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[PATCH] make two combine functions more simplify_rtx-like
- From: Paolo Bonzini <bonzini at gnu dot org>
- To: gcc at gcc dot gnu dot org
- Date: Wed, 21 Dec 2005 17:08:54 +0100
- Subject: [PATCH] make two combine functions more simplify_rtx-like
This patch splits simplify_and_const_int and simplify_shift_const
into two functions (each): one that tries to simplify and returns
NULL_RTX if it cannot produce anything, and one that has the same
calling convention as before. In the meanwhile, I made them
produce new RTXen instead of substituting into the preexisting
expressions, which is another tiny step towards moving these
many valuable transformations into simplify-rtx.c. In particular,
I believe that they could help the forward propagation that
I'm submitting in stage2.
In the meanwhile I removed the need to have two variables for
the shift count (one signed and one unsigned) in
simplify_shift_const. This is ok because the count is constrained
at the beginning of the function to be between 0 and
GET_MODE_BITSIZE (mode) - 1, and care is taken to make it positive
again if it goes negative. The places where this is done are
easy to find, because they are exactly where the signed_count
variable was used. It was very hard to split this in two patches.
I am sending a single patch for simplify_and_const_int and
simplify_shift_const because the split is very logical. Tell
me if it is better to send two separate patches.
A previous version of this patch exhibited an infinite loop in
simplify_comparison. simplify_and_const_int is called to transform
(and REG (ashift 1 N)) to (and (ashiftrt REG N) 1) when it is only
being checked for non-zeroness. After this patch, however, the first
argument must be NULL because op0 is not equal to
(and (ashiftrt REG N) 1). I scanned other invocations of
simplify_and_const_int and simplify_shift_const with a non-NULL first
parameter, and there seem to be only two cases where this convention
is not obeyed: this one in simplify_comparison and one in
force_to_mode, whose code is really obscure and can be simplified
a good deal.
Bootstrapped and regtested i686-pc-linux-gnu (all languages except
Java which is broken for me on this box), together with
the other combine patches that were approved, but not committed
yet. A powerpc-apple-darwin8.3.0 bootstrap will finish overnight,
this time including Java.
Paolo
2005-12-18 Paolo Bonzini <bonzini@gnu.org>
* combine.c (simplify_shift_const): Leave only the fallback
case when no simplification is possible. Extract to...
(simplify_shift_const_1): ... here. Always create a new
RTX instead of substituting. Remove the signed_count variable.
Return NULL_RTX if no substitution is possible.
(simplify_and_const_int): Leave only the fallback
case when no simplification is possible. Extract to...
(simplify_and_const_int_1): ... here. Always create a new
RTX instead of substituting. Return NULL_RTX if no substitution
is possible.
(force_to_mode, simplify_comparison): Don't pass a non-NULL first
parameter to simplify_and_const_int and simplify_shift_const,
unless it is equal to the expected non-simplified result.
Index: combine.c
===================================================================
--- combine.c (revision 108634)
+++ combine.c (working copy)
@@ -394,11 +394,14 @@ static int rtx_equal_for_field_assignmen
static rtx make_field_assignment (rtx);
static rtx apply_distributive_law (rtx);
static rtx distribute_and_simplify_rtx (rtx, int);
+static rtx simplify_and_const_int_1 (enum machine_mode, rtx,
+ unsigned HOST_WIDE_INT);
static rtx simplify_and_const_int (rtx, enum machine_mode, rtx,
unsigned HOST_WIDE_INT);
static int merge_outer_ops (enum rtx_code *, HOST_WIDE_INT *, enum rtx_code,
HOST_WIDE_INT, enum machine_mode, int *);
-static rtx simplify_shift_const (rtx, enum rtx_code, enum machine_mode, rtx,
+static rtx simplify_shift_const_1 (enum rtx_code, enum machine_mode, rtx, int);
+static rtx simplify_shift_const (rtx, enum rtx_code, enum machine_mode, rtx,
int);
static int recog_for_combine (rtx *, rtx, rtx *);
static rtx gen_lowpart_for_combine (enum machine_mode, rtx);
@@ -6921,7 +6915,7 @@ force_to_mode (rtx x, enum machine_mode
if (GET_CODE (XEXP (x, 1)) == CONST_INT && INTVAL (XEXP (x, 1)) >= 0
&& INTVAL (XEXP (x, 1)) < HOST_BITS_PER_WIDE_INT)
{
- int i = -1;
+ int i;
/* If the considered data is wider than HOST_WIDE_INT, we can't
represent a mask for all its bits in a single scalar.
