[fpc-devel] Linux compilation question

[J. Gareth Moreton]

Hi everyone,

I have a little question.  I'm having problems compiling fpc under
x86_64-linux.  At first I thought it was a bug in one of my changes, but
it seems to occur on the trunk as well.  After successfully compiling the
compiler a few times, the following happens:

/usr/bin/diff ppc3 ppcx64
Binary files ppc3 and ppcx64 differ

And then it drops out.  I've tried the usual things of doing a "make
distclean", but am I missing something obvious?  Preliminary Linux testing
is the only thing I'm missing before I'm ready to present a patch.

Gareth aka. Kit

[J. Gareth Moreton]

Never mind.  Got it working after I got a clean copy ("svn update" then
"svn revert -R .") - now the adventure continues!

Gareth aka. Kit

On Fri 30/11/18 13:39 , "J. Gareth Moreton" ***@moreton-family.com
sent:
Hi everyone,

I have a little question.  I'm having problems compiling fpc under
x86_64-linux.  At first I thought it was a bug in one of my changes, but
it seems to occur on the trunk as well.  After successfully compiling the
compiler a few times, the following happens:

/usr/bin/diff ppc3 ppcx64
Binary files ppc3 and ppcx64 differ

And then it drops out.  I've tried the usual things of doing a "make
distclean", but am I missing something obvious?  Preliminary Linux testing
is the only thing I'm missing before I'm ready to present a patch.

Gareth aka. Kit
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[J. Gareth Moreton]

Actually still having lots of problems here.  Can anyone give me some
advice?  Admittedly my skills with Linux are lacking, but I would like to
get it to build on x86_64-linux before I submit my patch to everyone.

What I've discovered so far is that if I pull a clean copy from the SVN
trunk, it builds without a problem, but if I change one of the source files
or do "make clean", it fails with that diff error.

Gareth aka. Kit

On Fri 30/11/18 15:36 , "J. Gareth Moreton" ***@moreton-family.com
sent:
Never mind.  Got it working after I got a clean copy ("svn update" then
"svn revert -R .") - now the adventure continues!

Gareth aka. Kit

On Fri 30/11/18 13:39 , "J. Gareth Moreton" ***@moreton-family.com
sent:
Hi everyone,

I have a little question.  I'm having problems compiling fpc under
x86_64-linux.  At first I thought it was a bug in one of my changes, but
it seems to occur on the trunk as well.  After successfully compiling the
compiler a few times, the following happens:

/usr/bin/diff ppc3 ppcx64
Binary files ppc3 and ppcx64 differ

And then it drops out.  I've tried the usual things of doing a "make
distclean", but am I missing something obvious?  Preliminary Linux testing
is the only thing I'm missing before I'm ready to present a patch.

Gareth aka. Kit
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[Christo Crause]

Actually still having lots of problems here. Can anyone give me some
advice? Admittedly my skills with Linux are lacking, but I would like to
get it to build on x86_64-linux before I submit my patch to everyone.
What I've discovered so far is that if I pull a clean copy from the SVN
trunk, it builds without a problem, but if I change one of the source files
or do "make clean", it fails with that diff error.

The following make command worked (and has worked many times) for me with
latest trunk to rebuild trunk:

make FPC=~/fpc/installs/lib/3.0.4/ppcx64 clean all

Linux Mint 19 64 bit

[Florian Klämpfl]

Post by J. Gareth Moreton
Hi everyone,
I have a little question.  I'm having problems compiling fpc under x86_64-linux.  At first I thought it was a bug in one
of my changes, but it seems to occur on the trunk as well.  After successfully compiling the compiler a few times, the
/usr/bin/diff ppc3 ppcx64
Binary files ppc3 and ppcx64 differ
And then it drops out.  I've tried the usual things of doing a "make distclean", but am I missing something obvious?

