/* Common subexpression elimination for GNU compiler.
Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998
- 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+ 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
Free Software Foundation, Inc.
This file is part of GCC.
static int cse_change_cc_mode (rtx *, void *);
static void cse_change_cc_mode_insn (rtx, rtx);
static void cse_change_cc_mode_insns (rtx, rtx, rtx);
-static enum machine_mode cse_cc_succs (basic_block, rtx, rtx, bool);
+static enum machine_mode cse_cc_succs (basic_block, basic_block, rtx, rtx,
+ bool);
\f
#undef RTL_HOOKS_GEN_LOWPART
struct table_elt *p
= lookup (x, SAFE_HASH (x, VOIDmode), GET_MODE (x));
- /* If we are looking for a CONST_INT, the mode doesn't really matter, as
- long as we are narrowing. So if we looked in vain for a mode narrower
- than word_mode before, look for word_mode now. */
- if (p == 0 && code == CONST_INT
- && GET_MODE_SIZE (GET_MODE (x)) < GET_MODE_SIZE (word_mode))
- {
- x = copy_rtx (x);
- PUT_MODE (x, word_mode);
- p = lookup (x, SAFE_HASH (x, VOIDmode), word_mode);
- }
-
if (p == 0)
return 0;
{
case RTX_UNARY:
{
- int is_const = 0;
-
/* We can't simplify extension ops unless we know the
original mode. */
if ((code == ZERO_EXTEND || code == SIGN_EXTEND)
&& mode_arg0 == VOIDmode)
break;
- /* If we had a CONST, strip it off and put it back later if we
- fold. */
- if (const_arg0 != 0 && GET_CODE (const_arg0) == CONST)
- is_const = 1, const_arg0 = XEXP (const_arg0, 0);
-
new_rtx = simplify_unary_operation (code, mode,
const_arg0 ? const_arg0 : folded_arg0,
mode_arg0);
- /* NEG of PLUS could be converted into MINUS, but that causes
- expressions of the form
- (CONST (MINUS (CONST_INT) (SYMBOL_REF)))
- which many ports mistakenly treat as LEGITIMATE_CONSTANT_P.
- FIXME: those ports should be fixed. */
- if (new_rtx != 0 && is_const
- && GET_CODE (new_rtx) == PLUS
- && (GET_CODE (XEXP (new_rtx, 0)) == SYMBOL_REF
- || GET_CODE (XEXP (new_rtx, 0)) == LABEL_REF)
- && GET_CODE (XEXP (new_rtx, 1)) == CONST_INT)
- new_rtx = gen_rtx_CONST (mode, new_rtx);
}
break;
if (const_arg0 == 0 || const_arg1 == 0)
{
struct table_elt *p0, *p1;
- rtx true_rtx = const_true_rtx, false_rtx = const0_rtx;
+ rtx true_rtx, false_rtx;
enum machine_mode mode_arg1;
-#ifdef FLOAT_STORE_FLAG_VALUE
if (SCALAR_FLOAT_MODE_P (mode))
{
+#ifdef FLOAT_STORE_FLAG_VALUE
true_rtx = (CONST_DOUBLE_FROM_REAL_VALUE
(FLOAT_STORE_FLAG_VALUE (mode), mode));
+#else
+ true_rtx = NULL_RTX;
+#endif
false_rtx = CONST0_RTX (mode);
}
-#endif
+ else
+ {
+ true_rtx = const_true_rtx;
+ false_rtx = const0_rtx;
+ }
code = find_comparison_args (code, &folded_arg0, &folded_arg1,
&mode_arg0, &mode_arg1);
const_arg1))
|| (REG_P (folded_arg1)
&& (REG_QTY (REGNO (folded_arg1)) == ent->comparison_qty))))
- return (comparison_dominates_p (ent->comparison_code, code)
- ? true_rtx : false_rtx);
+ {
+ if (comparison_dominates_p (ent->comparison_code, code))
+ {
+ if (true_rtx)
+ return true_rtx;
+ else
+ break;
+ }
+ else
+ return false_rtx;
+ }
}
}
}
int is_shift
= (code == ASHIFT || code == ASHIFTRT || code == LSHIFTRT);
rtx y, inner_const, new_const;
+ rtx canon_const_arg1 = const_arg1;
enum rtx_code associate_code;
if (is_shift
|| INTVAL (const_arg1) < 0))
{
if (SHIFT_COUNT_TRUNCATED)
- const_arg1 = GEN_INT (INTVAL (const_arg1)
- & (GET_MODE_BITSIZE (mode) - 1));
+ canon_const_arg1 = GEN_INT (INTVAL (const_arg1)
+ & (GET_MODE_BITSIZE (mode)
+ - 1));
else
break;
}