@@ -6948,13 +6942,19 @@ force_to_mode (rtx x, enum machine_mode
nonzero >>= INTVAL (XEXP (x, 1));
}
- if ((mask & ~nonzero) == 0
- || (i = exact_log2 (mask)) >= 0)
+ if ((mask & ~nonzero) == 0)
+ {
+ x = simplify_shift_const (x, LSHIFTRT, GET_MODE (x),
+ XEXP (x, 0), INTVAL (XEXP (x, 1)));
+ if (GET_CODE (x) != ASHIFTRT)
+ return force_to_mode (x, mode, mask, next_select);
+ }
+
+ else if ((i = exact_log2 (mask)) >= 0)
{
x = simplify_shift_const
- (x, LSHIFTRT, GET_MODE (x), XEXP (x, 0),
- i < 0 ? INTVAL (XEXP (x, 1))
- : GET_MODE_BITSIZE (GET_MODE (x)) - 1 - i);
+ (NULL_RTX, LSHIFTRT, GET_MODE (x), XEXP (x, 0),
+ GET_MODE_BITSIZE (GET_MODE (x)) - 1 - i);
if (GET_CODE (x) != ASHIFTRT)
return force_to_mode (x, mode, mask, next_select);
@@ -7841,19 +7835,24 @@ distribute_and_simplify_rtx (rtx x, int
return NULL_RTX;
}
-/* We have X, a logical `and' of VAROP with the constant CONSTOP, to be done
- in MODE.
-
- Return an equivalent form, if different from X. Otherwise, return X. If
- X is zero, we are to always construct the equivalent form. */
+/* Simplify a logical `and' of VAROP with the constant CONSTOP, to be done
+ in MODE. Return an equivalent form, if different from X. Otherwise,
+ return NULL_RTX. */
static rtx
-simplify_and_const_int (rtx x, enum machine_mode mode, rtx varop,
- unsigned HOST_WIDE_INT constop)
+simplify_and_const_int_1 (enum machine_mode mode, rtx varop,
+ unsigned HOST_WIDE_INT constop)
{
unsigned HOST_WIDE_INT nonzero;
+ unsigned HOST_WIDE_INT orig_constop;
+ rtx orig_varop;
int i;
+ orig_varop = varop;
+ orig_constop = constop;
+ if (GET_CODE (varop) == CLOBBER)
+ return NULL_RTX;
+
/* Simplify VAROP knowing that we will be only looking at some of the
bits in it.
@@ -7924,41 +7923,46 @@ simplify_and_const_int (rtx x, enum mach
return o0;
}
- /* Get VAROP in MODE. Try to get a SUBREG if not. Don't make a new SUBREG
- if we already had one (just check for the simplest cases). */
- if (x && GET_CODE (XEXP (x, 0)) == SUBREG
- && GET_MODE (XEXP (x, 0)) == mode
- && SUBREG_REG (XEXP (x, 0)) == varop)
- varop = XEXP (x, 0);
- else
- varop = gen_lowpart (mode, varop);
-
- /* If we can't make the SUBREG, try to return what we were given. */
- if (GET_CODE (varop) == CLOBBER)
- return x ? x : varop;
+ /* Make a SUBREG if necessary. If we can't make it, fail. */
+ varop = gen_lowpart (mode, varop);
+ if (varop == NULL_RTX || GET_CODE (varop) == CLOBBER)
+ return NULL_RTX;
/* If we are only masking insignificant bits, return VAROP. */
if (constop == nonzero)
- x = varop;
- else
- {
- /* Otherwise, return an AND. */
- constop = trunc_int_for_mode (constop, mode);
- /* See how much, if any, of X we can use. */
- if (x == 0 || GET_CODE (x) != AND || GET_MODE (x) != mode)
- x = simplify_gen_binary (AND, mode, varop, GEN_INT (constop));
+ return varop;
- else
- {
- if (GET_CODE (XEXP (x, 1)) != CONST_INT
- || (unsigned HOST_WIDE_INT) INTVAL (XEXP (x, 1)) != constop)
- SUBST (XEXP (x, 1), GEN_INT (constop));
+ if (varop == orig_varop && constop == orig_constop)
+ return NULL_RTX;
- SUBST (XEXP (x, 0), varop);
- }
- }
+ /* Otherwise, return an AND. */
+ constop = trunc_int_for_mode (constop, mode);
+ return simplify_gen_binary (AND, mode, varop, GEN_INT (constop));
+}
- return x;
+
+/* We have X, a logical `and' of VAROP with the constant CONSTOP, to be done
+ in MODE.