This means that the compiler generates wrong code which results in wrong code generation :). These things are very hard
to debug. The only way is to compare the disassembly manually to find out where it differs and then to debug why it
generates this particular code at that location.

Post by J. Gareth Moreton
Preliminary Linux testing is the only thing I'm missing before I'm ready to present a patch.

Did you run regression tests?
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[J. Gareth Moreton]

The only thing I've managed to run so far
is the standard "make all". What's
mysterious though is that if I grab a
clean copy from the trunk, it builds fine.
However, if I do "make clean" first, that
error appears. Does anyone else get this?
(I'm using Ubuntu and compiling on x86_64)

I managed to get an assembly dump of
system.pp and compare the output between
ppc1, ppc2 and ppc3. Some procedures in
ppc3 look very different, as if compiled
by an older version of the compiler. It's
confusing, but I'll keep at it.

I don't want to scrap my changes, because
so far I've managed to make -O3 about 15%
faster.

Gareth aka. Kit

On Sat 01/12/18 09:05 , "Florian Klämpfl"

Am 30.11.2018 um 14:39 schrieb J. Gareth

Post by J. Gareth Moreton
Hi everyone,
I have a little question.  I'm having

problems compiling fpc under x86_64-

linux.  At first I thought it was

a bug in one

Post by J. Gareth Moreton
of my changes, but it seems to occur

on the

trunk as well.  After successfully

compiling the compiler a few times,

the

Post by J. Gareth Moreton
/usr/bin/diff ppc3 ppcx64
Binary files ppc3 and ppcx64 differ
And then it drops out.  I've tried the

usual things of doing a "make

distclean", but am I missing

something obvious?
This means that the compiler generates

wrong code which results in wrong

code generation :). These things are

very hard

to debug. The only way is to compare the

disassembly manually to find out

where it differs and then to debug why

it

generates this particular code at that

location.

Post by J. Gareth Moreton
Preliminary Linux testing is the only

thing I'm

missing before I'm ready to present a

patch.

Did you run regression tests?

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[J. Gareth Moreton]

I must have something configured incorrectly - I'm still getting the
error.  Apologies for bugging everyone.

Gareth aka. Kit

On Sat 01/12/18 06:14 , "Christo Crause" ***@gmail.com sent:
On Sat, 1 Dec 2018, 01:37 J. Gareth Moreton

[Bart]

On Fri, Nov 30, 2018 at 3:41 PM J. Gareth Moreton

Post by J. Gareth Moreton
/usr/bin/diff ppc3 ppcx64
Binary files ppc3 and ppcx64 differ
And then it drops out. I've tried the usual things of doing a "make distclean", but am I missing something obvious? Preliminary Linux testing is the only thing I'm missing before I'm ready to present a patch.

Works for me here.
svn co https://svn.freepascal.org/svn/fpc/trunk .
make

# after succesfull make:
make clean all

Fpc r40425, on Linux Mint 18.2 64-bit using fpc 3.0.4 as starting compiler.

[J. Gareth Moreton]

Thanks Bart,
I managed to get it to build after reinstalling the FPC compiler 3.0.4 -
it seems it was getting confused between two different versions on my
virtual machine - but after all that it does look like a bug in my new
code.  I've managed to get it to compile from a clean build and with a
couple of modified files that don't do anything drastic, so now I'll try to
isolate the issue and update my patch file.  An overhauled peephole
optimizer is no use if it breaks Linux!

Thanks for the tips everyone.

Gareth aka. Kit

On Sat 01/12/18 17:03 , "Bart" ***@gmail.com sent:
On Fri, Nov 30, 2018 at 3:41 PM J. Gareth Moreton

Post by J. Gareth Moreton
/usr/bin/diff ppc3 ppcx64
Binary files ppc3 and ppcx64 differ
And then it drops out. I've tried the usual things of doing a "make

distclean", but am I missing something obvious? Preliminary Linux testing
is the only thing I'm missing before I'm ready to present a patch.

