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[predsimplify] release run works fine, debug run goes crazy #1339

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lattner opened this issue Oct 25, 2006 · 7 comments
Closed

[predsimplify] release run works fine, debug run goes crazy #1339

lattner opened this issue Oct 25, 2006 · 7 comments
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bugzilla Issues migrated from bugzilla compile-fail Use [accepts-invalid] and [rejects-valid] instead

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@lattner
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lattner commented Oct 25, 2006

Bugzilla Link 967
Resolution FIXED
Resolved on Feb 22, 2010 12:47
Version trunk
OS All
Attachments bc file
CC @nlewycky

Extended Description

This is a nasty bug that points to some memory corruption issue or something.

time ~/llvm/Release/bin/opt -predsimplify -disable-output bugpoint-reduced-simplified.bc
0.055u 0.009s 0:00.06 83.3% 0+0k 0+1io 0pf+0w

time ~/llvm/Debug/bin/opt -predsimplify -disable-output bugpoint-reduced-simplified.bc

Note that the .bc does have a large nasty cfg, but it is strange that this issue should only affect a
debug opt and not a release opt. This points to some memory clobbering, or deleting something, but
not removing it from a map or something (i.e. it's address is still the key or value of some map).

I'm disabling predsimplify in llvm-gcc until this is resolved, this breaks debug bootstraps on both ppc
and x86.

-Chris
@llvmbot
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llvmbot commented Oct 26, 2006

Could it be a wonky assert?

Did you try Release+Asserts build?

Reid.

@lattner
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lattner commented Oct 26, 2006

entirely possible. No I didn't try.

@nlewycky
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I tried the testcase under valgrind and it didn't show any memory errors. That
said, I haven't been able to reproduce this yet on x86/linux.

@llvmbot
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llvmbot commented Nov 12, 2006

Given that predsimplify is being rewritten, the problem doesn't reproduce on
Linux and this hasn't shown up recently, can we just close this WONTFIX ?

@lattner
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lattner commented Nov 12, 2006

Perhaps when predsimplify is rewritten. Until then, we can't verify it.

-Chris

@nlewycky
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updated to current bytecode format
I was never able to reproduce the original bug, but this does seem to expose
poor performance, possibly due to debugging code. I'm seeing large numbers of
nodes with a lot of interconnections, probably constants. This isn't
surprising, as the constant code is full of fixme's at the moment.

@nlewycky
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nlewycky commented Apr 8, 2007

This is done.

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 3, 2021
This issue was closed.
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