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re PR rtl-optimization/55950 (Invalid sqrt constant propagation with -frounding-mode)

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PR rtl-optimization/55950
	* real.c (real_sqrt): Remove function.
	* real.h (real_sqrt): Remove prototype.
	* simplify-rtx.c (simplify_const_unary_operation): Do not fold
	SQRT using real_sqrt.

From-SVN: r205223
This commit is contained in:
Joseph Myers 2013-11-21 16:20:28 +00:00 committed by Joseph Myers
parent 15e693cc59
commit 3c8e8595ed
4 changed files with 10 additions and 88 deletions
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8
gcc/ChangeLog
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@ -1,3 +1,11 @@
2013-11-21 Joseph Myers <joseph@codesourcery.com>
PR rtl-optimization/55950
* real.c (real_sqrt): Remove function.
* real.h (real_sqrt): Remove prototype.
* simplify-rtx.c (simplify_const_unary_operation): Do not fold
SQRT using real_sqrt.
2013-11-21 Richard Biener <rguenther@suse.de>
PR tree-optimization/59058

78
gcc/real.c
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@ -4765,84 +4765,6 @@ const struct real_format real_internal_format =
false
};
/* Calculate the square root of X in mode MODE, and store the result
in R. Return TRUE if the operation does not raise an exception.
For details see "High Precision Division and Square Root",
Alan H. Karp and Peter Markstein, HP Lab Report 93-93-42, June
1993. http://www.hpl.hp.com/techreports/93/HPL-93-42.pdf. */
bool
real_sqrt (REAL_VALUE_TYPE *r, enum machine_mode mode,
const REAL_VALUE_TYPE *x)
{
static REAL_VALUE_TYPE halfthree;
static bool init = false;
REAL_VALUE_TYPE h, t, i;
int iter, exp;
/* sqrt(-0.0) is -0.0. */
if (real_isnegzero (x))
{
*r = *x;
return false;
}
/* Negative arguments return NaN. */
if (real_isneg (x))
{
get_canonical_qnan (r, 0);
return false;
}
/* Infinity and NaN return themselves. */
if (!real_isfinite (x))
{
*r = *x;
return false;
}
if (!init)
{
do_add (&halfthree, &dconst1, &dconsthalf, 0);
init = true;
}
/* Initial guess for reciprocal sqrt, i. */
exp = real_exponent (x);
real_ldexp (&i, &dconst1, -exp/2);
/* Newton's iteration for reciprocal sqrt, i. */
for (iter = 0; iter < 16; iter++)
{
/* i(n+1) = i(n) * (1.5 - 0.5*i(n)*i(n)*x). */
do_multiply (&t, x, &i);
do_multiply (&h, &t, &i);
do_multiply (&t, &h, &dconsthalf);
do_add (&h, &halfthree, &t, 1);
do_multiply (&t, &i, &h);
/* Check for early convergence. */
if (iter >= 6 && real_identical (&i, &t))
break;
/* ??? Unroll loop to avoid copying. */
i = t;
}
/* Final iteration: r = i*x + 0.5*i*x*(1.0 - i*(i*x)). */
do_multiply (&t, x, &i);
do_multiply (&h, &t, &i);
do_add (&i, &dconst1, &h, 1);
do_multiply (&h, &t, &i);
do_multiply (&i, &dconsthalf, &h);
do_add (&h, &t, &i, 0);
/* ??? We need a Tuckerman test to get the last bit. */
real_convert (r, mode, &h);
return true;
}
/* Calculate X raised to the integer exponent N in mode MODE and store
the result in R. Return true if the result may be inexact due to
loss of precision. The algorithm is the classic "left-to-right binary

4
gcc/real.h
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@ -461,10 +461,6 @@ bool real_can_shorten_arithmetic (enum machine_mode, enum machine_mode);
/* In tree.c: wrap up a REAL_VALUE_TYPE in a tree node. */
extern tree build_real (tree, REAL_VALUE_TYPE);
/* Calculate R as the square root of X in the given machine mode. */
extern bool real_sqrt (REAL_VALUE_TYPE *, enum machine_mode,
const REAL_VALUE_TYPE *);
/* Calculate R as X raised to the integer exponent N in mode MODE. */
extern bool real_powi (REAL_VALUE_TYPE *, enum machine_mode,
const REAL_VALUE_TYPE *, HOST_WIDE_INT);

8
gcc/simplify-rtx.c
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@ -1931,17 +1931,13 @@ simplify_const_unary_operation (enum rtx_code code, enum machine_mode mode,
&& SCALAR_FLOAT_MODE_P (mode)
&& SCALAR_FLOAT_MODE_P (GET_MODE (op)))
{
REAL_VALUE_TYPE d, t;
REAL_VALUE_TYPE d;
REAL_VALUE_FROM_CONST_DOUBLE (d, op);
switch (code)
{
case SQRT:
if (HONOR_SNANS (mode) && real_isnan (&d))
return 0;
real_sqrt (&t, mode, &d);
d = t;
break;
return 0;
case ABS:
d = real_value_abs (&d);
break;