c2565a31c1
Here is a complete patch to add std::bfloat16_t support on
x86 (AArch64 and ARM left for later). Almost no BFmode optabs
are added by the patch, so for binops/unops it extends to SFmode
first and then truncates back to BFmode.
For {HF,SF,DF,XF,TF}mode -> BFmode conversions libgcc has implementations
of all those conversions so that we avoid double rounding, for
BFmode -> {DF,XF,TF}mode conversions to avoid growing libgcc too much
it emits BFmode -> SFmode conversion first and then converts to the even
wider mode, neither step should be imprecise.
For BFmode -> HFmode, it first emits a precise BFmode -> SFmode conversion
and then SFmode -> HFmode, because neither format is subset or superset
of the other, while SFmode is superset of both.
expr.cc then contains a -ffast-math optimization of the BF -> SF and
SF -> BF conversions if we don't optimize for space (and for the latter
if -frounding-math isn't enabled either).
For x86, perhaps truncsfbf2 optab could be defined for TARGET_AVX512BF16
but IMNSHO should FAIL if !flag_finite_math || flag_rounding_math
|| !flag_unsafe_math_optimizations, because I think the insn doesn't
raise on sNaNs, hardcodes round to nearest and flushes denormals to zero.
By default (unless x86 -fexcess-precision=16) we use float excess
precision for BFmode, so truncate only on explicit casts and assignments.
The patch introduces a single __bf16 builtin - __builtin_nansf16b,
because (__bf16) __builtin_nansf ("") will drop the sNaN into qNaN,
and uses f16b suffix instead of bf16 because there would be ambiguity on
log vs. logb - __builtin_logbf16 could be either log with bf16 suffix
or logb with f16 suffix. In other cases libstdc++ should mostly use
__builtin_*f for std::bfloat16_t overloads (we have a problem with
std::nextafter though but that one we have also for std::float16_t).
2022-10-14 Jakub Jelinek <jakub@redhat.com>
gcc/
* tree-core.h (enum tree_index): Add TI_BFLOAT16_TYPE.
* tree.h (bfloat16_type_node): Define.
* tree.cc (excess_precision_type): Promote bfloat16_type_mode
like float16_type_mode.
(build_common_tree_nodes): Initialize bfloat16_type_node if
BFmode is supported.
* expmed.h (maybe_expand_shift): Declare.
* expmed.cc (maybe_expand_shift): No longer static.
* expr.cc (convert_mode_scalar): Don't ICE on BF -> HF or HF -> BF
conversions. If there is no optab, handle BF -> {DF,XF,TF,HF}
conversions as separate BF -> SF -> {DF,XF,TF,HF} conversions, add
-ffast-math generic implementation for BF -> SF and SF -> BF
conversions.
* builtin-types.def (BT_BFLOAT16, BT_FN_BFLOAT16_CONST_STRING): New.
* builtins.def (BUILT_IN_NANSF16B): New builtin.
* fold-const-call.cc (fold_const_call): Handle CFN_BUILT_IN_NANSF16B.
* config/i386/i386.cc (classify_argument): Handle E_BCmode.
(ix86_libgcc_floating_mode_supported_p): Also return true for BFmode
for -msse2.
(ix86_mangle_type): Mangle BFmode as DF16b.
(ix86_invalid_conversion, ix86_invalid_unary_op,
ix86_invalid_binary_op): Remove.
(TARGET_INVALID_CONVERSION, TARGET_INVALID_UNARY_OP,
TARGET_INVALID_BINARY_OP): Don't redefine.
* config/i386/i386-builtins.cc (ix86_bf16_type_node): Remove.
(ix86_register_bf16_builtin_type): Use bfloat16_type_node rather than
ix86_bf16_type_node, only create it if still NULL.
* config/i386/i386-builtin-types.def (BFLOAT16): Likewise.
* config/i386/i386.md (cbranchbf4, cstorebf4): New expanders.
gcc/c-family/
* c-cppbuiltin.cc (c_cpp_builtins): If bfloat16_type_node,
predefine __BFLT16_*__ macros and for C++23 also
__STDCPP_BFLOAT16_T__. Predefine bfloat16_type_node related
macros for -fbuilding-libgcc.
