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re PR rtl-optimization/19001 (Loops with power of two step and variable bounds not unrolled)

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PR rtl-optimization/19001
	* loop-iv.c (iv_number_of_iterations): Record assumptions for loops
	with power of two step to 'infinite' field.

From-SVN: r92361
This commit is contained in:
Zdenek Dvorak 2004-12-18 21:14:24 +01:00 committed by Zdenek Dvorak
parent 00f24ef794
commit 6b9b7b4cf8
2 changed files with 79 additions and 16 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2004-12-18 Zdenek Dvorak <dvorakz@suse.cz>
PR rtl-optimization/19001
* loop-iv.c (iv_number_of_iterations): Record assumptions for loops
with power of two step to 'infinite' field.
2004-12-18 Roger Sayle <roger@eyesopen.com> 2004-12-18 Roger Sayle <roger@eyesopen.com>
* Makefile.in (stor-layout.o): Depend upon gt-stor-layout.h. * Makefile.in (stor-layout.o): Depend upon gt-stor-layout.h.

89
gcc/loop-iv.c
View File

@ -2017,9 +2017,10 @@ iv_number_of_iterations (struct loop *loop, rtx insn, rtx condition,
enum machine_mode mode, comp_mode; enum machine_mode mode, comp_mode;
rtx mmin, mmax, mode_mmin, mode_mmax; rtx mmin, mmax, mode_mmin, mode_mmax;
unsigned HOST_WIDEST_INT s, size, d, inv; unsigned HOST_WIDEST_INT s, size, d, inv;
HOST_WIDEST_INT up, down, inc; HOST_WIDEST_INT up, down, inc, step_val;
int was_sharp = false; int was_sharp = false;
rtx old_niter; rtx old_niter;
bool step_is_pow2;
/* The meaning of these assumptions is this: /* The meaning of these assumptions is this:
if !assumptions if !assumptions
@ -2126,10 +2127,26 @@ iv_number_of_iterations (struct loop *loop, rtx insn, rtx condition,
if (iv0.step == const0_rtx && iv1.step == const0_rtx) if (iv0.step == const0_rtx && iv1.step == const0_rtx)
goto fail; goto fail;
/* Ignore loops of while (i-- < 10) type. */ if (cond != NE)
if (cond != NE {
&& (INTVAL (iv0.step) < 0 || INTVAL (iv1.step) > 0)) if (iv0.step == const0_rtx)
goto fail; step_val = -INTVAL (iv1.step);
else
step_val = INTVAL (iv1.step);
/* Ignore loops of while (i-- < 10) type. */
if (step_val < 0)
goto fail;
step_is_pow2 = !(step_val & (step_val - 1));
}
else
{
/* We do not care about whether the step is power of two in this
case. */
step_is_pow2 = false;
step_val = 0;
}
/* Some more condition normalization. We must record some assumptions /* Some more condition normalization. We must record some assumptions
due to overflows. */ due to overflows. */
@ -2270,8 +2287,7 @@ iv_number_of_iterations (struct loop *loop, rtx insn, rtx condition,
/* If the step is a power of two and the final value we have /* If the step is a power of two and the final value we have
computed overflows, the cycle is infinite. Otherwise it computed overflows, the cycle is infinite. Otherwise it
is nontrivial to compute the number of iterations. */ is nontrivial to compute the number of iterations. */
s = INTVAL (step); if (step_is_pow2)
if ((s & (s - 1)) == 0)
desc->infinite = alloc_EXPR_LIST (0, may_not_xform, desc->infinite = alloc_EXPR_LIST (0, may_not_xform,
desc->infinite); desc->infinite);
else else
@ -2372,11 +2388,32 @@ iv_number_of_iterations (struct loop *loop, rtx insn, rtx condition,
tmp1 = lowpart_subreg (mode, iv1.base, comp_mode); tmp1 = lowpart_subreg (mode, iv1.base, comp_mode);
bound = simplify_gen_binary (MINUS, mode, mode_mmax, bound = simplify_gen_binary (MINUS, mode, mode_mmax,
lowpart_subreg (mode, step, comp_mode)); lowpart_subreg (mode, step,
assumption = simplify_gen_relational (cond, SImode, mode, comp_mode));
tmp1, bound); if (step_is_pow2)
desc->assumptions = {
alloc_EXPR_LIST (0, assumption, desc->assumptions); rtx t0, t1;
/* If s is power of 2, we know that the loop is infinite if
a % s <= b % s and b + s overflows. */
assumption = simplify_gen_relational (reverse_condition (cond),
SImode, mode,
tmp1, bound);
t0 = simplify_gen_binary (UMOD, mode, copy_rtx (tmp0), step);
t1 = simplify_gen_binary (UMOD, mode, copy_rtx (tmp1), step);
tmp = simplify_gen_relational (cond, SImode, mode, t0, t1);
assumption = simplify_gen_binary (AND, SImode, assumption, tmp);
desc->infinite =
alloc_EXPR_LIST (0, assumption, desc->infinite);
}
else
{
assumption = simplify_gen_relational (cond, SImode, mode,
tmp1, bound);
desc->assumptions =
alloc_EXPR_LIST (0, assumption, desc->assumptions);
}
tmp = simplify_gen_binary (PLUS, comp_mode, iv1.base, iv0.step); tmp = simplify_gen_binary (PLUS, comp_mode, iv1.base, iv0.step);
tmp = lowpart_subreg (mode, tmp, comp_mode); tmp = lowpart_subreg (mode, tmp, comp_mode);
@ -2397,10 +2434,30 @@ iv_number_of_iterations (struct loop *loop, rtx insn, rtx condition,
bound = simplify_gen_binary (MINUS, mode, mode_mmin, bound = simplify_gen_binary (MINUS, mode, mode_mmin,
lowpart_subreg (mode, step, comp_mode)); lowpart_subreg (mode, step, comp_mode));
assumption = simplify_gen_relational (cond, SImode, mode, if (step_is_pow2)
bound, tmp0); {
desc->assumptions = rtx t0, t1;
alloc_EXPR_LIST (0, assumption, desc->assumptions);
/* If s is power of 2, we know that the loop is infinite if
a % s <= b % s and a - s overflows. */
assumption = simplify_gen_relational (reverse_condition (cond),
SImode, mode,
bound, tmp0);
t0 = simplify_gen_binary (UMOD, mode, copy_rtx (tmp0), step);
t1 = simplify_gen_binary (UMOD, mode, copy_rtx (tmp1), step);
tmp = simplify_gen_relational (cond, SImode, mode, t0, t1);
assumption = simplify_gen_binary (AND, SImode, assumption, tmp);
desc->infinite =
alloc_EXPR_LIST (0, assumption, desc->infinite);
}
else
{
assumption = simplify_gen_relational (cond, SImode, mode,
bound, tmp0);
desc->assumptions =
alloc_EXPR_LIST (0, assumption, desc->assumptions);
}
tmp = simplify_gen_binary (PLUS, comp_mode, iv0.base, iv1.step); tmp = simplify_gen_binary (PLUS, comp_mode, iv0.base, iv1.step);
tmp = lowpart_subreg (mode, tmp, comp_mode); tmp = lowpart_subreg (mode, tmp, comp_mode);