/* Optimize by combining instructions for GNU compiler.
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
This file is part of GCC.
#include "rtlhooks-def.h"
/* Include output.h for dump_file. */
#include "output.h"
+#include "params.h"
/* Number of attempts to combine instructions in this function. */
}
/* Don't change the mode of the MEM if that would change the meaning
- of the address. Similarly, don't allow widening, as that may
- access memory outside the defined object or using an address
- that is invalid for a wider mode. */
+ of the address. */
if (MEM_P (SUBREG_REG (x))
&& (MEM_VOLATILE_P (SUBREG_REG (x))
- || mode_dependent_address_p (XEXP (SUBREG_REG (x), 0))
- || (GET_MODE_SIZE (mode)
- > GET_MODE_SIZE (GET_MODE (SUBREG_REG (x))))))
+ || mode_dependent_address_p (XEXP (SUBREG_REG (x), 0))))
return gen_rtx_CLOBBER (mode, const0_rtx);
/* Note that we cannot do any narrowing for non-constants since
if (GET_CODE (op0) == AND)
{
- x = apply_distributive_law
+ rtx tmp = apply_distributive_law
(gen_binary (AND, mode,
gen_binary (IOR, mode, XEXP (op0, 0), op1),
gen_binary (IOR, mode, XEXP (op0, 1),
copy_rtx (op1))));
- if (GET_CODE (x) != IOR)
- return x;
+ if (GET_CODE (tmp) != IOR
+ && rtx_cost (tmp, SET) < rtx_cost (x, SET))
+ return tmp;
}
if (GET_CODE (op1) == AND)
{
- x = apply_distributive_law
+ rtx tmp = apply_distributive_law
(gen_binary (AND, mode,
gen_binary (IOR, mode, XEXP (op1, 0), op0),
gen_binary (IOR, mode, XEXP (op1, 1),
copy_rtx (op0))));
- if (GET_CODE (x) != IOR)
- return x;
+ if (GET_CODE (tmp) != IOR
+ && rtx_cost (tmp, SET) < rtx_cost (x, SET))
+ return tmp;
}
/* Convert (ior (ashift A CX) (lshiftrt A CY)) where CX+CY equals the
return x;
}
- else if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == SUBREG
- && subreg_lowpart_p (XEXP (src, 0))
- && (GET_MODE_SIZE (GET_MODE (XEXP (src, 0)))
- < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (src, 0)))))
- && GET_CODE (SUBREG_REG (XEXP (src, 0))) == ROTATE
- && GET_CODE (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == CONST_INT
- && INTVAL (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == -2
- && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1)))
+ if (GET_CODE (src) == AND && GET_CODE (XEXP (src, 0)) == SUBREG
+ && subreg_lowpart_p (XEXP (src, 0))
+ && (GET_MODE_SIZE (GET_MODE (XEXP (src, 0)))
+ < GET_MODE_SIZE (GET_MODE (SUBREG_REG (XEXP (src, 0)))))
+ && GET_CODE (SUBREG_REG (XEXP (src, 0))) == ROTATE
+ && GET_CODE (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == CONST_INT
+ && INTVAL (XEXP (SUBREG_REG (XEXP (src, 0)), 0)) == -2
+ && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1)))
{
assign = make_extraction (VOIDmode, dest, 0,
XEXP (SUBREG_REG (XEXP (src, 0)), 1),
/* If SRC is (ior (ashift (const_int 1) POS) DEST), this is a set of a
one-bit field. */
- else if (GET_CODE (src) == IOR && GET_CODE (XEXP (src, 0)) == ASHIFT
- && XEXP (XEXP (src, 0), 0) == const1_rtx
- && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1)))
+ if (GET_CODE (src) == IOR && GET_CODE (XEXP (src, 0)) == ASHIFT
+ && XEXP (XEXP (src, 0), 0) == const1_rtx