* c-lex.cc (interpret_float): Handle CPP_N_BFLOAT16.
gcc/c/
* c-typeck.cc (convert_arguments): Don't promote __bf16 to
double.
gcc/cp/
* cp-tree.h (extended_float_type_p): Return true for
bfloat16_type_node.
* typeck.cc (cp_compare_floating_point_conversion_ranks): Set
extended{1,2} if mv{1,2} is bfloat16_type_node. Adjust comment.
gcc/testsuite/
* lib/target-supports.exp (check_effective_target_bfloat16,
check_effective_target_bfloat16_runtime, add_options_for_bfloat16):
New.
* gcc.dg/torture/bfloat16-basic.c: New test.
* gcc.dg/torture/bfloat16-builtin.c: New test.
* gcc.dg/torture/bfloat16-builtin-issignaling-1.c: New test.
* gcc.dg/torture/bfloat16-complex.c: New test.
* gcc.dg/torture/builtin-issignaling-1.c: Allow to be includable
from bfloat16-builtin-issignaling-1.c.
* gcc.dg/torture/floatn-basic.h: Allow to be includable from
bfloat16-basic.c.
* gcc.target/i386/vect-bfloat16-typecheck_2.c: Adjust expected
diagnostics.
* gcc.target/i386/sse2-bfloat16-scalar-typecheck.c: Likewise.
* gcc.target/i386/vect-bfloat16-typecheck_1.c: Likewise.
* g++.target/i386/bfloat_cpp_typecheck.C: Likewise.
libcpp/
* include/cpplib.h (CPP_N_BFLOAT16): Define.
* expr.cc (interpret_float_suffix): Handle bf16 and BF16 suffixes for
C++.
libgcc/
* config/i386/t-softfp (softfp_extensions): Add bfsf.
(softfp_truncations): Add tfbf xfbf dfbf sfbf hfbf.
(CFLAGS-extendbfsf2.c, CFLAGS-truncsfbf2.c, CFLAGS-truncdfbf2.c,
CFLAGS-truncxfbf2.c, CFLAGS-trunctfbf2.c, CFLAGS-trunchfbf2.c): Add
-msse2.
* config/i386/libgcc-glibc.ver (GCC_13.0.0): Export
__extendbfsf2 and __trunc{s,d,x,t,h}fbf2.
* config/i386/sfp-machine.h (_FP_NANSIGN_B): Define.
* config/i386/64/sfp-machine.h (_FP_NANFRAC_B): Define.
* config/i386/32/sfp-machine.h (_FP_NANFRAC_B): Define.
* soft-fp/brain.h: New file.
* soft-fp/truncsfbf2.c: New file.
* soft-fp/truncdfbf2.c: New file.
* soft-fp/truncxfbf2.c: New file.
* soft-fp/trunctfbf2.c: New file.
* soft-fp/trunchfbf2.c: New file.
* soft-fp/truncbfhf2.c: New file.
* soft-fp/extendbfsf2.c: New file.
libiberty/
* cp-demangle.h (D_BUILTIN_TYPE_COUNT): Increment.
* cp-demangle.c (cplus_demangle_builtin_types): Add std::bfloat16_t
entry.
(cplus_demangle_type): Demangle DF16b.
* testsuite/demangle-expected (_Z3xxxDF16b): New test.
