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Simon Marlow authored
Summary: The main goal here is enable stack traces in GHCi. After this change, if you start GHCi like this: ghci -fexternal-interpreter -prof (which requires packages to be built for profiling, but not GHC itself) then the interpreter manages cost-centre stacks during execution and can produce a stack trace on request. Call locations are available for all interpreted code, and any compiled code that was built with the `-fprof-auto` familiy of flags. There are a couple of ways to get a stack trace: * `error`/`undefined` automatically get one attached * `Debug.Trace.traceStack` can be used anywhere, and prints the current stack Because the interpreter is running in a separate process, only the interpreted code is running in profiled mode and the compiler itself isn't slowed down by profiling. The GHCi debugger still doesn't work with -fexternal-interpreter, although this patch gets it a step closer. Most of the functionality of breakpoints is implemented, but the runtime value introspection is still not supported. Along the way I also did some refactoring and added type arguments to the various remote pointer types in `GHCi.RemotePtr`, so there's better type safety and documentation in the bridge code between GHC and ghc-iserv. Test Plan: validate Reviewers: bgamari, ezyang, austin, hvr, goldfire, erikd Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1747 GHC Trac Issues: #11047, #11100
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