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lib: sbi_scratch: Optimize hartid and scratch lookup

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The compiler generates much better code for sbi_hartindex_to_hartid()
and sbi_hartindex_to_scratch() when using a constant for the bounds
check. This works out nicely because the underlying arrays are already
a constant size, so the only change needed is to fill the remainder of
each array with the appropriate default/out-of-bounds value. The
ellipsis in the designated initializer is a GCC extension (also
supported by Clang), but avoids runtime initialization of the array.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Samuel Holland
2025-02-20 10:42:28 -08:00
committed by Anup Patel
parent ef4ed2dda7
commit 6b97950cf5
2 changed files with 5 additions and 5 deletions
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4
include/sbi/sbi_scratch.h
View File

@@ -226,7 +226,7 @@ extern u32 hartindex_to_hartid_table[];
/** Get sbi_scratch from HART index */
#define sbi_hartindex_to_hartid(__hartindex) \
({ \
((__hartindex) <= sbi_scratch_last_hartindex()) ?\
((__hartindex) < SBI_HARTMASK_MAX_BITS) ? \
hartindex_to_hartid_table[__hartindex] : -1U; \
})
@@ -236,7 +236,7 @@ extern struct sbi_scratch *hartindex_to_scratch_table[];
/** Get sbi_scratch from HART index */
#define sbi_hartindex_to_scratch(__hartindex) \
({ \
((__hartindex) <= sbi_scratch_last_hartindex()) ?\
((__hartindex) < SBI_HARTMASK_MAX_BITS) ? \
hartindex_to_scratch_table[__hartindex] : NULL; \
})

4
lib/sbi/sbi_scratch.c
View File

@@ -15,8 +15,8 @@
#include <sbi/sbi_string.h>
u32 last_hartindex_having_scratch = 0;
u32 hartindex_to_hartid_table[SBI_HARTMASK_MAX_BITS] = { -1U };
struct sbi_scratch *hartindex_to_scratch_table[SBI_HARTMASK_MAX_BITS] = { 0 };
u32 hartindex_to_hartid_table[SBI_HARTMASK_MAX_BITS] = { [0 ... SBI_HARTMASK_MAX_BITS-1] = -1U };
struct sbi_scratch *hartindex_to_scratch_table[SBI_HARTMASK_MAX_BITS];
static spinlock_t extra_lock = SPIN_LOCK_INITIALIZER;
static unsigned long extra_offset = SBI_SCRATCH_EXTRA_SPACE_OFFSET;