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(maybe_eliminate_biv_1): Disable all but two cases of biv elimination with givs... 

(maybe_eliminate_biv_1): Disable all but two cases of biv elimination
with givs and restrict those two cases to an ADD_VAL that is an
address.

From-SVN: r11968
This commit is contained in:
Richard Kenner 1996-05-10 19:01:08 -04:00
parent cb9e8ad176
commit fbdc6da816
1 changed files with 27 additions and 9 deletions
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36
gcc/loop.c
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@ -6178,13 +6178,16 @@ maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where)
{
/* Can replace with any giv that was reduced and
that has (MULT_VAL != 0) and (ADD_VAL == 0).
Require a constant for MULT_VAL, so we know it's nonzero. */
Require a constant for MULT_VAL, so we know it's nonzero.
??? We disable this optimization to avoid potential
overflows. */
for (v = bl->giv; v; v = v->next_iv)
if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx
&& v->add_val == const0_rtx
&& ! v->ignore && ! v->maybe_dead && v->always_computable
&& v->mode == mode)
&& v->mode == mode
&& 0)
{
/* If the giv V had the auto-inc address optimization applied
to it, and INSN occurs between the giv insn and the biv
@ -6215,12 +6218,19 @@ maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where)
/* Look for a giv with (MULT_VAL != 0) and (ADD_VAL != 0);
replace test insn with a compare insn (cmp REDUCED_GIV ADD_VAL).
Require a constant for MULT_VAL, so we know it's nonzero. */
Require a constant for MULT_VAL, so we know it's nonzero.
??? Do this only if ADD_VAL is a pointer to avoid a potential
overflow problem. */
for (v = bl->giv; v; v = v->next_iv)
if (CONSTANT_P (v->mult_val) && v->mult_val != const0_rtx
&& ! v->ignore && ! v->maybe_dead && v->always_computable
&& v->mode == mode)
&& v->mode == mode
&& (GET_CODE (v->add_val) == SYMBOL_REF
|| GET_CODE (v->add_val) == LABEL_REF
|| GET_CODE (v->add_val) == CONST
|| (GET_CODE (v->add_val) == REG
&& REGNO_POINTER_FLAG (REGNO (v->add_val)))))
{
/* If the giv V had the auto-inc address optimization applied
to it, and INSN occurs between the giv insn and the biv
@ -6286,7 +6296,11 @@ maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where)
for (v = bl->giv; v; v = v->next_iv)
if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
&& CONSTANT_P (v->add_val)
&& (GET_CODE (v->add_val) == SYMBOL_REF
|| GET_CODE (v->add_val) == LABEL_REF
|| GET_CODE (v->add_val) == CONST
|| (GET_CODE (v->add_val) == REG
&& REGNO_POINTER_FLAG (REGNO (v->add_val))))
&& ! v->ignore && ! v->maybe_dead && v->always_computable
&& v->mode == mode)
{
@ -6330,12 +6344,14 @@ maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where)
}
/* Look for giv with positive constant mult_val and nonconst add_val.
Insert insns to calculate new compare value. */
Insert insns to calculate new compare value.
??? Turn this off due to possible overflow. */
for (v = bl->giv; v; v = v->next_iv)
if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
&& ! v->ignore && ! v->maybe_dead && v->always_computable
&& v->mode == mode)
&& v->mode == mode
&& 0)
{
rtx tem;
@ -6372,12 +6388,14 @@ maybe_eliminate_biv_1 (x, insn, bl, eliminate_p, where)
if (invariant_p (arg) == 1)
{
/* Look for giv with constant positive mult_val and nonconst
add_val. Insert insns to compute new compare value. */
add_val. Insert insns to compute new compare value.
??? Turn this off due to possible overflow. */
for (v = bl->giv; v; v = v->next_iv)
if (CONSTANT_P (v->mult_val) && INTVAL (v->mult_val) > 0
&& ! v->ignore && ! v->maybe_dead && v->always_computable
&& v->mode == mode)
&& v->mode == mode
&& 0)
{
rtx tem;