Reproducing this is easy.
cat > ICE.sample.c <<'EOF'
typedef unsigned int size_t;
extern void *memcpy (void *__restrict __dest,
__const void *__restrict __src, size_t __n)
__attribute__ ((__nothrow__)) __attribute__ ((__nonnull__ (1, 2)));
unsigned xxx(long double arg)
{
struct
{
char dummy[8];
unsigned yyy:7;
} copy;
memcpy(©, &arg, sizeof(copy));
return copy.yyy;
}
EOF
invoking 'gcc -c -O1 sample.c' then emits
/home/bernard/ICE.sample.c: In function xxx:
/home/bernard/ICE.sample.c:8: internal compiler error: in extract_bit_field_1,
at expmed.c:1271
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.
This is quite sensitive! Small changes make the ICE
go away. These include
using -O0
re-sizing the array member dummy[] in the struct
Replacing the memcpy() with an assignment via a
cast pointer:
give the struct a tag (e.g., struct fimbulwinter)
copy = *((struct fimbulwinter *)&arg)
renaming memcpy() at both occurrences to by-pass the built-in
The last is suggestive, no?
This is NOT a duplicate of bug 37269, though the ICE is reported from
the same function. I get the same behaviour after applying Andrew
Pinski's patch for that bug. In fact, I found this bug in an echt
4.3.1 bootstrap build, applied AP's patch, still had it, then used
that compiler to bootstrap a 4.3.2 build, also with AP's patch.
Even using xgcc/cc1 from the stage 1 boostrap build of 4.3.2
showed the bug (there was nothing extra interesting in the
diagnostics produced).
'configure' was invoked with
'../gcc-4.3.2/configure' '--prefix=/usr' '--libexecdir=/usr/lib'
'--infodir=/usr/share/info' '--mandir=/usr/share/man' '--enable-libada'
'--enable-libssp' '--disable-werror' '--with-mpfr=/usr' '--with-gmp=/usr'
'--with-datarootdir=/usr/share' '--with-docdir=/usr/share/gcc-4.3.2/doc'
'--with-pdfdir=/usr/share/gcc-4.3.2/doc'
'--with-htmldir=/usr/share/gcc-4.3.2/doc/html' '--disable-coverage'
'--enable-nls' '--enable-__cxa_atexit' '--enable-decimal-float'
'--disable-fixed-point' '--enable-threads=posix' '--enable-clocale=gnu'
'--enable-shared' '--disable-intermodule'
'--enable-languages=ada,c++,fortran,java,objc,obj-c++,treelang,c'
'--with-local-prefix=/usr' '--with-gnu-ld' '--with-demangler-in-ld'
'--with-gnu-as' '--with-system-libunwind' '--with-system-zlib'
'--enable-bootstrap'
All those single quotes derive from my build scripts, which quote-and-
escape everything in sight. The actual CPU is an Athlon64 X2 5600+
(the 2.9GHz flavour, not the 2.8GHz flavour).
My binutils are from release 2.18, built with an unpatched gcc-4.3.1 .
--
Summary: ICE in extract_bit_field_1
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bernard at brenda-arkle dot me dot uk
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37870