Works for me here.
svn co https://svn.freepascal.org/svn/fpc/trunk [1] .
make

# after succesfull make:
make clean all

Fpc r40425, on Linux Mint 18.2 64-bit using fpc 3.0.4 as starting
compiler.
--
Bart



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[Florian Klämpfl]

Post by J. Gareth Moreton
Thanks Bart,
I managed to get it to build after reinstalling the FPC compiler 3.0.4 - it seems it was getting confused between two
different versions on my virtual machine - but after all that it does look like a bug in my new code.  I've managed to
get it to compile from a clean build and with a couple of modified files that don't do anything drastic, so now I'll try
to isolate the issue and update my patch file.  An overhauled peephole optimizer is no use if it breaks Linux!

I had a quick look at the patch and I strongly recommend to split it in multiple patches which can be reviewed more
easily. This allows also to detect easier which change breaks things and also to measure which change increases speed
and which change is not needed.

In general, I am not happy with the merge of the four passes as it makes maintenance much harder.
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[J. Gareth Moreton]

Aw, okay.  Well, post peephole is still a separate stage, since that
prevents a lot of other optimisations (e.g. changing mov 0,%reg into xor
%reg,%reg).

I'll start breaking it up into smaller chunks.

Gareth aka. Kit

Post by J. Gareth Moreton
Thanks Bart,
I managed to get it to build after reinstalling the FPC compiler 3.0.4 -

it seems it was getting confused between two

Post by J. Gareth Moreton
different versions on my virtual machine - but after all that it does

look like a bug in my new code.  I've managed to

Post by J. Gareth Moreton
get it to compile from a clean build and with a couple of modified files

that don't do anything drastic, so now I'll try

Post by J. Gareth Moreton
to isolate the issue and update my patch file.  An overhauled peephole

optimizer is no use if it breaks Linux!

I had a quick look at the patch and I strongly recommend to split it in
multiple patches which can be reviewed more
easily. This allows also to detect easier which change breaks things and
also to measure which change increases speed
and which change is not needed.

In general, I am not happy with the merge of the four passes as it makes
maintenance much harder.
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[J. Gareth Moreton]

I admit I do wonder how hard maintenance will be.  True, there is some
more looking ahead, but it's not really any more complex than what it is
already (e.g. take a look at OptPass1MOV in the trunk).

When it comes to debugging the peephole optimiser, one thing I did was
write a function that wrote the assembly of the current block to the
console, so I could visually see the commands ahead.  It's not part of the
submitted patches because it only works for i386 and x86_64 under Windows,
but it's proven useful.
If there's interest, I can submit it as a separate patch, but it's not
really suitable as a permanent fixture unless someone wants to try to make
it a feature only enabled with debug defines.

Gareth aka. Kit

On Sat 01/12/18 18:57 , "J. Gareth Moreton" ***@moreton-family.com
sent:
Aw, okay.  Well, post peephole is still a separate stage, since that
prevents a lot of other optimisations (e.g. changing mov 0,%reg into xor
%reg,%reg).

I'll start breaking it up into smaller chunks.

Gareth aka. Kit

Post by J. Gareth Moreton
Thanks Bart,
I managed to get it to build after reinstalling the FPC compiler 3.0.4 -

it seems it was getting confused between two

Post by J. Gareth Moreton
different versions on my virtual machine - but after all that it does

look like a bug in my new code.  I've managed to

Post by J. Gareth Moreton
get it to compile from a clean build and with a couple of modified files

that don't do anything drastic, so now I'll try

Post by J. Gareth Moreton
to isolate the issue and update my patch file.  An overhauled peephole

optimizer is no use if it breaks Linux!

I had a quick look at the patch and I strongly recommend to split it in
multiple patches which can be reviewed more
easily. This allows also to detect easier which change breaks things and
also to measure which change increases speed
and which change is not needed.

In general, I am not happy with the merge of the four passes as it makes
maintenance much harder.
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