GCC port for eBPF

This patch series introduces a port of GCC to eBPF, which is a virtual
machine that resides in the Linux kernel.  Initially intended for
user-level packet capture and filtering, eBPF is nowadays generalized
to serve as a general-purpose infrastructure also for non-networking
purposes.

The binutils support is already upstream.  See
https://sourceware.org/ml/binutils/2019-05/msg00306.html.

ChangeLog:

	* MAINTAINERS: Add myself as the maintainer of the eBPF port.
	Remove myself from Write After Approval section.
	* configure.ac: Support for bpf-*-* targets.
	* configure: Regenerate.

contrib/ChangeLog:

	* config-list.mk (LIST): Disable go in bpf-*-* targets.

gcc/ChangeLog:

	* doc/invoke.texi (Option Summary): Cover eBPF.
	(eBPF Options): New section.
	* doc/extend.texi (BPF Built-in Functions): Likewise.
	(BPF Kernel Helpers): Likewise.
	* config.gcc: Support for bpf-*-* targets.
	* common/config/bpf/bpf-common.c: New file.
	* config/bpf/t-bpf: Likewise.
	* config/bpf/predicates.md: Likewise.
	* config/bpf/constraints.md: Likewise.
	* config/bpf/bpf.opt: Likewise.
	* config/bpf/bpf.md: Likewise.
	* config/bpf/bpf.h: Likewise.
	* config/bpf/bpf.c: Likewise.
	* config/bpf/bpf-protos.h: Likewise.
	* config/bpf/bpf-opts.h: Likewise.
	* config/bpf/bpf-helpers.h: Likewise.
	* config/bpf/bpf-helpers.def: Likewise.

gcc/testsuite/ChangeLog:

	* gcc.dg/builtins-config.h: eBPF doesn't support C99 standard
	functions.
	* gcc.c-torture/compile/20101217-1.c: Add a function prototype for
	printf.
	* gcc.c-torture/compile/20000211-1.c: Skip if target bpf-*-*.
	* gcc.c-torture/compile/poor.c: Likewise.
	* gcc.c-torture/compile/pr25311.c: Likewise.
	* gcc.c-torture/compile/pr39928-1.c: Likewise.
	* gcc.c-torture/compile/pr70061.c: Likewise.
	* gcc.c-torture/compile/920501-7.c: Likewise.
	* gcc.c-torture/compile/20000403-1.c: Likewise.
	* gcc.c-torture/compile/20001226-1.c: Likewise.
	* gcc.c-torture/compile/20030903-1.c: Likewise.
	* gcc.c-torture/compile/20031125-1.c: Likewise.
	* gcc.c-torture/compile/20040101-1.c: Likewise.
	* gcc.c-torture/compile/20040317-2.c: Likewise.
	* gcc.c-torture/compile/20040726-1.c: Likewise.
	* gcc.c-torture/compile/20051216-1.c: Likewise.
	* gcc.c-torture/compile/900313-1.c: Likewise.
	* gcc.c-torture/compile/920625-1.c: Likewise.
	* gcc.c-torture/compile/930421-1.c: Likewise.
	* gcc.c-torture/compile/930623-1.c: Likewise.
	* gcc.c-torture/compile/961004-1.c: Likewise.
	* gcc.c-torture/compile/980504-1.c: Likewise.
	* gcc.c-torture/compile/980816-1.c: Likewise.
	* gcc.c-torture/compile/990625-1.c: Likewise.
	* gcc.c-torture/compile/DFcmp.c: Likewise.
	* gcc.c-torture/compile/HIcmp.c: Likewise.
	* gcc.c-torture/compile/HIset.c: Likewise.
	* gcc.c-torture/compile/QIcmp.c: Likewise.
	* gcc.c-torture/compile/QIset.c: Likewise.
	* gcc.c-torture/compile/SFset.c: Likewise.
	* gcc.c-torture/compile/SIcmp.c: Likewise.
	* gcc.c-torture/compile/SIset.c: Likewise.
	* gcc.c-torture/compile/UHIcmp.c: Likewise.
	* gcc.c-torture/compile/UQIcmp.c: Likewise.
	* gcc.c-torture/compile/USIcmp.c: Likewise.
	* gcc.c-torture/compile/consec.c: Likewise.
	* gcc.c-torture/compile/limits-fndefn.c: Likewise.
	* gcc.c-torture/compile/lll.c: Likewise.
	* gcc.c-torture/compile/parms.c: Likewise.
	* gcc.c-torture/compile/pass.c: Likewise.
	* gcc.c-torture/compile/pp.c: Likewise.
	* gcc.c-torture/compile/pr32399.c: Likewise.
	* gcc.c-torture/compile/pr34091.c: Likewise.
	* gcc.c-torture/compile/pr34688.c: Likewise.
	* gcc.c-torture/compile/pr37258.c: Likewise.
	* gcc.c-torture/compile/pr37327.c: Likewise.
	* gcc.c-torture/compile/pr37381.c: Likewise.
	* gcc.c-torture/compile/pr37669-2.c: Likewise.
	* gcc.c-torture/compile/pr37669.c: Likewise.
	* gcc.c-torture/compile/pr37742-3.c: Likewise.
	* gcc.c-torture/compile/pr44063.c: Likewise.
	* gcc.c-torture/compile/pr48596.c: Likewise.
	* gcc.c-torture/compile/pr51856.c: Likewise.
	* gcc.c-torture/compile/pr54428.c: Likewise.
	* gcc.c-torture/compile/pr54713-1.c: Likewise.
	* gcc.c-torture/compile/pr54713-2.c: Likewise.
	* gcc.c-torture/compile/pr54713-3.c: Likewise.
	* gcc.c-torture/compile/pr55921.c: Likewise.
	* gcc.c-torture/compile/pr70240.c: Likewise.
	* gcc.c-torture/compile/pr70355.c: Likewise.
	* gcc.c-torture/compile/pr82052.c: Likewise.
	* gcc.c-torture/compile/pr83487.c: Likewise.
	* gcc.c-torture/compile/pr86122.c: Likewise.
	* gcc.c-torture/compile/pret-arg.c: Likewise.
	* gcc.c-torture/compile/regs-arg-size.c: Likewise.
	* gcc.c-torture/compile/structret.c: Likewise.
	* gcc.c-torture/compile/uuarg.c: Likewise.
	* gcc.dg/20001009-1.c: Likewise.
	* gcc.dg/20020418-1.c: Likewise.
	* gcc.dg/20020426-2.c: Likewise.
	* gcc.dg/20020430-1.c: Likewise.
	* gcc.dg/20040306-1.c: Likewise.
	* gcc.dg/20040622-2.c: Likewise.
