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(count_reg_usage): Don't count a register used within a SET that sets it. 

(delete_dead_from_cse): Pass new parm to count_reg_usage.

From-SVN: r6327
This commit is contained in:
Richard Kenner 1993-12-26 08:30:32 -05:00
parent c2cc077888
commit 79644f0689
1 changed files with 20 additions and 14 deletions
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34
gcc/cse.c
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@ -647,7 +647,7 @@ static void invalidate_skipped_block PROTO((rtx));
static void cse_check_loop_start PROTO((rtx, rtx));
static void cse_set_around_loop PROTO((rtx, rtx, rtx));
static rtx cse_basic_block PROTO((rtx, rtx, struct branch_path *, int));
static void count_reg_usage PROTO((rtx, int *, int));
static void count_reg_usage PROTO((rtx, int *, rtx, int));
/* Return an estimate of the cost of computing rtx X.
One use is in cse, to decide which expression to keep in the hash table.
@ -8282,12 +8282,17 @@ cse_basic_block (from, to, next_branch, around_loop)
/* Count the number of times registers are used (not set) in X.
COUNTS is an array in which we accumulate the count, INCR is how much
we count each register usage. */
we count each register usage.
Don't count a usage of DEST, which is the SET_DEST of a SET which
contains X in its SET_SRC. This is because such a SET does not
modify the liveness of DEST. */
static void
count_reg_usage (x, counts, incr)
count_reg_usage (x, counts, dest, incr)
rtx x;
int *counts;
rtx dest;
int incr;
{
enum rtx_code code = GET_CODE (x);
@ -8297,7 +8302,8 @@ count_reg_usage (x, counts, incr)
switch (code)
{
case REG:
counts[REGNO (x)] += incr;
if (x != dest)
counts[REGNO (x)] += incr;
return;
case PC:
@ -8313,28 +8319,28 @@ count_reg_usage (x, counts, incr)
case SET:
/* Unless we are setting a REG, count everything in SET_DEST. */
if (GET_CODE (SET_DEST (x)) != REG)
count_reg_usage (SET_DEST (x), counts, incr);
count_reg_usage (SET_SRC (x), counts, incr);
count_reg_usage (SET_DEST (x), counts, NULL_RTX, incr);
count_reg_usage (SET_SRC (x), counts, SET_DEST (x), incr);
return;
case INSN:
case JUMP_INSN:
case CALL_INSN:
count_reg_usage (PATTERN (x), counts, incr);
count_reg_usage (PATTERN (x), counts, NULL_RTX, incr);
/* Things used in a REG_EQUAL note aren't dead since loop may try to
use them. */
if (REG_NOTES (x))
count_reg_usage (REG_NOTES (x), counts, incr);
count_reg_usage (REG_NOTES (x), counts, NULL_RTX, incr);
return;
case EXPR_LIST:
case INSN_LIST:
if (REG_NOTE_KIND (x) == REG_EQUAL)
count_reg_usage (XEXP (x, 0), counts, incr);
count_reg_usage (XEXP (x, 0), counts, NULL_RTX, incr);
if (XEXP (x, 1))
count_reg_usage (XEXP (x, 1), counts, incr);
count_reg_usage (XEXP (x, 1), counts, NULL_RTX, incr);
return;
}
@ -8342,10 +8348,10 @@ count_reg_usage (x, counts, incr)
for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
{
if (fmt[i] == 'e')
count_reg_usage (XEXP (x, i), counts, incr);
count_reg_usage (XEXP (x, i), counts, dest, incr);
else if (fmt[i] == 'E')
for (j = XVECLEN (x, i) - 1; j >= 0; j--)
count_reg_usage (XVECEXP (x, i, j), counts, incr);
count_reg_usage (XVECEXP (x, i, j), counts, dest, incr);
}
}
@ -8371,7 +8377,7 @@ delete_dead_from_cse (insns, nreg)
/* First count the number of times each register is used. */
bzero (counts, sizeof (int) * nreg);
for (insn = next_real_insn (insns); insn; insn = next_real_insn (insn))
count_reg_usage (insn, counts, 1);
count_reg_usage (insn, counts, NULL_RTX, 1);
/* Go from the last insn to the first and delete insns that only set unused
registers or copy a register to itself. As we delete an insn, remove
@ -8446,7 +8452,7 @@ delete_dead_from_cse (insns, nreg)
if (! live_insn)
{
count_reg_usage (insn, counts, -1);
count_reg_usage (insn, counts, NULL_RTX, -1);
delete_insn (insn);
}