[Mesa-dev] [PATCH] anv/formats: Fix build on gcc-4 and earlier

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

gcc-4 and earlier don't allow compound literals where a constant
is required in -std=c99/gnu99 mode, so we can't use ISL_SWIZZLE()
when populating the anv_formats[] array. There are a few ways around
it: First one would be -std=c89/gnu89, but the rest of the code
depends on c99 so it's not really an option. The second option
would be to upgrade to gcc-5+ where the compiler behaviour was relaxed
a bit [1]. And the third option is just to avoid using compound
literals. I chose the last option since it keeps gcc-4 and earlier
working.

[1] https://gcc.gnu.org/gcc-5/porting_to.html

Cc: Jason Ekstrand <jason at jlekstrand.net>
Cc: Topi Pohjolainen <topi.pohjolainen at intel.com>
Fixes: 7ddb21708c80 ("intel/isl: Add an isl_swizzle structure and use it for isl_view swizzles")
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 src/intel/vulkan/anv_formats.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/intel/vulkan/anv_formats.c b/src/intel/vulkan/anv_formats.c
index 7341d725cd0a..f6915540fb3d 100644
--- a/src/intel/vulkan/anv_formats.c
+++ b/src/intel/vulkan/anv_formats.c
@@ -24,9 +24,24 @@
 #include "anv_private.h"
 #include "vk_format_info.h"
 
-#define RGBA ISL_SWIZZLE(RED, GREEN, BLUE, ALPHA)
-#define BGRA ISL_SWIZZLE(BLUE, GREEN, RED, ALPHA)
-#define RGB1 ISL_SWIZZLE(RED, GREEN, BLUE, ONE)
+/*
+ * gcc-4 and earlier don't allow compound literals where a constant
+ * is required in -std=c99/gnu99 mode, so we can't use ISL_SWIZZLE()
+ * here. -std=c89/gnu89 would allow it, but we depend on c99 features
+ * so using -std=c89/gnu89 is not an option. Starting from gcc-5
+ * compound literals can also be considered constant in -std=c99/gnu99
+ * mode.
+ */
+#define _ISL_SWIZZLE(r, g, b, a) { \
+      ISL_CHANNEL_SELECT_##r, \
+      ISL_CHANNEL_SELECT_##g, \
+      ISL_CHANNEL_SELECT_##b, \
+      ISL_CHANNEL_SELECT_##a, \
+}
+
+#define RGBA _ISL_SWIZZLE(RED, GREEN, BLUE, ALPHA)
+#define BGRA _ISL_SWIZZLE(BLUE, GREEN, RED, ALPHA)
+#define RGB1 _ISL_SWIZZLE(RED, GREEN, BLUE, ONE)
 
 #define swiz_fmt(__vk_fmt, __hw_fmt, __swizzle)     \
    [__vk_fmt] = { \
@@ -276,7 +291,7 @@ anv_get_format(const struct gen_device_info *devinfo, VkFormat vk_format,
          format.isl_format = rgbx;
       } else {
          format.isl_format = isl_format_rgb_to_rgba(format.isl_format);
-         format.swizzle = RGB1;
+         format.swizzle = ISL_SWIZZLE(RED, GREEN, BLUE, ONE);
       }
    }
 
-- 
2.7.4