diff options
author | José Fonseca <jfonseca@vmware.com> | 2009-06-28 11:12:22 +0100 |
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committer | José Fonseca <jfonseca@vmware.com> | 2009-06-28 11:12:22 +0100 |
commit | bb8f3090ba37aa3f24943fdb43c4120776289658 (patch) | |
tree | a2079dcea02c8302eb1fbe6ab078c48a4286711b /src | |
parent | 72ad039d19e033baff774b184ece9ffbfef4a2ff (diff) |
scons: Disable optimizations only for gcc-4.2
gcc-4.2's optimizer has a strange bug where it looses code from inner
loops in certain situations. For example, if the appearently innocent
looking code below is compiled with gcc-4.2 -S -O1, the inner loop's
code is missing from the outputed assembly.
struct Size {
unsigned width;
};
struct Command {
unsigned length;
struct Size sizes[32];
};
extern void emit_command(void *command, unsigned length);
void
create_surface( struct Size size, unsigned faces, unsigned levels)
{
struct Command cmd;
unsigned face;
unsigned level;
cmd.length = faces*levels*sizeof(cmd.sizes[0]);
for(face = 0; face < faces; ++face) {
for(level = 0; level < levels; ++level) {
cmd.sizes[face*levels + level] = size;
// This should generate a shrl statement, but the whole for body
// disappears in gcc-4.2 -O1/-O2/-O3!
size.width >>= 1;
}
}
emit(&cmd, sizeof cmd.length + cmd.length);
}
Note that this is not specific to MinGW's gcc-4.2 crosscompiler (the
version typically found in debian/ubuntu's mingw32 packages). gcc-4.2 on
Linux also displays the same error. gcc-4.3 and above gets this
correctly though.
Updated MinGW debian packages with gcc-4.3 are available from
http://people.freedesktop.org/~jrfonseca/debian/pool/main/m/
Diffstat (limited to 'src')
0 files changed, 0 insertions, 0 deletions