BPF currently limits the number of registers used to pass arguments to functions to five registers. There is a check for this at function expansion time. However, if a function is guaranteed to be always inlined (and its body never generated) by virtue of the always_inline attribute, it can "receive" any number of arguments.
Tested in host x86_64-linux-gnu and target bpf-unknown-none. gcc/ChangeLog * config/bpf/bpf.cc (bpf_function_arg_advance): Do not complain about too many arguments if function is always inlined. gcc/testsuite/ChangeLog * gcc.target/bpf/diag-funargs-inline-1.c: New test. * gcc.target/bpf/diag-funargs.c: Adapt test. --- gcc/config/bpf/bpf.cc | 9 +++++++- .../gcc.target/bpf/diag-funargs-inline-1.c | 21 +++++++++++++++++++ gcc/testsuite/gcc.target/bpf/diag-funargs.c | 8 ++++++- 3 files changed, 36 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.target/bpf/diag-funargs-inline-1.c diff --git a/gcc/config/bpf/bpf.cc b/gcc/config/bpf/bpf.cc index 33218b3a818..d27a971d0af 100644 --- a/gcc/config/bpf/bpf.cc +++ b/gcc/config/bpf/bpf.cc @@ -732,7 +732,14 @@ bpf_function_arg_advance (cumulative_args_t ca, unsigned num_words = CEIL (num_bytes, UNITS_PER_WORD); if (*cum <= 5 && *cum + num_words > 5) - error ("too many function arguments for eBPF"); + { + /* Too many arguments for BPF. However, if the function is + gonna be inline for sure, we let it pass. Otherwise, issue + an error. */ + if (!lookup_attribute ("always_inline", + DECL_ATTRIBUTES (cfun->decl))) + error ("too many function arguments for eBPF"); + } *cum += num_words; } diff --git a/gcc/testsuite/gcc.target/bpf/diag-funargs-inline-1.c b/gcc/testsuite/gcc.target/bpf/diag-funargs-inline-1.c new file mode 100644 index 00000000000..e917ef1294e --- /dev/null +++ b/gcc/testsuite/gcc.target/bpf/diag-funargs-inline-1.c @@ -0,0 +1,21 @@ +/* { dg-do compile } */ +/* { dg-options "" } */ + +inline int __attribute__ ((always_inline)) +foo (int a1, + int a2, + int a3, + int a4, + int a5, + int a6) +{ + return a1 + a2 + a3 + a4 + a5 + a6; +} + +int +bar (int i1, int i2, int i3, int i4, int i5) +{ + return foo (i1, i2, i3, i4, i5, 10); +} + +/* { dg-final { scan-assembler-not "call\t.*" } } */ diff --git a/gcc/testsuite/gcc.target/bpf/diag-funargs.c b/gcc/testsuite/gcc.target/bpf/diag-funargs.c index d4e9c0683f2..42b5f05b67c 100644 --- a/gcc/testsuite/gcc.target/bpf/diag-funargs.c +++ b/gcc/testsuite/gcc.target/bpf/diag-funargs.c @@ -11,5 +11,11 @@ foo (int a1, /* { dg-error "too many function arguments" } */ int a5, int a6) { - return a6; + return a1 + a2 + a3 + a4 + a5 + a6; +} + +int +bar (int i1, int i2, int i3, int i4, int i5) +{ + return foo (i1, i2, i3, i4, i5, 10); } -- 2.30.2