101 lines
3.2 KiB
C
101 lines
3.2 KiB
C
#ifdef __MINGW32__
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/* Make sure we are using gnu-style bitfield handling. */
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#define _FP_STRUCT_LAYOUT __attribute__ ((gcc_struct))
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#endif
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/* The type of the result of a floating point comparison. This must
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match `__libgcc_cmp_return__' in GCC for the target. */
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typedef int __gcc_CMPtype __attribute__ ((mode (__libgcc_cmp_return__)));
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#define CMPtype __gcc_CMPtype
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#ifdef __x86_64__
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#include "config/i386/64/sfp-machine.h"
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#else
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#include "config/i386/32/sfp-machine.h"
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#endif
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#define _FP_KEEPNANFRACP 1
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#define _FP_QNANNEGATEDP 0
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#define _FP_NANSIGN_H 1
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#define _FP_NANSIGN_B 1
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#define _FP_NANSIGN_S 1
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#define _FP_NANSIGN_D 1
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#define _FP_NANSIGN_E 1
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#define _FP_NANSIGN_Q 1
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/* Here is something Intel misdesigned: the specs don't define
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the case where we have two NaNs with same mantissas, but
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different sign. Different operations pick up different NaNs. */
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#define _FP_CHOOSENAN(fs, wc, R, X, Y, OP) \
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do { \
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if (_FP_FRAC_GT_##wc(X, Y) \
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|| (_FP_FRAC_EQ_##wc(X,Y) && (OP == '+' || OP == '*'))) \
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{ \
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R##_s = X##_s; \
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_FP_FRAC_COPY_##wc(R,X); \
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} \
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else \
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{ \
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R##_s = Y##_s; \
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_FP_FRAC_COPY_##wc(R,Y); \
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} \
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R##_c = FP_CLS_NAN; \
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} while (0)
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#ifndef _SOFT_FLOAT
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#define FP_EX_INVALID 0x01
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#define FP_EX_DENORM 0x02
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#define FP_EX_DIVZERO 0x04
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#define FP_EX_OVERFLOW 0x08
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#define FP_EX_UNDERFLOW 0x10
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#define FP_EX_INEXACT 0x20
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#define FP_EX_ALL \
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(FP_EX_INVALID | FP_EX_DENORM | FP_EX_DIVZERO | FP_EX_OVERFLOW \
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| FP_EX_UNDERFLOW | FP_EX_INEXACT)
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void __sfp_handle_exceptions (int);
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#define FP_HANDLE_EXCEPTIONS \
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do { \
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if (__builtin_expect (_fex, 0)) \
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__sfp_handle_exceptions (_fex); \
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} while (0)
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#define FP_TRAPPING_EXCEPTIONS ((~_fcw >> FP_EX_SHIFT) & FP_EX_ALL)
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#define FP_ROUNDMODE (_fcw & FP_RND_MASK)
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#endif
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#define _FP_TININESS_AFTER_ROUNDING 1
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#define __LITTLE_ENDIAN 1234
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#define __BIG_ENDIAN 4321
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#define __BYTE_ORDER __LITTLE_ENDIAN
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/* Define ALIASNAME as a strong alias for NAME. */
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#if defined __APPLE__
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/* Mach-O doesn't support aliasing, so we build a secondary function for
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the alias - we need to do a bit of a dance to find out what the type of
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the arguments is and then apply that to the secondary function.
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If these functions ever return anything but CMPtype we need to revisit
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this... */
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typedef float alias_HFtype __attribute__ ((mode (HF)));
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typedef float alias_SFtype __attribute__ ((mode (SF)));
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typedef float alias_DFtype __attribute__ ((mode (DF)));
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typedef float alias_TFtype __attribute__ ((mode (TF)));
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#define ALIAS_SELECTOR \
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CMPtype (*) (alias_HFtype, alias_HFtype): (alias_HFtype) 0, \
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CMPtype (*) (alias_SFtype, alias_SFtype): (alias_SFtype) 0, \
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CMPtype (*) (alias_DFtype, alias_DFtype): (alias_DFtype) 0, \
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CMPtype (*) (alias_TFtype, alias_TFtype): (alias_TFtype) 0
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#define strong_alias(name, aliasname) \
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CMPtype aliasname (__typeof (_Generic (name, ALIAS_SELECTOR)) a, \
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__typeof (_Generic (name, ALIAS_SELECTOR)) b) \
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{ return name (a, b); }
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#else
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# define strong_alias(name, aliasname) _strong_alias(name, aliasname)
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# define _strong_alias(name, aliasname) \
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extern __typeof (name) aliasname __attribute__ ((alias (#name)));
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#endif
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