	* gcc.dg/20050603-2.c: Likewise.
	* gcc.dg/20050629-1.c: Likewise.
	* gcc.dg/20061026.c: Likewise.
	* gcc.dg/Warray-bounds-3.c: Likewise.
	* gcc.dg/Warray-bounds-30.c: Likewise.
	* gcc.dg/Wframe-larger-than-2.c: Likewise.
	* gcc.dg/Wframe-larger-than.c: Likewise.
	* gcc.dg/Wrestrict-11.c: Likewise.
	* gcc.c-torture/compile/20000804-1.c: Likewise.
	* lib/target-supports.exp (check_effective_target_trampolines):
	Adapt to eBPF.
	(check_effective_target_indirect_jumps): Likewise.
	(check_effective_target_nonlocal_goto): Likewise.
	(check_effective_target_global_constructor): Likewise.
	(check_effective_target_return_address): Likewise.
	* gcc.target/bpf/bpf.exp: New file.
	* gcc.target/bpf/builtin-load.c: Likewise.
	* cc.target/bpf/constant-calls.c: Likewise.
	* gcc.target/bpf/diag-funargs.c: Likewise.
	* gcc.target/bpf/diag-funargs-2.c: Likewise.
	* gcc.target/bpf/diag-funargs-3.c: Likewise.
	* gcc.target/bpf/diag-indcalls.c: Likewise.
	* gcc.target/bpf/helper-bind.c: Likewise.
	* gcc.target/bpf/helper-bpf-redirect.c: Likewise.
	* gcc.target/bpf/helper-clone-redirect.c: Likewise.
	* gcc.target/bpf/helper-csum-diff.c: Likewise.
	* gcc.target/bpf/helper-csum-update.c: Likewise.
	* gcc.target/bpf/helper-current-task-under-cgroup.c: Likewise.
	* gcc.target/bpf/helper-fib-lookup.c: Likewise.
	* gcc.target/bpf/helper-get-cgroup-classid.c: Likewise.
	* gcc.target/bpf/helper-get-current-cgroup-id.c: Likewise.
	* gcc.target/bpf/helper-get-current-comm.c: Likewise.
	* gcc.target/bpf/helper-get-current-pid-tgid.c: Likewise.
	* gcc.target/bpf/helper-get-current-task.c: Likewise.
	* gcc.target/bpf/helper-get-current-uid-gid.c: Likewise.
	* gcc.target/bpf/helper-get-hash-recalc.c: Likewise.
	* gcc.target/bpf/helper-get-listener-sock.c: Likewise.
	* gcc.target/bpf/helper-get-local-storage.c: Likewise.
	* gcc.target/bpf/helper-get-numa-node-id.c: Likewise.
	* gcc.target/bpf/helper-get-prandom-u32.c: Likewise.
	* gcc.target/bpf/helper-get-route-realm.c: Likewise.
	* gcc.target/bpf/helper-get-smp-processor-id.c: Likewise.
	* gcc.target/bpf/helper-get-socket-cookie.c: Likewise.
	* gcc.target/bpf/helper-get-socket-uid.c: Likewise.
	* gcc.target/bpf/helper-getsockopt.c: Likewise.
	* gcc.target/bpf/helper-get-stack.c: Likewise.
	* gcc.target/bpf/helper-get-stackid.c: Likewise.
	* gcc.target/bpf/helper-ktime-get-ns.c: Likewise.
	* gcc.target/bpf/helper-l3-csum-replace.c: Likewise.
	* gcc.target/bpf/helper-l4-csum-replace.c: Likewise.
	* gcc.target/bpf/helper-lwt-push-encap.c: Likewise.
	* gcc.target/bpf/helper-lwt-seg6-action.c: Likewise.
	* gcc.target/bpf/helper-lwt-seg6-adjust-srh.c: Likewise.
	* gcc.target/bpf/helper-lwt-seg6-store-bytes.c: Likewise.
	* gcc.target/bpf/helper-map-delete-elem.c: Likewise.
	* gcc.target/bpf/helper-map-lookup-elem.c: Likewise.
	* gcc.target/bpf/helper-map-peek-elem.c: Likewise.
	* gcc.target/bpf/helper-map-pop-elem.c: Likewise.
	* gcc.target/bpf/helper-map-push-elem.c: Likewise.
	* gcc.target/bpf/helper-map-update-elem.c: Likewise.
	* gcc.target/bpf/helper-msg-apply-bytes.c: Likewise.
	* gcc.target/bpf/helper-msg-cork-bytes.c: Likewise.
	* gcc.target/bpf/helper-msg-pop-data.c: Likewise.
	* gcc.target/bpf/helper-msg-pull-data.c: Likewise.
	* gcc.target/bpf/helper-msg-push-data.c: Likewise.
	* gcc.target/bpf/helper-msg-redirect-hash.c: Likewise.
	* gcc.target/bpf/helper-msg-redirect-map.c: Likewise.
	* gcc.target/bpf/helper-override-return.c: Likewise.
