> This patch updates the support for the BPF CO-RE builtins
> __builtin_preserve_access_index and __builtin_preserve_field_info,
> and adds support for the CO-RE builtins __builtin_btf_type_id,
> __builtin_preserve_type_info and __builtin_preserve_enum_value.
>
> These CO-RE relocations are now converted to __builtin_core_reloc which
> abstracts all of the original builtins in a polymorphic relocation
> specific builtin.
>
> The builtin processing is now split in 2 stages, the first (pack) is
> executed right after the front-end and the second (process) right before
> the asm output.
>
> In expand pass the __builtin_core_reloc is converted to a
> unspec:UNSPEC_CORE_RELOC rtx entry.
>
> The data required to process the builtin is now collected in the packing
> stage (after front-end), not allowing the compiler to optimize any of
> the relevant information required to compose the relocation when
> necessary.
> At expansion, that information is recovered and CTF/BTF is queried to
> construct the information that will be used in the relocation.
> At this point the relocation is added to specific section and the
> builtin is expanded to the expected default value for the builtin.
>
> In order to process __builtin_preserve_enum_value, it was necessary to
> hook the front-end to collect the original enum value reference.
> This is needed since the parser folds all the enum values to its
> integer_cst representation.
>
> More details can be found within the core-builtins.cc.
>
> Regtested in host x86_64-linux-gnu and target bpf-unknown-none.
> ---
> gcc/config.gcc | 4 +-
> gcc/config/bpf/bpf-passes.def | 20 -
> gcc/config/bpf/bpf-protos.h | 4 +-
> gcc/config/bpf/bpf.cc | 817 +---------
> gcc/config/bpf/bpf.md | 17 +
> gcc/config/bpf/core-builtins.cc | 1397 +++++++++++++++++
> gcc/config/bpf/core-builtins.h | 36 +
> gcc/config/bpf/coreout.cc | 50 +-
> gcc/config/bpf/coreout.h | 13 +-
> gcc/config/bpf/t-bpf | 6 +-
> gcc/doc/extend.texi | 51 +
> ...core-builtin-fieldinfo-const-elimination.c | 29 +
> 12 files changed, 1639 insertions(+), 805 deletions(-)
> delete mode 100644 gcc/config/bpf/bpf-passes.def
> create mode 100644 gcc/config/bpf/core-builtins.cc
> create mode 100644 gcc/config/bpf/core-builtins.h
> create mode 100644
> gcc/testsuite/gcc.target/bpf/core-builtin-fieldinfo-const-elimination.c
>
> diff --git a/gcc/config.gcc b/gcc/config.gcc
> index eba69a463be0..c521669e78b1 100644
> --- a/gcc/config.gcc
> +++ b/gcc/config.gcc
> @@ -1597,8 +1597,8 @@ bpf-*-*)
> use_collect2=no
> extra_headers="bpf-helpers.h"
> use_gcc_stdint=provide
> - extra_objs="coreout.o"
> - target_gtfiles="$target_gtfiles \$(srcdir)/config/bpf/coreout.cc"
> + extra_objs="coreout.o core-builtins.o"
> + target_gtfiles="$target_gtfiles \$(srcdir)/config/bpf/coreout.cc
> \$(srcdir)/config/bpf/core-builtins.cc"
> ;;
> cris-*-elf | cris-*-none)
> tm_file="elfos.h newlib-stdint.h ${tm_file}"
> diff --git a/gcc/config/bpf/bpf-passes.def b/gcc/config/bpf/bpf-passes.def
> deleted file mode 100644
> index deeaee988a01..000000000000
> --- a/gcc/config/bpf/bpf-passes.def
> +++ /dev/null
> @@ -1,20 +0,0 @@
> -/* Declaration of target-specific passes for eBPF.
> - Copyright (C) 2021-2023 Free Software Foundation, Inc.
> -
> - This file is part of GCC.
> -
> - GCC is free software; you can redistribute it and/or modify it
> - under the terms of the GNU General Public License as published by
> - the Free Software Foundation; either version 3, or (at your option)
> - any later version.
> -
> - GCC is distributed in the hope that it will be useful, but
> - WITHOUT ANY WARRANTY; without even the implied warranty of
> - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> - General Public License for more details.