+
+ Return an equivalent form, if different from X. Otherwise, return X. If
+ X is zero, we are to always construct the equivalent form. */
+
+static rtx
+simplify_and_const_int (rtx x, enum machine_mode mode, rtx varop,
+ unsigned HOST_WIDE_INT constop)
+{
+ rtx tem = simplify_and_const_int_1 (mode, varop, constop);
+ if (tem)
+ return tem;
+ else
+ {
+ if (!x)
+ x = simplify_gen_binary (AND, GET_MODE (varop), varop,
+ GEN_INT (constop));
+ if (GET_MODE (x) != mode)
+ x = gen_lowpart (mode, x);
+ return x;
+ }
}
/* Given a REG, X, compute which bits in X can be nonzero.
@@ -8241,21 +8245,20 @@ merge_outer_ops (enum rtx_code *pop0, HO
}
/* Simplify a shift of VAROP by COUNT bits. CODE says what kind of shift.
- The result of the shift is RESULT_MODE. X, if nonzero, is an expression
- that we started with.
+ The result of the shift is RESULT_MODE. Return NULL_RTX if we cannot
+ simplify it. Otherwise, return a simplified value.
The shift is normally computed in the widest mode we find in VAROP, as
long as it isn't a different number of words than RESULT_MODE. Exceptions
- are ASHIFTRT and ROTATE, which are always done in their original mode, */
+ are ASHIFTRT and ROTATE, which are always done in their original mode. */
static rtx
-simplify_shift_const (rtx x, enum rtx_code code,
- enum machine_mode result_mode, rtx varop,
- int orig_count)
+simplify_shift_const_1 (enum rtx_code code, enum machine_mode result_mode,
+ rtx varop, int orig_count)
{
enum rtx_code orig_code = code;
- unsigned int count;
- int signed_count;
+ rtx orig_varop = varop;
+ int count;
enum machine_mode mode = result_mode;
enum machine_mode shift_mode, tmode;
unsigned int mode_words
@@ -8263,9 +8266,8 @@ simplify_shift_const (rtx x, enum rtx_co
/* We form (outer_op (code varop count) (outer_const)). */
enum rtx_code outer_op = UNKNOWN;
HOST_WIDE_INT outer_const = 0;
- rtx const_rtx;
int complement_p = 0;
- rtx new;
+ rtx new, x;
/* Make sure and truncate the "natural" shift on the way in. We don't
want to do this inside the loop as it makes it more difficult to
@@ -8277,12 +8279,7 @@ simplify_shift_const (rtx x, enum rtx_co
what was requested. */
if (orig_count < 0 || orig_count >= (int) GET_MODE_BITSIZE (mode))
- {
- if (x)
- return x;
-
- return gen_rtx_fmt_ee (code, mode, varop, GEN_INT (orig_count));
- }
+ return NULL_RTX;
count = orig_count;
@@ -8291,10 +8288,9 @@ simplify_shift_const (rtx x, enum rtx_co
while (count != 0)
{
- /* If we have an operand of (clobber (const_int 0)), just return that
- value. */
+ /* If we have an operand of (clobber (const_int 0)), fail. */
if (GET_CODE (varop) == CLOBBER)
- return varop;
+ return NULL_RTX;
/* If we discovered we had to complement VAROP, leave. Making a NOT
here would cause an infinite loop. */
@@ -8330,7 +8326,7 @@ simplify_shift_const (rtx x, enum rtx_co
multiple operations, each of which are defined, we know what the
result is supposed to be. */
- if (count > (unsigned int) (GET_MODE_BITSIZE (shift_mode) - 1))
+ if (count > (GET_MODE_BITSIZE (shift_mode) - 1))
{
if (code == ASHIFTRT)
count = GET_MODE_BITSIZE (shift_mode) - 1;
@@ -8504,7 +8473,7 @@ simplify_shift_const (rtx x, enum rtx_co
interpreted as the sign bit in a narrower mode, so, if
the result is narrower, don't discard the shift. */
if (code == LSHIFTRT
- && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
+ && count == (GET_MODE_BITSIZE (result_mode) - 1)
&& (GET_MODE_BITSIZE (result_mode)
>= GET_MODE_BITSIZE (GET_MODE (varop))))
{
@@ -8538,8 +8507,7 @@ simplify_shift_const (rtx x, enum rtx_co
(ashiftrt:M1 (ashift:M1 (and:M1 (subreg:M1 FOO 0 C2) C3) C1).