	* gcc.target/bpf/helper-perf-event-output.c: Likewise.
	* gcc.target/bpf/helper-perf-event-read.c: Likewise.
	* gcc.target/bpf/helper-perf-event-read-value.c: Likewise.
	* gcc.target/bpf/helper-perf-prog-read-value.c: Likewise.
	* gcc.target/bpf/helper-probe-read.c: Likewise.
	* gcc.target/bpf/helper-probe-read-str.c: Likewise.
	* gcc.target/bpf/helper-probe-write-user.c: Likewise.
	* gcc.target/bpf/helper-rc-keydown.c: Likewise.
	* gcc.target/bpf/helper-rc-pointer-rel.c: Likewise.
	* gcc.target/bpf/helper-rc-repeat.c: Likewise.
	* gcc.target/bpf/helper-redirect-map.c: Likewise.
	* gcc.target/bpf/helper-set-hash.c: Likewise.
	* gcc.target/bpf/helper-set-hash-invalid.c: Likewise.
	* gcc.target/bpf/helper-setsockopt.c: Likewise.
	* gcc.target/bpf/helper-skb-adjust-room.c: Likewise.
	* gcc.target/bpf/helper-skb-cgroup-id.c: Likewise.
	* gcc.target/bpf/helper-skb-change-head.c: Likewise.
	* gcc.target/bpf/helper-skb-change-proto.c: Likewise.
	* gcc.target/bpf/helper-skb-change-tail.c: Likewise.
	* gcc.target/bpf/helper-skb-change-type.c: Likewise.
	* gcc.target/bpf/helper-skb-ecn-set-ce.c: Likewise.
	* gcc.target/bpf/helper-skb-get-tunnel-key.c: Likewise.
	* gcc.target/bpf/helper-skb-get-tunnel-opt.c: Likewise.
	* gcc.target/bpf/helper-skb-get-xfrm-state.c: Likewise.
	* gcc.target/bpf/helper-skb-load-bytes.c: Likewise.
	* gcc.target/bpf/helper-skb-load-bytes-relative.c: Likewise.
	* gcc.target/bpf/helper-skb-pull-data.c: Likewise.
	* gcc.target/bpf/helper-skb-set-tunnel-key.c: Likewise.
	* gcc.target/bpf/helper-skb-set-tunnel-opt.c: Likewise.
	* gcc.target/bpf/helper-skb-store-bytes.c: Likewise.
	* gcc.target/bpf/helper-skb-under-cgroup.c: Likewise.
	* gcc.target/bpf/helper-skb-vlan-pop.c: Likewise.
	* gcc.target/bpf/helper-skb-vlan-push.c: Likewise.
	* gcc.target/bpf/helper-skc-lookup-tcp.c: Likewise.
	* gcc.target/bpf/helper-sk-fullsock.c: Likewise.
	* gcc.target/bpf/helper-sk-lookup-tcp.c: Likewise.
	* gcc.target/bpf/helper-sk-lookup-upd.c: Likewise.
	* gcc.target/bpf/helper-sk-redirect-hash.c: Likewise.
	* gcc.target/bpf/helper-sk-redirect-map.c: Likewise.
	* gcc.target/bpf/helper-sk-release.c: Likewise.
	* gcc.target/bpf/helper-sk-select-reuseport.c: Likewise.
	* gcc.target/bpf/helper-sk-storage-delete.c: Likewise.
	* gcc.target/bpf/helper-sk-storage-get.c: Likewise.
	* gcc.target/bpf/helper-sock-hash-update.c: Likewise.
	* gcc.target/bpf/helper-sock-map-update.c: Likewise.
	* gcc.target/bpf/helper-sock-ops-cb-flags-set.c: Likewise.
	* gcc.target/bpf/helper-spin-lock.c: Likewise.
	* gcc.target/bpf/helper-spin-unlock.c: Likewise.
	* gcc.target/bpf/helper-strtol.c: Likewise.
	* gcc.target/bpf/helper-strtoul.c: Likewise.
	* gcc.target/bpf/helper-sysctl-get-current-value.c: Likewise.
	* gcc.target/bpf/helper-sysctl-get-name.c: Likewise.
	* gcc.target/bpf/helper-sysctl-get-new-value.c: Likewise.
	* gcc.target/bpf/helper-sysctl-set-new-value.c: Likewise.
	* gcc.target/bpf/helper-tail-call.c: Likewise.
	* gcc.target/bpf/helper-tcp-check-syncookie.c: Likewise.
	* gcc.target/bpf/helper-tcp-sock.c: Likewise.
	* gcc.target/bpf/helper-trace-printk.c: Likewise.
	* gcc.target/bpf/helper-xdp-adjust-head.c: Likewise.
	* gcc.target/bpf/helper-xdp-adjust-meta.c: Likewise.
	* gcc.target/bpf/helper-xdp-adjust-tail.c: Likewise.
	* gcc.target/bpf/skb-ancestor-cgroup-id.c: Likewise.
	* gcc.target/bpf/sync-fetch-and-add.c: Likewise.

