[SIL] Added lexical flag to alloc_stack. #39291
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The new flag will be used to track whether a borrow scope corresponds to a source-level lexical scope. Here, the flag is just documented, added to the instruction, represented in textual and serialized SIL, and cloned.
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@swift-ci please test |
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@swift-ci please clean test linux platform |
nate-chandler
deleted the
lexical_lifetimes/alloc_stack/lexical_flag
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| @@ -3102,6 +3102,9 @@ The ``dynamic_lifetime`` attribute specifies that the initialization and | |||
| destruction of the stored value cannot be verified at compile time. | |||
| This is the case, e.g. for conditionally initialized objects. | |||
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| The optional ``lexical`` attribute specifies that the operand corresponds to a | |||
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alloc_stack does not have an operand.
How is lexical different to debug-var-attr? Doesn't alloc_stack correspond to a variable if debug-var-attr is present?
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As a general rule, debug information is not supposed to affect semantics. If we decide to reuse the same information for both purposes, then we need to specify in the class and API that it is not simply for debug information, audit, and verify the implementation.
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Still, I would prefer to not have redundant information in the instruction attributes.
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@adrian-prantl do you know in which cases debug-var-attr is present?
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debug-var-attr is present iff the alloc_stack is the only storage location for a (part of a) source variable. It is there regardless of whether -g is on or not. There can be alloc_stack instructions that don't have a debug-var-attr, in purely compiler-generated code (thunks, etc).
The new flag will be used to track whether a borrow scope corresponds to a source-level lexical scope. Here, the flag is just documented, added to the instruction, represented in textual and serialized SIL, and cloned.