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convert.c (convert_to_real): Guard those unsafe math function convertions with flag_unsafe_math_optimizations. 

2013-10-24  Cong Hou  <congh@google.com>

    * convert.c (convert_to_real): Guard those unsafe math function
      convertions with flag_unsafe_math_optimizations.  Handle sqrt()
      specially. 

2013-10-24  Cong Hou  <congh@google.com>

    * gcc.c-torture/execute/20030125-1.c: Update.

From-SVN: r204028
This commit is contained in:
Cong Hou 2013-10-24 14:10:38 -04:00 committed by Cong Hou
parent 51ce05475c
commit 247dbcf4ab
4 changed files with 50 additions and 6 deletions
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6
gcc/ChangeLog
View File

@ -1,3 +1,9 @@
2013-10-24 Cong Hou <congh@google.com>
* convert.c (convert_to_real): Guard those unsafe math function
convertions with flag_unsafe_math_optimizations. Handle sqrt()
specially.
2013-10-24 Markus Trippelsdorf <markus@trippelsdorf.de>
PR ipa/58712

42
gcc/convert.c
View File

@ -135,16 +135,19 @@ convert_to_real (tree type, tree expr)
CASE_MATHFN (COS)
CASE_MATHFN (ERF)
CASE_MATHFN (ERFC)
CASE_MATHFN (FABS)
CASE_MATHFN (LOG)
CASE_MATHFN (LOG10)
CASE_MATHFN (LOG2)
CASE_MATHFN (LOG1P)
CASE_MATHFN (LOGB)
CASE_MATHFN (SIN)
CASE_MATHFN (SQRT)
CASE_MATHFN (TAN)
CASE_MATHFN (TANH)
/* The above functions are not safe to do this conversion. */
if (!flag_unsafe_math_optimizations)
break;
CASE_MATHFN (SQRT)
CASE_MATHFN (FABS)
CASE_MATHFN (LOGB)
#undef CASE_MATHFN
{
tree arg0 = strip_float_extensions (CALL_EXPR_ARG (expr, 0));
@ -155,13 +158,44 @@ convert_to_real (tree type, tree expr)
if (TYPE_PRECISION (TREE_TYPE (arg0)) > TYPE_PRECISION (type))
newtype = TREE_TYPE (arg0);
/* We consider to convert
(T1) sqrtT2 ((T2) exprT3)
to
(T1) sqrtT4 ((T4) exprT3)
, where T1 is TYPE, T2 is ITYPE, T3 is TREE_TYPE (ARG0),
and T4 is NEWTYPE. All those types are of floating point types.
T4 (NEWTYPE) should be narrower than T2 (ITYPE). This conversion
is safe only if P1 >= P2*2+2, where P1 and P2 are precisions of
T2 and T4. See the following URL for a reference:
http://stackoverflow.com/questions/9235456/determining-
floating-point-square-root
*/
if ((fcode == BUILT_IN_SQRT || fcode == BUILT_IN_SQRTL)
&& !flag_unsafe_math_optimizations)
{
/* The following conversion is unsafe even the precision condition
below is satisfied:
(float) sqrtl ((long double) double_val) -> (float) sqrt (double_val)
*/
if (TYPE_MODE (type) != TYPE_MODE (newtype))
break;
int p1 = REAL_MODE_FORMAT (TYPE_MODE (itype))->p;
int p2 = REAL_MODE_FORMAT (TYPE_MODE (newtype))->p;
if (p1 < p2 * 2 + 2)
break;
}
/* Be careful about integer to fp conversions.
These may overflow still. */
if (FLOAT_TYPE_P (TREE_TYPE (arg0))
&& TYPE_PRECISION (newtype) < TYPE_PRECISION (itype)
&& (TYPE_MODE (newtype) == TYPE_MODE (double_type_node)
|| TYPE_MODE (newtype) == TYPE_MODE (float_type_node)))
{
{
tree fn = mathfn_built_in (newtype, fcode);
if (fn)

4
gcc/testsuite/ChangeLog
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@ -1,3 +1,7 @@
2013-10-24 Cong Hou <congh@google.com>
* gcc.c-torture/execute/20030125-1.c: Update.
2013-08-24 Tobias Burnus <burnus@net-b.de>
PR fortran/44646

4
gcc/testsuite/gcc.c-torture/execute/20030125-1.c
View File

@ -44,11 +44,11 @@ __attribute__ ((noinline))
double
sin(double a)
{
abort ();
return a;
}
__attribute__ ((noinline))
float
sinf(float a)
{
return a;
abort ();
}