesa: Reset image unit state to the default values when a bound image is deleted.

The ES31-CTS.shader_image_load_store.basic-api-bind conformance test
expects the whole image unit state to be reset when the bound texture
object is deleted.  The ARB_shader_image_load_store extension is
rather vague regarding what should happen with image unit state other
than the texture object in that case, but the GL 4.2 and GLES 3.1
specifications (section "Automatic Unbinding of Deleted Objects")
explicitly require it to be reset to the default values.

Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/mesa/main/shaderimage.c

@@ -394,17 +394,24 @@ is_image_format_supported(const struct gl_context *ctx, GLenum format)
    }
 }
 
+struct gl_image_unit
+_mesa_default_image_unit(struct gl_context *ctx)
+{
+   const struct gl_image_unit u = {
+      .Access = GL_READ_ONLY,
+      .Format = GL_R8,
+      ._ActualFormat = _mesa_get_shader_image_format(GL_R8)
+   };
+   return u;
+}
+
 void
 _mesa_init_image_units(struct gl_context *ctx)
 {
    unsigned i;
 
-   for (i = 0; i < ARRAY_SIZE(ctx->ImageUnits); ++i) {
-      struct gl_image_unit *u = &ctx->ImageUnits[i];
-      u->Access = GL_READ_ONLY;
-      u->Format = GL_R8;
-      u->_ActualFormat = _mesa_get_shader_image_format(u->Format);
-   }
+   for (i = 0; i < ARRAY_SIZE(ctx->ImageUnits); ++i)
+      ctx->ImageUnits[i] = _mesa_default_image_unit(ctx);
 }
 
 static GLboolean

src/mesa/main/shaderimage.h

@@ -42,6 +42,12 @@ struct gl_context;
 mesa_format
 _mesa_get_shader_image_format(GLenum format);
 
+/**
+ * Get a single image unit struct with the default state.
+ */
+struct gl_image_unit
+_mesa_default_image_unit(struct gl_context *ctx);
+
 /**
  * Initialize a context's shader image units to the default state.
  */

src/mesa/main/texobj.c

@@ -37,6 +37,7 @@
 #include "hash.h"
 #include "imports.h"
 #include "macros.h"
+#include "shaderimage.h"
 #include "teximage.h"
 #include "texobj.h"
 #include "texstate.h"
@@ -1411,8 +1412,10 @@ unbind_texobj_from_image_units(struct gl_context *ctx,
    for (i = 0; i < ctx->Const.MaxImageUnits; i++) {
       struct gl_image_unit *unit = &ctx->ImageUnits[i];
 
-      if (texObj == unit->TexObj)
+      if (texObj == unit->TexObj) {
          _mesa_reference_texobj(&unit->TexObj, NULL);
+         *unit = _mesa_default_image_unit(ctx);
+      }
    }
 }