Reverted! Apologies for the mistake.
Jose E. Marchesi writes:
>> Hi Cuper.
>> OK. Thanks for the patch.
>
> This commit is breaking the BPF build, because libgcc emits libcalls to
> __builtin_abort. We need to rethink this.
>
> Please revert:
>
> commit faf5b148588bd7fbb60ec669aefa704044037cdc
> Author: Cupertino Miranda <cupertino.mira...@oracle.com>
> Date: Thu Nov 23 22:28:01 2023 +0000
>
> Thanks!
>
>>
>>> Hi everyone,
>>>
>>> The attached patch is a temporary solution for the lack of proper linker
>>> and external library linking of the eBPF platform.
>>> Any calls created by the compiler, that would usually be defined within
>>> libgcc, will endup being undefined in bpftool, when GCC the compiled
>>> code is passed.
>>>
>>> This patch anticipates that error to the compiler, by verifiying if
>>> any of those calls are being generated, and reporting as an error.
>>>
>>> Looking forward to your comments.
>>>
>>> Cheers,
>>> Cupertino
>>>
>>> commit c2110ae497c7ff83c309f172bc265973652b760d
>>> Author: Cupertino Miranda <cupertino.mira...@oracle.com>
>>> Date: Thu Nov 23 22:28:01 2023 +0000
>>>
>>> This patch enables errors when external calls are created.
>>>
>>> When architectural limitations or usage of builtins implies the compiler
>>> to create function calls to external libraries that implement the
>>> functionality, GCC will now report an error claiming that this function
>>> calls are not compatible with eBPF target.
>>> Examples of those are the usage of __builtin_memmove and a sign division
>>> in BPF ISA v3 or below that will require to call __divdi3.
>>> This is currently an eBPF limitation which does not support linking of
>>> object files but rather "raw" non linked ones. Those object files are
>>> loaded and relocated by libbpf and the kernel.
>>>
>>> gcc/ChangeLog:
>>> * config/bpf/bpf.cc (bpf_output_call): Report error in case the
>>> function call is for a builtin.
>>> (bpf_external_libcall): Added target hook to detect and report
>>> error when other external calls that are not builtins.
>>>
>>> diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc
>>> index 0c9d5257c384..1c84113055b1 100644
>>> --- a/gcc/config/bpf/bpf.cc
>>> +++ b/gcc/config/bpf/bpf.cc
>>> @@ -744,6 +744,15 @@ bpf_output_call (rtx target)
>>> xops[0] = GEN_INT (TREE_INT_CST_LOW (TREE_VALUE (attr_args)));
>>> output_asm_insn ("call\t%0", xops);
>>> }
>>> + else if (fndecl_built_in_p (decl))
>>> + {
>>> + /* For now lets report this as an error while we are not able to
>>> + link eBPF object files. In particular with libgcc. */
>>> + tree name = DECL_NAME (decl);
>>> + error ("call to external builtin %s in function, which is not
>>> supported by "
>>> + "eBPF", name != NULL_TREE ? IDENTIFIER_POINTER (name) :
>>> "(anon)");
>>> + output_asm_insn ("call 0", NULL);
>>> + }
>>> else
>>> output_asm_insn ("call\t%0", &target);
>>>
>>> @@ -763,6 +772,18 @@ bpf_output_call (rtx target)
>>> return "";
>>> }
>>>
>>> +static void
>>> +bpf_external_libcall (rtx fun)
>>> +{
>>> + tree decl = SYMBOL_REF_DECL (fun);
>>> + tree name = DECL_NAME (decl);
>>> + error ("call to external libcall %s in function, which is not supported
>>> by "
>>> + "eBPF", name != NULL_TREE ? IDENTIFIER_POINTER (name) : "(anon)");
>>> +}
>>> +
>>> +#undef TARGET_ASM_EXTERNAL_LIBCALL
>>> +#define TARGET_ASM_EXTERNAL_LIBCALL bpf_external_libcall
>>> +
>>> /* Print register name according to assembly dialect. In normal
>>> syntax registers are printed like %rN where N is the register
>>> number.
