[PATCH] D63083: [DebugInfo][Docs] Document that prologue/epilogue variable location changes are ignored

[Reid Kleckner via Phabricator via llvm-commits]

rnk added a comment.

My initial reaction to the commit message was to disagree with it. In optimized builds, the SDAG builder does a bunch of work to track variable locations of arguments starting at function entry before the prologue is through. I think you can say something more general, which is that variables whose location is described by dbg.declare only ever have one location. That memory location may not be valid during the prologue. This documents what happens when you try to mix dbg.declare with dbg.value. In that case, dbg.declare wins.


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https://reviews.llvm.org/D63083