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* [gcc r14-316] Add targetm.libm_function_max_error
@ 2023-04-28 7:00 Jakub Jelinek
0 siblings, 0 replies; only message in thread
From: Jakub Jelinek @ 2023-04-28 7:00 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:bd539c9b801bde3a919a5ad16b741ab4f5eca6e3
commit r14-316-gbd539c9b801bde3a919a5ad16b741ab4f5eca6e3
Author: Jakub Jelinek <jakub@redhat.com>
Date: Fri Apr 28 08:59:29 2023 +0200
Add targetm.libm_function_max_error
As has been discussed before, the following patch adds target hook
for math library function maximum errors measured in ulps.
The default is to return ~0U which is a magic maximum value which means
nothing is known about precision of the match function.
The first argument is unsigned int because enum combined_fn isn't available
everywhere where target hooks are included but is expected to be given
the enum combined_fn value, although it should be used solely to find out
which kind of match function (say sin vs. cos vs. sqrt vs. exp10) rather
than its variant (f suffix, no suffix, l suffix, f128 suffix, ...), for
which there is the machine_mode argument.
The last argument is a bool, if it is false, the function should return
maximum known error in ulps for a given function (taking -frounding-math
into account if enabled), with 0.5ulps being represented as 0.
If it is true, it is about whether the function can return values outside of
an intrinsic finite range for the function and by how many ulps.
E.g. sin/cos should return result in [-1.,1], if the function is expected
to never return values outside of that finite interval, the hook should
return 0. Similarly for sqrt such range is [-0.,+Inf].
The patch implements it for glibc only so far, I hope other maintainers
can submit details for Solaris, musl, perhaps BSDs, etc.
For glibc I've gathered data from:
1) https://www.gnu.org/software/libc/manual/html_node/Errors-in-Math-Functions.html
as latest published glibc data
2) https://www.gnu.org/software/libc/manual/2.22/html_node/Errors-in-Math-Functions.html
as a few years old glibc data
3) using attached libc-ulps.sh script from glibc git
4) using attached ulp-tester.c (how to invoke in file comment; tested
both x86_64, ppc64, ppc64le 50M pseudo-random values in all 4 rounding
modes, plus on x86_64 float/double sin/cos using libmvec - see
attached libmvec-wrapper.c as well)
5) using attached boundary-tester.c to test for whether sin/cos/sqrt return
values outside of the intrinsic ranges for those functions (again,
tested on x86_64, ppc64, ppc64le plus on x86_64 using libmvec as well;
libmvec with non-default rounding modes is pretty much random number
generator it seems)
The data is added to various hooks, the generic and generic glibc versions
being in targhooks.c so that the various targets can easily override it.
The intent is that the generic glibc version handles most of the stuff
and specific target arch overrides handle the outliers or special cases.
The patch has special case for x86_64 when __FAST_MATH__ is defined (as
one can use in that case either libm or libmvec and we don't know which
one will be used; so it uses maximum of what libm provides and libmvec),
rs6000 (had to add one because cosf has 3ulps on ppc* rather than 1-2ulps
on most other targets; MODE_COMPOSITE_P could be in theory handled in the
generic code too, but as we have rs6000-linux specific function, it can be
done just there), arc-linux (because DFmode sin has 7ulps there compared to
1ulps on other targets, both in default rounding mode and in others) and
or1k-linux (while DFmode sin has 1ulps there for default rounding mode,
for other rounding modes it has up to 7ulps).
Now, for -frounding-math I'm trying to add a few ulps more because I expect
it to be much less tested, except that for boundary_p I try to use
the numbers I got from the 5) tester.
2023-04-28 Jakub Jelinek <jakub@redhat.com>
* target.def (libm_function_max_error): New target hook.
* doc/tm.texi.in (TARGET_LIBM_FUNCTION_MAX_ERROR): Add.
* doc/tm.texi: Regenerated.
* targhooks.h (default_libm_function_max_error,
glibc_linux_libm_function_max_error): Declare.
* targhooks.cc: Include case-cfn-macros.h.
