riscv: error: expected '(' or optional integer offset after LLVM commit f281543a48905e58359c6b0f1b9c3b42bd67e315

[samitolvanen]

ToT Clang fails to build RISC-V defconfig after commit f281543a48905e58359c6b0f1b9c3b42bd67e315 ("[RISCV] Teach RISCVMergeBaseOffset to handle inline asm") with plenty of these errors:

In file included from ../ipc/namespace.c:7:
In file included from ../include/linux/ipc.h:5:
In file included from ../include/linux/spinlock.h:63:
In file included from ../include/linux/lockdep.h:14:
In file included from ../include/linux/smp.h:15:
In file included from ../include/linux/smp_types.h:5:
../include/linux/llist.h:239:9: error: expected '(' or optional integer offset
  239 |         return xchg(&head->first, NULL);
      |                ^
../include/linux/atomic/atomic-instrumented.h:4716:2: note: expanded from macro 'xchg'
 4716 |         raw_xchg(__ai_ptr, __VA_ARGS__); \
      |         ^
../include/linux/atomic/atomic-arch-fallback.h:12:18: note: expanded from macro 'raw_xchg'
   12 | #define raw_xchg arch_xchg
      |                  ^
../arch/riscv/include/asm/cmpxchg.h:146:23: note: expanded from macro 'arch_xchg'
  146 |         (__typeof__(*(ptr))) __arch_xchg((ptr), _x_, sizeof(*(ptr)));   \
      |                              ^
../arch/riscv/include/asm/cmpxchg.h:132:4: note: expanded from macro '__arch_xchg'
  132 |                         "       amoswap.d.aqrl %0, %2, %1\n"            \
      |                         ^
<inline asm>:1:26: note: instantiated into assembly here
    1 |                 amoswap.d.aqrl a0, a0, %pcrel_lo(.Lpcrel_hi18)(a1)
      |                                        ^

[nickdesaulniers]

Thanks for the report, reported upstream.

[nickdesaulniers]

I think this is the preprocessed output from the case above.

static inline __attribute__((__gnu_inline__)) __attribute__((__unused__))
__attribute__((__no_instrument_function__))
__attribute__((__always_inline__)) int
raw_atomic_xchg(atomic_t *v, int new) {

  return ({
    __typeof__(*(&v->counter)) _x_ = (new);
    (__typeof__(*(&v->counter)))({
      __typeof__((&v->counter)) __ptr = ((&v->counter));
      __typeof__(_x_) __new = (_x_);
      __typeof__(*((&v->counter))) __ret;
      switch (sizeof(*(&v->counter))) {
      case 4:
        __asm__ __volatile__("	amoswap.w.aqrl %0, %2, %1\n"
                             : "=r"(__ret), "+A"(*__ptr)
                             : "r"(__new)
                             : "memory");
        break;
      case 8:
        __asm__ __volatile__("	amoswap.d.aqrl %0, %2, %1\n"
                             : "=r"(__ret), "+A"(*__ptr)
                             : "r"(__new)
                             : "memory");
        break;
      default:
        do {
          __attribute__((__noreturn__)) extern void __compiletime_assert_35(
              void) __attribute__((__error__("BUILD_BUG failed")));
          if (!(!(1)))
            __compiletime_assert_35();
        } while (0);
      }
      __ret;
    });
  });
}

running cvise now. @topperc gave the green light to revert. I'll do that now.

[nickdesaulniers]

cvise reported:

typedef struct {
  int counter
} atomic_t;
int arch_atomic_fetch_sub_i, atomic_dec_return_ret;
void genl_sk_destructing_cnt() {
  atomic_t *__trans_tmp_8 = genl_sk_destructing_cnt;
  __asm__("	amo"
          "add"
          "."
          "w"
          ".aqrl  %1, %2, %0"
          : "+A"(__trans_tmp_8->counter), "=r"(atomic_dec_return_ret)
          : "r"(arch_atomic_fetch_sub_i));
}

[nickdesaulniers]

reverted: llvm/llvm-project@fc5306d