From 144b8e6b5ba9f255b49c203d427a917dd9c0b8a3 Mon Sep 17 00:00:00 2001
From: Anthony D'Agostino <anthony.d.dagostino@gmail.com>
Date: Sun, 18 Oct 2026 09:35:21 -0400
Subject: [PATCH] cogl/shader: Don't keep the compilation pipeline alive

CoglShader kept a reference to the pipeline it was last compiled for,
so it could skip recompiling when the layer numbers had not changed.
That pipeline owns the user program, which owns the shader, so the
reference made a cycle: the pipeline and its layer textures were never
freed.

ClutterShaderEffect hits this for every effect with its own shader
source. Each one leaks a stage-sized texture (about 4 MB at 1366x768),
so extensions that create these effects per window, like BlurCinnamon,
leak tens of megabytes of GPU memory each time a window is opened and
closed.

Store the layer indices instead (texture units follow layer order, so
they cover the same check), and free them and the shader source with
the shader.

Ref: https://github.com/klangman/BlurCinnamon/issues/60
---
 cogl/cogl/deprecated/cogl-shader-private.h |  2 +-
 cogl/cogl/deprecated/cogl-shader.c         | 38 +++++++++++++++-------
 2 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/cogl/cogl/deprecated/cogl-shader-private.h b/cogl/cogl/deprecated/cogl-shader-private.h
index f19aaa22c..78f7bef89 100644
--- a/cogl/cogl/deprecated/cogl-shader-private.h
+++ b/cogl/cogl/deprecated/cogl-shader-private.h
@@ -42,7 +42,7 @@ struct _CoglShader
 {
   CoglHandleObject _parent;
   GLuint gl_handle;
-  CoglPipeline *compilation_pipeline;
+  GArray *compiled_layers; /* layer indices, not the pipeline: it owns us */
   CoglShaderType type;
   char *source;
 };
diff --git a/cogl/cogl/deprecated/cogl-shader.c b/cogl/cogl/deprecated/cogl-shader.c
index 701545477..ceef60a02 100644
--- a/cogl/cogl/deprecated/cogl-shader.c
+++ b/cogl/cogl/deprecated/cogl-shader.c
@@ -62,6 +62,8 @@ _cogl_shader_free (CoglShader *shader)
     if (shader->gl_handle)
       GE (ctx, glDeleteShader (shader->gl_handle));
 
+  g_clear_pointer (&shader->compiled_layers, g_array_unref);
+  g_free (shader->source);
   g_slice_free (CoglShader, shader);
 }
 
@@ -85,7 +87,8 @@ cogl_create_shader (CoglShaderType type)
 
   shader = g_slice_new (CoglShader);
   shader->gl_handle = 0;
-  shader->compilation_pipeline = NULL;
+  shader->compiled_layers = NULL;
+  shader->source = NULL;
   shader->type = type;
 
   return _cogl_shader_handle_new (shader);
@@ -101,11 +104,7 @@ delete_shader (CoglShader *shader)
 
   shader->gl_handle = 0;
 
-  if (shader->compilation_pipeline)
-    {
-      cogl_object_unref (shader->compilation_pipeline);
-      shader->compilation_pipeline = NULL;
-    }
+  g_clear_pointer (&shader->compiled_layers, g_array_unref);
 }
 
 void
@@ -124,6 +123,15 @@ cogl_shader_source (CoglHandle   handle,
   shader->source = g_strdup (source);
 }
 
+static gboolean
+append_layer_index_cb (CoglPipeline *pipeline,
+                       int           layer_index,
+                       void         *user_data)
+{
+  g_array_append_val ((GArray *) user_data, layer_index);
+  return TRUE;
+}
+
 void
 _cogl_shader_compile_real (CoglHandle handle,
                            CoglPipeline *pipeline)
@@ -131,20 +139,28 @@ _cogl_shader_compile_real (CoglHandle handle,
   CoglShader *shader = handle;
   GLenum gl_type;
   GLint status;
+  GArray *layers;
 
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
+  layers = g_array_new (TRUE, FALSE, sizeof (int));
+  cogl_pipeline_foreach_layer (pipeline, append_layer_index_cb, layers);
+
   if (shader->gl_handle)
     {
-      CoglPipeline *prev = shader->compilation_pipeline;
+      GArray *prev = shader->compiled_layers;
 
       /* XXX: currently the only things that will affect the
        * boilerplate for user shaders, apart from driver features,
        * are the pipeline layer-indices and texture-unit-indices
+       * (units follow layer order, so the indices cover both)
        */
-      if (pipeline == prev ||
-          _cogl_pipeline_layer_and_unit_numbers_equal (prev, pipeline))
-        return;
+      if (layers->len == prev->len &&
+          memcmp (layers->data, prev->data, layers->len * sizeof (int)) == 0)
+        {
+          g_array_unref (layers);
+          return;
+        }
     }
 
   if (shader->gl_handle)
@@ -176,7 +192,7 @@ _cogl_shader_compile_real (CoglHandle handle,
 
   GE (ctx, glCompileShader (shader->gl_handle));
 
-  shader->compilation_pipeline = cogl_object_ref (pipeline);
+  shader->compiled_layers = layers;
 
   GE (ctx, glGetShaderiv (shader->gl_handle, GL_COMPILE_STATUS, &status));
   if (!status)