https://bugs.freedesktop.org/show_bug.cgi?id=30416
Summary: r300compiler: build_loop_info: expected conditional Product: Mesa Version: git Platform: x86-64 (AMD64) OS/Version: Linux (All) Status: NEW Severity: normal Priority: medium Component: Drivers/Gallium/r300 AssignedTo: dri-devel@lists.freedesktop.org ReportedBy: wixorpeek@gmail.com CC: maraeo@gmail.com
Compilation of the following fragment shader fails:
uniform vec4 vecX, vecY; uniform int iter;
void main() { for(;;) { bool b = (dot(gl_TexCoord[0], gl_TexCoord[0]) < 4.0); gl_FragColor.z = iter == 0 ? vecX.z - vecY.z : 15.0; if(b) break; gl_FragColor.x = 1.0; } }
r300: Initial fragment program FRAG DCL IN[0], GENERIC[0], PERSPECTIVE DCL OUT[0], COLOR DCL CONST[0..2] DCL TEMP[0..2] IMM FLT32 { 4.0000, 0.0000, 15.0000, 1.0000} 0: BGNLOOP :16 1: DP4 TEMP[0].x, IN[0], IN[0] 2: SLT TEMP[1].x, TEMP[0].xxxx, IMM[0].xxxx 3: MOV TEMP[0].x, TEMP[1].xxxx 4: SEQ TEMP[1].x, CONST[0].xxxx, IMM[0].yyyy 5: IF TEMP[1].xxxx :8 6: ADD TEMP[1].x, CONST[2].zzzz, -CONST[1].zzzz 7: MOV TEMP[2].x, TEMP[1].xxxx 8: ELSE :10 9: MOV TEMP[2].x, IMM[0].zzzz 10: ENDIF 11: MOV OUT[0].z, TEMP[2].xxxx 12: IF TEMP[0].xxxx :14 13: BRK 14: ENDIF 15: MOV OUT[0].x, IMM[0].wwww 16: ENDLOOP :0 17: END
Another example that fails is (maybe more common):
uniform vec4 vecX, vecY; uniform int iter;
void main() { for(;;) { gl_FragColor.z = vecX.z - vecY.z; if(dot(gl_TexCoord[0], gl_TexCoord[0]) < 4.0 && iter > 15) break; gl_FragColor.x = 1.0; } }
r300: Initial fragment program FRAG DCL IN[0], GENERIC[0], PERSPECTIVE DCL OUT[0], COLOR DCL CONST[0..2] DCL TEMP[0..1] IMM FLT32 { 4.0000, 15.0000, 0.0000, 1.0000} 0: BGNLOOP :15 1: ADD TEMP[0].x, CONST[2].zzzz, -CONST[1].zzzz 2: MOV OUT[0].z, TEMP[0].xxxx
3: DP4 TEMP[0].x, IN[0], IN[0] 4: SLT TEMP[1].x, TEMP[0].xxxx, IMM[0].xxxx 5: IF TEMP[1].xxxx :8 6: SGT TEMP[0].x, CONST[0].xxxx, IMM[0].yyyy 7: MOV TEMP[1].x, TEMP[0].xxxx 8: ELSE :10 9: MOV TEMP[1].x, IMM[0].zzzz 10: ENDIF
11: IF TEMP[1].xxxx :13 12: BRK 13: ENDIF 14: MOV OUT[0].x, IMM[0].wwww 15: ENDLOOP :0 16: END
The driver could cope with that by inserting something like CMP x, -x, 1, 0 before the IF.