Intel® Fortran Compiler
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Problem with -O3 optimization level

Hello everybody. I found a reproducible problem which appears only for level 3 optimization. I have an array, where N_lay is a defined constant integer somewhere in a module: real :: layers_prop(0:N_lay+1) Problem appears during execution of a following line: if (any ((layers_prop(0:N_lay) - layers_prop(1:N_lay+1)) < 0.)) cycle If optimization level is <= 2, it works perfectly (or any level of optimization if code is compiled with GCC). If optimization level is 3, it fails: forrtl: severe (408): fort: (3): Subscript #1 of the array LAYERS_PROP has value -1 which is less than the lower bound of 0 I use ifort (IFORT) 18.0.2 20180210 running on x86_64 Linux computer and compiling line is following: ifort -O3 -traceback -DD -debug -check bounds -check format -check uninit -autodouble -132 -warn all -fpp -no-wrap-margin -heap-arrays -mcmodel=medium -shared-intel -c Could anybody comment on this? Thank you in advance! PS: I failed to produce a minimum working example: it works perfectly if I cut those lines out of the project (which is a big bunch of software). However, I'm ready to provide the code to Intel engineers (without further distribution, since it is a proprietary scientific software).
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Black Belt

Problem reports filed at are kept confidential, so that appears to be what you should do (using the account to which your compiler is registered).