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util: rewrite remap util to avoid looping list

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Here we write the binary search to avoid looping over the list
by keeping track of the mid point entries and moving directly
from the last test point.

Fixes: bf946bcc ("util: add range remap util")

Acked-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/37386>
This commit is contained in:
Timothy Arceri
2025-09-16 14:10:50 +10:00
committed by Marge Bot
parent 57ac68f616
commit db2126f8ef
1 changed files with 55 additions and 29 deletions
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src/util/u_range_remap.c
+55 -29
View File
@@ -24,21 +24,6 @@
#include "ralloc.h"
#include "u_range_remap.h"
/* Loop over the list and get the list entry after i interations*/
static struct range_entry *
get_list_entry(unsigned n, const struct list_head *r_list)
{
unsigned i = 0;
list_for_each_entry_safe(struct range_entry, entry, r_list, node) {
if (i == n)
return entry;
i++;
}
return NULL;
}
/* Binary search for the range that contains n */
static struct range_entry *
get_range_entry(unsigned n, const struct list_head *r_list)
@@ -48,25 +33,49 @@ get_range_entry(unsigned n, const struct list_head *r_list)
unsigned low = 0;
unsigned high = list_length(r_list) - 1;
unsigned mid = (low + high) / 2;
struct range_entry *mid_entry =
list_first_entry(r_list, struct range_entry, node);
/* Advance to the initial mid position */
unsigned i = 0;
while (i < mid) {
mid_entry = list_entry(mid_entry->node.next, struct range_entry, node);
i++;
}
while (low <= high) {
int mid = (low + high) / 2;
struct range_entry *mid_entry = get_list_entry(mid, r_list);
if (n < mid_entry->start) {
if (low == high || low == mid) {
if (low == high || mid == low) {
/* No entry found for n */
return NULL;
}
high = mid - 1;
unsigned new_mid = (low + high) / 2;
/* Move backward to new_mid */
while (mid > new_mid) {
mid_entry = list_entry(mid_entry->node.prev, struct range_entry, node);
mid--;
}
} else if (n > mid_entry->end) {
if (low == high) {
if (low == high || mid == high) {
/* No entry found for n */
return NULL;
}
low = mid + 1;
unsigned new_mid = (low + high) / 2;
/* Move forward to new_mid */
while (mid < new_mid) {
mid_entry = list_entry(mid_entry->node.next, struct range_entry, node);
mid++;
}
} else {
/* n is within the current range */
return mid_entry;
}
}
@@ -100,30 +109,47 @@ util_range_insert_remap(unsigned start, unsigned end,
unsigned low = 0;
unsigned high = list_length(r_list) - 1;
unsigned mid = (low + high) / 2;
struct range_entry *mid_entry =
list_first_entry(r_list, struct range_entry, node);
unsigned i = 0;
while (i < mid) {
mid_entry = list_entry(mid_entry->node.next, struct range_entry, node);
i++;
}
while (low <= high) {
int mid = (low + high) / 2;
struct range_entry *mid_entry = get_list_entry(mid, r_list);
if (end < mid_entry->start) {
if (low == high || low == mid) {
if (low == high || mid == low) {
entry = rzalloc(r_list, struct range_entry);
list_addtail(&entry->node, &mid_entry->node);
break;
list_addtail(&entry->node, &mid_entry->node); /* insert before mid */
goto insert_end;
}
high = mid - 1;
unsigned new_mid = (low + high) / 2;
while (mid > new_mid) {
mid_entry = list_entry(mid_entry->node.prev, struct range_entry, node);
mid--;
}
} else if (start > mid_entry->end) {
if (low == high) {
if (low == high || mid == high) {
entry = rzalloc(r_list, struct range_entry);
list_add(&entry->node, &mid_entry->node);
break;
list_add(&entry->node, &mid_entry->node); /* insert after mid */
goto insert_end;
}
low = mid + 1;
unsigned new_mid = (low + high) / 2;
while (mid < new_mid) {
mid_entry =
list_entry(mid_entry->node.next, struct range_entry, node);
mid++;
}
} else if (mid_entry->start == start && mid_entry->end == end) {
entry = mid_entry;
break;
goto insert_end;
} else {
/* Attempting to insert an entry that overlaps an existing range */
return NULL;