Bug 28385

Summary: g++ -O hangs while compiling file
Product: [Retired] Red Hat Linux Reporter: David Baron <dbaron>
Component: gccAssignee: Jakub Jelinek <jakub>
Status: CLOSED RAWHIDE QA Contact: David Lawrence <dkl>
Severity: high Docs Contact:
Priority: high    
Version: 7.0CC: akkzilla, bbaetz, blizzard, dmose, dr, shaver
Target Milestone: ---   
Target Release: ---   
Hardware: i386   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2001-02-21 21:23:47 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Flags
nsStyleContext.ii - preprocessed source none

Description David Baron 2001-02-20 04:56:41 UTC 
As of this afternoon, g++ hangs while compiling nsStyleContext.cpp in the
Mozilla tree with -O2.  I'll attach the preprocessed output to make for
easy testing.  Given nsStyleContext.ii that I will attach, the command

c++ -c -o nsStyleContext.o -O2 nsStyleContext.ii

hangs, while the command

c++ -c -o nsStyleContext.o nsStyleContext.ii

works correctly.

I'm seeing this with gcc-2.96-70 and -O2.  tor reports the same problem
with gcc-2.96-74 and -O (rather than -O2).  mao reports it with
gcc-2.96-69.
Comment 1 David Baron 2001-02-20 04:57:44 UTC 
Created attachment 10440 [details]
nsStyleContext.ii - preprocessed source
Comment 2 Jakub Jelinek 2001-02-20 11:36:31 UTC 
Thanks. Actually, CVS head hangs on this as well.
The culprit is:
inline void CalcSidesFor(const nsIFrame* aFrame, const nsStyleSides& aSides,
                         PRUint8 aSpacing,
                         const nscoord* aEnumTable, PRInt32 aNumEnums,
                         nsMargin& aResult)
{
  nsStyleCoord coord;

  aResult.left = CalcSideFor(aFrame, aSides.GetLeft(coord), aSpacing, 3,
                             aEnumTable, aNumEnums);
  aResult.top = CalcSideFor(aFrame, aSides.GetTop(coord), aSpacing, 0,
                            aEnumTable, aNumEnums);
  aResult.right = CalcSideFor(aFrame, aSides.GetRight(coord), aSpacing, 1,
                              aEnumTable, aNumEnums);
  aResult.bottom = CalcSideFor(aFrame, aSides.GetBottom(coord), aSpacing, 2,
                               aEnumTable, aNumEnums);
}
and the tree based inlining for some reason does not limit itself in doing
further and further inlines of itself in this case (because CalcSideFor indirectly
calls CalcSidesFor). I'll try to simplify it first.
Comment 3 Akkana 2001-02-20 20:18:36 UTC 
With -O (not O3) and with gcc-2.96-54, it takes a long time, and finally gives
up with:
Cannot allocate 892625676 bytes after allocating 16260924 bytes
Comment 4 Jakub Jelinek 2001-02-20 20:22:17 UTC 
I've narrowed it down to a 3K testcase and it really does not hang, it just
does a lot of inlining and eats gobs of memory (if I remove one of the 4
routines for inlining, it actually succeeds on my 256MB box, otherwise I never
had the patience to let it finish). I hope I'll know more tomorrow.
Comment 5 Christopher Blizzard 2001-02-21 20:16:59 UTC 
Any movement on this?  It's a real killer.
Comment 6 Jakub Jelinek 2001-02-21 21:23:43 UTC 
Yes, I think I've fixed this by:
http://gcc.gnu.org/ml/gcc-patches/2001-02/msg01310.html
Mark Mitchell approved it, if Jason Merrill does not have anything
against it until tomorrow, I'll commit it and will include it into
gcc-c++-2.96-76.
Comment 7 David Baron 2001-02-23 19:25:32 UTC 
Are you committing the patch to both the gcc trunk and the gcc 3.0 branch?  I
sure hope this is fixed in gcc 3.0 also.
Comment 8 Jakub Jelinek 2001-02-23 20:42:54 UTC 
Sure, I've commited it to both branch and head.
Comment 9 Jakub Jelinek 2001-03-16 10:36:24 UTC 
*** Bug 31937 has been marked as a duplicate of this bug. ***