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/cpplib.h') 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/cpplib.h') 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 From f3b957ea8b9dadfb1ed30f24f463529684b7a36a Mon Sep 17 00:00:00 2001 From: Lewis Hyatt Date: Fri, 14 Oct 2022 13:52:12 -0400 Subject: pch: Fix streaming of strings with embedded null bytes When a GTY'ed struct is streamed to PCH, any plain char* pointers it contains (whether they live in GC-controlled memory or not) will be marked for PCH output by the routine gt_pch_note_object in ggc-common.cc. This routine special-cases plain char* strings, and in particular it uses strlen() to get their length. Thus it does not handle strings with embedded null bytes, but it is possible for something PCH cares about (such as a string literal token in a macro definition) to contain such embedded nulls. To fix that up, add a new GTY option "string_length" so that gt_pch_note_object can be informed the actual length it ought to use, and use it in the relevant libcpp structs (cpp_string and ht_identifier) accordingly. gcc/ChangeLog: * gengtype.cc (output_escaped_param): Add missing const. (get_string_option): Add missing check for option type. (walk_type): Support new "string_length" GTY option. (write_types_process_field): Likewise. * ggc-common.cc (gt_pch_note_object): Add optional length argument. * ggc.h (gt_pch_note_object): Adjust prototype for new argument. (gt_pch_n_S2): Declare... * stringpool.cc (gt_pch_n_S2): ...new function. * doc/gty.texi: Document new GTY((string_length)) option. libcpp/ChangeLog: * include/cpplib.h (struct cpp_string): Use new "string_length" GTY. * include/symtab.h (struct ht_identifier): Likewise. gcc/testsuite/ChangeLog: * g++.dg/pch/pch-string-nulls.C: New test. * g++.dg/pch/pch-string-nulls.Hs: New test. --- libcpp/include/cpplib.h | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'libcpp/include/cpplib.h') diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h index d5ef12a..1d34c00 100644 --- a/libcpp/include/cpplib.h +++ b/libcpp/include/cpplib.h @@ -179,7 +179,11 @@ enum c_lang {CLK_GNUC89 = 0, CLK_GNUC99, CLK_GNUC11, CLK_GNUC17, CLK_GNUC2X, /* Payload of a NUMBER, STRING, CHAR or COMMENT token. */ struct GTY(()) cpp_string { unsigned int len; - const unsigned char *text; + + /* TEXT is always null terminated (terminator not included in len); but this + GTY markup arranges that PCH streaming works properly even if there is a + null byte in the middle of the string. */ + const unsigned char * GTY((string_length ("1 + %h.len"))) text; }; /* Flags for the cpp_token structure. */ -- cgit v1.1