RE: reporting "errors" or "bugs" to nmusers -> -O3 optimization r esults corroborated

From: Erik Olofsen [mailto:e.olofsen@xs4all.nl] Subject: [NMusers] RE: reporting "errors" or "bugs" to nmusers -> -O3 optimization r esults corroborated Date: 12/15/2003 9:50 AM Bill, >> My results with gcc 3.2.2 on Red Hat Linux 9 are as follows: >> >> -O and '-O3 -fno-gcse': >> MINIMIZATION TERMINATED >> DUE TO PROXIMITY OF LAST ITERATION EST. TO A VALUE >> AT WHICH THE OBJ. FUNC. IS INFINITE (ERROR=136) >> >> obj. fcn for -O: 785.8 >> obj. fcn for '-O3 -fno-gcse': 498.5 It could be that the latter result is also correctly computed, but that with this unstable model/data combination, rounding errors accumulate in a different way in the (correctly) optimized code causing NONMEM to abort at quite another point. >> -O3: PK PARAMETER FOR K12 IS NON-POSITIVE >> >> These results corroborate your results. Additionally, results with runs of >> CONTROL5 and THEOPP (distributed with NONMEM) indicate there indeed is a >> problem with -O3 optimization in general: >> >> -O and '-O3 -fno-gcse': minimization successful >> -O3: PK PARAMETERS FOR KA AND K ARE EQUAL And (see above) I guess with -O and '-O3 -fno-gcse' the obj. func. values are equal. >> My recommendation for g77 would be to use -O optimization for versions 3.2.2 >> and 3.2.3 and test optimization options for future versions. >> Have you been able to get any additional information on the source of the >> problem? I haven't found a description of exactly this problem on the gnu bug lists, but some other reports of problems with optimization. Indeed it is best to be careful with strong optimization with any compiler. Erik