libgcc/ChangeLog:

	* config.host: Set cpu_type for bpf-*-* targets.
	* config/bpf/t-bpf: Likewise.
	* config/bpf/crtn.S: Likewise.
	* config/bpf/crti.S: New file.

From-SVN: r275506

1 files changed, 539 insertions, 0 deletions

diff --git a/gcc/config/bpf/bpf.h b/gcc/config/bpf/bpf.h
new file mode 100644
index 0000000..70ad818
--- /dev/null
+++ b/gcc/config/bpf/bpf.h
@@ -0,0 +1,539 @@
+/* Definition of the eBPF target for GCC.
+   Copyright (C) 2019 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/>.  */
+
+#ifndef GCC_BPF_H
+#define GCC_BPF_H
+
+/**** Controlling the Compilation Driver.  */
+
+#define ASM_SPEC "%{mbig-endian:-EB} %{!mbig-endian:-EL}"
+#define LINK_SPEC "%{mbig-endian:-EB} %{!mbig-endian:-EL}"
+#define LIB_SPEC ""
+#define STARTFILE_SPEC ""
+
+/**** Run-time Target Specification.  */
+
+#define TARGET_CPU_CPP_BUILTINS() bpf_target_macros (pfile)
+
+/**** Storage Layout.  */
+
+/* Endianness and word size.  */
+#define BITS_BIG_ENDIAN 0
+#define BYTES_BIG_ENDIAN (TARGET_BIG_ENDIAN)
+#define WORDS_BIG_ENDIAN (TARGET_BIG_ENDIAN)
+#define BITS_PER_WORD 64
+#define UNITS_PER_WORD 8
+
+/* When storing an integer whose size is less than 64-bit in a
+   register, promote it to a DImode.  */
+#define PROMOTE_MODE(M, UNSIGNEDP, TYPE)	\
+  do						\
+    {						\
+      if (GET_MODE_CLASS (M) == MODE_INT	\
+	  && GET_MODE_SIZE (M) < 8)		\
+	M = DImode;				\
+    } while (0)
+
+/* Biggest alignment supported by the object file format of this
+   machine.  In this case this is ELF.  Use the same definition than
+   in elfos.h */
+#define MAX_OFILE_ALIGNMENT (((unsigned int) 1 << 28) * 8)
+
+/* Align argument parameters on the stack to 64-bit, at a minimum.  */
+#define PARM_BOUNDARY 64
+
+/* The hardware enforces that the stack pointer should be aligned to
+   64-bit at any time.  */
+#define STACK_BOUNDARY 64
+
+/* Function entry points are aligned to 128 bits.  */
+#define FUNCTION_BOUNDARY 128
+
+/* Maximum alignment required by data of any type.  */
+#define BIGGEST_ALIGNMENT 64
+
+/* The best alignment to use in cases where we have a choice.  */
+#define FASTEST_ALIGNMENT 64
+
+/* Use a fast alignment when storing arrays of chars in a local.  */
+#define LOCAL_ALIGNMENT(TYPE, ALIGN)					\
+  (TREE_CODE (TYPE) == ARRAY_TYPE					\
+   && TYPE_MODE (TREE_TYPE (TYPE)) == QImode				\
+   && (ALIGN) < FASTEST_ALIGNMENT ? FASTEST_ALIGNMENT : (ALIGN))
+
+/* The load and store instructions won't work if the data is not in
+   it's expected alignment.  */
+#define STRICT_ALIGNMENT 1
+
+/* We use Pmode as the mode of the size increment operand in an
+   `allocate_stack' pattern.  */
+#define STACK_SIZE_MODE Pmode
+
+/**** Layout of Source Language Data Types.  */
+
+#define INT_TYPE_SIZE         32
+#define SHORT_TYPE_SIZE       16
+#define LONG_TYPE_SIZE        64
+#define LONG_LONG_TYPE_SIZE   64
+#define CHAR_TYPE_SIZE         8
+#define FLOAT_TYPE_SIZE       32
+#define DOUBLE_TYPE_SIZE      64
+#define LONG_DOUBLE_TYPE_SIZE 64
+
+#define INTPTR_TYPE	"long int"
+#define UINTPTR_TYPE	"long unsigned int"
+#define SIZE_TYPE	"long unsigned int"
+#define PTRDIFF_TYPE "long int"
+
+#define SIG_ATOMIC_TYPE "char"
+
+#define INT8_TYPE "char"
+#define INT16_TYPE "short int"
+#define INT32_TYPE "int"
+#define INT64_TYPE "long int"
+#define UINT8_TYPE "unsigned char"
+#define UINT16_TYPE "short unsigned int"
+#define UINT32_TYPE "unsigned int"
+#define UINT64_TYPE "long unsigned int"
+
+#define INT_LEAST8_TYPE INT8_TYPE
+#define INT_LEAST16_TYPE INT16_TYPE
+#define INT_LEAST32_TYPE INT32_TYPE
+#define INT_LEAST64_TYPE INT64_TYPE
+#define UINT_LEAST8_TYPE UINT8_TYPE
+#define UINT_LEAST16_TYPE UINT16_TYPE
+#define UINT_LEAST32_TYPE UINT32_TYPE
+#define UINT_LEAST64_TYPE UINT64_TYPE
+
+#define INT_FAST8_TYPE INT8_TYPE
+#define INT_FAST16_TYPE INT16_TYPE
+#define INT_FAST32_TYPE INT32_TYPE
+#define INT_FAST64_TYPE INT64_TYPE
+#define UINT_FAST8_TYPE UINT8_TYPE
+#define UINT_FAST16_TYPE UINT16_TYPE
+#define UINT_FAST32_TYPE UINT32_TYPE
+#define UINT_FAST64_TYPE UINT64_TYPE
+
+/* `char' is signed by default, like in x86.  */
+#define DEFAULT_SIGNED_CHAR 1
+
+/* `wchar_t' is a signed 32-bit type.  The second constant is used by
+   cpp, which can't use WCHAR_TYPE.  */
+#define WCHAR_TYPE "int"
+#define WCHAR_TYPE_SIZE 32
+
+/* `wint_t' is a signed 32-bit type.  */
+#define WINT_TYPE "int"
+#define WINT_TYPE_SIZE 32
+
+/**** Register Usage.  */
+
+/*** Basic Characteristics of Registers.  */
+