This simplifies certain SIGN_EXTEND operations. */
if (code == ASHIFT && first_code == ASHIFTRT
- && count == (unsigned int)
- (GET_MODE_BITSIZE (result_mode)
+ && count == (GET_MODE_BITSIZE (result_mode)
- GET_MODE_BITSIZE (GET_MODE (varop))))
{
/* C3 has the low-order C1 bits zero. */
@@ -8569,12 +8537,12 @@ simplify_shift_const (rtx x, enum rtx_co
> first_count))
{
varop = XEXP (varop, 0);
-
- signed_count = count - first_count;
- if (signed_count < 0)
- count = -signed_count, code = ASHIFT;
- else
- count = signed_count;
+ count -= first_count;
+ if (count < 0)
+ {
+ count = -count;
+ code = ASHIFT;
+ }
continue;
}
@@ -8635,25 +8603,22 @@ simplify_shift_const (rtx x, enum rtx_co
/* If the shifts are in the same direction, we add the
counts. Otherwise, we subtract them. */
- signed_count = count;
if ((code == ASHIFTRT || code == LSHIFTRT)
== (first_code == ASHIFTRT || first_code == LSHIFTRT))
- signed_count += first_count;
+ count += first_count;
else
- signed_count -= first_count;
+ count -= first_count;
/* If COUNT is positive, the new shift is usually CODE,
except for the two exceptions below, in which case it is
FIRST_CODE. If the count is negative, FIRST_CODE should
always be used */
- if (signed_count > 0
+ if (count > 0
&& ((first_code == ROTATE && code == ASHIFT)
|| (first_code == ASHIFTRT && code == LSHIFTRT)))
- code = first_code, count = signed_count;
- else if (signed_count < 0)
- code = first_code, count = -signed_count;
- else
- count = signed_count;
+ code = first_code;
+ else if (count < 0)
+ code = first_code, count = -count;
varop = XEXP (varop, 0);
continue;
@@ -8696,8 +8661,7 @@ simplify_shift_const (rtx x, enum rtx_co
&& XEXP (XEXP (varop, 0), 1) == constm1_rtx
&& (STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
&& (code == LSHIFTRT || code == ASHIFTRT)
- && count == (unsigned int)
- (GET_MODE_BITSIZE (GET_MODE (varop)) - 1)
+ && count == (GET_MODE_BITSIZE (GET_MODE (varop)) - 1)
&& rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1)))
{
count = 0;
@@ -8764,7 +8728,7 @@ simplify_shift_const (rtx x, enum rtx_co
if (code == LSHIFTRT
&& XEXP (varop, 1) == const0_rtx
&& GET_MODE (XEXP (varop, 0)) == result_mode
- && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
+ && count == (GET_MODE_BITSIZE (result_mode) - 1)
&& GET_MODE_BITSIZE (result_mode) <= HOST_BITS_PER_WIDE_INT
&& STORE_FLAG_VALUE == -1
&& nonzero_bits (XEXP (varop, 0), result_mode) == 1
@@ -8784,7 +8746,7 @@ simplify_shift_const (rtx x, enum rtx_co
/* (lshiftrt (neg A) C) where A is either 0 or 1 and C is one less
than the number of bits in the mode is equivalent to A. */
if (code == LSHIFTRT
- && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
+ && count == (GET_MODE_BITSIZE (result_mode) - 1)
&& nonzero_bits (XEXP (varop, 0), result_mode) == 1)
{
varop = XEXP (varop, 0);
@@ -8809,7 +8771,7 @@ simplify_shift_const (rtx x, enum rtx_co
is one less than the number of bits in the mode is
equivalent to (xor A 1). */
if (code == LSHIFTRT
- && count == (unsigned int) (GET_MODE_BITSIZE (result_mode) - 1)
+ && count == (GET_MODE_BITSIZE (result_mode) - 1)
&& XEXP (varop, 1) == constm1_rtx
&& nonzero_bits (XEXP (varop, 0), result_mode) == 1
&& merge_outer_ops (&outer_op, &outer_const, XOR,
@@ -8894,12 +8856,10 @@ simplify_shift_const (rtx x, enum rtx_co
if ((STORE_FLAG_VALUE == 1 || STORE_FLAG_VALUE == -1)
&& GET_CODE (XEXP (varop, 0)) == ASHIFTRT
- && count == (unsigned int)
- (GET_MODE_BITSIZE (GET_MODE (varop)) - 1)
+ && count == (GET_MODE_BITSIZE (GET_MODE (varop)) - 1)
&& (code == LSHIFTRT || code == ASHIFTRT)
&& GET_CODE (XEXP (XEXP (varop, 0), 1)) == CONST_INT
- && (unsigned HOST_WIDE_INT) INTVAL (XEXP (XEXP (varop, 0), 1))
- == count
+ && INTVAL (XEXP (XEXP (varop, 0), 1)) == count
&& rtx_equal_p (XEXP (XEXP (varop, 0), 0), XEXP (varop, 1)))
{
count = 0;
@@ -8956,44 +8916,31 @@ simplify_shift_const (rtx x, enum rtx_co
a shift of type CODE with SHIFT_MODE shifting VAROP COUNT places. If
OUTER_OP is non-UNKNOWN, it is an operation that needs to be applied
to the result of the shift. OUTER_CONST is the relevant constant,
- but we must turn off all bits turned off in the shift.
