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(fold): Simplify more FP ops if -ffast-math. 

From-SVN: r6335
This commit is contained in:
Richard Kenner 1993-12-27 08:48:58 -05:00
parent a83afb65d0
commit fab446b8c3
1 changed files with 18 additions and 12 deletions
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30
gcc/fold-const.c
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@ -3766,7 +3766,9 @@ fold (expr)
/* Convert A - (-B) to A + B. */
else if (TREE_CODE (arg1) == NEGATE_EXPR)
return fold (build (PLUS_EXPR, type, arg0, TREE_OPERAND (arg1, 0)));
else if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT)
else if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
|| flag_fast_math)
{
/* Except with IEEE floating point, 0-x equals -x. */
if (! wins && real_zerop (arg0))
@ -3774,16 +3776,18 @@ fold (expr)
/* Except with IEEE floating point, x-0 equals x. */
if (real_zerop (arg1))
return non_lvalue (convert (type, arg0));
/* Fold &x - &x. This can happen from &x.foo - &x.
This is unsafe for certain floats even in non-IEEE formats.
In IEEE, it is unsafe because it does wrong for NaNs.
Also note that operand_equal_p is always false if an operand
is volatile. */
if (operand_equal_p (arg0, arg1, FLOAT_TYPE_P (type)))
return convert (type, integer_zero_node);
}
/* Fold &x - &x. This can happen from &x.foo - &x.
This is unsafe for certain floats even in non-IEEE formats.
In IEEE, it is unsafe because it does wrong for NaNs.
Also note that operand_equal_p is always false if an operand
is volatile. */
if (operand_equal_p (arg0, arg1,
FLOAT_TYPE_P (type) && ! flag_fast_math))
return convert (type, integer_zero_node);
goto associate;
case MULT_EXPR:
@ -3807,7 +3811,8 @@ fold (expr)
else
{
/* x*0 is 0, except for IEEE floating point. */
if (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
if ((TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
|| flag_fast_math)
&& real_zerop (arg1))
return omit_one_operand (type, arg1, arg0);
/* In IEEE floating point, x*1 is not equivalent to x for snans.
@ -4630,7 +4635,8 @@ fold (expr)
if (TREE_CODE_CLASS (TREE_CODE (arg0)) == '<'
&& (TARGET_FLOAT_FORMAT != IEEE_FLOAT_FORMAT
|| ! FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0))))
|| ! FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (arg0, 0)))
|| flag_fast_math)
&& operand_equal_for_comparison_p (TREE_OPERAND (arg0, 0),
arg1, TREE_OPERAND (arg0, 1)))
{