+#define BPF_R0	0
+#define BPF_R1	1
+#define BPF_R2	2
+#define BPF_R3	3
+#define BPF_R4	4
+#define BPF_R5	5
+#define BPF_R6	6
+#define BPF_CTX BPF_R6
+#define BPF_R7	7
+#define BPF_R8	8
+#define BPF_R9	9
+#define BPF_SP BPF_R9
+#define BPF_R10	10
+#define BPF_FP  BPF_R10
+/* 11 is not a real eBPF hard register and is eliminated or not used
+   in the final assembler.  See below.  */
+
+#define FIRST_PSEUDO_REGISTER 12
+
+/* The registers %r0..%r8 are available for general allocation.
+   %r9 is the pseudo-stack pointer.
+   %r10 is the stack frame, which is read-only.
+   %r11 (__arg__) is a fake register that always gets eliminated.  */
+#define FIXED_REGISTERS				\
+  {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1}
+
+/* %r0..%r5 are clobbered by function calls.  */
+#define CALL_USED_REGISTERS				\
+  {1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1}
+
+/**** Register Classes.  */
+
+enum reg_class
+{
+  NO_REGS,		/* no registers in set.  */
+  ALL_REGS,		/* all registers.  */
+  LIM_REG_CLASSES	/* max value + 1.  */
+};
+
+#define N_REG_CLASSES (int) LIM_REG_CLASSES
+#define GENERAL_REGS ALL_REGS
+
+/* An initializer containing the names of the register classes as C
+   string constants.  These names are used in writing some of the
+   debugging dumps.  */
+#define REG_CLASS_NAMES				\
+{						\
+  "NO_REGS",					\
+  "ALL_REGS"					\
+}
+
+/* An initializer containing the contents of the register classes, as
+   integers which are bit masks.  The Nth integer specifies the
+   contents of class N.  The way the integer MASK is interpreted is
+   that register R is in the class if `MASK & (1 << R)' is 1.
+
+   In eBPF all the hard registers are considered general-purpose
+   integer registers.  */
+#define REG_CLASS_CONTENTS			\
+{						\
+   0x00000000, /* NO_REGS */			\
+   0x00000fff, /* ALL_REGS */		        \
+}
+
+/* A C expression whose value is a register class containing hard
+   register REGNO.  In general there is more that one such class;
+   choose a class which is "minimal", meaning that no smaller class
+   also contains the register.  */
+#define REGNO_REG_CLASS(REGNO) GENERAL_REGS
+
+/* A macro whose definition is the name of the class to which a
+   valid base register must belong.  A base register is one used in
+   an address which is the register value plus a displacement.  */
+#define BASE_REG_CLASS GENERAL_REGS
+
+/* A macro whose definition is the name of the class to which a
+   valid index register must belong.  An index register is one used
+   in an address where its value is either multiplied by a scale
+   factor or added to another register (as well as added to a
+   displacement).  */
+#define INDEX_REG_CLASS NO_REGS
+
+/* C expression which is nonzero if register number REGNO is suitable
+   for use as a base register in operand addresses.  In eBPF every
+   hard register can be used for this purpose.  */
+#define REGNO_OK_FOR_BASE_P(REGNO) 			\
+  ((REGNO) < FIRST_PSEUDO_REGISTER)
+
+/* C expression which is nonzero if register number REGNO is suitable
+   for use as an index register in operand addresses.  */
+#define REGNO_OK_FOR_INDEX_P(REGNO) false
+
+/**** Debugging Info ****/
+
+/* We cannot support DWARF2 because of the limitations of eBPF.  */
+#define DBX_DEBUGGING_INFO
+
+/**** Stack Layout and Calling Conventions.  */
+
+/*** Basic Stack Layout.  */
+
+#define STACK_GROWS_DOWNWARD 1
+#define FRAME_GROWS_DOWNWARD 1
+
+/* The argument pointer always points to the first argument.  */
+#define FIRST_PARM_OFFSET(FNDECL) 0
+
+/* Unsupported.  */
+#define RETURN_ADDR_RTX(count, frame) const0_rtx
+
+/*** Registers That Address the Stack Frame.  */
+
+#define FRAME_POINTER_REGNUM 10
+#define STACK_POINTER_REGNUM 9
+#define ARG_POINTER_REGNUM 11
+#define STATIC_CHAIN_REGNUM 8
+
+/*** Registers elimination.  */
+
+#define ELIMINABLE_REGS					\
+  {{ ARG_POINTER_REGNUM, FRAME_POINTER_REGNUM },	\
+   { ARG_POINTER_REGNUM, STACK_POINTER_REGNUM }}
+
+/* Define the offset between two registers, one to be eliminated, and
+   the other its replacement, at the start of a routine.  */
+#define INITIAL_ELIMINATION_OFFSET(FROM, TO, OFFSET)		\
+  do								\
+    {								\
+      (OFFSET) = bpf_initial_elimination_offset ((FROM), (TO));	\
+    } while (0)
+
+/*** Passing Function Arguments on the Stack.  */
+
+/* The eBPF ABI doesn't support passing arguments on the stack.  Only
+   in the first five registers.  Code in bpf.c assures the stack is
