On Thu, Apr 07, 2011 at 03:51:40AM +0000, Matt Turner wrote: > On Thu, Apr 7, 2011 at 3:06 AM, Tom Stellard <tstel...@gmail.com> wrote: > > I don't know anything about this code, but I just want to verify that > T0 (tee zero) and TO (tee oh) are different things and are used in the > right places. > > > +/** > > + * This pass replaces CMP T0, T1 T2 T0 with MOV TO, T2 when the CMP > > + * instruction is the first instruction to write to register T0. The are > > + * several lowering passes done in GLSL IR (e.g. branches and > > + * relative addressing) that create a large number of conditional > > assignments > > + * that ir_to_mesa converts to CMP instructions like the one mentioned > > above. > > + * > > + * Here is why this conversion is safe: > > + * CMP TO, T1 T2 T0 can be expanded to: > > + * if (T1 < 0.0) > > + * MOV T0, T2; > > + * else > > + * MOV T0, TO; > > + * > > + * If (T1 < 0.0) evaluates to true then our replacement MOV T0, T2 is the > > same > > + * as the original program. If (T1 < 0.0) evaluates to false, executing > > + * MOV T0, T0 will store a garbage value in T0 since T0 is uninitialized. > > + * Therefore, it doesn't matter that we are replacing MOV T0, T0 with MOV > > TO, T2 > > + * because any instruction that was going to read from T0 after this was > > going > > + * to read a garbage value anyway. > > I see "This pass replaces CMP T0, T1 T2 T0" but also "CMP TO, T1 T2 T0 > can be expanded to" where the first has T0 twice and the second has TO > and T0. And a few other seemingly strange occurrences of TO also. >
All occurrences of TO (tee oh) are typos. It should be T0 (tee zero) everywhere. -Tom _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
