The piglit glsl-fs-shadow2dproj-bias.shader_test uses the following texture function:

 	gl_FragColor = shadow2DProj(tex, vec4(texcoords.xyy, 2.0), 1.0);

Note that 3rd component of the texture coordinate is the depth value which will be compared to the texture sample.  According to the GL spec, is must be divided by the W component (2.0 in this case) just like the S, T coords.

The generated code does this, but the 3rd component gets clobbered by an errant MOV instruction (at line 5):

  0: (assign (constant bool (1)) (w) (var_ref vec_ctor@0x949390)  (constant float (2.000000)) ) 
     MOV TEMP[1].w, CONST[1].xxxx;
  1: (assign (constant bool (1)) (xyz) (var_ref vec_ctor@0x949390)  (swiz xyy (var_ref texcoords@0xa2d390) )) 
     MOV TEMP[1].xyz, INPUT[14].xyyx;
  2: (txb (var_ref tex@0xb37b00)  (swiz xy (var_ref vec_ctor@0x949390) ) (0 0 0) (constant float (2.000000))  (swiz z (var_ref vec_ctor@0x949390) ) (constant float (1.000000)) )
     MOV TEMP[2], TEMP[1].xyyy;
  3: RCP TEMP[2].w, CONST[1].xxxx;
  4: MUL TEMP[2].xyz, TEMP[2], TEMP[2].wwww;
  5: MOV TEMP[2].z, TEMP[1].zzzz;

Here, instruction 5 is overwriting TEMP[2].z.  We want to keep the .z value that resulted from instruction 4. I don't know where the MOV instruction is coming from.


  6: MOV TEMP[2].w, CONST[1].yyyy;
  7: TXB TEMP[3], TEMP[2], texture[0], 2D SHADOW;
  8: (assign (constant bool (1)) (xyzw) (var_ref gl_FragColor@0xa2cf10)  (txb (var_ref tex@0xb37b00)  (swiz xy (var_ref vec_ctor@0x949390) ) (0 0 0) (constant float (2.000000))  (swiz z (var_ref vec_ctor@0x949390) ) (constant float (1.000000)) )) 
     MOV OUTPUT[2], TEMP[3];
  9: END