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expmed.c (synth_mult): Mask bits of the multiplier to the machine mode of the multiplication.

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* expmed.c (synth_mult): Mask bits of the multiplier to the
	machine mode of the multiplication.  Don't consider shifts
	by more than (or equal to) the width of the operation's mode.

From-SVN: r83187
This commit is contained in:
Roger Sayle 2004-06-15 15:06:14 +00:00 committed by Roger Sayle
parent 5a4f18181b
commit 0792ab197b
2 changed files with 15 additions and 5 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2004-06-15 Roger Sayle <roger@eyesopen.com>
* expmed.c (synth_mult): Mask bits of the multiplier to the
machine mode of the multiplication. Don't consider shifts
by more than (or equal to) the width of the operation's mode.
2004-06-15 Paolo Bonzini <bonzini@gnu.org>
* doc/install.texi: Yet another update for autoconf

14
gcc/expmed.c
View File

@ -2191,6 +2191,7 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
struct algorithm *alg_in, *best_alg;
int cost;
unsigned HOST_WIDE_INT q;
int maxm = MIN (BITS_PER_WORD, GET_MODE_BITSIZE (mode));
/* Indicate that no algorithm is yet found. If no algorithm
is found, this value will be returned and indicate failure. */
@ -2199,6 +2200,9 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
if (cost_limit <= 0)
return;
/* Restrict the bits of "t" to the multiplication's mode. */
t &= GET_MODE_MASK (mode);
/* t == 1 can be done in zero cost. */
if (t == 1)
{
@ -2234,7 +2238,7 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
if ((t & 1) == 0)
{
m = floor_log2 (t & -t); /* m = number of low zero bits */
if (m < BITS_PER_WORD)
if (m < maxm)
{
q = t >> m;
cost = shift_cost[mode][m];
@ -2319,7 +2323,7 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
unsigned HOST_WIDE_INT d;
d = ((unsigned HOST_WIDE_INT) 1 << m) + 1;
if (t % d == 0 && t > d && m < BITS_PER_WORD)
if (t % d == 0 && t > d && m < maxm)
{
cost = add_cost[mode] + shift_cost[mode][m];
if (shiftadd_cost[mode][m] < cost)
@ -2340,7 +2344,7 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
}
d = ((unsigned HOST_WIDE_INT) 1 << m) - 1;
if (t % d == 0 && t > d && m < BITS_PER_WORD)
if (t % d == 0 && t > d && m < maxm)
{
cost = add_cost[mode] + shift_cost[mode][m];
if (shiftsub_cost[mode][m] < cost)
@ -2367,7 +2371,7 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
q = t - 1;
q = q & -q;
m = exact_log2 (q);
if (m >= 0 && m < BITS_PER_WORD)
if (m >= 0 && m < maxm)
{
cost = shiftadd_cost[mode][m];
synth_mult (alg_in, (t - 1) >> m, cost_limit - cost, mode);
@ -2386,7 +2390,7 @@ synth_mult (struct algorithm *alg_out, unsigned HOST_WIDE_INT t,
q = t + 1;
q = q & -q;
m = exact_log2 (q);
if (m >= 0 && m < BITS_PER_WORD)
if (m >= 0 && m < maxm)
{
cost = shiftsub_cost[mode][m];
synth_mult (alg_in, (t + 1) >> m, cost_limit - cost, mode);