(default_libm_function_max_error,
glibc_linux_libm_function_max_error): New functions.
* config/linux.h (TARGET_LIBM_FUNCTION_MAX_ERROR): Redefine.
* config/linux-protos.h (linux_libm_function_max_error): Declare.
* config/linux.cc: Include target.h and targhooks.h.
(linux_libm_function_max_error): New function.
* config/arc/arc.cc: Include targhooks.h and case-cfn-macros.h.
(arc_libm_function_max_error): New function.
(TARGET_LIBM_FUNCTION_MAX_ERROR): Redefine.
* config/i386/i386.cc (ix86_libc_has_fast_function): Formatting fix.
(ix86_libm_function_max_error): New function.
(TARGET_LIBM_FUNCTION_MAX_ERROR): Redefine.
* config/rs6000/rs6000-protos.h
(rs6000_linux_libm_function_max_error): Declare.
* config/rs6000/rs6000-linux.cc: Include target.h, targhooks.h, tree.h
and case-cfn-macros.h.
(rs6000_linux_libm_function_max_error): New function.
* config/rs6000/linux.h (TARGET_LIBM_FUNCTION_MAX_ERROR): Redefine.
* config/rs6000/linux64.h (TARGET_LIBM_FUNCTION_MAX_ERROR): Redefine.
* config/or1k/or1k.cc: Include targhooks.h and case-cfn-macros.h.
(or1k_libm_function_max_error): New function.
(TARGET_LIBM_FUNCTION_MAX_ERROR): Redefine.
Diff:
---
gcc/config/arc/arc.cc | 36 +++++++++++++++++++++
gcc/config/i386/i386.cc | 55 ++++++++++++++++++++++++++++++-
gcc/config/linux-protos.h | 2 ++
gcc/config/linux.cc | 11 +++++++
gcc/config/linux.h | 3 ++
gcc/config/or1k/or1k.cc | 31 ++++++++++++++++++
gcc/config/rs6000/linux.h | 3 ++
gcc/config/rs6000/linux64.h | 3 ++
gcc/config/rs6000/rs6000-linux.cc | 40 +++++++++++++++++++++++
gcc/config/rs6000/rs6000-protos.h | 2 ++
gcc/doc/tm.texi | 15 +++++++++
gcc/doc/tm.texi.in | 2 ++
gcc/target.def | 17 ++++++++++
gcc/targhooks.cc | 68 +++++++++++++++++++++++++++++++++++++++
gcc/targhooks.h | 3 ++
15 files changed, 290 insertions(+), 1 deletion(-)
diff --git a/gcc/config/arc/arc.cc b/gcc/config/arc/arc.cc
index 22eb2e9cb45..b47935a9214 100644
--- a/gcc/config/arc/arc.cc
+++ b/gcc/config/arc/arc.cc
@@ -68,6 +68,8 @@ along with GCC; see the file COPYING3. If not see
#include "alias.h"
#include "opts.h"
#include "hw-doloop.h"
+#include "targhooks.h"
+#include "case-cfn-macros.h"
/* Which cpu we're compiling for (ARC600, ARC601, ARC700). */
static char arc_cpu_name[10] = "";
@@ -11808,6 +11810,37 @@ arc_insn_cost (rtx_insn *insn, bool speed)
return cost;
}
+static unsigned
+arc_libm_function_max_error (unsigned cfn, machine_mode mode,
+ bool boundary_p)
+{
+#ifdef OPTION_GLIBC
+ bool glibc_p = OPTION_GLIBC;
