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Hi, the reason why this is a duplicate of RFE 88095 is because both the C/C++ and PL/I compilers share the same backend component that would have needed to be modified.
Please explain: Why has this RFE been closed? In my opinion it is _not_ a duplicate. RFE 88095 is for PL/1 Compiler. This one is for C/C++-Compiler!
This RFE is a duplicate of RFE 88095.
As mentioned in RFE 88095, the main issue is the increased compile time that this change would add. The RFE is being marked a dup of RFE 88095 (which has been rejected).
First, it will be the best way, to avoid unknown instructions.
The Compilierlisting scan for UKNWN is to much overhead for us too.
But, if you detect (in any way) a unknown instruction (for example, at generating the Assembly list) please stop the compile.
The Assembly list generator (or before) have to signal the compiler to stop if it detects unknown instruction. But i don't know about the internally compiler process so there may be better ways...
The suggested capability has a worst case cost and space performance proportional to the number of instructions.
This cost is paid by the end user regardless if compiler has generated bad code, a.k.a. UNKWN instruction.
Therefore we believe compiler should only implement such capability under an option.
We believe it's hard to justify all our clients to use this option and pay the extra MIPS, to stop on some error that may or may not happen.
We have done the root cause analysis, and we believe the product will be in a better position if we worked on avoiding generation of UKNWN instruction altogether.
Therefore, we would like to see if you'd be open to adding a check in your build process.
We suggest the following option:
-Request a compiler listing and grep for UNKWN
Time + space cost
*If you are compiling NOOPT, most of the CPU time used by the compiler will be spent in generating the LIST file. The time/space cost reduces as optimization level increases.
Please let us know if this is acceptable.
Maybe.
If you are 100% sure it will never again in any possible situation to generate UNKWN instructions, then this is ok for me.
But if there is a little possibility that in any way it may generate UNKWN instructions, please implement to stop the compiler.
We intend to fix the compiler from generating UNKWN altogether (instead of issuing an error message everytime it does). Please let us know if you have any concerns with that?