>>> diff --git a/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c
>>> b/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c
>>> index 4036570ac601..fec720584e48 100644
>>> --- a/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c
>>> +++ b/gcc/testsuite/gcc.target/bpf/atomic-cmpxchg-2.c
>>> @@ -6,7 +6,7 @@ foo (int *p, int *expected, int desired)
>>> {
>>> return __atomic_compare_exchange (p, expected, &desired, 0,
>>> __ATOMIC_ACQUIRE, __ATOMIC_RELAXED);
>>> -}
>>> +} /* { dg-error "call to external builtin" } */
>>>
>>> int
>>> foo64 (long *p, long *expected, long desired)
>>> diff --git a/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c
>>> b/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c
>>> index 044a2f76474b..ea1b8e48928a 100644
>>> --- a/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c
>>> +++ b/gcc/testsuite/gcc.target/bpf/atomic-fetch-op-3.c
>>> @@ -9,7 +9,7 @@ long
>>> test_atomic_fetch_add (long x)
>>> {
>>> return __atomic_fetch_add (&val, x, __ATOMIC_ACQUIRE);
>>> -}
>>> +} /* { dg-error "call to external builtin" } */
>>>
>>> long
>>> test_atomic_fetch_sub (long x)
>>> diff --git a/gcc/testsuite/gcc.target/bpf/atomic-op-3.c
>>> b/gcc/testsuite/gcc.target/bpf/atomic-op-3.c
>>> index b2ce28926347..fefafd6b748f 100644
>>> --- a/gcc/testsuite/gcc.target/bpf/atomic-op-3.c
>>> +++ b/gcc/testsuite/gcc.target/bpf/atomic-op-3.c
>>> @@ -20,7 +20,7 @@ void
>>> test_atomic_and (int x)
>>> {
>>> __atomic_and_fetch (&val, x, __ATOMIC_ACQUIRE);
>>> -}
>>> +} /* { dg-error "call to external builtin" } */
>>>
>>> void
>>> test_atomic_nand (int x)
>>> diff --git a/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c
>>> b/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c
>>> index 3b6324e966b8..eab695bf388c 100644
>>> --- a/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c
>>> +++ b/gcc/testsuite/gcc.target/bpf/atomic-xchg-2.c
>>> @@ -7,7 +7,7 @@ int foo (int *p, int *new)
>>> int old;
>>> __atomic_exchange (p, new, &old, __ATOMIC_RELAXED);
>>> return old;
>>> -}
>>> +} /* { dg-error "call to external builtin" } */
>>>
>>> int foo64 (long *p, long *new)
>>> {
>>> diff --git a/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
>>> b/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
>>> index c48bbf03df97..c3332558e7d2 100644
>>> --- a/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
>>> +++ b/gcc/testsuite/gcc.target/bpf/diag-sdiv.c
>>> @@ -7,6 +7,6 @@ foo ()
>>> {
>>> signed int x = 5;
>>> signed int y = 2;
>>> - signed int z = x / y;
>>> + signed int z = x / y; /* { dg-error "call to external libcall" } */
>>> }
>>> /* { dg-final { scan-assembler-not "sdiv(32)?\t%r" } } */
>>> diff --git a/gcc/testsuite/gcc.target/bpf/diag-smod.c
>>> b/gcc/testsuite/gcc.target/bpf/diag-smod.c
>>> index d3df308217f3..25bcb1e4ffdb 100644
>>> --- a/gcc/testsuite/gcc.target/bpf/diag-smod.c
>>> +++ b/gcc/testsuite/gcc.target/bpf/diag-smod.c
>>> @@ -7,6 +7,6 @@ foo ()
>>> {
>>> signed int x = 5;
>>> signed int y = 2;
>>> - signed int z = x % y;
>>> + signed int z = x % y; /* { dg-error "call to external libcall" } */
>>> }
>>> /* { dg-final { scan-assembler-not "smod(32)?\t%r" } } */