+#else
+ bool glibc_p = false;
+#endif
+ if (glibc_p)
+ {
+ int rnd = flag_rounding_math ? 4 : 0;
+ switch (cfn)
+ {
+ CASE_CFN_SIN:
+ CASE_CFN_SIN_FN:
+ if (!boundary_p && mode == DFmode)
+ return 7 + rnd;
+ break;
+ CASE_CFN_COS:
+ CASE_CFN_COS_FN:
+ if (!boundary_p && mode == DFmode)
+ return 4 + rnd;
+ default:
+ break;
+ }
+ return glibc_linux_libm_function_max_error (cfn, mode, boundary_p);
+ }
+ return default_libm_function_max_error (cfn, mode, boundary_p);
+}
+
#undef TARGET_USE_ANCHORS_FOR_SYMBOL_P
#define TARGET_USE_ANCHORS_FOR_SYMBOL_P arc_use_anchors_for_symbol_p
@@ -11832,6 +11865,9 @@ arc_insn_cost (rtx_insn *insn, bool speed)
#undef TARGET_INSN_COST
#define TARGET_INSN_COST arc_insn_cost
+#undef TARGET_LIBM_FUNCTION_MAX_ERROR
+#define TARGET_LIBM_FUNCTION_MAX_ERROR arc_libm_function_max_error
+
struct gcc_target targetm = TARGET_INITIALIZER;
#include "gt-arc.h"
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index a3db55642e3..cf1cfb722a9 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -25250,7 +25250,8 @@ ix86_libgcc_floating_mode_supported_p
#undef TARGET_MEMTAG_TAG_SIZE
#define TARGET_MEMTAG_TAG_SIZE ix86_memtag_tag_size
-static bool ix86_libc_has_fast_function (int fcode ATTRIBUTE_UNUSED)
+static bool
+ix86_libc_has_fast_function (int fcode ATTRIBUTE_UNUSED)
{
#ifdef OPTION_GLIBC
if (OPTION_GLIBC)
@@ -25265,6 +25266,58 @@ static bool ix86_libc_has_fast_function (int fcode ATTRIBUTE_UNUSED)
#undef TARGET_LIBC_HAS_FAST_FUNCTION
#define TARGET_LIBC_HAS_FAST_FUNCTION ix86_libc_has_fast_function
+static unsigned
+ix86_libm_function_max_error (unsigned cfn, machine_mode mode,
+ bool boundary_p)
+{
+#ifdef OPTION_GLIBC
+ bool glibc_p = OPTION_GLIBC;
+#else
+ bool glibc_p = false;
+#endif
+ if (glibc_p)
+ {
+ /* If __FAST_MATH__ is defined, glibc provides libmvec. */
+ unsigned int libmvec_ret = 0;
+ if (!flag_trapping_math
+ && flag_unsafe_math_optimizations
+ && flag_finite_math_only
+ && !flag_signed_zeros
+ && !flag_errno_math)
+ switch (cfn)
+ {
+ CASE_CFN_COS:
+ CASE_CFN_COS_FN:
+ CASE_CFN_SIN:
+ CASE_CFN_SIN_FN:
+ if (!boundary_p)
+ {
+ /* With non-default rounding modes, libmvec provides
+ complete garbage in results. E.g.
+ _ZGVcN8v_sinf for 1.40129846e-45f in FE_UPWARD
+ returns 0.00333309174f rather than 1.40129846e-45f. */
+ if (flag_rounding_math)
+ return ~0U;
+ /* https://www.gnu.org/software/libc/manual/html_node/Errors-in-Math-Functions.html
+ claims libmvec maximum error is 4ulps.