+   never used when passing arguments.  However, we still have to
+   define the constants below.  */
+
+/* If nonzero, push insns will be used to pass outgoing arguments.  */
+#define PUSH_ARGS 0
+
+/* If nonzero, function arguments will be evaluated from last to
+   first, rather than from first to last.  */
+#define PUSH_ARGS_REVERSED 1
+
+/* Allocate stack space for arguments at the beginning of each
+   function.  */
+#define ACCUMULATE_OUTGOING_ARGS 1
+
+/*** Passing Arguments in Registers.  */
+
+/* Use an integer in order to keep track of the number of arguments
+   passed to a function in integer registers, up to
+   MAX_ARGS_IN_REGISTERS.  */
+#define CUMULATIVE_ARGS int
+
+/* INIT_CUMULATIVE_ARGS initializes a variable CUM of type
+   CUMULATIVE_ARGS for a call to a function whose data type is FNTYPE.
+   For a library call, FNTYPE is 0.  */
+#define INIT_CUMULATIVE_ARGS(CUM,FNTYPE,LIBNAME,FNDECL,N_NAMED_ARGS) \
+  memset (&(CUM), 0, sizeof (CUM))
+
+/* Nonzero if N is the number of a hard register in which function
+   arguments are sometimes passed.  */
+#define FUNCTION_ARG_REGNO_P(N) ((N) >= 1 && (N) <= 5)
+
+/*** How Scalar Function Values are Returned.  */
+
+/* Define how to find the value returned by a library function
+   assuming the value has mode MODE.  This is always %r0 for eBPF.  */
+#define LIBCALL_VALUE(MODE)  \
+  gen_rtx_REG ((MODE), 0)
+
+/*** Generating Code for Profiling.  */
+
+/* We do not support profiling yet, so do not call `mcount'.  */
+#define FUNCTION_PROFILER(FILE, LABELNO) do { } while (0)
+
+/*** Function Entry and Exit.  */
+
+/* We do not require an accurate stack pointer at function return.
+   This is because the stack pointer's original value is initialized
+   from the frame pointer, rather than decreased, to satisfy the
+   kernel's verifier.  Thus, we have to save the stack pointer in
+   function prologue and restore it in function epilogue.  If
+   EXIT_IGNORE_STACK is not set, then superfluous instructions are
+   generated to save and restore the stack pointer after and before
+   the function epilogue, respectively.  */
+#define EXIT_IGNORE_STACK 1
+
+/**** Support for Nested Functions.  */
+
+/* We have to define TRAMPOLINE_SIZE even if we don't ever generate
+   them.  Set to 64 arbitrarily.  */
+#define TRAMPOLINE_SIZE 64
+
+/**** Addressing Modes.  */
+
+/* Maximum number of registers that can appear in a valid memory
+   address.  */
+#define MAX_REGS_PER_ADDRESS 1
+
+/* 1 if X is an rtx for a constant that is a valid address.  */
+
+#define CONSTANT_ADDRESS_P(X) 0
+
+/**** Describing Relative Costs of Operations.  */
+
+/* Cost of a branch instruction.  A value of 1 is the default.  */
+#define BRANCH_COST(SPEED_P,PREDICTABLE_P) 1
+
+/* The SPARC port says: Nonzero if access to memory by bytes is slow
+   and undesirable.  For RISC chips, it means that access to memory by
+   bytes is no better than access by words when possible, so grab a
+   whole word and maybe make use of that.  */
+#define SLOW_BYTE_ACCESS 1
+
+/* Threshold of number of scalar memory-to-memory move instructions,
+   _below_ which a sequence of insns should be generated instead of a
+   string move insn or a library call.  */
+#define MOVE_RATIO(speed) 128
+
+/* Threshold of number of scalar move instructions, _below_ which a
+   sequence of insns should be generated to clear memory instead of a
+   string clear insn or a library call.  */
+#define CLEAR_RATIO(speed) 128
+
+/* Threshold of number of scalar move instructions, _below_ which a
+   sequence of insns should be generated to set memory to a constant
+   value, instead of a block set insn or a library call.  */
+#define SET_RATIO(speed) 128
+
+/* True if it is as good or better to call a constant function address
+   than to call an address kept in a register.  */
+#define NO_FUNCTION_CSE 1
+
+/**** Dividing the Output into Sections.  */
+
+#define TEXT_SECTION_ASM_OP "\t.text"
+#define DATA_SECTION_ASM_OP "\t.data"
+#define BSS_SECTION_ASM_OP "\t.bss"
+#define COMMON_ASM_OP "\t.common\t"
+
+/**** Defining the Output Assembler Language.  */
+
+/*** The Overall Framework of an Assembler File.  */
+
+#define ASM_COMMENT_START ";"
+
+/* Output to assembler file text saying following lines
+   may contain character constants, extra white space, comments, etc.  */
+
+#ifndef ASM_APP_ON
+#define ASM_APP_ON " #APP\n"
+#endif
+
+/* Output to assembler file text saying following lines
+   no longer contain unusual constructs.  */
