From c2565a31c1622ab0926aeef4a6579413e121b9f9 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Fri, 14 Oct 2022 09:37:01 +0200 Subject: middle-end, c++, i386, libgcc: std::bfloat16_t and __bf16 arithmetic support 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 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. --- libcpp/include/cpplib.h | 1 + 1 file changed, 1 insertion(+) (limited to 'libcpp/include') diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h index 2db1e9c..e97993e 100644 --- a/libcpp/include/cpplib.h +++ b/libcpp/include/cpplib.h @@ -1275,6 +1275,7 @@ struct cpp_num #define CPP_N_USERDEF 0x1000000 /* C++11 user-defined literal. */ #define CPP_N_SIZE_T 0x2000000 /* C++23 size_t literal. */ +#define CPP_N_BFLOAT16 0x4000000 /* std::bfloat16_t type. */ #define CPP_N_WIDTH_FLOATN_NX 0xF0000000 /* _FloatN / _FloatNx value of N, divided by 16. */ -- cgit v1.1 From 36d20fa4a83d1a294462c2622ca76eac93465c2c Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Fri, 14 Oct 2022 23:07:50 +0000 Subject: preprocessor: C2x identifier rules C2x has, like C++, adopted rules for identifiers based directly on an unversioned normative reference to Unicode. Make libcpp follow those rules for c2x / gnu2x standards (this involves bringing back a flag separate from the C++ one for whether to use these identifier rules, but this time enabled for all C++ language versions since that was the conclusion adopted for C++ identifier handling). There is one change here that affects C++. I believe the new normative requirement for NFC only applies to identifiers, not to the use of identifier-continue characters in pp-numbers, where there is no such requirement and so the diagnostic ought to be a warning not a pedwarn in pp-numbers, and that this is the case for both C and C++. Bootstrapped with no regressions for x86_64-pc-linux-gnu. libcpp/ * charset.cc (ucn_valid_in_identifier): Check xid_identifiers not cplusplus to determine whether to use CXX23 and NXX23 flags. * include/cpplib.h (struct cpp_options): Add xid_identifiers. * init.cc (struct lang_flags, lang_defaults): Add xid_identifiers. (cpp_set_lang): Set xid_identifiers. * lex.cc (warn_about_normalization): Add parameter identifier. Only pedwarn about non-NFC for identifiers, not pp-numbers. (_cpp_lex_direct): Update calls to warn_about_normalization. gcc/testsuite/ * gcc.dg/cpp/c2x-ucnid-1-utf8.c, gcc.dg/cpp/c2x-ucnid-1.c: New tests. --- libcpp/include/cpplib.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'libcpp/include') diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h index e97993e..d5ef12a 100644 --- a/libcpp/include/cpplib.h +++ b/libcpp/include/cpplib.h @@ -496,6 +496,10 @@ struct cpp_options in C11. */ unsigned char c11_identifiers; + /* Nonzero means extended identifiers allow the characters specified + by Unicode XID_Start and XID_Continue properties. */ + unsigned char xid_identifiers; + /* Nonzero for C++ 2014 Standard binary constants. */ unsigned char binary_constants; -- cgit v1.1