+ My own random testing indicates 2ulps for SFmode and
+ 0.5ulps for DFmode, but let's go with the 4ulps. */
+ libmvec_ret = 4;
+ }
+ break;
+ default:
+ break;
+ }
+ unsigned int ret = glibc_linux_libm_function_max_error (cfn, mode,
+ boundary_p);
+ return MAX (ret, libmvec_ret);
+ }
+ return default_libm_function_max_error (cfn, mode, boundary_p);
+}
+
+#undef TARGET_LIBM_FUNCTION_MAX_ERROR
+#define TARGET_LIBM_FUNCTION_MAX_ERROR ix86_libm_function_max_error
+
#if CHECKING_P
#undef TARGET_RUN_TARGET_SELFTESTS
#define TARGET_RUN_TARGET_SELFTESTS selftest::ix86_run_selftests
diff --git a/gcc/config/linux-protos.h b/gcc/config/linux-protos.h
index 147b4ebdb24..f2ea930ace7 100644
--- a/gcc/config/linux-protos.h
+++ b/gcc/config/linux-protos.h
@@ -20,3 +20,5 @@ along with GCC; see the file COPYING3. If not see
extern bool linux_has_ifunc_p (void);
extern bool linux_libc_has_function (enum function_class fn_class, tree);
+
+extern unsigned linux_libm_function_max_error (unsigned, machine_mode, bool);
diff --git a/gcc/config/linux.cc b/gcc/config/linux.cc
index 28c8c15dbc0..9114e55d44e 100644
--- a/gcc/config/linux.cc
+++ b/gcc/config/linux.cc
@@ -23,6 +23,8 @@ along with GCC; see the file COPYING3. If not see
#include "tm.h"
#include "tree.h"
#include "linux-protos.h"
+#include "target.h"
+#include "targhooks.h"
bool
linux_libc_has_function (enum function_class fn_class,
@@ -38,3 +40,12 @@ linux_libc_has_function (enum function_class fn_class,
return false;
}
+
+unsigned
+linux_libm_function_max_error (unsigned cfn, machine_mode mode,
+ bool boundary_p)
+{
+ if (OPTION_GLIBC)
+ return glibc_linux_libm_function_max_error (cfn, mode, boundary_p);
+ return default_libm_function_max_error (cfn, mode, boundary_p);
+}
diff --git a/gcc/config/linux.h b/gcc/config/linux.h
index e3aca79cccc..ac56816bfca 100644
--- a/gcc/config/linux.h
+++ b/gcc/config/linux.h
@@ -212,4 +212,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
# undef TARGET_LIBC_HAS_FUNCTION
# define TARGET_LIBC_HAS_FUNCTION linux_libc_has_function
+# undef TARGET_LIBM_FUNCTION_MAX_ERROR
+# define TARGET_LIBM_FUNCTION_MAX_ERROR linux_libm_function_max_error
+
#endif
diff --git a/gcc/config/or1k/or1k.cc b/gcc/config/or1k/or1k.cc
index f98f1ec685b..ec30bc8156c 100644
--- a/gcc/config/or1k/or1k.cc
+++ b/gcc/config/or1k/or1k.cc
@@ -44,6 +44,8 @@
#include "explow.h"
#include "cfgrtl.h"
#include "alias.h"
+#include "targhooks.h"
+#include "case-cfn-macros.h"
/* These 4 are needed to allow using satisfies_constraint_J. */
#include "insn-config.h"
@@ -2191,6 +2193,32 @@ or1k_output_mi_thunk (FILE *file, tree thunk_fndecl,
epilogue_completed = 0;
}
+static unsigned
+or1k_libm_function_max_error (unsigned cfn, machine_mode mode,
+ bool boundary_p)
+{
+#ifdef OPTION_GLIBC
+ bool glibc_p = OPTION_GLIBC;
+#else
+ bool glibc_p = false;
+#endif
+ if (glibc_p)
+ {
+ switch (cfn)
+ {
+ CASE_CFN_SIN:
+ CASE_CFN_SIN_FN:
+ if (!boundary_p && mode == DFmode && flag_rounding_math)
+ return 7;
+ break;
+ default:
+ break;
+ }
+ return glibc_linux_libm_function_max_error (cfn, mode, boundary_p);
+ }
+ return default_libm_function_max_error (cfn, mode, boundary_p);
+}
+
#undef TARGET_ASM_OUTPUT_MI_THUNK
#define TARGET_ASM_OUTPUT_MI_THUNK or1k_output_mi_thunk
#undef TARGET_ASM_CAN_OUTPUT_MI_THUNK
@@ -2214,6 +2242,9 @@ or1k_output_mi_thunk (FILE *file, tree thunk_fndecl,
#undef TARGET_HAVE_SPECULATION_SAFE_VALUE
