<html> <head> <base href="https://bugs.freedesktop.org/" /> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW --- - llvmpipe: Fragment Shader with "return" in main causes back output" href="https://bugs.freedesktop.org/show_bug.cgi?id=62357#c7">Comment # 7</a> on <a class="bz_bug_link bz_status_NEW " title="NEW --- - llvmpipe: Fragment Shader with "return" in main causes back output" href="https://bugs.freedesktop.org/show_bug.cgi?id=62357">bug 62357</a> from <a class="email" href="mailto:sroland@vmware.com" title="Roland Scheidegger <sroland@vmware.com>"> Roland Scheidegger</a> <pre>After a quick look at the generated IR, it indeed seems broken. However, it is broken the opposite way, that is the early exit path is ok but if the path isn't taken it will pick zero as the output color. So if you swap the test like so: [test] uniform vec4 v 1 0 1 0 Then it fails. tgsi looks like this: 0: SLT TEMP[0].x, CONST[0].xxxx, IMM[0].xxxx 1: F2I TEMP[0].x, -TEMP[0] 2: SLT TEMP[1].x, IMM[0].yyyy, CONST[0].yyyy 3: F2I TEMP[1].x, -TEMP[1] 4: OR TEMP[1].x, TEMP[0].xxxx, TEMP[1].xxxx 5: SLT TEMP[2].x, CONST[0].zzzz, IMM[0].xxxx 6: F2I TEMP[2].x, -TEMP[2] 7: OR TEMP[1].x, TEMP[1].xxxx, TEMP[2].xxxx 8: IF TEMP[1].xxxx :0 9: MOV_SAT OUT[0], CONST[0] 10: RET 11: ENDIF 12: ADD TEMP[0], IMM[0].xxxx, -CONST[0] 13: MOV_SAT OUT[0], TEMP[0] 14: END And the IR part like this: %53 = fcmp une <8 x float> %52, zeroinitializer %54 = sext <8 x i1> %53 to <8 x i32> // %54 is the result of the if condition of line 8 ... %70 = call <8 x float> @llvm.x86.avx.max.ps.256(<8 x float> %57, <8 x float> zeroinitializer) %71 = call <8 x float> @llvm.x86.avx.min.ps.256(<8 x float> %70, <8 x float> <float 1.000000e+00, float 1.000000e+00, float 1.000000e+00, float 1.000000e+00, float 1.000000e+00, float 1.000000e+00, float 1.000000e+00, float 1.000000e+00>) // %71 contains mov_sat of line 9 %72 = bitcast <8 x i32> %54 to <8 x float> // %72 is still condition of line 8 as float %73 = call <8 x float> @llvm.x86.avx.blendv.ps.256(<8 x float> zeroinitializer, <8 x float> %71, <8 x float> %72) // %73 contains the output going to color pack - you can see that if the condition (%72) wasn't true, it simply selects zero.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>