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6a18491e03
configure.ac:
Run the C compiler to check if it actually targets x86-64.
Previously we assumed if $host is x86_64 then the C compiler will be
targeting x86-64, but that is not true if gcc -m32 or gcc -mx32 is
used.
Then, as before, if the C compiler targets x86 and dynamic linking
is enabled (except on Windows) and GCC is version 5+ then disable
selection of any grades that use gcc labels.
runtime/mercury_goto.h:
Report an error if the user tries to use non-local gotos with PIC
on x86 with GCC 5+.
README.x86:
Document the issue.
README.md:
Add reference to README.x86.
25 lines
1.0 KiB
Plaintext
25 lines
1.0 KiB
Plaintext
Due to improvements in GCC, the following combination is not supported:
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- GCC version 5 and above
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- x86
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- PIC (position-independent code), i.e. dynamic linking
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- low-level C grades using non-local gotos, i.e. asm_fast.*
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The configure script will not select asm_fast grades when the above combination
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is detected. If you try to use that combination by selecting an asm_fast grade
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manually, you will encounter compilation errors.
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We recommend using high-level C grades (hlc.*) on x86. If you require a
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low-level C grade, e.g. for debugging, then you can use a reg.* grade.
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If you must use an asm_fast grade, you will need to tell the C compiler not to
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generate position-independent code, and disable building of shared libraries.
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Alternatively, you could downgrade to gcc 4.9.
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Note that Windows is unaffected by this issue as Windows does not use PIC,
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and we do not yet support shared libraries (DLLs) on Windows anyway.
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Also note x86-64 is not affected by this issue, only x86.
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<https://bugs.mercurylang.org/view.php?id=453>
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