[PATCH] D59272: [DebugInfo] Select debug intrinsic line-numbers more carefully when promoting dbg.declare

[Adrian Prantl via Phabricator via llvm-commits]

aprantl added a comment.

In D59272#1426904 <https://reviews.llvm.org/D59272#1426904>, @rnk wrote:

> This makes me nervous. The pair of the DIVariable and DILocation is used to uniquely identify the variable that a dbg.value applies to. In practice, inlining is usually what creates multiple instances of the same variable that get updated by dbg.values. You can see how the location is used in `DwarfDebug::collectVariableInfoFromMFTable`.


Last time I checked, the file, line number and column of a dbg.value was completely unused. To uniquely identify and inlined instance of a variable you need to the combination of inlinedAt field of the dbg.value's DILocation and the dbg.value's DILocalVariable.

> I see other places in the code that seem to assume that the scope of the location of a dbg.value will get the scope in which the variable is declared. Your change breaks that invariant. I think we could update such code to get the scope from the DIVariable, but maybe that would be wrong since it would lack inlining information.

Isn't the scope coming from the DILocalVariable though?


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