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varargs handling #364

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robdockins opened this issue Dec 5, 2019 · 0 comments · Fixed by #376
Closed

varargs handling #364

robdockins opened this issue Dec 5, 2019 · 0 comments · Fixed by #376
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llvm

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@robdockins
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Currently, crucible-llvm assumes that declaration and call sites for functions will agree about wether a function uses varargs or not. However, it appears that actually clang assumes that call sites need not know if a function is varargs or not; i.e. it assumes that the ABI of varargs functions is compatible with a standard non-varargs function of a particular signature.

This is compounded by the fact that C allows extern functions to be declared without an argument signature; this is interpreted by clang as a varargs function declaration, even though the actual function declaration may be a non-varargs function.

A somewhat more sophisticated approach to function argument matching is required to get this right.
@robdockins robdockins added the llvm label Dec 5, 2019
robdockins added a commit that referenced this issue Dec 10, 2019
@robdockins
TEMPORARY fix for varargs problem #364. This change causes functions …
117216c 
…that

are declared as varargs with no fixed argumenst to be considered functions
that take no arguments at all.  This treats the declaration `extern void foo()`
as though it was written `extern void foo(void)` instead.  This isn't actually
correct, but works around most of the problems that otherwise arise from
the SV-COMP benchmark set.
@robdockins robdockins mentioned this issue Dec 13, 2019
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Improved varargs handling GaloisInc/crucible
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@robdockins