#define TARGET_HAVE_SPECULATION_SAFE_VALUE speculation_safe_value_not_needed
+#undef TARGET_LIBM_FUNCTION_MAX_ERROR
+#define TARGET_LIBM_FUNCTION_MAX_ERROR or1k_libm_function_max_error
+
/* Calling Conventions. */
#undef TARGET_FUNCTION_VALUE
#define TARGET_FUNCTION_VALUE or1k_function_value
diff --git a/gcc/config/rs6000/linux.h b/gcc/config/rs6000/linux.h
index 5d21befe8e4..8dc2a89684a 100644
--- a/gcc/config/rs6000/linux.h
+++ b/gcc/config/rs6000/linux.h
@@ -50,6 +50,9 @@
#undef TARGET_LIBC_HAS_FUNCTION
#define TARGET_LIBC_HAS_FUNCTION linux_libc_has_function
+#undef TARGET_LIBM_FUNCTION_MAX_ERROR
+#define TARGET_LIBM_FUNCTION_MAX_ERROR rs6000_linux_libm_function_max_error
+
#undef TARGET_OS_CPP_BUILTINS
#define TARGET_OS_CPP_BUILTINS() \
do \
diff --git a/gcc/config/rs6000/linux64.h b/gcc/config/rs6000/linux64.h
index 9e457033d11..6e4acaf00c2 100644
--- a/gcc/config/rs6000/linux64.h
+++ b/gcc/config/rs6000/linux64.h
@@ -288,6 +288,9 @@ extern int dot_symbols;
#undef TARGET_LIBC_HAS_FUNCTION
#define TARGET_LIBC_HAS_FUNCTION linux_libc_has_function
+#undef TARGET_LIBM_FUNCTION_MAX_ERROR
+#define TARGET_LIBM_FUNCTION_MAX_ERROR rs6000_linux_libm_function_max_error
+
#undef TARGET_OS_CPP_BUILTINS
#define TARGET_OS_CPP_BUILTINS() \
do \
diff --git a/gcc/config/rs6000/rs6000-linux.cc b/gcc/config/rs6000/rs6000-linux.cc
index 35dc1097416..0f89cb47777 100644
--- a/gcc/config/rs6000/rs6000-linux.cc
+++ b/gcc/config/rs6000/rs6000-linux.cc
@@ -23,6 +23,10 @@ along with GCC; see the file COPYING3. If not see
#include "system.h"
#include "coretypes.h"
#include "tm.h"
+#include "target.h"
+#include "targhooks.h"
+#include "tree.h"
+#include "case-cfn-macros.h"
/* Implement TARGET_FLOAT_EXCEPTIONS_ROUNDING_SUPPORTED_P. */
@@ -36,3 +40,39 @@ rs6000_linux_float_exceptions_rounding_supported_p (void)
else
return TARGET_HARD_FLOAT;
}
+
+/* Implement TARGET_LIBM_FUNCTION_MAX_ERROR. */
+
+unsigned
+rs6000_linux_libm_function_max_error (unsigned cfn, machine_mode mode,
+ bool boundary_p)
+{
+ if (OPTION_GLIBC)
+ {
+ int rnd = flag_rounding_math ? 4 : 0;
+ switch (cfn)
+ {
+ CASE_CFN_SQRT:
+ CASE_CFN_SQRT_FN:
+ if (!boundary_p && MODE_COMPOSITE_P (mode))
+ return 1 + rnd;
+ break;
+ CASE_CFN_COS:
+ CASE_CFN_COS_FN:
+ if (!boundary_p && mode == SFmode)
+ return 3 + rnd;
+ if (!boundary_p && MODE_COMPOSITE_P (mode))
+ return 4 + rnd;
+ break;
+ CASE_CFN_SIN:
+ CASE_CFN_SIN_FN:
+ if (!boundary_p && MODE_COMPOSITE_P (mode))
+ return 1 + rnd;
+ break;
+ default:
+ break;
+ }
+ return glibc_linux_libm_function_max_error (cfn, mode, boundary_p);
+ }
+ return default_libm_function_max_error (cfn, mode, boundary_p);
+}
diff --git a/gcc/config/rs6000/rs6000-protos.h b/gcc/config/rs6000/rs6000-protos.h
index 1a4fc1df668..9a4cc18c6d3 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -334,6 +334,8 @@ extern unsigned char rs6000_class_max_nregs[][LIM_REG_CLASSES];
extern unsigned char rs6000_hard_regno_nregs[][FIRST_PSEUDO_REGISTER];
extern bool rs6000_linux_float_exceptions_rounding_supported_p (void);
+extern unsigned rs6000_linux_libm_function_max_error (unsigned, machine_mode,
+ bool);
/* Pass management. */
namespace gcc { class context; }
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index a660e33739b..33e7ffc8af5 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -5760,6 +5760,21 @@ This hook determines whether a function from a class of functions
@code{(enum function_class)}@var{fcode} has a fast implementation.