+ && rtx_equal_for_field_assignment_p (dest, XEXP (src, 1)))
{
assign = make_extraction (VOIDmode, dest, 0, XEXP (XEXP (src, 0), 1),
1, 1, 1, 0);
return x;
}
+ /* If DEST is already a field assignment, i.e. ZERO_EXTRACT, and the
+ SRC is an AND with all bits of that field set, then we can discard
+ the AND. */
+ if (GET_CODE (dest) == ZERO_EXTRACT
+ && GET_CODE (XEXP (dest, 1)) == CONST_INT
+ && GET_CODE (src) == AND
+ && GET_CODE (XEXP (src, 1)) == CONST_INT)
+ {
+ HOST_WIDE_INT width = INTVAL (XEXP (dest, 1));
+ unsigned HOST_WIDE_INT and_mask = INTVAL (XEXP (src, 1));
+ unsigned HOST_WIDE_INT ze_mask;
+
+ if (width >= HOST_BITS_PER_WIDE_INT)
+ ze_mask = -1;
+ else
+ ze_mask = ((unsigned HOST_WIDE_INT)1 << width) - 1;
+
+ /* Complete overlap. We can remove the source AND. */
+ if ((and_mask & ze_mask) == ze_mask)
+ return gen_rtx_SET (VOIDmode, dest, XEXP (src, 0));
+
+ /* Partial overlap. We can reduce the source AND. */
+ if ((and_mask & ze_mask) != and_mask)
+ {
+ mode = GET_MODE (src);
+ src = gen_rtx_AND (mode, XEXP (src, 0),
+ gen_int_mode (and_mask & ze_mask, mode));
+ return gen_rtx_SET (VOIDmode, dest, src);
+ }
+ }
+
/* The other case we handle is assignments into a constant-position
field. They look like (ior/xor (and DEST C1) OTHER). If C1 represents
a mask that has all one bits except for a group of zero bits and
break;
case SUBREG:
- /* Check for the case where we are comparing A - C1 with C2,
- both constants are smaller than 1/2 the maximum positive
- value in MODE, and the comparison is equality or unsigned.
- In that case, if A is either zero-extended to MODE or has
- sufficient sign bits so that the high-order bit in MODE
- is a copy of the sign in the inner mode, we can prove that it is
- safe to do the operation in the wider mode. This simplifies
- many range checks. */
+ /* Check for the case where we are comparing A - C1 with C2, that is
+
+ (subreg:MODE (plus (A) (-C1))) op (C2)
+
+ with C1 a constant, and try to lift the SUBREG, i.e. to do the
+ comparison in the wider mode. One of the following two conditions
+ must be true in order for this to be valid:
+
+ 1. The mode extension results in the same bit pattern being added
+ on both sides and the comparison is equality or unsigned. As
+ C2 has been truncated to fit in MODE, the pattern can only be
+ all 0s or all 1s.
+
+ 2. The mode extension results in the sign bit being copied on
+ each side.
+
+ The difficulty here is that we have predicates for A but not for
+ (A - C1) so we need to check that C1 is within proper bounds so
+ as to perturbate A as little as possible. */
if (mode_width <= HOST_BITS_PER_WIDE_INT
&& subreg_lowpart_p (op0)
+ && GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0))) > mode_width
&& GET_CODE (SUBREG_REG (op0)) == PLUS
- && GET_CODE (XEXP (SUBREG_REG (op0), 1)) == CONST_INT
- && INTVAL (XEXP (SUBREG_REG (op0), 1)) < 0
- && (-INTVAL (XEXP (SUBREG_REG (op0), 1))
- < (HOST_WIDE_INT) (GET_MODE_MASK (mode) / 2))
- && (unsigned HOST_WIDE_INT) const_op < GET_MODE_MASK (mode) / 2
- && (0 == (nonzero_bits (XEXP (SUBREG_REG (op0), 0),
- GET_MODE (SUBREG_REG (op0)))
- & ~GET_MODE_MASK (mode))
