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riscv-gcc-1
Commit 350f4ea8 by Roger Sayle Committed by Roger Sayle
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fold-const.c (fold): Rewrite optimization to transform "foo++ == const" into "++foo == const+incr". 


	* fold-const.c (fold) <EQ_EXPR>: Rewrite optimization to transform
	"foo++ == const" into "++foo == const+incr".

	* gcc.c-torture/execute/20040307-1.c: New test case.

From-SVN: r79064
parent 688556b9
Showing with 106 additions and 140 deletions
gcc/ChangeLog
2004-03-07 Roger Sayle <roger@eyesopen.com>
* fold-const.c (fold) <EQ_EXPR>: Rewrite optimization to transform
"foo++ == const" into "++foo == const+incr".
2004-03-07 Richard Sandiford <rsandifo@redhat.com>
* config/mips/mips.c (mips_in_small_data_p): Return false if
......
gcc/fold-const.c
......@@ -7295,150 +7295,81 @@ fold (tree expr)
}
}
/* Convert foo++ == CONST into ++foo == CONST + INCR.
First, see if one arg is constant; find the constant arg
and the other one. */
{
tree constop = 0, varop = NULL_TREE;
int constopnum = -1;
/* Convert foo++ == CONST into ++foo == CONST + INCR. */
if (TREE_CONSTANT (arg1)
&& (TREE_CODE (arg0) == POSTINCREMENT_EXPR
|| TREE_CODE (arg0) == POSTDECREMENT_EXPR)
/* This optimization is invalid for ordered comparisons
if CONST+INCR overflows or if foo+incr might overflow.
This optimization is invalid for floating point due to rounding.
For pointer types we assume overflow doesn't happen. */
&& (POINTER_TYPE_P (TREE_TYPE (arg0))
|| (INTEGRAL_TYPE_P (TREE_TYPE (arg0))
&& (code == EQ_EXPR || code == NE_EXPR))))
{
tree varop, newconst;
if (TREE_CONSTANT (arg1))
constopnum = 1, constop = arg1, varop = arg0;
if (TREE_CONSTANT (arg0))
constopnum = 0, constop = arg0, varop = arg1;
if (TREE_CODE (arg0) == POSTINCREMENT_EXPR)
{
newconst = fold (build2 (PLUS_EXPR, TREE_TYPE (arg0),
arg1, TREE_OPERAND (arg0, 1)));
varop = build2 (PREINCREMENT_EXPR, TREE_TYPE (arg0),
TREE_OPERAND (arg0, 0),
TREE_OPERAND (arg0, 1));
}
else
{
newconst = fold (build2 (MINUS_EXPR, TREE_TYPE (arg0),
arg1, TREE_OPERAND (arg0, 1)));
varop = build2 (PREDECREMENT_EXPR, TREE_TYPE (arg0),
TREE_OPERAND (arg0, 0),
TREE_OPERAND (arg0, 1));
}
if (constop && TREE_CODE (varop) == POSTINCREMENT_EXPR)
{
/* This optimization is invalid for ordered comparisons
if CONST+INCR overflows or if foo+incr might overflow.
This optimization is invalid for floating point due to rounding.
For pointer types we assume overflow doesn't happen. */
if (POINTER_TYPE_P (TREE_TYPE (varop))
|| (! FLOAT_TYPE_P (TREE_TYPE (varop))
&& (code == EQ_EXPR || code == NE_EXPR)))
{
tree newconst
= fold (build (PLUS_EXPR, TREE_TYPE (varop),
constop, TREE_OPERAND (varop, 1)));
/* Do not overwrite the current varop to be a preincrement,
create a new node so that we won't confuse our caller who
might create trees and throw them away, reusing the
arguments that they passed to build. This shows up in
the THEN or ELSE parts of ?: being postincrements. */
varop = build (PREINCREMENT_EXPR, TREE_TYPE (varop),
TREE_OPERAND (varop, 0),
TREE_OPERAND (varop, 1));
/* If VAROP is a reference to a bitfield, we must mask
the constant by the width of the field. */
if (TREE_CODE (TREE_OPERAND (varop, 0)) == COMPONENT_REF
&& DECL_BIT_FIELD(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)))
{
int size
= TREE_INT_CST_LOW (DECL_SIZE
(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)));
tree mask, unsigned_type;
unsigned int precision;
tree folded_compare;
/* First check whether the comparison would come out
always the same. If we don't do that we would
change the meaning with the masking. */
if (constopnum == 0)
folded_compare = fold (build (code, type, constop,
TREE_OPERAND (varop, 0)));
else
folded_compare = fold (build (code, type,
TREE_OPERAND (varop, 0),
constop));
if (integer_zerop (folded_compare)
|| integer_onep (folded_compare))
return omit_one_operand (type, folded_compare, varop);
unsigned_type = (*lang_hooks.types.type_for_size)(size, 1);
precision = TYPE_PRECISION (unsigned_type);
mask = build_int_2 (~0, ~0);
TREE_TYPE (mask) = unsigned_type;
