From: David S. <da...@da...> - 2004-04-29 06:07:02
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John Klein <jk2...@ya...> writes: [interesting experiment] > So it looks like you might be right and it could be an alignment issue. Did you by any chance note the size of the sbcl executable for the builds? I would expect GCC to produce good code for that unless the compiler and linker settings were completely wrong. How does the size of the mach-o executable affect the way the core file comes out either in terms of size or how it is loaded into memory? I'm not sure where to look in my documentation, but I presume there is a specification somewhere for mach-o executables and dylib files. More importantly, there should be documentation for the instruction alignment for PPC executables. Is it 32 bit word aligned or 64 bit word aligned? Aren't all instructions the same size? I came to believe that the way SBCL worked was by memory mapping the core file into virtual memory at a fixed location. So that should mean that the core file is appropriately structured for the PPC architecture when things go well. What I don't understand is how the core file comes out differently (if indeed it does) just because some C code is a little different. I'm not saying you're wrong. I can't make that determination. I do find it odd enough to make me go, "huh?" One thing that has always puzzled me about building SBCL is the way the final sbcl.core size will just change from build to build of the same code base. I first built SBCL successfully using OpenMCL. From that point on, I did my builds with SBCL itself. Even without doing an update (although not running clean.sh), the sbcl.core file would come out to a different size each time. I don't know why this should be so, but it is definitely not what I would expect from a deterministic process. Mind you, I am also puzzled as to why including the sb-ldb feature would make a build succeed. I only enabled it to trap the bug related to creating a large array of double-floats. I'm going to go ahead an try a few build experiments with the code I have on hand (no cvs update) to see if I can get the build failure and reproduce your results. I don't expect to solve anything, but maybe I can add another data point. -- I wouldn't mind the rat race so much if it wasn't for all the damn cats. |