[WIP] SILGen: Capture address-only lets with the in_guaranteed convention.
#17047
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Fixes rdar://problem/40828667. If we capture a `let` as inout_aliasable, then definite initialization mistakes capture of the `let` from a defer closure as an inappropriate inout use.
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slavapestov
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Jun 7, 2018
| @@ -1925,8 +1925,12 @@ void IRGenDebugInfoImpl::emitVariableDeclaration( | |||
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| // There are variables without storage, such as "struct { func foo() {} | |||
| // }". Emit them as constant 0. | |||
| if (isa<llvm::UndefValue>(Piece)) | |||
| Piece = llvm::ConstantInt::get(IGM.Int64Ty, 0); | |||
| if (isa<llvm::UndefValue>(Piece)) { | |||
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The existing behavior is broken for an undef of any type that isn't 64 bits in size. I should break it out into its own commit.
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Unfortunately this appears to cause a lot of downstream breakage in the optimizer I can't cleanly detangle. I might have to look for a more targeted fix for the DI regression. |
jckarter
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lets with the in_guaranteed convention.lets with the in_guaranteed convention.
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Jun 11, 2018
Sema enforces that closures can't modify the let properties of their captured contexts, but we consider the capture argument to be @inout_aliasable at the SIL level. Add an exception to our normal handling so that this use is considered read-only. Fixes rdar://problem/40828667. A more principled solution would be to treat let captures as @in_guaranteed (see swiftlang#17047), but that unfortunately leads to breakage elsewhere in the optimizer.
jckarter
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Jun 11, 2018
Sema enforces that closures can't modify the let properties of their captured contexts, but we consider the capture argument to be @inout_aliasable at the SIL level. Add an exception to our normal handling so that this use is considered read-only. Fixes rdar://problem/40828667. A more principled solution would be to treat let captures as @in_guaranteed (see swiftlang#17047), but that unfortunately leads to breakage elsewhere in the optimizer.
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Fixes rdar://problem/40828667. If we capture a
letas inout_aliasable, then definite initialization mistakes capture of theletfrom a defer closure as an inappropriate inout use.