Got it! I would have solved this much sooner if I had just dived into
the code instead of getting lost with git bisect!
https://gitlab.com/freepascal.org/fpc/source/-/merge_requests/655
It was an infinite loop in the "var13", "var14" and "var15"
optimisations that don't trigger on the Pentium II (default option) and
later. They set the Result to True even if no changes were actually
made and caused the compiler to check for the same optimisation over and
over again without progressing.
Kit
P.S. Admittedly those optimisations could use some maintenance since I
shouldn't need to set the operand sizes, but I'll save that for another day.
On 24/04/2024 05:08, J. Gareth Moreton via fpc-devel wrote:
I've gotten back as far as here, and it's still bad:
commit 7fbda0e0e8b1d071e72ccbc5e487dbb1c2173c63 (HEAD)
Author: Jonas Maebe <jo...@freepascal.org>
Date: Wed Mar 24 14:33:09 2021 +0000
* support building with FPC 3.2.2
git-svn-id: trunk@49045 -
I can't check earlier without difficulty because 3.2.2 doesn't work.
However the hang (and also an eventual out of memory error) doesn't
occur if -OoNOPEEPHOLE is specified, meaning the problem is located in
the peephole optimizer. So it looks like I'll have to try to debug
this the hard way!
Kit
On 23/04/2024 17:27, J. Gareth Moreton via fpc-devel wrote:
I've reproduced the hang doing "make clean all CPU_TARGET=i386
OS_TARGET=win32 OPT="-Cp80486 -Op80486"" on my x86_64-win64 machine.
So far I haven't found the bad commit - this problem has been here a
while.
Kit
I still haven't found the bad commit!
On 23/04/2024 12:46, J. Gareth Moreton via fpc-devel wrote:
Absolutely I can. I'll see what I can find.
Gareth aka. Kit
On 23/04/2024 12:09, Tomas Hajny via fpc-devel wrote:
On 2024-04-23 11:50, Marģers . via fpc-devel wrote:
1) does not work
make clean singlezipinstall OS_TARGET=win32 CPU_TARGET=i386
ALLOW_WARNINGS=1 OPT=" -O2 -vxitl -Cp80486 -Op80486"
hangs on
system.inc(421,2) Start reading includefile
C:\Users\Lietotajs\Downloads\fora\a\486\gh\rtl\inc\generic.inc
.
.
Indeed. This is clearly an issue related to optimizations. The
important point missing here is that it happens when compiling with
ppc1.exe. I just tried building a trunk compiler (make rtl_all
compiler_all) with "OPT=-O- -Cp80486 -Op80486" and then started
another compilation round with compiler built this way, but using
-O2 this time, in order to make sure that it wasn't an optimization
bug in the released 3.2.2 compiler. The new compilation round
(using a non-optimized compiler) hangs at an exactly the same
place, i.e. it's a bug (probably endless loop?) in the optimization
code specific to the trunk compiler. @Gareth, could you please have
a look at it?
Tomas
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