@end deftypefn
+@deftypefn {Target Hook} unsigned TARGET_LIBM_FUNCTION_MAX_ERROR (unsigned @var{cfn}, machine_mode @var{mode}, bool @var{boundary_p})
+This hook determines expected maximum errors for math functions measured
+in ulps (units of the last place). 0 means 0.5ulps precision (correctly
+rounded). ~0U means unknown errors. The @code{combined_fn} @var{cfn}
+argument should identify just which math built-in function it is rather than
+its variant, @var{mode} the variant in terms of floating-point machine mode.
+The hook should also take into account @code{flag_rounding_math} whether it
+is maximum error just in default rounding mode, or in all possible rounding
+modes. @var{boundary_p} is @code{true} for maximum errors on intrinsic math
+boundaries of functions rather than errors inside of the usual result ranges
+of the functions. E.g.@ the sin/cos function finite result is in between
+-1.0 and 1.0 inclusive, with @var{boundary_p} true the function returns how
+many ulps below or above those boundaries result could be.
+@end deftypefn
+
@defmac NEXT_OBJC_RUNTIME
Set this macro to 1 to use the "NeXT" Objective-C message sending conventions
by default. This calling convention involves passing the object, the selector
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index f7ab5d48a63..c98b2447e28 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -4004,6 +4004,8 @@ macro, a reasonable default is used.
@hook TARGET_LIBC_HAS_FAST_FUNCTION
+@hook TARGET_LIBM_FUNCTION_MAX_ERROR
+
@defmac NEXT_OBJC_RUNTIME
Set this macro to 1 to use the "NeXT" Objective-C message sending conventions
by default. This calling convention involves passing the object, the selector
diff --git a/gcc/target.def b/gcc/target.def
index 171bbd1caf1..cda6c51e516 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -2670,6 +2670,23 @@ DEFHOOK
bool, (int fcode),
default_libc_has_fast_function)
+DEFHOOK
+(libm_function_max_error,
+ "This hook determines expected maximum errors for math functions measured\n\
+in ulps (units of the last place). 0 means 0.5ulps precision (correctly\n\
+rounded). ~0U means unknown errors. The @code{combined_fn} @var{cfn}\n\
+argument should identify just which math built-in function it is rather than\n\
+its variant, @var{mode} the variant in terms of floating-point machine mode.\n\
+The hook should also take into account @code{flag_rounding_math} whether it\n\
+is maximum error just in default rounding mode, or in all possible rounding\n\
+modes. @var{boundary_p} is @code{true} for maximum errors on intrinsic math\n\
+boundaries of functions rather than errors inside of the usual result ranges\n\
+of the functions. E.g.@ the sin/cos function finite result is in between\n\
+-1.0 and 1.0 inclusive, with @var{boundary_p} true the function returns how\n\
+many ulps below or above those boundaries result could be.",
+ unsigned, (unsigned cfn, machine_mode mode, bool boundary_p),
+ default_libm_function_max_error)
+
/* True if new jumps cannot be created, to replace existing ones or
not, at the current point in the compilation. */
DEFHOOK
diff --git a/gcc/targhooks.cc b/gcc/targhooks.cc
index 51bf3fb7a82..e190369f87a 100644
--- a/gcc/targhooks.cc
+++ b/gcc/targhooks.cc
@@ -94,6 +94,7 @@ along with GCC; see the file COPYING3. If not see
#include "cfgloop.h"
#include "tree-vectorizer.h"
#include "options.h"
+#include "case-cfn-macros.h"
bool
default_legitimate_address_p (machine_mode mode ATTRIBUTE_UNUSED,
@@ -1903,6 +1904,73 @@ bsd_libc_has_function (enum function_class fn_class,
return false;
}
+unsigned
+default_libm_function_max_error (unsigned, machine_mode, bool)
+{
+ return ~0U;
+}
+
+unsigned
+glibc_linux_libm_function_max_error (unsigned cfn, machine_mode mode,
+ bool boundary_p)
+{
+ /* Let's use
+ https://www.gnu.org/software/libc/manual/2.22/html_node/Errors-in-Math-Functions.html
+ https://www.gnu.org/software/libc/manual/html_node/Errors-in-Math-Functions.html
+ with usual values recorded here and significant outliers handled in
+ target CPU specific overriders. The tables only record default
+ rounding to nearest, for -frounding-math let's add some extra ulps.
