allow ccall library name to be non-constant #37123
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JeffBezanson
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Fantabulous! |
vtjnash
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It seems to work, though as you mention, still an awful hack. Not great that if the user makes a slight mistake, the ccall will just segfault.
julia> f(x) = (y = x + 1; ccall((:a, y), Cvoid, ()))
f (generic function with 1 method)
julia> f(1)
signal (11): Segmentation fault: 11
Is it possible to instead modify the new @ccall macro to let us do this without the syntactic ambiguity?
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Should also document that the user code may be called multiple times and it's undefined behavior if they return different values. |
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I added a check to replace some of the more likely crashes with a lowering error. AFAICT everything caught by this error used to segfault, so it should be ok. |
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vtjnash
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Sep 2, 2020
| be executed when the `ccall` itself is executed. However, it is assumed that the library | ||
| location does not change once it is determined, so the result of the call can be cached and | ||
| reused. Therefore, the number of times the expression executes is undefined, and returning | ||
| different values for multiple calls results in undefined behavior. |
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UB has a rather strong connotation, when this seems merely unspecified?
| gvname += f_name; | ||
| gvname += "_"; | ||
| gvname += std::to_string(globalUnique++); | ||
| Module *M = ctx.emission_context.shared_module(jl_LLVMContext); |
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Seems odd to explicitly share a private variable. This could go in jl_Module
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Yay! 🎉 |
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Fixes #36458.
This is a bit ugly since
ccallstill has non-standard IR with call expressions nested inside it. The nice part is that we can piggyback on the existing caching mechanism, and still do only one NULL pointer check.cc @staticfloat