[ruby-core:62477] [ruby-trunk - Bug #9818] [Closed] __builtin_setjmp and __builtin_longjmp caused a build failure on PPC Linux with gcc 4.4.0

Issue #9818 has been updated by Nobuyoshi Nakada.

Status changed from Open to Closed
% Done changed from 0 to 100

Applied in changeset r45885.

----------
configure.in: check for setjmp type with CCDLFLAGS

* configure.in (RUBY_SETJMP_TYPE): check for setjmp type after
  CCDLFLAGS is appended to CFLAGS, since __builtin_setjmp can be
  affected.  [ruby-core:62469] [Bug #9818]

----------------------------------------
Bug #9818: __builtin_setjmp and __builtin_longjmp caused a build failure on PPC Linux with gcc 4.4.0
https://bugs.ruby-lang.org/issues/9818#change-46634

* Author: Rei Odaira
* Status: Closed
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.2.0dev (2014-05-04) [powerpc64-linux]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
From a certain revision around r45503 to r45515, Ruby began to use `__builtin_setjmp` and `__builtin_longjmp` on PPC Linux, instead of `_setjmp` and `_longjmp`. However, `__builtin_setjmp` and `__builtin_longjmp` cause a build failure because they are not compatible with the -fPIE option, at least with gcc 4.4.0 on PPC Linux.

~~~
compiling eval.c
eval.c: In function ?setup_exception?:
eval.c:515: warning: ?_th? may be used uninitialized in this function
eval.c:467: warning: ?file? may be used uninitialized in this function
eval.c: In function ?ruby_setup?:
eval.c:55: warning: ?_th? may be used uninitialized in this function
eval.c: In function ?ruby_options?:
eval.c:97: warning: ?_th? may be used uninitialized in this function
In file included from eval.c:31:
eval_jump.c: In function ?rb_exec_end_proc?:
eval_jump.c:119: warning: ?_th? may be used uninitialized in this function
eval_jump.c:116: warning: ?th? may be used uninitialized in this function
eval.c: In function ?ruby_cleanup?:
eval.c:174: warning: ?_th? may be used uninitialized in this function
eval.c:184: warning: ?_th? may be used uninitialized in this function
eval.c:164: warning: ?_th? may be used uninitialized in this function
/tmp/cc9lE3AW.s: Assembler messages:
/tmp/cc9lE3AW.s:16477: Error: symbol `.LCF26' is already defined
/tmp/cc9lE3AW.s:16935: Error: symbol `.LCF28' is already defined
/tmp/cc9lE3AW.s:16967: Error: symbol `.LCF28' is already defined
/tmp/cc9lE3AW.s:17260: Error: symbol `.LCF29' is already defined
/tmp/cc9lE3AW.s:17860: Error: symbol `.LCF32' is already defined
/tmp/cc9lE3AW.s:19246: Error: symbol `.LCF38' is already defined
/tmp/cc9lE3AW.s:19256: Error: symbol `.LCF38' is already defined
/tmp/cc9lE3AW.s:19599: Error: symbol `.LCF41' is already defined
/tmp/cc9lE3AW.s:24083: Error: symbol `.LCF65' is already defined
/tmp/cc9lE3AW.s:25419: Error: symbol `.LCF68' is already defined
/tmp/cc9lE3AW.s:25429: Error: symbol `.LCF68' is already defined
/tmp/cc9lE3AW.s:25798: Error: symbol `.LCF69' is already defined
/tmp/cc9lE3AW.s:26042: Error: symbol `.LCF70' is already defined
/tmp/cc9lE3AW.s:26301: Error: symbol `.LCF72' is already defined
/tmp/cc9lE3AW.s:26313: Error: symbol `.LCF72' is already defined
/tmp/cc9lE3AW.s:26668: Error: symbol `.LCF72' is already defined
/tmp/cc9lE3AW.s:26701: Error: symbol `.LCF72' is already defined
/tmp/cc9lE3AW.s:26712: Error: symbol `.LCF72' is already defined
/tmp/cc9lE3AW.s:26723: Error: symbol `.LCF72' is already defined
~~~

By specifying the --disable-pie option to configure, I succeed in bulding Ruby.

Interestingly, the build succeeds on the Ruby CI environment for PPC Linux, which is using gcc 4.7.2, so this might be a bug in gcc 4.4.0.  In any case, I suppose `__builtin_setjmp` and `__builtin_longjmp` are undocumented functions of gcc (aren't they?), so we should be careful to use them. I hope this problem is avoided on the Ruby side even if this is a bug in gcc 4.4.0 on PPC Linux.

How about specifying -fPIE (unless --disable-pie is specified) when checking `__builtin_setjmp` and `__builtin_longjmp` in the configure script?



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