binutils-2.15 - work around for gcc optimization problem on sparc -sun-solaris2.7

[Kelvin Lee]

When I am building binutils-2.15 on sparc-sun-solaris2.7 using gcc-3.4, it seems the combination triggered a bug of gcc that would generate incorrect code for the function elf_sort_symbol() of bfd/elflink.c. At elflink.c line 2703 inside elf_sort_symbol(), the calculation of sdiff would be wrong and hence confusing qsort() and causing ld to crash in some situations. In my case, ld crashed when it was used to build gcc-3.4.

Attached test.c is code extracted from elflink.c to demonstrate the problem. You can use attached comp.sh to compile the test program. The test program must be compile inside the bfd directory of the binutils-2.15 package. The embedded data is the data extract from the gcc-3.4 build which caused ld-2.15 to crash. BTW, the test program also shows a possible work around of the problem, i.e. instead of doing the calculation, simply comparing the values inside elf_sort_symbol. (You may also use the attached diff file to patch elflink.c.) The patch seems working fine or at least survived the gcc build cycle.

Notes:
1. gcc-2.95 and gcc-3.3 also generate incorrect code for elf_sort_symbol(). You can verify that with my test program.
2. The qsort() comes with Solaris does not seem to be robust enough against this kind of confusing comparing results. Replacing that with other implementation of qsort() does not cause crashing but the comparisons were wrong anyway.

3. Also the qsort() crashing also depends gcc optimization level and data surrounding the data to be sorted. See my test program which I need to add some dummy variables to cause crashing if no optimization is used.

Regards,
Kelvin Lee
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binutils-2.15-bfd-elflink.c-sparc-sun-solaris2.7-bug.diff
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comp.sh
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test.c
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