force_fit_type (mask, 0);
mask = const_binop (RSHIFT_EXPR, mask,
size_int (precision - size), 0);
newconst = fold (build (BIT_AND_EXPR,
TREE_TYPE (varop), newconst,
fold_convert (TREE_TYPE (varop),
mask)));
}
t = build (code, type,
(constopnum == 0) ? newconst : varop,
(constopnum == 1) ? newconst : varop);
return t;
}
}
else if (constop && TREE_CODE (varop) == POSTDECREMENT_EXPR)
{
if (POINTER_TYPE_P (TREE_TYPE (varop))
|| (! FLOAT_TYPE_P (TREE_TYPE (varop))
&& (code == EQ_EXPR || code == NE_EXPR)))
{
tree newconst
= fold (build (MINUS_EXPR, TREE_TYPE (varop),
constop, TREE_OPERAND (varop, 1)));
/* Do not overwrite the current varop to be a predecrement,
create a new node so that we won't confuse our caller who
might create trees and throw them away, reusing the
arguments that they passed to build. This shows up in
the THEN or ELSE parts of ?: being postdecrements. */
varop = build (PREDECREMENT_EXPR, TREE_TYPE (varop),
TREE_OPERAND (varop, 0),
TREE_OPERAND (varop, 1));
if (TREE_CODE (TREE_OPERAND (varop, 0)) == COMPONENT_REF
&& DECL_BIT_FIELD(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)))
{
int size
= TREE_INT_CST_LOW (DECL_SIZE
(TREE_OPERAND
(TREE_OPERAND (varop, 0), 1)));
tree mask, unsigned_type;
unsigned int precision;
tree folded_compare;
if (constopnum == 0)
folded_compare = fold (build (code, type, constop,
TREE_OPERAND (varop, 0)));
else
folded_compare = fold (build (code, type,
TREE_OPERAND (varop, 0),
constop));
if (integer_zerop (folded_compare)
|| integer_onep (folded_compare))
return omit_one_operand (type, folded_compare, varop);
unsigned_type = (*lang_hooks.types.type_for_size)(size, 1);
precision = TYPE_PRECISION (unsigned_type);
mask = build_int_2 (~0, ~0);
TREE_TYPE (mask) = TREE_TYPE (varop);
force_fit_type (mask, 0);
mask = const_binop (RSHIFT_EXPR, mask,
size_int (precision - size), 0);
newconst = fold (build (BIT_AND_EXPR,
TREE_TYPE (varop), newconst,
fold_convert (TREE_TYPE (varop),
mask)));
}
/* If VAROP is a reference to a bitfield, we must mask
the constant by the width of the field. */
if (TREE_CODE (TREE_OPERAND (varop, 0)) == COMPONENT_REF
&& DECL_BIT_FIELD(TREE_OPERAND (TREE_OPERAND (varop, 0), 1)))
{
tree fielddecl = TREE_OPERAND (TREE_OPERAND (varop, 0), 1);
int size = TREE_INT_CST_LOW (DECL_SIZE (fielddecl));
tree folded_compare;
tree mask = 0;
/* First check whether the comparison would come out
always the same. If we don't do that we would
change the meaning with the masking. */
folded_compare = fold (build2 (code, type,
TREE_OPERAND (varop, 0),
arg1));
if (integer_zerop (folded_compare)
|| integer_onep (folded_compare))
return omit_one_operand (type, folded_compare, varop);
if (size < HOST_BITS_PER_WIDE_INT)
{
unsigned HOST_WIDE_INT lo = ((unsigned HOST_WIDE_INT) 1
<< size) - 1;
mask = build_int_2 (lo, 0);
}
else if (size < 2 * HOST_BITS_PER_WIDE_INT)
{
HOST_WIDE_INT hi = ((HOST_WIDE_INT) 1
<< (size - HOST_BITS_PER_WIDE_INT)) - 1;
mask = build_int_2 (~0, hi);
}
if (mask)
{
mask = fold_convert (TREE_TYPE (varop), mask);
newconst = fold (build2 (BIT_AND_EXPR, TREE_TYPE (varop),
newconst, mask));
}
}
t = build (code, type,
(constopnum == 0) ? newconst : varop,
(constopnum == 1) ? newconst : varop);
return t;
}
}
}
return fold (build2 (code, type, varop, newconst));
}
/* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
This transformation affects the cases which are handled in later
......
gcc/testsuite/ChangeLog
2004-03-07 Roger Sayle <roger@eyesopen.com>
* gcc.c-torture/execute/20040307-1.c: New test case.
2004-03-07 Richard Sandiford <rsandifo@redhat.com>
* gcc.dg/torture/mips-sdata-1.c: Restrict to mips*-*-elf*.
......
gcc/testsuite/gcc.c-torture/execute/20040307-1.c 0 → 100644
int main()
{
int b = 0;
struct {
unsigned int bit0:1;
unsigned int bit1:1;
unsigned int bit2:1;
unsigned int bit3:1;
unsigned int bit4:1;
unsigned int bit5:1;
unsigned int bit6:1;
unsigned int bit7:1;
unsigned int ubyte:24;
} sdata = {0x01};
while ( sdata.bit0-- > 0 ) {
b++ ;
if ( b > 100 ) break;
}
if (b != 1)
abort ();
return 0;
}
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