[PATCH] D138869: [Docs][RFC] Add AMDGPU LLVM Extensions for Heterogeneous Debugging

[Paul Robinson via Phabricator via llvm-commits]

probinson added a comment.

> There are actually multiple locations at runtime; as you say, the compiler must guarantee they contain the same value at runtime, so the debug info consumer can read from any location. However, the debug info consumer must write to each location.

Right, that's how multiple-locations has to work. DWARF already allows this, it's a matter of persuading LLVM to understand multiple concurrent locations and emit the DWARF accordingly.  And getting the debuggers to DTRT.

> Instead of intrinsics acting as assignments to a mutable, singleton "variable location" they instead each act independently and must refer to a distinct "lifetime" (DILifetime). If in the old world there are 4 calls to dbg.value for a single variable, the new version would instead create 4 DILifetimes and replace each dbg.value with a pair of non-overlapping dbg.def+dbg.kill

...but I don't see how non-overlapping lifetimes gets us to multiple concurrent locations.


Repository:
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https://reviews.llvm.org/D138869