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authorJosé Fonseca <jfonseca@vmware.com>2009-06-28 11:12:22 +0100
committerJosé Fonseca <jfonseca@vmware.com>2009-06-28 11:12:22 +0100
commitbb8f3090ba37aa3f24943fdb43c4120776289658 (patch)
treea2079dcea02c8302eb1fbe6ab078c48a4286711b /scons/gallium.py
parent72ad039d19e033baff774b184ece9ffbfef4a2ff (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 'scons/gallium.py')
-rw-r--r--scons/gallium.py6
1 files changed, 4 insertions, 2 deletions
diff --git a/scons/gallium.py b/scons/gallium.py
index b69f2f2a75a..217478bd50d 100644
--- a/scons/gallium.py
+++ b/scons/gallium.py
@@ -324,8 +324,10 @@ def generate(env):
if gcc:
if debug:
ccflags += ['-O0', '-g3']
- elif env['toolchain'] == 'crossmingw':
- ccflags += ['-O0', '-g3'] # mingw 4.2.1 optimizer is broken
+ elif env['CCVERSION'].startswith('4.2.'):
+ # gcc 4.2.x optimizer is broken
+ print "warning: gcc 4.2.x optimizer is broken -- disabling optimizations"
+ ccflags += ['-O0', '-g3']
else:
ccflags += ['-O3', '-g3']
if env['profile']: