From: Ian Romanick <[email protected]>
Due to the total number of bits used in the bitfield, this does not
increase the size of the structure.
It does, however, reduce the number of instructions required each time
one of these fields is accessed. To access ::matrix_columns with the
bitfield, three instructions were required:
movzbl 0x9(%rdx),%eax
shr %al
and $0x7,%eax
As a uint8_t, only one instruction is required.
movzbl 0xa(%rdx),%eax
These fields are accessed *a lot*.
Signed-off-by: Ian Romanick <[email protected]>
---
src/glsl/glsl_types.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/glsl/glsl_types.h b/src/glsl/glsl_types.h
index 6543041..096f546 100644
--- a/src/glsl/glsl_types.h
+++ b/src/glsl/glsl_types.h
@@ -153,8 +153,8 @@ struct glsl_type {
* these will be 0.
*/
/*@{*/
- unsigned vector_elements:3; /**< 1, 2, 3, or 4 vector elements. */
- unsigned matrix_columns:3; /**< 1, 2, 3, or 4 matrix columns. */
+ uint8_t vector_elements; /**< 1, 2, 3, or 4 vector elements. */
+ uint8_t matrix_columns; /**< 1, 2, 3, or 4 matrix columns. */
/*@}*/
/**
--
1.8.1.4
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