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simon
Joined: 05 Jul 2006
Posts: 276
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 Posted: Mon Nov 11, 2024 8:49 pm Post subject: Character string is lost |
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I have what seems to be an impossible-to-report problem with a character string getting lost in the 64-bit version! The core of the problem looks something like the following:
| Code: | Use m, Only: c2 ! c2 is a character string
Character(Len=16) :: c1
Write ( Unit=c1, Fmt='(A)' ) c2
c1 = c1 ! bug is avoided with this line, as long as this comment is deleted!
Print * c1
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I recognise that the above is incomplete code, so it cannot be tested. But I don't know where to begin to start to create an example to illustrate this because the bug does not occur when (a) compiling in 32-bit, (b) adding useless lines like line 4. Even more perplexing, the problem reappears when adding a comment to line 4, and it can also be made to disappear if I delete code that is never even called. The full code is about 160,000 lines. I am happy to try to forward that to Paul if diagnosing this problem does not look like a massive task. |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8062
Location: Salford, UK
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| Posted: Tue Nov 12, 2024 8:47 am Post subject: |
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Simon
I have not seen UNIT=<character variable> before. Is that legal? It is not faulted by FTN95 but perhaps it should be. |
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simon
Joined: 05 Jul 2006
Posts: 276
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| Posted: Wed Nov 13, 2024 9:10 pm Post subject: |
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Hi Paul,
I've been using Unit=character for years, actually probably decades.
Actually, in this case, I don't think it is integral to the problem I am experiencing since I have other examples that do not use this construct anyway. But, yes, it is probably worth checking how FTN95 handles it. I am uncertain of what the Fortran standard is, but my understanding is that Unit becomes a negative number when it is using an internal file. But it may well be illegal to attempt to pass the character explicitly as the Unit number. If anybody knows I would be happy to hear.
Simon |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8062
Location: Salford, UK
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| Posted: Thu Nov 14, 2024 8:41 am Post subject: |
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Simon
Ah yes. I did not recognise it as an internal write statement.
Have you looked at the point of failure using the debugger?
Have you tried omitting the ONLY in the USE statement? |
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simon
Joined: 05 Jul 2006
Posts: 276
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| Posted: Sat Nov 16, 2024 1:24 am Post subject: |
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Hi Paul,
Unfortunately, if I try to compile using /DEBUG /CHECK, I get the following error somewhere else in the program:
| Quote: | | AMD backend failure:Failed to do register-memory emit for MOV_Q at ... |
in each case at a Subroutine declaration. Plus I get some Internal compiler errors, again at some Subroutine declarations. None of these problems occur when compiling without those options, nor do they occur when compiling in 32-bit, with or without. |
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PaulLaidler
Site Admin
Joined: 21 Feb 2005
Posts: 8062
Location: Salford, UK
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| Posted: Sat Nov 16, 2024 8:58 am Post subject: |
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Simon
1) Please send a simple program that illustrates the /64 /CHECK failure. This is probably something that we need to fix.
2) Try using /DEBUG on its own. That might help you to work out what is going wrong. |
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simon
Joined: 05 Jul 2006
Posts: 276
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| Posted: Sat Nov 16, 2024 5:32 pm Post subject: |
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Hi Paul,
I will try to send a simple program, but I estimate it will take more than a full day's work, so I can't promise to do it soon.
If I remove /CHECK, then I no longer et compilation errors. and some of the runtime errors go away. When I get some free time, I will try to isolate all these issues ... |
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mecej4
Joined: 31 Oct 2006
Posts: 1898
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| Posted: Tue Nov 19, 2024 4:26 am Post subject: |
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Here are portions of F2008 that pertain:
| Quote: | F2008:
9.6.2R913: io-control-spec is UNIT = io-unit OR ...
9.5.1: R901: io-unit is file-unit-number OR * OR internal-file-variable
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Here is the source of a modified version of the test program that runs correctly with the 9.05 version of FTN95
| Code: |
module m
character(12) :: c2 = 'String c2xyz'
end module
program buggy
Use m, Only: c2 ! c2 is a character string
Character(Len=16) :: c1
Write ( Unit=c1, Fmt='(A)' ) c2
Print *, c1
end program |
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simon
Joined: 05 Jul 2006
Posts: 276
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| Posted: Tue Nov 19, 2024 5:37 pm Post subject: |
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| Thanks for the confirmation. It appears that my partial code was legal, so I'll have to try and find a way to isolate the problem. |
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