Created attachment 115602 [details]
terasology.tgsi

The problem is that the attached shader compiles to:

...
 34: mov u32 $r0 $r3 (8)
 35: mov u32 $r1 $r5 (8)
 36: tex 2D $r0 $s0 f32 $r0t $r0d (8)
 37: join mov u32 $r7 $r1 (8)
BB:3 (4 instructions) - idom = BB:0, df = { BB:4 }
 -> BB:4 (forward)
 38: mov u32 $r0 $r3 (8)
 39: mov u32 $r1 $r5 (8)
 40: tex 2D $r1 $s0 f32 $r0t $r0d (8)
 41: join mov u32 $r7 $r1 (8)
...

And there is no texbar before the mov happens. This causes funky rendering in Terasology.

Somehow things get merged during RA s.t. the findFirstUses logic decides that the tex itself is a use (it isn't!) and so it never picks up on the actual use in that BB (since there's a check to make sure that we only pick the earliest use in a BB). This much shorter shader reproduces a similar issue as well:

FRAG
DCL IN[0], COLOR, COLOR
DCL OUT[0], COLOR
DCL OUT[1], COLOR[1]
DCL SAMP[0]
DCL SAMP[1]
DCL TEMP[0..4], LOCAL
IMM[0] FLT32 {    0.0010,     1.0000,     0.0000,     2.5000}
  5: MOV TEMP[0].xy, IN[0].xyxx
  7: FSLT TEMP[2].x, IMM[0].yyyy, IN[0].xxxx
 10: UIF TEMP[2].xxxx :0
 30:   TEX TEMP[1], TEMP[0], SAMP[0], 2D
 32: ELSE :0
 34:   TEX TEMP[1], TEMP[0], SAMP[1], 2D
 36: ENDIF
 47: UIF TEMP[2].xxxx :0
 50:   MUL TEMP[1], TEMP[1], IMM[0].xyyy
 54: ENDIF
 84: MOV TEMP[0].xyz, TEMP[1].xyzx
 93: MOV TEMP[1].xyz, TEMP[0].wwww
 94: MOV OUT[0], TEMP[0]
 95: MOV OUT[1], TEMP[1]
 97: END