-
- If we were passed a value for X, see if we can use any pieces of
- it. If not, make new rtx. */
-
- if (x && GET_RTX_CLASS (GET_CODE (x)) == RTX_BIN_ARITH
- && GET_CODE (XEXP (x, 1)) == CONST_INT
- && (unsigned HOST_WIDE_INT) INTVAL (XEXP (x, 1)) == count)
- const_rtx = XEXP (x, 1);
- else
- const_rtx = GEN_INT (count);
-
- if (x && GET_CODE (XEXP (x, 0)) == SUBREG
- && GET_MODE (XEXP (x, 0)) == shift_mode
- && SUBREG_REG (XEXP (x, 0)) == varop)
- varop = XEXP (x, 0);
- else if (GET_MODE (varop) != shift_mode)
- varop = gen_lowpart (shift_mode, varop);
+ but we must turn off all bits turned off in the shift. */
- /* If we can't make the SUBREG, try to return what we were given. */
- if (GET_CODE (varop) == CLOBBER)
- return x ? x : varop;
+ if (outer_op == UNKNOWN
+ && orig_code == code && orig_count == count
+ && varop == orig_varop
+ && shift_mode == GET_MODE (varop))
+ return NULL_RTX;
- new = simplify_binary_operation (code, shift_mode, varop, const_rtx);
- if (new != 0)
- x = new;
- else
- x = gen_rtx_fmt_ee (code, shift_mode, varop, const_rtx);
+ /* Make a SUBREG if necessary. If we can't make it, fail. */
+ varop = gen_lowpart (shift_mode, varop);
+ if (varop == NULL_RTX || GET_CODE (varop) == CLOBBER)
+ return NULL_RTX;
/* If we have an outer operation and we just made a shift, it is
possible that we could have simplified the shift were it not
for the outer operation. So try to do the simplification
recursively. */
- if (outer_op != UNKNOWN && GET_CODE (x) == code
- && GET_CODE (XEXP (x, 1)) == CONST_INT)
- x = simplify_shift_const (x, code, shift_mode, XEXP (x, 0),
- INTVAL (XEXP (x, 1)));
+ if (outer_op != UNKNOWN)
+ x = simplify_shift_const_1 (code, shift_mode, varop, count);
+ else
+ x = NULL_RTX;
+
+ if (x == NULL_RTX)
+ x = simplify_gen_binary (code, shift_mode, varop, GEN_INT (count));
/* If we were doing an LSHIFTRT in a wider mode than it was originally,
turn off all the bits that the shift would have turned off. */
@@ -9029,6 +8965,25 @@ simplify_shift_const (rtx x, enum rtx_co
return x;
}
+
+static rtx
+simplify_shift_const (rtx x, enum rtx_code code, enum machine_mode result_mode,
+ rtx varop, int count)
+{
+ rtx tem = simplify_shift_const_1 (code, result_mode, varop, count);
+ if (tem)
+ return tem;
+ else
+ {
+ if (!x)
+ x = simplify_gen_binary (code, GET_MODE (varop), varop,
+ GEN_INT (count));
+ if (GET_MODE (x) != result_mode)
+ x = gen_lowpart (result_mode, x);
+ return x;
+ }
+}
+
/* Like recog, but we receive the address of a pointer to a new pattern.
We try to match the rtx that the pointer points to.
@@ -10033,9 +9988,9 @@ simplify_comparison (enum rtx_code code,
&& XEXP (XEXP (op0, 0), 0) == const1_rtx)
{
op0 = simplify_and_const_int
- (op0, mode, gen_rtx_LSHIFTRT (mode,
- XEXP (op0, 1),
- XEXP (XEXP (op0, 0), 1)),
+ (NULL_RTX, mode, gen_rtx_LSHIFTRT (mode,
+ XEXP (op0, 1),
+ XEXP (XEXP (op0, 0), 1)),
(HOST_WIDE_INT) 1);
continue;
}