> -
> - You should have received a copy of the GNU General Public License
> - along with GCC; see the file COPYING3. If not see
> - <http://www.gnu.org/licenses/>. */
> -
> -INSERT_PASS_AFTER (pass_df_initialize_opt, 1, pass_bpf_core_attr);
> diff --git a/gcc/config/bpf/bpf-protos.h b/gcc/config/bpf/bpf-protos.h
> index b484310e8cbf..fbcf5111eb21 100644
> --- a/gcc/config/bpf/bpf-protos.h
> +++ b/gcc/config/bpf/bpf-protos.h
> @@ -30,7 +30,7 @@ extern void bpf_print_operand_address (FILE *, rtx);
> extern void bpf_expand_prologue (void);
> extern void bpf_expand_epilogue (void);
> extern void bpf_expand_cbranch (machine_mode, rtx *);
> -
> -rtl_opt_pass * make_pass_bpf_core_attr (gcc::context *);
> +const char *bpf_add_core_reloc (rtx *operands, const char *templ);
> +void bpf_process_move_operands (rtx *operands);
>
> #endif /* ! GCC_BPF_PROTOS_H */
> diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc
> index b5b5674edbb5..101e994905d2 100644
> --- a/gcc/config/bpf/bpf.cc
> +++ b/gcc/config/bpf/bpf.cc
> @@ -69,10 +69,7 @@ along with GCC; see the file COPYING3. If not see
> #include "gimplify.h"
> #include "gimplify-me.h"
>
> -#include "ctfc.h"
> -#include "btf.h"
> -
> -#include "coreout.h"
> +#include "core-builtins.h"
>
> /* Per-function machine data. */
> struct GTY(()) machine_function
> @@ -174,22 +171,7 @@ static const struct attribute_spec bpf_attribute_table[]
> =
> one. */
> #define BPF_BUILTIN_MAX_ARGS 5
>
> -enum bpf_builtins
> -{
> - BPF_BUILTIN_UNUSED = 0,
> - /* Built-ins for non-generic loads and stores. */
> - BPF_BUILTIN_LOAD_BYTE,
> - BPF_BUILTIN_LOAD_HALF,
> - BPF_BUILTIN_LOAD_WORD,
> -
> - /* Compile Once - Run Everywhere (CO-RE) support. */
> - BPF_BUILTIN_PRESERVE_ACCESS_INDEX,
> - BPF_BUILTIN_PRESERVE_FIELD_INFO,
> -
> - BPF_BUILTIN_MAX,
> -};
> -
> -static GTY (()) tree bpf_builtins[(int) BPF_BUILTIN_MAX];
> +GTY (()) tree bpf_builtins[(int) BPF_BUILTIN_MAX];
>
> void bpf_register_coreattr_pass (void);
>
> @@ -546,6 +528,17 @@ bpf_expand_cbranch (machine_mode mode, rtx *operands)
> }
> }
>
> +/* This is used define_expand "mov<MM:mode>" to verofy if we need to replace
Typo; verofy
> + any of the operands. Currently this is used to replace the
> + __attribute__((preserve_access_index)) by the respective
> __builtin_core_reloc
> + which will at final create the relocation and respective label. */
> +
> +void
> +bpf_process_move_operands (rtx *operands)
> +{
> + bpf_replace_core_move_operands (operands);
> +}
Is this intermediary function really necessary? Just call
bpf_place_core_move_operands from the expand.
> +(define_insn "mov_reloc_core<MM:mode>"
> + [(set (match_operand:MM 0 "nonimmediate_operand" "=r,q,r")
> + (unspec:MM [
> + (match_operand:MM 1 "immediate_operand" " I,I,B")
> + (match_operand:SI 2 "immediate_operand" " I,I,I")
> + ] UNSPEC_CORE_RELOC)
> + )]
> + ""
> + "@
> + *return bpf_add_core_reloc (operands, \"{mov\t%0,%1|%0 = %1}\");
> + *return bpf_add_core_reloc (operands, \"{st<mop>\t%0,%1|*(<smop> *) (%0)
> = %1}\");
> + *return bpf_add_core_reloc (operands, \"{lddw\t%0,%1|%0 = %1 ll}\");"
> + [(set_attr "type" "alu,st,alu")])
> +
I am assuming that this insn only has to implement whatever situations
supported by valid operands and usage of the builtins in any possible
context, right? i.e. it doesn't have to handle all the situations that
"*movMODE" handles. And this is checked by the builtin implementation?
> +struct cr_builtins {
Brace in first column please.
> + /* FIXED: This wat not Ok.
Hm? If that is fixed, do we still need that comment? :)
> + emit_insn ( \
> + gen_mov_reloc_coredi (reg, \
> + gen_rtx_CONST_INT (Pmode, 0), \
> + gen_rtx_CONST_INT (Pmode, index))); \
These backslahes... was that in a macro originally?
> + return true;
> + }
> + }
> + return false;
> +}
