Hi,

how can I tell fpc to use only instructions supported on a specific processor?

I'm compiling on an athlon for running on a geode (restriction has to define instruction set from x686 to x586, I think).

Sometimes my program crashes on the target machine with signal 4 (illegal instruction).

TIA,
Marc

In theory, the code generated by FPC should always run on an i386 (even if you use e.g. -Op3), unless you use some special command line switches I cannot find in the help. Other behaviour indicates a bug. Can you figure out which instruction it is that causes this?

Jonas

-C<x> code generation options:
-Cc<x> set default calling convention to <x>
-CD create also dynamic library (not supported) -Ce Compilation with emulated floating point opcodes -Cf<x> Select fpu instruction set to use, see fpc -i for possible values
-Cg Generate PIC code
-Ch<n> <n> bytes heap (between 1023 and 67107840) -Ci IO-checking
-Cn omit linking stage
-Co check overflow of integer operations
-Cp<x> select instruction set, see fpc -i for possible values

That is it :)

Date sent: Sun, 19 Jun 2005 22:49:44 +0200
From: Florian Klaempfl
To: FPC-Pascal users discussions
Subject: Re: [fpc-pascal] selecting target processor Send reply to: FPC-Pascal users discussions

Nice can of worms I haven't been aware of... ;-) So what is the best - Cp option for my Athlon then? ;-))) And what would be correct for AMD K6 and all other non-Intel CPUs > 386? Looks as a lot of work for Michael...

Tomas

PENTIUM afaik nothing new
PENTIUM2 mainly cmov and fcmov, cmov creates nice code for length(<ansistring>) or max if max is inlined:

# [14] i:=length(s);
movl U_P$PROGRAM_S,%eax
testl %eax,%eax
cmovnel -4(%eax),%eax
movl %eax,U_P$PROGRAM_I
# [15] j:=max(j,k);
movl U_P$PROGRAM_K,%ecx
movl U_P$PROGRAM_J,%edx
cmpl %ecx,%edx
cmovgl %edx,%eax
.L29:
cmovngl %ecx,%eax
movl %eax,U_P$PROGRAM_J

PENTIUM3 sse1 for usual code possible (e.g. prefetch) PENTIUM4 sse2 for usual code possible

K6 -> Pentium
Athlon/Duron -> Pentium2
AthlonXP/Sempron -> Pentium3
Athlon64 -> Pentium4

So it should work:

I'm using "-dRELEASE" for releasing and my fpg.cfg has standard "-OG2p3" and "-Xs". Testing is done with "-XX -B".

Can you figure out which instruction it is that causes this?

How would I do that? Would a saved core dump do? It seems to occur on when redirecting stdout to a file, but I'm not sure yet.

Thanks,
Marc

Yes, it should.

> Can you figure out which instruction it is that causes this? How would I do that? Would a saved core dump do? It seems to occur on when redirecting stdout to a file, but I'm not sure yet.

Normally, you'd do this by running the program under gdb and checking what the faulting instruction is. A coredump should contain the necessary information as well, yes.

Jonas

Are you using any dll or lib.so :? Perhaps the external code is compiled for a specific processor.

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Am Montag, den 20.06.2005, 17:19 +0200 schrieb Eduardo: [...]

Are you using any dll or lib.so :? Perhaps the external code is compiled for a specific processor.

This in fact seems to be tha cause. The error happens inside the GTK library which i'll try to recompile and check again.

Thanks to you all so far,
Marc