- || (num_sign_bit_copies (XEXP (SUBREG_REG (op0), 0),
- GET_MODE (SUBREG_REG (op0)))
- > (unsigned int)
- (GET_MODE_BITSIZE (GET_MODE (SUBREG_REG (op0)))
- - GET_MODE_BITSIZE (mode)))))
- {
- op0 = SUBREG_REG (op0);
- continue;
+ && GET_CODE (XEXP (SUBREG_REG (op0), 1)) == CONST_INT)
+ {
+ enum machine_mode inner_mode = GET_MODE (SUBREG_REG (op0));
+ rtx a = XEXP (SUBREG_REG (op0), 0);
+ HOST_WIDE_INT c1 = -INTVAL (XEXP (SUBREG_REG (op0), 1));
+
+ if ((c1 > 0
+ && (unsigned HOST_WIDE_INT) c1
+ < (unsigned HOST_WIDE_INT) 1 << (mode_width - 1)
+ && (equality_comparison_p || unsigned_comparison_p)
+ /* (A - C1) zero-extends if it is positive and sign-extends
+ if it is negative, C2 both zero- and sign-extends. */
+ && ((0 == (nonzero_bits (a, inner_mode)
+ & ~GET_MODE_MASK (mode))
+ && const_op >= 0)
+ /* (A - C1) sign-extends if it is positive and 1-extends
+ if it is negative, C2 both sign- and 1-extends. */
+ || (num_sign_bit_copies (a, inner_mode)
+ > (unsigned int) (GET_MODE_BITSIZE (inner_mode)
+ - mode_width)
+ && const_op < 0)))
+ || ((unsigned HOST_WIDE_INT) c1
+ < (unsigned HOST_WIDE_INT) 1 << (mode_width - 2)
+ /* (A - C1) always sign-extends, like C2. */
+ && num_sign_bit_copies (a, inner_mode)
+ > (unsigned int) (GET_MODE_BITSIZE (inner_mode)
+ - mode_width - 1)))
+ {
+ op0 = SUBREG_REG (op0);
+ continue;
+ }
}
/* If the inner mode is narrower and we are extracting the low part,
return gen_binary (reversed_code, mode, op0, op1);
}
\f
+/* Utility function for record_value_for_reg. Count number of
+ rtxs in X. */
+static int
+count_rtxs (rtx x)
+{
+ enum rtx_code code = GET_CODE (x);
+ const char *fmt;
+ int i, ret = 1;
+
+ if (GET_RTX_CLASS (code) == '2'
+ || GET_RTX_CLASS (code) == 'c')
+ {
+ rtx x0 = XEXP (x, 0);
+ rtx x1 = XEXP (x, 1);
+
+ if (x0 == x1)
+ return 1 + 2 * count_rtxs (x0);
+
+ if ((GET_RTX_CLASS (GET_CODE (x1)) == '2'
+ || GET_RTX_CLASS (GET_CODE (x1)) == 'c')
+ && (x0 == XEXP (x1, 0) || x0 == XEXP (x1, 1)))
+ return 2 + 2 * count_rtxs (x0)
+ + count_rtxs (x == XEXP (x1, 0)
+ ? XEXP (x1, 1) : XEXP (x1, 0));
+
+ if ((GET_RTX_CLASS (GET_CODE (x0)) == '2'
+ || GET_RTX_CLASS (GET_CODE (x0)) == 'c')
+ && (x1 == XEXP (x0, 0) || x1 == XEXP (x0, 1)))
+ return 2 + 2 * count_rtxs (x1)
+ + count_rtxs (x == XEXP (x0, 0)
+ ? XEXP (x0, 1) : XEXP (x0, 0));
+ }
+
+ fmt = GET_RTX_FORMAT (code);
+ for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
+ if (fmt[i] == 'e')
+ ret += count_rtxs (XEXP (x, i));
+
+ return ret;
+}
+\f
/* Utility function for following routine. Called when X is part of a value
being stored into last_set_value. Sets last_set_table_tick
for each register mentioned. Similar to mention_regs in cse.c */
&& GET_CODE (XEXP (tem, 0)) == CLOBBER
&& GET_CODE (XEXP (tem, 1)) == CLOBBER)
tem = XEXP (tem, 0);
+ else if (count_occurrences (value, reg, 1) >= 2)
+ {
+ /* If there are two or more occurrences of REG in VALUE,
+ prevent the value from growing too much. */
+ if (count_rtxs (tem) > MAX_LAST_VALUE_RTL)
+ tem = gen_rtx_CLOBBER (GET_MODE (tem), const0_rtx);
+ }
value = replace_rtx (copy_rtx (value), reg, tem);
}
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