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" } } */