debug: Add skeleton for switchable logging

No real flags are defined, only the macros and functions.

  VREND_DEBUG(flag, ctx, ...) translates to fprintf(stderr, ...)
    that is enabled based on whether logging is enabled  for flag
    in context ctx

  VREND_DEBUG_EXT(flag, ctx, X) can be used to add code sequenses
    as X, e.g. specific logging calls like for streams.

v2: Make use of variadic macros to make the VREND_DEBUG macro more
    like a call to *printf (Following a suggestion by Gurchetan)

v3: Already include debug header in vrend_renderer.c

Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Jakob Bornecrantz <jakob@collabora.com>
Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Signed-off-by: Jakob Bornecrantz <jakob@collabora.com>

src/Makefile.am

@@ -27,6 +27,8 @@ libvrend_la_SOURCES = \
         vrend_shader.h \
         vrend_object.c \
         vrend_object.h \
+        vrend_debug.c \
+        vrend_debug.h \
         vrend_decode.c \
         vrend_formats.c \
         vrend_blitter.c \

src/vrend_debug.c

@@ -0,0 +1,48 @@
+/**************************************************************************
+ *
+ * Copyright (C) 2018 Collabora Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#include "vrend_debug.h"
+#include "vrend_renderer.h"
+#include "util/u_debug.h"
+#include <stdlib.h>
+#include <stdio.h>
+static const struct debug_named_value vrend_debug_options[] = {
+   DEBUG_NAMED_VALUE_END
+};
+
+static uint64_t vrend_debug_flags = 0;
+static int vrend_debug_flags_initalized = 0;
+void vrend_init_debug_flags()
+{
+   if (!vrend_debug_flags_initalized)  {
+      vrend_debug_flags_initalized = 1;
+      vrend_debug_flags = debug_get_flags_option("VREND_DEBUG",
+                                                 vrend_debug_options, 0);
+   }
+}
+
+unsigned vrend_debug(struct vrend_context *ctx, enum virgl_debug_flags flag)
+{
+   return (vrend_debug_flags & flag) || vrend_context_has_debug_flag(ctx, flag);
+}

src/vrend_debug.h

@@ -0,0 +1,59 @@
+/**************************************************************************
+ *
+ * Copyright (C) 2018 Collabora Ltd
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ **************************************************************************/
+
+#ifndef vrend_debug_h
+#define vrend_debug_h
+
+struct vrend_context;
+void vrend_print_context_name(struct vrend_context *ctx);
+
+enum virgl_debug_flags {
+   dummy
+};
+
+void vrend_init_debug_flags(void);
+
+unsigned vrend_debug(struct vrend_context *ctx, enum virgl_debug_flags flag);
+
+#ifndef NDEBUG
+#define VREND_DEBUG(flag, ctx,  ...) \
+   if (vrend_debug(ctx, flag)) \
+      do { \
+            vrend_print_context_name(ctx); \
+            fprintf(stderr, __VA_ARGS__); \
+      } while (0)
+
+#define VREND_DEBUG_EXT(flag, ctx, X) \
+   if (vrend_debug(ctx, flag)) \
+      do { \
+            vrend_print_context_name(ctx); \
+            X; \
+      } while (0)
+
+#else
+#define VREND_DEBUG(flag, ctx, fmt, ...)
+#define VREND_DEBUG_EXT(flag, ctx, X)
+#endif
+
+#endif

src/vrend_renderer.c

@@ -47,6 +47,7 @@
 #include "vrend_shader.h"
 
 #include "vrend_renderer.h"
+#include "vrend_debug.h"
 
 #include "virgl_hw.h"
 
@@ -577,6 +578,8 @@ struct vrend_context {
    struct list_head ctx_entry;
 
    struct vrend_shader_cfg shader_cfg;
+
+   unsigned debug_flags;
 };
 
 static struct vrend_resource *vrend_renderer_ctx_res_lookup(struct vrend_context *ctx, int res_handle);
@@ -8632,6 +8635,19 @@ void vrend_renderer_create_sub_ctx(struct vrend_context *ctx, int sub_ctx_id)
       ctx->sub0 = sub;
 }
 
+unsigned vrend_context_has_debug_flag(struct vrend_context *ctx, enum virgl_debug_flags flag)
+{
+   return ctx && (ctx->debug_flags & flag);
+}
+
+void vrend_print_context_name(struct vrend_context *ctx)
+{
+   if (ctx)
+      fprintf(stderr, "%s: ", ctx->debug_name);
+   else
+      fprintf(stderr, "HOST: ");
+}
+
 void vrend_renderer_destroy_sub_ctx(struct vrend_context *ctx, int sub_ctx_id)
 {
    struct vrend_sub_context *sub, *tofree = NULL;
@@ -8699,7 +8715,7 @@ void vrend_renderer_reset(void)
    vrend_object_fini_resource_table();
    vrend_decode_reset(true);
    vrend_object_init_resource_table();
-   vrend_renderer_context_create_internal(0, 0, NULL);
+   vrend_renderer_context_create_internal(0, strlen("HOST"), "HOST");
 }
 
 int vrend_renderer_get_poll_fd(void)

src/vrend_renderer.h

@@ -28,6 +28,7 @@
 #include "pipe/p_state.h"
 #include "util/u_inlines.h"
 #include "virgl_protocol.h"
+#include "vrend_debug.h"
 #include "vrend_iov.h"
 #include "virgl_hw.h"
 #include <epoxy/gl.h>
@@ -409,6 +410,9 @@ void vrend_renderer_reset(void);
 int vrend_renderer_get_poll_fd(void);
 void vrend_decode_reset(bool ctx_0_only);
 
+unsigned vrend_context_has_debug_flag(struct vrend_context *ctx,
+                                      enum virgl_debug_flags flag);
+
 unsigned vrend_renderer_query_multisample_caps(unsigned max_samples,
                                                struct virgl_caps_v2 *caps);