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util: improve BITFIELD_MASK and BITFIELD64_MASK on clang

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gcc is able to optimize away either the modulo or the logical and.  This
makes no difference to gcc.

clang is only able to optimize away the logical and.  This allows clang
to generate faster code for BITFIELD_MASK.

As for BITFIELD64_MASK, this also makes no difference to clang except it
fixes a compile error for BITFIELD64_MASK(64):

  error: shift count >= width of type [-Werror,-Wshift-count-overflow]

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/9989
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25757>
This commit is contained in:
Chia-I Wu
2023-10-16 10:02:50 -07:00
committed by Marge Bot
parent 35ae5dce39
commit 6e2bb716b0
1 changed files with 2 additions and 2 deletions
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4
src/util/macros.h
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@@ -388,7 +388,7 @@ do { \
#define BITFIELD_BIT(b) (1u << (b))
/** Set all bits up to excluding bit b */
#define BITFIELD_MASK(b) \
((b) == 32 ? (~0u) : BITFIELD_BIT((b) % 32) - 1)
((b) == 32 ? (~0u) : BITFIELD_BIT((b) & 31) - 1)
/** Set count bits starting from bit b */
#define BITFIELD_RANGE(b, count) \
(BITFIELD_MASK((b) + (count)) & ~BITFIELD_MASK(b))
@@ -397,7 +397,7 @@ do { \
#define BITFIELD64_BIT(b) (1ull << (b))
/** Set all bits up to excluding bit b */
#define BITFIELD64_MASK(b) \
((b) == 64 ? (~0ull) : BITFIELD64_BIT(b) - 1)
((b) == 64 ? (~0ull) : BITFIELD64_BIT((b) & 63) - 1)
/** Set count bits starting from bit b */
#define BITFIELD64_RANGE(b, count) \
(BITFIELD64_MASK((b) + (count)) & ~BITFIELD64_MASK(b))