From d5d2fb5c4c100300f17976dbc4cf4c7045a2b688 Mon Sep 17 00:00:00 2001 From: Kenneth Graunke Date: Thu, 6 Jun 2019 17:36:09 -0700 Subject: [PATCH] isl: Mark enum isl_channel_select packed so it becomes 1 byte. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit I recently discovered that the following code lead to valgrind errors: struct isl_swizzle swizzle = ISL_SWIZZLE_IDENTITY; VALGRIND_CHECK_MEM_IS_DEFINED(&swizzle, sizeof(swizzle)); which is surprising, because struct isl_swizzle is simply: struct isl_swizzle { enum isl_channel_select r:4; enum isl_channel_select g:4; enum isl_channel_select b:4; enum isl_channel_select a:4; }; and the above code initializes all of them with a C99 initializer. Iván Briano reminded me that C99 initializers don't necessarily zero padding. A quick inspection revealed that sizeof(struct isl_swizzle) was 4 (rather than the expected 2). Ian Romanick suggested changing it to uint16_t, since this is essentially dicing up an unsigned, and that worked. This patch marks enum isl_channel_select packed, changing its size from 4 bytes to 1 byte. This then makes struct isl_swizzle 2 bytes, with no bogus padding fields. This eliminates valgrind undefined memory warnings. These isl_swizzle values become part of our BLORP blit program keys, which are then hashed. This undefined padding was being included in the hashing, possibly leading to issues. I originally saw this error when running KHR-GL45.texture_size_promotion.functional in iris under valgrind. Reviewed-by: Jason Ekstrand --- src/intel/isl/isl.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/intel/isl/isl.h b/src/intel/isl/isl.h index 6790ba002ad..0218f05d175 100644 --- a/src/intel/isl/isl.h +++ b/src/intel/isl/isl.h @@ -861,7 +861,7 @@ typedef uint8_t isl_channel_mask_t; /** * @brief A channel select (also known as texture swizzle) value */ -enum isl_channel_select { +enum PACKED isl_channel_select { ISL_CHANNEL_SELECT_ZERO = 0, ISL_CHANNEL_SELECT_ONE = 1, ISL_CHANNEL_SELECT_RED = 4, -- 2.30.2