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Cache reals for 1/4, 1/6 and 1/9

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We have a global 1/2 and a cached 1/3, but recalculate 1/4, 1/6 and 1/9
each time we need them.  That seems a bit arbitrary and makes the folding
code more noisy (especially once it's moved to match.pd).

This patch caches the other three constants too.  Bootstrapped &
regression-tested on x86_64-linux-gnu.

gcc/
	* real.h (dconst_quarter, dconst_sixth, dconst_ninth): New macros.
	(dconst_quarter_ptr, dconst_sixth_ptr, dconst_ninth_ptr): Declare.
	* real.c (CACHED_FRACTION): New helper macro.
	(dconst_third_ptr): Use it.
	(dconst_quarter_ptr, dconst_sixth_ptr, dconst_ninth_ptr): New.
	* builtins.c (fold_builtin_sqrt): Use dconst_quarter and
	dconst_sixth.
	(fold_builtin_cbrt): Use dconst_sixth and dconst_ninth.

From-SVN: r228561
This commit is contained in:
Richard Sandiford 2015-10-07 08:09:45 +00:00 committed by Richard Sandiford
parent 5b5dce39b8
commit d01db77a06
4 changed files with 46 additions and 43 deletions
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11
gcc/ChangeLog
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@ -1,3 +1,14 @@
2015-10-07 Richard Sandiford <richard.sandiford@arm.com>
* real.h (dconst_quarter, dconst_sixth, dconst_ninth): New macros.
(dconst_quarter_ptr, dconst_sixth_ptr, dconst_ninth_ptr): Declare.
* real.c (CACHED_FRACTION): New helper macro.
(dconst_third_ptr): Use it.
(dconst_quarter_ptr, dconst_sixth_ptr, dconst_ninth_ptr): New.
* builtins.c (fold_builtin_sqrt): Use dconst_quarter and
dconst_sixth.
(fold_builtin_cbrt): Use dconst_sixth and dconst_ninth.
2015-10-06 Jeff Law <law@redhat.com>
PR tree-optimization/67816

31
gcc/builtins.c
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@ -7742,20 +7742,10 @@ fold_builtin_sqrt (location_t loc, tree arg, tree type)
if (powfn)
{
tree arg0 = CALL_EXPR_ARG (arg, 0);
tree tree_root;
/* The inner root was either sqrt or cbrt. */
/* This was a conditional expression but it triggered a bug
in Sun C 5.5. */
REAL_VALUE_TYPE dconstroot;
if (BUILTIN_SQRT_P (fcode))
dconstroot = dconsthalf;
else
dconstroot = dconst_third ();
/* Adjust for the outer root. */
SET_REAL_EXP (&dconstroot, REAL_EXP (&dconstroot) - 1);
tree_root = build_real_truncate (type, dconstroot);
return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
tree arg1 = (BUILTIN_SQRT_P (fcode)
? build_real (type, dconst_quarter ())
: build_real_truncate (type, dconst_sixth ()));
return build_call_expr_loc (loc, powfn, 2, arg0, arg1);
}
}
@ -7815,11 +7805,7 @@ fold_builtin_cbrt (location_t loc, tree arg, tree type)
if (powfn)
{
tree arg0 = CALL_EXPR_ARG (arg, 0);
tree tree_root;
REAL_VALUE_TYPE dconstroot = dconst_third ();
SET_REAL_EXP (&dconstroot, REAL_EXP (&dconstroot) - 1);
tree_root = build_real_truncate (type, dconstroot);
tree tree_root = build_real_truncate (type, dconst_sixth ());
return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
}
}
@ -7834,12 +7820,7 @@ fold_builtin_cbrt (location_t loc, tree arg, tree type)
if (powfn)
{
tree tree_root;
REAL_VALUE_TYPE dconstroot;
real_arithmetic (&dconstroot, MULT_EXPR,
dconst_third_ptr (), dconst_third_ptr ());
tree_root = build_real_truncate (type, dconstroot);
tree tree_root = build_real_truncate (type, dconst_ninth ());
return build_call_expr_loc (loc, powfn, 2, arg0, tree_root);
}
}

31
gcc/real.c
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@ -2395,21 +2395,26 @@ dconst_e_ptr (void)
return &value;
}
/* Returns the special REAL_VALUE_TYPE corresponding to 1/3. */
/* Returns a cached REAL_VALUE_TYPE corresponding to 1/n, for various n. */
const REAL_VALUE_TYPE *
dconst_third_ptr (void)
{
static REAL_VALUE_TYPE value;
#define CACHED_FRACTION(NAME, N) \
const REAL_VALUE_TYPE * \
NAME (void) \
{ \
static REAL_VALUE_TYPE value; \
\
/* Initialize mathematical constants for constant folding builtins. \
These constants need to be given to at least 160 bits \
precision. */ \
if (value.cl == rvc_zero) \
real_arithmetic (&value, RDIV_EXPR, &dconst1, real_digit (N)); \
return &value; \
}
/* Initialize mathematical constants for constant folding builtins.
These constants need to be given to at least 160 bits precision. */
if (value.cl == rvc_zero)
{
real_arithmetic (&value, RDIV_EXPR, &dconst1, real_digit (3));
}
return &value;
}
CACHED_FRACTION (dconst_third_ptr, 3)
CACHED_FRACTION (dconst_quarter_ptr, 4)
CACHED_FRACTION (dconst_sixth_ptr, 6)
CACHED_FRACTION (dconst_ninth_ptr, 9)
/* Returns the special REAL_VALUE_TYPE corresponding to sqrt(2). */

16
gcc/real.h
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@ -409,15 +409,21 @@ extern REAL_VALUE_TYPE dconst2;
extern REAL_VALUE_TYPE dconstm1;
extern REAL_VALUE_TYPE dconsthalf;
#define dconst_e() (*dconst_e_ptr ())
#define dconst_third() (*dconst_third_ptr ())
#define dconst_sqrt2() (*dconst_sqrt2_ptr ())
#define dconst_e() (*dconst_e_ptr ())
#define dconst_third() (*dconst_third_ptr ())
#define dconst_quarter() (*dconst_quarter_ptr ())
#define dconst_sixth() (*dconst_sixth_ptr ())
#define dconst_ninth() (*dconst_ninth_ptr ())
#define dconst_sqrt2() (*dconst_sqrt2_ptr ())
/* Function to return the real value special constant 'e'. */
extern const REAL_VALUE_TYPE * dconst_e_ptr (void);
/* Returns the special REAL_VALUE_TYPE corresponding to 1/3. */
extern const REAL_VALUE_TYPE * dconst_third_ptr (void);
/* Returns a cached REAL_VALUE_TYPE corresponding to 1/n, for various n. */
extern const REAL_VALUE_TYPE *dconst_third_ptr (void);
extern const REAL_VALUE_TYPE *dconst_quarter_ptr (void);
extern const REAL_VALUE_TYPE *dconst_sixth_ptr (void);
extern const REAL_VALUE_TYPE *dconst_ninth_ptr (void);
/* Returns the special REAL_VALUE_TYPE corresponding to sqrt(2). */
extern const REAL_VALUE_TYPE * dconst_sqrt2_ptr (void);