+ For boundary_p values (say finite results outside of [-1.,1.] for
+ sin/cos, or [-0.,+Inf] for sqrt etc. let's use custom random testers. */
+ int rnd = flag_rounding_math ? 4 : 0;
+ bool sf = (REAL_MODE_FORMAT (mode) == &ieee_single_format
+ || REAL_MODE_FORMAT (mode) == &mips_single_format
+ || REAL_MODE_FORMAT (mode) == &motorola_single_format);
+ bool df = (REAL_MODE_FORMAT (mode) == &ieee_double_format
+ || REAL_MODE_FORMAT (mode) == &mips_double_format
+ || REAL_MODE_FORMAT (mode) == &motorola_double_format);
+ bool xf = (REAL_MODE_FORMAT (mode) == &ieee_extended_intel_96_format
+ || REAL_MODE_FORMAT (mode) == &ieee_extended_intel_128_format
+ || REAL_MODE_FORMAT (mode) == &ieee_extended_motorola_format);
+ bool tf = (REAL_MODE_FORMAT (mode) == &ieee_quad_format
+ || REAL_MODE_FORMAT (mode) == &mips_quad_format);
+
+ switch (cfn)
+ {
+ CASE_CFN_SQRT:
+ CASE_CFN_SQRT_FN:
+ if (boundary_p)
+ /* https://gcc.gnu.org/pipermail/gcc-patches/2023-April/616595.html */
+ return 0;
+ if (sf || df || xf || tf)
+ return 0 + rnd;
+ break;
+ CASE_CFN_COS:
+ CASE_CFN_COS_FN:
+ /* cos is generally errors like sin, but far more arches have 2ulps
+ for double. */
+ if (!boundary_p && df)
+ return 2 + rnd;
+ gcc_fallthrough ();
+ CASE_CFN_SIN:
+ CASE_CFN_SIN_FN:
+ if (boundary_p)
+ /* According to
+ https://sourceware.org/pipermail/gcc-patches/2023-April/616315.html
+ seems default rounding sin/cos stay strictly in [-1.,1.] range,
+ with rounding to infinity it can be 1ulp larger/smaller. */
+ return flag_rounding_math ? 1 : 0;
+ if (sf || df)
+ return 1 + rnd;
+ if (xf || tf)
+ return 2 + rnd;
+ break;
+ default:
+ break;
+ }
+
+ return default_libm_function_max_error (cfn, mode, boundary_p);
+}
tree
default_builtin_tm_load_store (tree ARG_UNUSED (type))
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index cf3d3107a0d..1a0db8dddd5 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -219,6 +219,9 @@ extern bool default_libc_has_fast_function (int fcode);
extern bool no_c99_libc_has_function (enum function_class, tree);
extern bool gnu_libc_has_function (enum function_class, tree);
extern bool bsd_libc_has_function (enum function_class, tree);
+extern unsigned default_libm_function_max_error (unsigned, machine_mode, bool);
+extern unsigned glibc_linux_libm_function_max_error (unsigned, machine_mode,
+ bool);
extern tree default_builtin_tm_load_store (tree);
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2023-04-28 7:00 [gcc r14-316] Add targetm.libm_function_max_error Jakub Jelinek
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