associate_code = (is_shift || code == MINUS ? PLUS : code);
new_const = simplify_binary_operation (associate_code, mode,
- const_arg1, inner_const);
+ canon_const_arg1,
+ inner_const);
if (new_const == 0)
break;
if (GET_CODE (x) == SUBREG)
{
+ enum machine_mode mode = GET_MODE (x);
+ enum machine_mode imode = GET_MODE (SUBREG_REG (x));
rtx new_rtx;
/* See if we previously assigned a constant value to this SUBREG. */
|| (new_rtx = lookup_as_function (x, CONST_FIXED)) != 0)
return new_rtx;
+ /* If we didn't and if doing so makes sense, see if we previously
+ assigned a constant value to the enclosing word mode SUBREG. */
+ if (GET_MODE_SIZE (mode) < GET_MODE_SIZE (word_mode)
+ && GET_MODE_SIZE (word_mode) < GET_MODE_SIZE (imode))
+ {
+ int byte = SUBREG_BYTE (x) - subreg_lowpart_offset (mode, word_mode);
+ if (byte >= 0 && (byte % UNITS_PER_WORD) == 0)
+ {
+ rtx y = gen_rtx_SUBREG (word_mode, SUBREG_REG (x), byte);
+ new_rtx = lookup_as_function (y, CONST_INT);
+ if (new_rtx)
+ return gen_lowpart (mode, new_rtx);
+ }
+ }
+
+ /* Otherwise see if we already have a constant for the inner REG. */
if (REG_P (SUBREG_REG (x))
&& (new_rtx = equiv_constant (SUBREG_REG (x))) != 0)
- return simplify_subreg (GET_MODE (x), SUBREG_REG (x),
- GET_MODE (SUBREG_REG (x)), SUBREG_BYTE (x));
+ return simplify_subreg (mode, new_rtx, imode, SUBREG_BYTE (x));
return 0;
}
enum machine_mode wider_mode;
for (wider_mode = GET_MODE_WIDER_MODE (mode);
- GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
+ wider_mode != VOIDmode
+ && GET_MODE_BITSIZE (wider_mode) <= BITS_PER_WORD
&& src_related == 0;
wider_mode = GET_MODE_WIDER_MODE (wider_mode))
{
edge pointing to that bb. */
if (bb_has_eh_pred (bb))
{
- struct df_ref **def_rec;
+ df_ref *def_rec;
for (def_rec = df_get_artificial_defs (bb->index); *def_rec; def_rec++)
{
- struct df_ref *def = *def_rec;
+ df_ref def = *def_rec;
if (DF_REF_FLAGS (def) & DF_REF_AT_TOP)
invalidate (DF_REF_REG (def), GET_MODE (DF_REF_REG (def)));
}
permitted to change the mode of CC_SRC to a compatible mode. This
returns VOIDmode if no equivalent assignments were found.
Otherwise it returns the mode which CC_SRC should wind up with.
+ ORIG_BB should be the same as BB in the outermost cse_cc_succs call,
+ but is passed unmodified down to recursive calls in order to prevent
+ endless recursion.
The main complexity in this function is handling the mode issues.
We may have more than one duplicate which we can eliminate, and we
try to find a mode which will work for multiple duplicates. */
static enum machine_mode
-cse_cc_succs (basic_block bb, rtx cc_reg, rtx cc_src, bool can_change_mode)
+cse_cc_succs (basic_block bb, basic_block orig_bb, rtx cc_reg, rtx cc_src,
+ bool can_change_mode)
{
bool found_equiv;
enum machine_mode mode;
continue;
if (EDGE_COUNT (e->dest->preds) != 1
- || e->dest == EXIT_BLOCK_PTR)
+ || e->dest == EXIT_BLOCK_PTR
+ /* Avoid endless recursion on unreachable blocks. */
+ || e->dest == orig_bb)
continue;
end = NEXT_INSN (BB_END (e->dest));
{
enum machine_mode submode;
- submode = cse_cc_succs (e->dest, cc_reg, cc_src, false);
+ submode = cse_cc_succs (e->dest, orig_bb, cc_reg, cc_src, false);
if (submode != VOIDmode)
{
gcc_assert (submode == mode);
the basic block. */
orig_mode = GET_MODE (cc_src);
- mode = cse_cc_succs (bb, cc_reg, cc_src, true);
+ mode = cse_cc_succs (bb, bb, cc_reg, cc_src, true);
if (mode != VOIDmode)
{
gcc_assert (mode == GET_MODE (cc_src));
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