[Bug c/63461] New: Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[Bug c/63461] New: Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[akiss at inf dot u-szeged.hu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63461

            Bug ID: 63461
           Summary: Inconsistent behaviour on ARM64 when inline assembly
                    with .text directive is followed by a static variable
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: akiss at inf dot u-szeged.hu

On ARM64/Ubuntu 14.04.1 with the stock gcc (Ubuntu/Linaro 4.8.2-19ubuntu1) I've
experienced the following: 

First, I wrote a macro with inline assembly containing a .text directive
followed by a static variable (still in the macro). Then, I expanded that macro
multiple times. The generated assembly output contains a .data directive before
the first variable declaration but not afterwards.

This caused problems with dynamically linking shared libraries in WebKit
(https://bugs.webkit.org/show_bug.cgi?id=137434).


gcc details:

Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.8.2-19ubuntu1' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.8 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap
--disable-libitm --disable-libsanitizer --disable-libquadmath --enable-plugin
--with-system-zlib --disable-browser-plugin --enable-java-awt=gtk
--enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-arm64/jre
--enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-arm64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-arm64
--with-arch-directory=arm64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-multiarch --disable-werror --enable-checking=release
--build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu
Thread model: posix
gcc version 4.8.2 (Ubuntu/Linaro 4.8.2-19ubuntu1)

[Bug c/63461] Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[akiss at inf dot u-szeged.hu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63461

--- Comment #1 from Akos Kiss <akiss at inf dot u-szeged.hu> ---
Created attachment 33649
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33649&action=edit
Example C source code

[Bug c/63461] Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[akiss at inf dot u-szeged.hu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63461

--- Comment #2 from Akos Kiss <akiss at inf dot u-szeged.hu> ---
Created attachment 33650
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33650&action=edit
Preprocessed source

[Bug c/63461] Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[akiss at inf dot u-szeged.hu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63461

--- Comment #3 from Akos Kiss <akiss at inf dot u-szeged.hu> ---
Created attachment 33651
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33651&action=edit
Assembly output

[Bug c/63461] Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[schwab@linux-m68k.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63461

Andreas Schwab <schwab@linux-m68k.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #4 from Andreas Schwab <schwab@linux-m68k.org> ---
Don't do that then.  Switching sections behind the compiler's back is
undefined.

[Bug c/63461] Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[mikpelinux at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63461

--- Comment #5 from Mikael Pettersson <mikpelinux at gmail dot com> ---
Use .pushsection and .popsection .

[Bug c/63461] Inconsistent behaviour on ARM64 when inline assembly with .text directive is followed by a static variable

[akiss at inf dot u-szeged.hu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63461

--- Comment #6 from Akos Kiss <akiss at inf dot u-szeged.hu> ---
Thanks for the feedback!