From:
[email protected]
Package: gcc-3.4
Version: 3.4.1-4sarge1
Severity: normal
I'm compiling the following code example under both gcc 3.3.4-2 and 3.4.1-4sarge1:
#include <stdio.h>
typedef int v4si __attribute__ ((mode(V4SI)));
static void
print_v4si (const char * name, v4si val)
{
int x;
printf ("%s:\n", name);
for (x = 0; x < 4; ++x)
printf (" vals[%d] = %d\n", x, ((int *)&val)[x]);
printf ("\n");
}
int
main ()
{
v4si a = { 1, 2, 3, 4 };
v4si b = { 2, 3, 4, 5 };
print_v4si ("a", a);
print_v4si ("b", b);
print_v4si ("a+b", a + b);
return 0;
}
And here are some shell outputs compiling with 3.3 and 3.4 with and
without sse (along with running the results and commentary):
$ gcc-3.3 foo.c -o foo-3.3
foo.c: In function `print_v4si':
foo.c:14: internal compiler error: in ix86_function_arg_boundary, at config/i386/i386.c:2476
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:
http://gcc.gnu.org/bugs.html> for instructions.
For Debian GNU/Linux specific bug reporting instructions, see
<URL:file:///usr/share/doc/gcc-3.3/README.Bugs>.
This is wrong, but it seems fixed in 3.4:
$ gcc-3.4 foo.c -o foo-3.4
foo.c: In function `print_v4si':
foo.c:7: warning: SSE vector argument without SSE enabled changes the ABI
foo.c: In function `main':
foo.c:22: warning: SSE vector argument without SSE enabled changes the ABI
foo.c:23: warning: SSE vector argument without SSE enabled changes the ABI
foo.c:24: warning: SSE vector argument without SSE enabled changes the ABI
$ ./foo-3.4
a:
vals[0] = 1
vals[1] = 2
vals[2] = 3
vals[3] = 4
b:
vals[0] = 2
vals[1] = 3
vals[2] = 4
vals[3] = 5
a+b:
vals[0] = 3
vals[1] = 5
vals[2] = 7
vals[3] = 9
Only nuissance is that the warnings seems superfluous (others may
disagree).
$ gcc-3.3 foo.c -o foo-3.3-sse -msse
$ ./foo-3.3-sse
a:
vals[0] = 1
vals[1] = 2
vals[2] = 3
vals[3] = 4
b:
vals[0] = 2
vals[1] = 3
vals[2] = 4
vals[3] = 5
a+b:
vals[0] = 3
vals[1] = 5
vals[2] = 7
vals[3] = 9
This is correct.
$ gcc-3.4 foo.c -o foo-3.4-sse -msse
$ ./foo-3.4-sse
a:
vals[0] = 1
vals[1] = 2
vals[2] = 1
vals[3] = -1073743580
b:
vals[0] = 2
vals[1] = 3
vals[2] = 1
vals[3] = -1073743580
a+b:
vals[0] = 3
vals[1] = 5
vals[2] = 1
vals[3] = -1073743580
No warning, but the generated code seems incorrect (or at least a
regression from 3.3) unless ((int *)&val)[x] isn't the correct
portable way to access a vector element, but there doesn't seem to be
an alternative that I've been able to deduce (and the documentation
doesn't list any).
-- System Information:
Debian Release: 3.1
APT prefers testing
APT policy: (500, 'testing')
Architecture: i386 (i686)
Kernel: Linux 2.6.7
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8
Versions of packages gcc-3.4 depends on:
ii binutils 2.14.90.0.7-8 The GNU assembler, linker and bina ii cpp-3.4 3.4.1-4sarge1 The GNU C preprocessor
ii gcc-3.4-base 3.4.1-4sarge1 The GNU Compiler Collection (base ii libc6 2.3.2.ds1-13 GNU C Library: Shared libraries an ii libgcc1 1:3.4.1-4sarge1 GCC support library
-- no debconf information
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