Commit 8f88f7d3 authored by Paul Eggert's avatar Paul Eggert
Browse files

Avoid undefined behavior with signed left shift.

Caught by 'gcc -fsanitize=undefined'.
* dispextern.h, scroll.c (scrolling_max_lines_saved, scrolling_1):
* dispnew.c (line_hash_code, scrolling):
* scroll.c (calculate_scrolling, calculate_direct_scrolling):
Use 'unsigned', not 'int', for line hashes.
(scrolling_max_lines_saved): Avoid mystery constants for hash sizes.
parent 5fe16efb
2014-08-03 Paul Eggert <eggert@cs.ucla.edu>
Avoid undefined behavior with signed left shift.
Caught by 'gcc -fsanitize=undefined'.
* dispextern.h, scroll.c (scrolling_max_lines_saved, scrolling_1):
* dispnew.c (line_hash_code, scrolling):
* scroll.c (calculate_scrolling, calculate_direct_scrolling):
Use 'unsigned', not 'int', for line hashes.
(scrolling_max_lines_saved): Avoid mystery constants for hash sizes.
2014-08-02 Paul Eggert <eggert@cs.ucla.edu>
Make compare-strings more compatible with old behavior (Bug#17903).
......
......@@ -3507,13 +3507,13 @@ extern void tty_append_glyph (struct it *);
/* Defined in scroll.c */
extern int scrolling_max_lines_saved (int, int, int *, int *, int *);
extern int scrolling_max_lines_saved (int, int, unsigned *, unsigned *, int *);
extern void do_line_insertion_deletion_costs (struct frame *, const char *,
const char *, const char *,
const char *, const char *,
const char *, int);
void scrolling_1 (struct frame *, int, int, int, int *, int *, int *,
int *, int);
void scrolling_1 (struct frame *, int, int, int, int *, int *, unsigned *,
unsigned *, int);
/* Defined in frame.c */
......
......@@ -1108,10 +1108,10 @@ prepare_desired_row (struct window *w, struct glyph_row *row, bool mode_line_p)
/* Return a hash code for glyph row ROW, which may
be from current or desired matrix of frame F. */
static int
static unsigned
line_hash_code (struct frame *f, struct glyph_row *row)
{
int hash = 0;
unsigned hash = 0;
if (row->enabled_p)
{
......@@ -4647,8 +4647,8 @@ scrolling (struct frame *frame)
int unchanged_at_top, unchanged_at_bottom;
int window_size;
int changed_lines;
int *old_hash = alloca (FRAME_TOTAL_LINES (frame) * sizeof (int));
int *new_hash = alloca (FRAME_TOTAL_LINES (frame) * sizeof (int));
unsigned *old_hash = alloca (FRAME_TOTAL_LINES (frame) * sizeof (int));
unsigned *new_hash = alloca (FRAME_TOTAL_LINES (frame) * sizeof (int));
int *draw_cost = alloca (FRAME_TOTAL_LINES (frame) * sizeof (int));
int *old_draw_cost = alloca (FRAME_TOTAL_LINES (frame) * sizeof (int));
register int i;
......
......@@ -90,7 +90,7 @@ calculate_scrolling (struct frame *frame,
/* matrix is of size window_size + 1 on each side. */
struct matrix_elt *matrix,
int window_size, int lines_below,
int *draw_cost, int *old_hash, int *new_hash,
int *draw_cost, unsigned *old_hash, unsigned *new_hash,
int free_at_end)
{
register int i, j;
......@@ -427,7 +427,7 @@ calculate_direct_scrolling (struct frame *frame,
struct matrix_elt *matrix,
int window_size, int lines_below,
int *draw_cost, int *old_draw_cost,
int *old_hash, int *new_hash,
unsigned *old_hash, unsigned *new_hash,
int free_at_end)
{
register int i, j;
......@@ -794,7 +794,7 @@ do_direct_scrolling (struct frame *frame, struct glyph_matrix *current_matrix,
void
scrolling_1 (struct frame *frame, int window_size, int unchanged_at_top,
int unchanged_at_bottom, int *draw_cost, int *old_draw_cost,
int *old_hash, int *new_hash, int free_at_end)
unsigned *old_hash, unsigned *new_hash, int free_at_end)
{
struct matrix_elt *matrix
= alloca ((window_size + 1) * (window_size + 1) * sizeof *matrix);
......@@ -829,12 +829,14 @@ scrolling_1 (struct frame *frame, int window_size, int unchanged_at_top,
int
scrolling_max_lines_saved (int start, int end,
int *oldhash, int *newhash,
unsigned *oldhash, unsigned *newhash,
int *cost)
{
struct { int hash; int count; } lines[01000];
register int i, h;
register int matchcount = 0;
enum { LOG2_NLINES = 9 };
enum { NLINES = 1 << LOG2_NLINES };
struct { unsigned hash; int count; } lines[NLINES];
int i, h;
int matchcount = 0;
int avg_length = 0;
int threshold;
......@@ -855,7 +857,7 @@ scrolling_max_lines_saved (int start, int end,
{
if (cost[i] > threshold)
{
h = newhash[i] & 0777;
h = newhash[i] & (NLINES - 1);
lines[h].hash = newhash[i];
lines[h].count++;
}
......@@ -865,7 +867,7 @@ scrolling_max_lines_saved (int start, int end,
matches between old lines and new. */
for (i = start; i < end; i++)
{
h = oldhash[i] & 0777;
h = oldhash[i] & (NLINES - 1);
if (oldhash[i] == lines[h].hash)
{
matchcount++;
......
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