+
+#ifndef ASM_APP_OFF
+#define ASM_APP_OFF " #NO_APP\n"
+#endif
+
+/*** Output of Data.  */
+
+/*** Output of Uninitialized Variables.  */
+
+/* How to output an assembler line to define a local common
+   symbol.  */
+
+#define ASM_OUTPUT_ALIGNED_COMMON(FILE, NAME, SIZE, ALIGN)		\
+  do									\
+    {									\
+      fprintf ((FILE), "%s", COMMON_ASM_OP);				\
+      assemble_name ((FILE), (NAME));					\
+      fprintf ((FILE), ",%u,%u\n", (int)(SIZE), (ALIGN) / (BITS_PER_UNIT)); \
+    }									\
+  while (0)
+
+/* A C statement (sans semicolon) to output to the stdio stream
+   FILE the assembler definition of uninitialized global DECL named
+   NAME whose size is SIZE bytes and alignment is ALIGN bytes.
+   Try to use asm_output_aligned_bss to implement this macro.  */
+
+#define ASM_OUTPUT_ALIGNED_BSS(FILE, DECL, NAME, SIZE, ALIGN)	\
+  do {								\
+    ASM_OUTPUT_ALIGNED_LOCAL (FILE, NAME, SIZE, ALIGN);		\
+  } while (0)
+
+/* This says how to output an assembler line to define a local common
+   symbol.  */
+
+#define ASM_OUTPUT_ALIGNED_LOCAL(FILE,NAME,SIZE,ALIGN)			\
+  ( fputs ("\t.lcomm ", (FILE)),					\
+    assemble_name ((FILE), (NAME)),					\
+    fprintf ((FILE), "," HOST_WIDE_INT_PRINT_UNSIGNED "\n",		\
+	     (SIZE), ((ALIGN) / BITS_PER_UNIT)))
+
+/*** Output and Generation of Labels.  */
+
+/* Globalizing directive for a label.  */
+#define GLOBAL_ASM_OP "\t.global\t"
+
+/* This is how to store into the string LABEL
+   the symbol_ref name of an internal numbered label where
+   PREFIX is the class of label and NUM is the number within the class.
+   This is suitable for output with `assemble_name'.  */
+
+#undef ASM_GENERATE_INTERNAL_LABEL
+#define ASM_GENERATE_INTERNAL_LABEL(LABEL,PREFIX,NUM)			\
+  sprintf ((LABEL), "*%s%s%ld", (LOCAL_LABEL_PREFIX), (PREFIX), (long)(NUM))
+
+/*** Macros Controlling Initialization Routines.  */
+
+#define INIT_SECTION_ASM_OP "\t.init"
+#define FINI_SECTION_ASM_OP "\t.fini"
+
+/*** Output of Assembler Instructions.  */
+
+#define REGISTER_NAMES						\
+  { "%r0", "%r1", "%r2", "%r3", "%r4", "%r5", "%r6", "%r7",	\
+    "%r8", "%r9", "%fp", "__arg__" }
+
+#define ADDITIONAL_REGISTER_NAMES		\
+  { { "%a", 0 }, { "%ctx", 6 }, { "%r10" , 10 } }
+
+#define LOCAL_LABEL_PREFIX "."
+#define USER_LABEL_PREFIX  ""
+
+#define PRINT_OPERAND(STREAM,X,CODE)		\
+  bpf_print_operand ((STREAM),(X),(CODE))
+
+#define PRINT_OPERAND_ADDRESS(STREAM,X)		\
+  bpf_print_operand_address ((STREAM), (X))
+
+/*** Assembler Commands for Alignment.  */
+
+/* This is how to output an assembler line that says to advance the
+   location counter to a multiple of 2**LOG bytes.  */
+#define ASM_OUTPUT_ALIGN(STREAM,LOG)		\
+  fprintf (STREAM, "\t.align\t%d\n", (LOG))
+
+/* This is how to output an assembler line
+   that says to advance the location counter by SIZE bytes.  */
+#define ASM_OUTPUT_SKIP(FILE,SIZE)		\
+  fprintf (FILE, "\t.skip\t" HOST_WIDE_INT_PRINT_UNSIGNED "\n", (SIZE))
+
+/**** Miscellaneous Parameters.  */
+
+/* Specify the machine mode that this machine uses for the index in
+   the tablejump instruction.  */
+#define CASE_VECTOR_MODE DImode
+
+/* Define if operations between registers with integral mode smaller
+   than a word are always performed on the entire register.  */
+#define WORD_REGISTER_OPERATIONS 1
+
+/* C expression indicating when insns that read memory in MEM_MODE, an
+   integral mode narrower than a word, set the bits outsize of
+   MEM_MODE to be either the sign-extension or the zero-extension of
+   the data read.  */
+#define LOAD_EXTEND_OP(MODE) ZERO_EXTEND
+
+/* The maximum number of bytes that a single instruction can move
+   quickly between memory and registers or between two memory
+   locations.  */
+#define MOVE_MAX 8
+
+/* An alias for the machine mode for pointers.  */
+#define Pmode DImode
+
+/* An alias for the machine mode used for memory references to
+   functions being called, in 'call' RTL expressions.  */
+#define FUNCTION_MODE Pmode
+
+/* No libm on eBPF (for now.)  */
+#define MATH_LIBRARY ""
+
+/**** libgcc settings.  */
+
+/* Iterating over the global constructors and destructors and
+   executing them requires the ability of doing indirect calls.
+
+   eBPF doesn't support indirect calls, so no chance of supporting
+   constructors and destructors.  */
+#define DO_GLOBAL_CTORS_BODY			\
+  do { } while (0)
+#define DO_GLOBAL_DTORS_BODY			\
+  do { } while (0)
+
+#endif /* ! GCC_BPF_H */