ERL-1123: Cannot compile 22.1.4 under Elbrus

[OTP-Maintainer]

Original reporter: maxlapshin
Affected version: OTP-22.1.4
Component: erts
Migrated from: https://bugs.erlang.org/browse/ERL-1123

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Cannot compile latest erlang under e2k-4c  (elbrus).

lcc compiler complains on reaching end of function with return type without return value.

I've added patch that helps to compile.

 

[OTP-Maintainer]

mikael pettersson said:

Seems your lcc can't detect unreachable code properly.  I just attached a cleaner patch for the issue (otp22-lcc-workaround.patch).  Does it work for you?

[OTP-Maintainer]

maxlapshin said:

I am afraid that it doesn't help:

 
{code:java}
// code placeholder
 CC obj/e2k-unknown-linux-gnu/opt/smp/erl_bif_counters.o 
 CC obj/e2k-unknown-linux-gnu/opt/smp/erl_bif_counters.o 
 CC obj/e2k-unknown-linux-gnu/opt/smp/erl_bif_trace.o
lcc: "beam/erl_bif_lists.c", line 959: error: missing return statement at end
          of non-void function "subtract_continue" [-Werror=return-type]
  }  ^
1 error detected in the compilation of "beam/erl_bif_lists.c".
{code}
Maybe it is a wrong behaviour of compiler and I should report it to them?

[OTP-Maintainer]

mikael pettersson said:

Thanks for testing.  My patch would have required lcc to understand "noreturn" function calls, which it apparently doesn't.

I would be hesitant to add obviously dead code just to satisfy this version of lcc, especially since that may result in warnings from compilers with better control-flow analysis.

Your best bet is probably to compile without -Werror, or to carry a local patch kit of workarounds due to the compiler you're stuck with.

Also your compiler provider should consider upgrading to something more modern than lcc, e.g. a clang/llvm toolchain should be much more compatible with modern software (gcc would be great too, but that would also require a binutils port to the e2k).

[OTP-Maintainer]

maxlapshin said:

They cannot port to llvm yet due to very specific nature of the CPU: it is a VLIW.  Ok, will work with ad-hoc patch for now.