[Bug middle-end/56759] New: result of __builtin_constant_p( ) is not constant enough for __builtin_choose_expr( )

[gcc-bugzilla at codyps dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56759



 Bug #: 56759

   Summary: result of __builtin_constant_p( ) is not constant

enough for __builtin_choose_expr( )

Classification: Unclassified

   Product: gcc

   Version: 4.8.1

Status: UNCONFIRMED

  Severity: normal

  Priority: P3

 Component: middle-end

AssignedTo: unassig...@gcc.gnu.org

ReportedBy: gcc-bugzi...@codyps.com





Testcase:

---

static inline int x(int y)

{

return __builtin_choose_expr(__builtin_constant_p(y), 1, 0);

}



int foo(void)

{

return x(3);

}

---





$ i386-linux-gcc constant_not_constant.c  -O3 -c

constant_not_constant.c: In function 'x':

constant_not_constant.c:4:9: error: first argument to '__builtin_choose_expr'

not a constant

  return __builtin_choose_expr(__builtin_constant_p(y), 1, 0);

 ^



$ i386-linux-gcc -v

Using built-in specs.

COLLECT_GCC=i386-linux-gcc

COLLECT_LTO_WRAPPER=/home/cody/x-buildall/libexec/gcc/i386-linux/4.8.1/lto-wrapper

Target: i386-linux

Configured with: /home/cody/g/gcc/configure --target=i386-linux

--enable-targets=all --prefix=/home/cody/x-buildall --enable-languages=c

--without-headers --enable-sjlj-exceptions --with-system-libunwind

--disable-nls --disable-threads --disable-shared --disable-libmudflap

--disable-libssp --disable-libgomp --disable-decimal-float

--disable-libquadmath --enable-checking=release --disable-libatomic :

(reconfigured) /home/cody/g/gcc/configure --target=i386-linux

--enable-targets=all --prefix=/home/cody/x-buildall --enable-languages=c

--without-headers --enable-sjlj-exceptions --with-system-libunwind

--disable-nls --disable-threads --disable-shared --disable-libmudflap

--disable-libssp --disable-libgomp --disable-decimal-float

--disable-libquadmath --enable-checking=release --disable-libatomic :

(reconfigured) /home/cody/g/gcc/configure --target=i386-linux

--enable-targets=all --prefix=/home/cody/x-buildall --enable-languages=c

--without-headers --enable-sjlj-exceptions --with-system-libunwind

--disable-nls --disable-threads --disable-shared --disable-libmudflap

--disable-libssp --disable-libgomp --disable-decimal-float

--disable-libquadmath --enable-checking=release --disable-libatomic :

(reconfigured) /home/cody/g/gcc/configure --target=i386-linux

--enable-targets=all --prefix=/home/cody/x-buildall --enable-languages=c

--without-headers --enable-sjlj-exceptions --with-system-libunwind

--disable-nls --disable-threads --disable-shared --disable-libmudflap

--disable-libssp --disable-libgomp --disable-decimal-float

--disable-libquadmath --enable-checking=release --disable-libatomic

Thread model: single

gcc version 4.8.1 20130328 (prerelease) (GCC)

[Bug middle-end/56759] result of __builtin_constant_p( ) is not constant enough for __builtin_choose_expr( )

[gcc-bugzilla at codyps dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56759

--- Comment #1 from Cody P Schafer  2013-03-28 
00:56:11 UTC ---
This also affects my ubuntu gcc install:

$ gcc constant_not_constant.c  -O3 -c
constant_not_constant.c: In function ‘x’:
constant_not_constant.c:4:31: error: first argument to ‘__builtin_choose_expr’
not a constant

$ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.6/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
4.6.3-1ubuntu5' --with-bugurl=file:///usr/share/doc/gcc-4.6/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.6 --enable-shared --enable-linker-build-id
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.6
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object
--enable-plugin --enable-objc-gc --disable-werror --with-arch-32=i686
--with-tune=generic --enable-checking=release --build=x86_64-linux-gnu
--host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5)